imagerintense flowmaster piv

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LaVisionWe count on Photons

Product-Manual

Imager Intense & FlowMaster3

Item-Number(s): 1101024, 1101030


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Product-Manual for DaVis 7.2

LaVision GmbH, Anna-Vandenhoeck-Ring 19, D-37081 Göttingen

Produced by LaVision GmbH, Göttingen

Printed in Germany

Göttingen, June 1, 2010

Document name: 1003027_ImagerIntense&FlowMaster3_D72.pdf


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Contents

Contents

1 Safety Precautions 7

1.1 Laser Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

1.2 Seizures Warning . . . . . . . . . . . . . . . . . . . . . . . . . . 8

1.3 Camera / Image Intensifier Safety . . . . . . . . . . . . . . . . . 9

2 CCD cameras 11

2.1 Electronic imaging . . . . . . . . . . . . . . . . . . . . . . . . . 11

2.2 Micro lenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

2.3 Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

2.4 Frame Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

2.5 Dynamic Range . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

2.6 Spectral sensitivity . . . . . . . . . . . . . . . . . . . . . . . . . 17

2.7 Sources of noise . . . . . . . . . . . . . . . . . . . . . . . . . . . 172.8 Binning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

2.9 CCD recording modes . . . . . . . . . . . . . . . . . . . . . . . 19

2.9.1 Single frame . . . . . . . . . . . . . . . . . . . . . . . . . 19

2.9.2 Double frame . . . . . . . . . . . . . . . . . . . . . . . . 19

3 PC interface board 21

3.1 PC Interface Board . . . . . . . . . . . . . . . . . . . . . . . . . 21

3.2 Driver Installation . . . . . . . . . . . . . . . . . . . . . . . . . 21

3.2.1 Driver location . . . . . . . . . . . . . . . . . . . . . . . 21

3.2.2 Install the driver . . . . . . . . . . . . . . . . . . . . . . 22

3.2.3 Verify the driver installation . . . . . . . . . . . . . . . . 24

4 PTU 9 27

4.1 PTU 9 part numbers . . . . . . . . . . . . . . . . . . . . . . . . 27

4.2 PTU 9 versions . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

4.3 PTU 9 Sequencer I/O Specifications . . . . . . . . . . . . . . . 29

4.4 PTU 9 TTL I/O Lines . . . . . . . . . . . . . . . . . . . . . . . 29

4.5 PTU9 Board Layout . . . . . . . . . . . . . . . . . . . . . . . . 30

4.5.1 Internal connectors . . . . . . . . . . . . . . . . . . . . . 30

4.6 Driver Installation PTU (PCI) . . . . . . . . . . . . . . . . . . 31

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Contents

4.6.1 Driver location . . . . . . . . . . . . . . . . . . . . . . . 31

4.6.2 Uninstall the driver . . . . . . . . . . . . . . . . . . . . . 32



4.7 Driver Installation PTU (USB) . . . . . . . . . . . . . . . . . . 37

4.7.1 Driver location . . . . . . . . . . . . . . . . . . . . . . . 37

4.7.2 Uninstall the driver . . . . . . . . . . . . . . . . . . . . . 37



4.8 PTU Terminals . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

4.8.1 PTU Trigger Terminal . . . . . . . . . . . . . . . . . . . 44

4.8.2 PTU Trigger Adapter . . . . . . . . . . . . . . . . . . . 44

4.9 Status LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

4.10 General Description . . . . . . . . . . . . . . . . . . . . . . . . 46

4.10.1 Fully synchronized recording . . . . . . . . . . . . . . . 46

4.10.2 Flexible independent reference times (optional) . . . . . 47

4.10.3 Phase trigger . . . . . . . . . . . . . . . . . . . . . . . . 48

4.10.4 Multiple device control (optional) . . . . . . . . . . . . . 48

4.10.5 User defined trigger (optional) . . . . . . . . . . . . . . 49

4.10.6 Device delay control . . . . . . . . . . . . . . . . . . . . 51

4.10.7 Graphical Connector Interface (GCI) . . . . . . . . . . . 52

4.10.8 Frequency strategies (optional) . . . . . . . . . . . . . . 52

4.10.9 Software controlled TTL Lines (PIO) . . . . . . . . . . . 53

4.10.10 Time scan capability . . . . . . . . . . . . . . . . . . . . 54

4.10.11 Rotary Decoder and Phase Scan (optionally) . . . . . . 54

5 Imager Intense & FlowMaster3 59

5.1 Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

5.2 Lens Mount . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

5.3 Camera-to-Board Connections . . . . . . . . . . . . . . . . . . . 61

5.3.1 Coaxial Version (BNC) . . . . . . . . . . . . . . . . . . . 61

5.3.2 Fiber Optic Version (FOL) . . . . . . . . . . . . . . . . 61

5.3.3 Back Focal Length Adjustment . . . . . . . . . . . . . . 62

5.4 Functional Principle . . . . . . . . . . . . . . . . . . . . . . . . 62

5.5 Data Stream . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

5.6 Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

5.6.1 FM3S Standard Mode . . . . . . . . . . . . . . . . . . . 63

5.6.2 FM3S Double Shutter . . . . . . . . . . . . . . . . . . . 63

5.6.3 ImagerIntense Standard Mode . . . . . . . . . . . . . . . 64

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Contents

5.6.4 ImagerIntense Double Shutter . . . . . . . . . . . . . . . 65

5.7 Trigger Control . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

5.8 TrigIn plug on the PCI-Board . . . . . . . . . . . . . . . . . . . 66

5.9 Jack Plug Socket at the PCI-Board . . . . . . . . . . . . . . . . 67

5.10 LEDs at the PCI-Board . . . . . . . . . . . . . . . . . . . . . . 68

5.11 Servicing, Maintenance and Cleaning Instructions . . . . . . . . 69

5.11.1 Cleaning Method for the Optical Part . . . . . . . . . . 69

5.11.2 Cleaning Method for the FOL . . . . . . . . . . . . . . . 69

5.12 Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

5.13 System Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

5.14 Spectral Response . . . . . . . . . . . . . . . . . . . . . . . . . 72

5.15 Definitions and Measurement Conditions . . . . . . . . . . . . . 72

6 Imager Intense & FlowMaster3 Wiring 75

6.1 System Requirements . . . . . . . . . . . . . . . . . . . . . . . . 75

6.2 Installing the PC-Interface-Boards . . . . . . . . . . . . . . . . 75

6.3 Cabling and Connections . . . . . . . . . . . . . . . . . . . . . . 76

6.4 Powering Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

7 DaVis Hardware Setup 797.1 PTU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

7.1.1 Timing Setup . . . . . . . . . . . . . . . . . . . . . . . . 82

7.1.2 Line Configuration . . . . . . . . . . . . . . . . . . . . . 85

7.2 Camera 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

8 Device Settings 89

8.1 Recording . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

8.2 Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

8.2.1 Internal trigger . . . . . . . . . . . . . . . . . . . . . . . 918.2.2 External random trigger . . . . . . . . . . . . . . . . . . 93

8.2.3 External cyclic trigger . . . . . . . . . . . . . . . . . . . 94

8.2.4 Recording information . . . . . . . . . . . . . . . . . . . 96

8.2.5 Device Offset . . . . . . . . . . . . . . . . . . . . . . . . 97

8.3 Camera 1: Imager Intense / FlowMaster 3 . . . . . . . . . . . . 98

8.4 Scales and Overlays . . . . . . . . . . . . . . . . . . . . . . . . . 100

8.5 Active Image Correction . . . . . . . . . . . . . . . . . . . . . . 100

8.6 Image Transformation . . . . . . . . . . . . . . . . . . . . . . . 101

8.7 Intensity correction . . . . . . . . . . . . . . . . . . . . . . . . . 102

8.8 Image Area Data . . . . . . . . . . . . . . . . . . . . . . . . . . 103

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Contents

9 Acquisition Settings 105

9.1 Recording sequence . . . . . . . . . . . . . . . . . . . . . . . . . 105

9.2 Image Acquisition . . . . . . . . . . . . . . . . . . . . . . . . . . 107

9.2.1 CL commands . . . . . . . . . . . . . . . . . . . . . . . 109

10 Troubleshooting 111

10.1 Exposure time


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1 Safety Precautions

Before working with your LaVision system we recommend to read the following

safety precautions. Observing these instructions helps to avoid danger, to

reduce repair costs and downtimes and to increase the reliability and life of

your LaVision system.

1.1 Laser Safety

If a laser1 is integrated in your system it is important that every person work-

ing with it has fully read and understood these safety precautions and the

laser manual of the specific laser.

Lasers included in LaVision systems may belong to CLASS 4 laser devices,

which are capable of emitting levels of both visible and invisible radiation that

can cause damage to the eyes and skin. It is absolutely necessary that protec-

tive eyewear with a sufficiently high optical density is worn at any time when

operating the laser. The goggles must protect against all wavelengths that can

be emitted, including harmonics. See your Laser´s manual for further details.

Class 4 laser beams are by definition a safety and fire hazard. The use of

controls, adjustments or performance of procedures other than those specified

in the LaVision manual and laser manual may result in hazardous radiation

exposure.

AVOID EYE AND SKIN EXPOSURE TO DIRECT OR SCATTERED RA-

DIATION. FOLLOW THE INSTRUCTIONS YOU CAN FIND IN THE COR-

RESPONDING LASER MANUAL FOR PROPER INSTALLATION AND

SAFE OPERATION. USE PROTECTIVE EYE WEAR ALL THE TIME

WHEN OPERATING THE LASER.

Important instructions for safe laser handling:

• Before operating the laser contact your laser safety officer.

1In the following ‘laser’ means any kind of laser, in particular Nd:YAG- and dye laser as

well as Optical Parametric Oscillators at any wave-length and output-energy.

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• Read and understand the instruction manual of the particular type of

laser. Take special care with respect to laser emission, high voltage and

hazardous gases if in use.

• Declare a controlled access area for laser operation. Limit access to

trained people. Never operate the laser in a room where laser light can

escape through windows or doors. If possible, cover beam paths to avoid

obstacles getting into the beam.

• Provide adequate and proper laser safety-goggles to all persons present

who may be exposed to laser light. The selection of the goggles depends

on the energy and the wavelength of the laser beam as well as the oper-ation conditions. Check the Laser´s manual for a detailed description.

• While working with lasers do not wear reflective jewelry like watches and

rings, as these might cause accidental hazardous reflections.

• Avoid looking at the output beam, even diffuse reflections can be dan-

gerous.

• Operate the laser at the lowest beam intensity possible.

• Avoid blocking the output beam or reflections with any part of the body.Use beam dumps to avoid reflections from the target.

• Wear clothes and gloves which cover arms and hands to avoid skin dam-

age when handling in the optical path. Especially UV-radiation can cause

skin cancer.

1.2 Seizures Warning

WARNING: HEALTH HAZARD! STROBE LIGHTING COULD TRIGGER

SEIZURES

Some people (about 1 in 4000) may have seizures or blackouts triggered by

flashing lights or patterns. This may occur when viewing stroboscopic lights

or objects illuminated by such devices, even if a seizure has never been pre-

viously experienced. Anyone who has had a seizure, loss of awareness, or

other symptoms linked to an epileptic condition should consult a doctor before

operating systems which include flashing lights, strobe lights, or a pulsed or

modulated laser.

Stop operating the system immediately and consult a doctor if you have one

of the following symptoms:

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1.3 Camera / Image Intensifier Safety

• convulsions, eye or muscle twitching, loss of awareness, altered vision,

involuntary movements, disorientation

To reduce the likelyhood of a seizure when operating a system:

• Do not look directly at flashing light sources or on illuminated objects,

e.g. into a strobe light or a flashing LED panel.

• Operate the system in a well-lit room.

• Take frequent breaks in normally illuminated areas.

1.3 Camera / Image Intensifier Safety

The camera integrated in your system is based on a CCD (Charge Coupled

Device) or CMOS (Complementary Metal-Oxide Semiconductor) sensor with

high resolution and high sensitivity. Optionally your system is equipped with

a built-in or external image intensifier.

A LASER BEAM FOCUSED ON THE CHIP OR INTENSIFIER, EITHER

DIRECTLY OR BY REFLECTION, CAN CAUSE PERMANENT DAMAGE

TO THE CHIP OR INTENSIFIER. ANY LASER POWERFUL ENOUGH

TO PRODUCE LOCALIZED HEATING AT THE SURFACE OF THE CHIP

OR INTENSIFIER WILL CAUSE DAMAGE EVEN WHEN THE CAMERA

OR INTENSIFIER POWER IS OFF. A CHIP OR INTENSIFIER DAM-

AGED BY LASER LIGHT IS NOT COVERED BY ITS WARRANTY.

Important instructions for safe camera handling:

• Fully read and understand the instruction manual of the specific type of

camera.

• Put the protection cap on the camera lens whenever you do not take

images, especially when the laser beam is adjusted. Switching off the

camera / image intensifier does not protect the chip from damage by

laser light.

• Use full resolution of the sensor and always read out the complete chip

to have control of the intensity on all areas of the sensor.

• Make sure that no parts of the image are saturated, i.e. the inten-

sity is below maximum gray level (< 4095 counts for a 12 bit camera,


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• Start measurements with the lowest laser power and a small aperture of

the camera lens.

• Increase laser power step by step and check the intensity on the corre-

sponding image. Make sure that the sensor does not run into saturation.

• Bright parts in the experiment, like reflections on walls or big particles,

will limit the maximum laser power. Modify the optical arrangement of

your setup in order to remove bright reflections from the camera image.

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2 CCD cameras

The following chapter describes the fundamentals of digital cameras. Note

that not all cameras will support necessarily all the features described below.

Please cross check the detailed camera specifications in order to verify this.

2.1 Electronic imaging

The digital image recording is done via a CCD (charge coupled device) camera

which converts photons to electric charge based on the photoelectric effect.

The CCD sensor consists of many individual CCD’s that are arranged in a

rectangular array. Each pixel (picture elements) has a size in the order of

10× 10 µm. It is built on a semiconducting substrate with a p-layer (cathode)

and n-layer (anode), an insulating oxide layer and metal conductors on the

surface. A small voltage generates an electric field in the semiconductor. An

incident photon produces an electron-hole pair in the p-n-junction and the

electrons migrate towards the minimum of the electric field. Here the electrons

are accumulated during the exposure time. The number of electrons correspond

to the intensity of the incident light.

Figure 2.1: Metal oxide

semiconductor (MOS)

capacitor.

metalconductors

light (photon)

n-Layer

p-Layer photoelectric effect

approx. 10µm

electric field

oxidelayer

The pixels are arranged in an array. In order to read out the sensor the pixels

have to be addressed sequentially. The electrons are shifted vertically one

row at a time into a masked analog shift register on the lower edge of the

sensor’s optically active area. Each row in the analog shift register is then

clocked pixel by pixel through a charge-to-voltage converter. This converter

generates a voltage for each pixel that is proportional to the detected amount

of light at this sensor position. The stream of pixel voltages compose the

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2 CCD cameras

analog video signal. The transmission format is either sequential (so called

progressive scan) or interlaced. The progressive scan approach preserves the

image integrity while the interlaced approach will read out of all odd rows

before the even rows are addressed. Therefore the progressive scan approach

is more useful for imaging applications.

analog shift register

r o w

t r a n s

f e r

d i r

e c

t i o n

charge-to-voltage

converter

pixel

column

row

CCD sensor

Figure 2.2: Typical CCD sensor

geometry.

The shift register also has a series of electrodes (vertical, i.e. parallel to the

columns) which are used to transfer the charge packets, one element at a time,

into the charge-to-voltage converter according to fig. 2.3.

analog shift register

r o w

t r a n s

f e r

d i r e c t i o n

charge-to-voltageconverter

Figure 2.3: Readout sequence of CCD (only subset of pixels

shown!).

1. Exposure to light causes a pattern of charge (an electronic image) to

build up on the frame (or ’image area’) of the CCD-chip.

2. Charge in the frame is shifted vertically by one row, so that the bottom

row of charge moves into the shift register.

3. Charge in the shift register is moved horizontally by one pixel, so that

charge on the endmost pixel of the shift register is moved into the charge-

to-voltage converter.

4. The charge in the charge-to-voltage converter is passed to the analog-to-

digital converter and is read out.

5. Steps 3 and 4 are repeated until the shift register is emptied of charge.

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2.1 Electronic imaging

6. The frame is shifted vertically again, so that the next row of charge moves

down into the shift register. The process is repeated from Step 3 until

the whole frame is read out.

The full frame CCD is the simplest form of sensor in which incoming pho-

tons fall on the full light sensitive sensor array. A disadvantage of full frame

is charge smearing caused by light falling on the sensor whilst accumulated

charge signal is being transferred to the readout register. To avoid this, de-

vices sometimes utilize a mechanical shutter to cover the sensor during the

readout process. However, mechanical shutters have lifetime issues and are

relatively slow. Shutters are not needed however in spectrographic operationsor when a pulsed light source is used. Full frame CCD’s are typically the most

sensitive CCD’s available and can work efficiently in many different illumina-

tion situations.

The frame transfer CCD uses a two-part sensor in which one-half of the paral-

lel array is used as a storage region and is protected from light by a light-tight

mask. Incoming photons are allowed to fall on the uncovered portion of the

array and the accumulated charge is then rapidly shifted (in the order of mil-

liseconds) into the masked storage region for charge transfer to the serial output

register. While the signal is being integrated on the light-sensitive portion of

the sensor, the stored charge is read out. Frame transfer devices have typically

faster frame rates than full frames devices and have the advantage of a high

duty cycle i.e. the sensor is always collecting light. A disadvantage of this

architecture is the charge smearing during the transfer from the light-sensitive

to the masked regions of the CCD, although they are significantly better than

full frame devices. The frame transfer CCD has the sensitivity of the full frame

device but are typically more expensive due to the larger sensor size needed to

accommodate the frame storage region.

Interline transfer CCD sensors use additional vertical transfer registers that

are located between the active pixels. Charge that is accumulated in the ac-

tive pixel area can be rapidly transferred into this storage area. These storage

areas are arranged around the active pixel areas and are shielded against light

exposure. Typically the transfer time from optical active area to the storage

area is less that 1 µs. This fast charge dumping feature allows full electronic

shuttering on the sensor level. This e.g. can be used in the single-frame mode

to define the gate for the exposure time. The exposure time that is selected in

the software is usually programmed to an internal timer in the camera head.

The start of the exposure time can be determined by an external trigger signal

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2 CCD cameras

that is received by the camera and/or framegrabber board.

vertical shift registers (masked)

horizontal shift register

r o w

t r a n s

f e r

d i r

e c

t i o n

charge-to-voltage

converter

simplified pixel layout

maskedvertical

shift register

light sensitivearea

potentialbarrier

maskedstorage area

chargebarrier

Figure 2.4: Progressive scan interline transfer CCD layout.

Full-frame interline transfer CCD cameras use a storage area for each active

pixel according to fig. 2.4. Cameras based on these progressive scan sensors are

widely used in imaging applications as they removed all the artifacts associated

with interlaced video imaging. The electronic shutter can be applied to the

entire image. The fast transfer of the entire exposed image into the adjoining

storage sites within a few microseconds in conjunction with higher resolution

formats has extended the field of applications, e.g. into velocity measurement

techniques like PIV (Particle image velocimetry). The on-chip storage area

allows to capture two successive frames with a very short time delay. The

recording of a double-frame image is done in two steps. The optical sensitive

area of a CCD is exposed and the accumulated charge for each pixel is shifted

rapidly to the masked area (interframe time


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2.3 Resolution

sensor with microlensessensor without microlenses

incident light

glass

lightsensitive

area

Figure 2.5: Microlenses on a CCD sensor.

The compensation usually works best for parallel light illumination but for

some applications which need wide angle illumination (small f/# number) the

sensitivity is significantly compromised.

2.3 Resolution

Figure 2.6: Test sample displayed using different spatial resolu-

tion.

The resolution of a CCD is a function of the number of pixels and their size

relative to the projected image. CCD arrays of over 1000×1000 pixel (1 Mega-

pixel) are now commonplace in scientific grade cameras. The trend in cameras

is for the sensor size to decrease, and cameras with pixels as small as 4×4

microns are currently available in the consumer market. Before we consider

the most appropriate pixel size of a particular application it is important to

consider the relative size of projected image to the pixel size to obtain a satis-

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2 CCD cameras

factory reproduction of the image. From sampling theory, adequate resolution

of an object can only be achieved if at least two samples are made for each

resolvable unit, many users prefer three samples per resolvable unit to ensure

sufficient sampling. When the size of the image projected onto the CCD is

appropriately adjusted for proper sampling, a larger number of pixels in the

CCD increases the field-of-view, not the resolution.

2.4 Frame Rate

The frame rate of a camera is the fastest rate at which an image can contin-

uously recorded and read out. Frame rates are governed principally by thenumber of pixels and the pixel readout rate but other factors such as whether

a sub array is used, whether there is binning and at which vertical shift clock

speeds are also factors.

2.5 Dynamic Range

Figure 2.7: Test sample displayed using different dynamic range.

The dynamic range of a CCD is typically defined as the full-well capacity di-

vided by the camera noise and relates to the ability of a camera to record

simultaneously very low light signals alongside bright signals. The ratio is of-

ten expressed in A/D units required to digitize the signal.

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2.6 Spectral sensitivity

The full well capacity is the largest charge a pixel can hold before saturation

which results in degradation of the signal. When the charge in a pixel exceeds

the saturation level, the charge starts to fill adjacent pixels, a process known as

Blooming. The camera also starts to deviate from a linear response and hence

compromises the quantitative performance of the camera. Larger pixels have

lower spatial resolution but their greater well capacity offers higher dynamic

range which can be important for some applications.

2.6 Spectral sensitivity

Like photographic film each CCD sensor has a sensitivity and spectral response.

The sensitivity of a pixel is given by its quantum efficiency (QE). This is defined

as ratio between number of collected photoelectrons and the number of incident

photons per pixel. The QE depends basically on the pixel architecture, i.e.

dimensions, material and thickness of the optically sensitive area. The CCD

substrate material silicon has a frequency dependent band gab. Therefore

photons of different frequencies will penetrate the sensor differently. As a

result the quantum efficiency is wavelength dependent.

Q E /

%

wavelength / nm

Figure 2.8: Quantum efficiency curves for several CCD sensors.

2.7 Sources of noise

A CCD pixel is as any electric device a subject of electronic noise. The major

part of noise is generated thermally. Heat can also generate electron-hole pairs

in the semiconductor that can not be separated from those generated by the

photoelectric effect. Thermal effects will reduce the signal-to-noise ratio. This

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2 CCD cameras

is especially a problem for low signal intensities. The dark current noise is has

a value of approximately the square root of the dark current and doubles for

about every 6◦C increase in temperature. Therefore a lot of CCD sensors are

cooled for scientific imaging.

Figure 2.9: Dark current noise versus CCD temperature.

Another source of noise is the read noise which is generated by the charge-to-

voltage conversion during the readout procedure. The read noise increases with

the readout frequency. A careful optimization of the conversion electronics, a

reduced readout frequency and a cooling of the sensor will limit the read noise

to a few electrons per pixel.

2.8 Binning

Most CCD’s have the ability to clock multiple pixel charges in both the hori-

zontal and vertical direction into a single larger charge or ’super pixel’. This

super pixel represents the area of all the individual pixels contributing to the

charge. This is referred to as binning. Binning of 1×1 means that the indi-

vidual pixel is used as is. A binning of 2×2 means that an area of 4 adjacent

pixels have been combined into one larger pixel, and so on. In this instance

the sensitivity to light has been increased by 4 times (the four pixel contri-

butions), but the resolution of the image has been cut in half. The following

figure illustrates the effect.

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2.9 CCD recording modes

1x1 binning 2x2 binning 3x3 binning

9 m

9 m

18 m

18 m

27 m

27 m

Figure 2.10: Principle of pixel binning.

2.9 CCD recording modes

For the image recording CCD cameras can operate in different modes. Any

CCD camera can operate in a single frame mode.

2.9.1 Single frame

Figure 2.11: Recording in single

frame mode. Camera 1amera

The single frame mode allows to take a single exposure of the camera. In

this case the CCD Exposure time can be specified and the integration islimited by the electronic shutter. This mode can be used for the acquisition

of images at a given exposure time with cw-light or synchronized to a pulsed

light source. Depending on the selected options this single frame can record

the light of a single light pulse or of two light pulses.

2.9.2 Double frame

The double frame mode allows to take two separate exposures within a very

short time delay in different frames. These are the so called first and second

frames of a recording. The acquisition of the two frames usually needs to the

synchronized to a pulsed light source as the exposure times for both frames

are quite different. Using cw-light typically will generate different intensities

on both frames, i.e. the first frame shows very low and the second frame very

high intensity.

Figure 2.12: Recording in dou-ble frame mode.

Camera 1amera

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2 CCD cameras

The size of images in double frame mode is twice as big as in the single frame

mode and the maximum repetition rate in double frame mode is typically ≤

half that of the single frame mode.

The exposure times for first and second frame of a recording in a double frame

mode are extremely different. Usually the exposure time for the first frame

is in the range of some microseconds, while the time for the second exposure

is determined by the time needed for the read out of the first exposure what

goes with the camera repetition rate. Typically this is in the order of hundred

milliseconds. To get rid of the different background in a double exposure due

to the different exposure times a suitable bandpass filter is used in front of the

camera lens. This makes sure that only the light of a certain wavelength canreach the CCD and the unwanted background light is suppressed. So actually

the length of the laser flash determines the effective exposure time.

time [µs]

dt

pulse1 pulse2

exposure1st frame

exposure 2nd frame,readout 1st frame

frame transfer frame transfer

readout 2nd frame

EXPOSURE

LIGHT

Figure 2.13: Timing scheme for a double frame recording.

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3 PC interface board

The FlowMaster3 and Imager Intense cameras are using a 525 KP or 525

LP PC interface board. This chapter describes how to install the board in the

PC and how to install the corresponding driver.

3.1 PC Interface Board

Figure 3.1: Imager Intense koaxial PC interface board #1000138.

The PC interface board needs to be installed into a PCI slot (32bit) of your

PC. Make sure that it is properly plugged into the slot.

3.2 Driver Installation

The paragraph describes how to update the driver for the PC interface board

for a WinXP/Win2k operation system.

3.2.1 Driver location

If you have a DaVis version installed on your PC the driver can be found in the

’/DaVis/driver/PlugAndPlay/Imager Family’ directory. Otherwise the driver

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for the PC interface board can be found on your DaVis installation CD in the

’/drivers/Imager Family’ folder.

3.2.2 Install the driver

The Windows Hardware Wizard will recognize the new device the first time

you start the PC after you have installed interface board in the PC. Or it will

recognize that its driver is missing after you have uninstalled it and restarted

the PC.

In both cases the Found New Hardware Wizard will come up.

On the question ’Can Windows connect to Windows update to search for soft-

ware’ select ’No, not this time’.

On the question ’What do you want the wizard to do’ select ’Install from a list

or specific location (Advanced)’.

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Please choose your search and installation options. Select ’Don’t search. I will

select the driver to install’.

Select the device driver you want to install for this hardware. Click the ’Have

Disk. . . ’ button.

Copy manufacturer’s files from: ’∼/DaVis/driver/PlugAndPlay/Imager Fam-

ily’. Confirm with ’OK’.

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Please wait while the wizard installs the software.

Terminate the installation using the ’Finish’ button and restart the PC.

3.2.3 Verify the driver installation

To make sure that the driver has been installed properly and to get an infor-

mation on the exact driver version that has been installed please check the

diver information in the Windows Device Manager.

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Select Start > Settings > Control Panel > System > Hardware (tab) > Device

Manager (button).

Open LaVision Devices > Imager3 / Imager Intense / NanoStar / UltraSpeed-

Star. Use a right mouse click on this entry and select Properties.

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Select the Driver tab and make sure that you have the Driver Version 5.21.0.0.

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4 PTU 9

The completely software controlled Programmable Timing Unit (PTU) Ver-

sion 9 is an embedded system for generation of complex patterns of pulses

(sequences) with highly accurate timing on multiple outputs (up to 16 inde-

pendent channels) as used for the synchronization of LaVision ’s Intelligent

Imaging Systems. The PTU 9 is available as PCI board or as stand alone USB

device. The pulse width and the interval between pulses are programmed au-

tomatically by the DaVis software according to the application, the connected

hardware (laser, camera, etc.) and the user settings in the dialog boxes inside

DaVis .

The microprocessor controlled timing sequence can be started by an external

trigger or constantly generated by an internal frequency generator (e.g. at a

specified laser repetition rate).

The entire functionality is embedded into an FPGA (Field Programmable Gate

Array) which allows in system updates and upgrades.

4.1 PTU 9 part numbers

part number Description

1108055 basic PCI internal

1108057 standard PCI internal

1108058 standard USB external

1108059 standard with rotary decoder (N◦trigger) PCI internal

1108060 standard with rotary decoder (N◦trigger) USB external

1108061 advanced PCI internal

1108062 advanced USB external

1108070 reference times upgrade 1 to 4

1108071 reference times upgrade 1 to 8

1108063 HighSpeedStar trigger controller PCI internal

1108064 HighSpeedStar trigger controller USB external

1108066 Phantom CMOS trigger controller PCI internal

1108065 UltraSpeedStar trigger controller PCI internal

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4 PTU 9

4.2 PTU 9 versions

Version Features Typical applications

BASIC Accurate camera trigger Camera stand-alone or

support synchronized recording. StrainMaster systems

STANDARD Multiple device control PIV, LIF, SprayMaster,

synchronized recording shock tubes

reference times available.

ROTARY DECODER Includes PTU standard and EngineMaster, Turbines

(incl. STANDARD) hardware rotary decoder for

precise phase trigger by encoder

signal readout. This PTU-internal

device increases the accuracy of

phase angle based triggers in case

of uneven running machines like

automotive engines. It resolves

the engine’s cycle by an additional

tick line. It supports all common

encoders (up to 0.1◦

resolution) and speeds (up to

20,000 rpm).

ADVANCED Includes the hardware rotary EngineMaster,

(incl. ROTARY encoder for precise phase trigger fixed frequency laser

DECODER) by encoder signal readout and at arbitrary trigger

dynamic frequency strategy source

calculation.

In case of a recording speed

different than the trigger speed,

a frequency strategy is needed.

This situation typically happens,

when your measurement object

generates a trigger faster than

or different to the speed of thelaser system. The frequency strategy

calculates the laser system speed

to get optimized performance for

any trigger situation.

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4.3 PTU 9 Sequencer I/O Specifications

4.3 PTU 9 Sequencer I/O Specifications

PTU Version BASIC STANDARD ROTARY ADVANCED

DECODER

sequencer lines 2 16 16 16

output drivers TTL 50Ω TTL 50Ω TTL 50Ω TL 50Ω

time resolution 10 ns 10 ns 10 ns 10 ns

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4 PTU 9

4.5 PTU9 Board Layout

G 2

G 1

G 4

G 3

1

G 5

P T U

P O R T A

( C a m e r a )

( L a s e r )

P T U

P O R T B

T T L I / O

P O R T A

T T L I / O

P O R T B

Power

Trigger InputDSUB15 (m)

11

11

Status LED’s

1

1

G 8

J 2

J 3

Service Jumper

Service Connector

Status LED Connector

Figure 4.1: Layout of a PTU9 board.

On the PTU 9 you find four double pin-row connectors G1-G4. G1 and G2

are the PTU Ports A (Camera) and B (Laser). G3 and G4 are the Parallel

Input Output (PIO) ports. The G5 connector on the slot bracket is a Dsub15

connector for delivery of external trigger signals from the experiment. For the

connection of BNC cables check the corresponding adapter (see paragraphs

below). Beside the Dsub15 connector 5 status LED’s are located (see figure

4.2). These LED’s indicate the states of the sequencer (trigger, arming, run,

wait, stop). The G8 port is used to control the LEDs on the front panel of the

PC. These LEDs are also used to indicate the states of the sequencer.

DSub15(Trigger Input) T

r i g g e r

A r m i n g

R u n

W a i t

S t o p

Figure 4.2: PTU9 Slot Bracket.

4.5.1 Internal connectors

On board of the PTU9 are the headers G1-G4 and the LED header. The pin

assignment of these connectors is shown in tables 4.1 for G1-G4, 4.2 for the

LED Connector. The board has an additional power connector which may

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4.6 Driver Installation PTU (PCI)

(but does not need to) be connected to a ATX power supply (recommended,

if all 32 output lines are driving 50 Ω at a static high state).

Pin G1 G2 G3 G4

PTU PortA PTU PortB Pio PortA Pio PortB

1 Seq. OUT A0 Seq. OUT B0 IN 1 high IN3 high

2 GND GND IN 1 low IN3 low

3 Seq. OUT A1 Seq. OUT B1 IN 2 high IN4 high

4 GND GND IN 2 low IN4 low

5 Seq. OUT A2 Seq. OUT B2 Pio OUT A0 Pio OUT B0

6 GND GND GND GND


8 GND GND GND GND


10 GND GND GND GND


12 GND GND GND GND


14 GND GND GND GND


16 GND GND GND GND

17 Arming input not connected Pio OUT A6 Pio OUT B6

18 GND GND GND GND

19 Seq. Trigger input not connected Pio OUT A7 Pio OUT B7

20 GND GND GND GND

21 Decoder output Decoder output +5V +5V

22 GND GND GND GND

23 Seq. Trigger output Seq. Trigger output not connected DAC output1

24 GND GND GND SGND

25 not connected not connected not connected DAC output2

26 GND GND GND SGND

Table 4.1: Pin assignment of PTU9 headers G1-G4.


The paragraph describes how to install or update the driver for the PTU9 PCI

board for a WinXP/Win2k operating system.


If you have a DaVis version installed on your PC the driver can be found

in the ’/DaVis/driver/PlugAndPlay/PTU9’ directory. Otherwise the driver

for the PTU9 board can be found on your DaVis installation CD in the

’/drivers/PTU9’ folder.

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4 PTU 9

Pin Name

2 not connected

4 not connected

6 WAIT status

8 RUN status

10 STOP status

12 Arming pulse

14 Trigger pulse

others VCC (+5V)

Table 4.2: Pin assignment of PTU9 G8 (LED) header.

4.6.2 Uninstall the driver

Before you update the PTU9 driver you may need to uninstall the current

driver. You can do this using the Windows Device Manager:

Start > Settings > Control Panel > System > Hardware (tab) > Device Man-

ager (button) > LaVision devices > PTU9 (right mouse click) > Uninstall

(button).



you start the PC after you have installed the PTU9 interface board in the PC.

Or it will recognize that its driver is missing after you have uninstalled it and

restarted the PC.


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On the question ’What do you want the wizard to do’ select ’Install from a listor specific location (Advanced)’.



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4 PTU 9



Copy manufacturer’s files from: ’∼/DaVis/driver/PlugAndPlay/PTU9’. Con-

firm with ’OK’.


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To make sure that the driver has been installed properly and to get an infor-mation on the exact driver version that has been installed please check the



Manager (button).

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4 PTU 9

Open LaVision Devices > PTU9. Use a right mouse click on the PTU9 entry

and select Properties.

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4.7 Driver Installation PTU (USB)


The paragraph describes how to install or update the driver for the USB PTU9

for a WinXP/Win2k operation system.


If you have a DaVis version installed on your PC the driver can be found in

the ’/DaVis/driver/PlugAndPlay/USB’ directory. Otherwise the driver for the

PTU9 board can be found on your DaVis installation CD in the ’/drivers/USB’

folder.

4.7.2 Uninstall the driver

Before you update the PTU9 driver you may need to uninstall the current

driver. You can do this using the Windows Device Manager:

Start > Settings > Control Panel > System > Hardware (tab) > Device Man-

ager (button) > LaVision devices > PTU9 (right mouse click) > Uninstall

(button).



you start the PC after you have installed the PTU9 interface board in the PC.

Or it will recognize that its driver is missing after you have uninstalled it and

restarted the PC.




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4 PTU 9

On the question ’What do you want the wizard to do’ select ’Install from a list

or specific location (Advanced)’.



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Copy manufacturer’s files from: ’∼/DaVis/driver/PlugAndPlay/USB’. Con-

firm with ’OK’.


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4 PTU 9



To make sure that the driver has been installed properly and to get an infor-mation on the exact driver version that has been installed please check the



Manager (button).

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Open LaVision Devices > PTU9. Use a right mouse click on the PTU9 entry

and select Properties.

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4 PTU 9

4.8 PTU Terminals

P T U

V G A

Power Printer Port

COM1 COM2

Mouse

Keyboard

PTU Port A PTU Port B

Computer Rear Panel

TTL I/O

USB USB External

trigger

Figure 4.3: Computer rear panel with PTU connectors.

Two DSUB25 connectors and one DSUB15C are installed at the rear panel of

the computer delivered with your system (respectively at front and rear panel

of the external PTU). These connectors are labeled PTU Port A (Camera),

PTU Port B (Laser) and TTL I/O Port.

Camera

Laser

Trigger InputPort A

Port B

USBPower

External PTUPower

USB

Trigger

Arming

RunStop

L VA I SI ON

V

Figure 4.4: Front and rear panel of external USB PTU.

Figure 4.3 shows the position of the connectors and the PTU card at the rear

panel of the PC. Figure 4.4 shows the connector of the USB PTU.

You find the pin assignment for PTU Port A and PTU Port B in table 4.3 and

for the TTL I/O Port B in table 4.4.

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4.8 PTU Terminals

PTU Port A: Camera PTU Port B: Laser

Pin Function Function

1 A1 Camera1 B1 Flashlamp1 (L1)

2 A2 Camera2 B2 Q-Switch1 (Q1)

3 A3 Camera3 B3 Flashlamp2 (L2)

4 A4 Camera4 B4 Q-Switch2 (Q2)

5 A5 I/I B5 Flashlamp3 (L3)

6 A6 Laser shutter B6 Q-Switch3 (Q3)

7 A7 Camera shutter B7 Flashlamp4 (L4)8 A8 Sync B8 Q-Switch4 (Q4)

9 Arm Arming Input N.C. not connected

10 TrigIn Trigger Input N.C. not connected

11 Dec Decoder Output Dec Decoder Output

12 TrigOut Sequencer Trigger Out TrigOut Sequencer Trigger Out

13 N.C. not connected N.C. not connected

14-25 GND GND

Table 4.3: PTU Port A (Camera) and PTU Port B (Laser); Con-

nector type: DSub25.

TTL I/O Port A

Pin Function

1 IN3 optional input

2 GND

3 IN4 optional input

4 GND

5 OUT1 optional output




9-15 not connected

Table 4.4: TTL I/O Port A; Connector type: DSub15C.

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4 PTU 9

4.8.1 PTU Trigger Terminal

The pin assignment of the external connectors G5 (DSub15) can be seen in

tables 4.5.

Pin Name Pin Name Pin Name

1 Seq. Trigger 6 n.c. 11 GND

2 Seq. Arming 7 Pio IN1 High 12 GND

3 Start 8 Pio IN2 High 13 GND

4 Increment 9 GND 14 Pio IN1 Low

5 input (unused) 10 GND 15 Pio IN2 Low

Table 4.5: Pin assignment of PTU9 G5 (DSub15) port.

4.8.2 PTU Trigger Adapter

P T U

Pin1: To receive an optional input trigger for the acquisition of each image

Connect to PTUDSub15 (f)

Arming

Start

Increment

50

Trigger

Pin3: To receive an optional input trigger to start the recording of a sequence

50

Pin2: To receive an optional arming trigger to prepare the acquisition of each image

50

Pin4: To receive an optional incremental trigger from an encoder (N per cycle)

50

Figure 4.5: PTU9 trigger adapter (#1002685) .

To connect input trigger signals to the PTU you can use the PTU connector for

the PTU DSub15 port. The Trigger line can be used to trigger the acquisition

of each recording. In general we recommend to use a BNC T-connector and a

50 Ω termination resistor in order to clean the TTL signal from overshooting

peaks. The recommended pulse width for the external trigger signal is ≥ 1 µs,

the detection limit is a pulse width of 20 ns.

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4.9 Status LEDs

For the readout of a rotary encoder send the Master trigger (1 per revolution)

to the Start input, the Incremental trigger to the Increment input. For

settings of the corresponding parameters check paragraph 4.10.11.

4.9 Status LEDs

The status LEDs may be used to check whether the PTU is programmed

properly. The LEDs are located on the slot bracket (Fig. 4.2) of the internal

PTU and additionally on the front panel of the system PC (Fig. 4.6). If you

use an external PTU you find them on the front panel (Fig. 4.4).

Figure 4.6: PC front panel with status LEDs.

The LEDs indicate following status:

Stop: Is on while the sequencer is stopped.

Wait: Is on while the sequencer is started or armed and waits for a trigger

signal.

Trigger: Is blinking any time a (qualified) trigger is starting a sequence.

Run: Is on while a sequence is running.

Arming: Is on while soft arming is applied and blinking while the PTU

arming signal is received.

Usually a sequence is programmed as soon as DaVis is started and the PTU is

initialized, i.e. you will not observe blinking LEDs immediately after the PC

is started up or the external PTU is switched on.

The typical sequence of blinking LEDs is Trigger→Run→Wait while the

luminous period of the Run LED is typically longest, Wait indicates the end

of the sequence and Trigger the start of a sequence.

The blinking frequency of the Trigger LED should correspond to the value

that is selected for the Recording rate in DaVis . In normal operation the

Arming and Stop LEDs should be off.

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4 PTU 9

If the Wait LED is continuously on this could indicate that the PTU is waiting

for an external trigger that is not detected.

If the Stop LED is continuously on although the PTU has been initialized

at DaVis start this could indicate a hardware problem. In this case contact

LaVision service.

4.10 General Description

The functional block diagram in figure 4.7 illustrates the components of the

PTU9 board. The Interface/Control unit forms the base of the device. It

consists of an embedded micro controller unit and interface units for PCI or

USB. In this layer the entire communication between the PC software and the

device’s components is handled.

Figure 4.7: PTU9 Block Diagram

The main application running on the PTU board is the Sequencer. It has 16

outputs and two inputs (arming and trigger). The 16 outputs are divided into2 × 8 channels PTU Port A and PTU Port B. According to the desired

timing the appropriate sequence of these 16 outputs is programmed at the

beginning and end of any acquisition routine. A sequence may either be started

by an internally generated frequency or by an external trigger event. The

trigger event is either a single TTL edge, or optionally an internally decoded

rotary encoder signal.

4.10.1 Fully synchronized recording

The PTU 9 takes control over the synchronization of all devices connected to

it. This is not only to trigger the devices at the right time - which is done

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with 10 ns resolution - but to accomplish a synchronized data readout from

all sources. The images files recorded with DaVis contain images and scalar

values from very different types of sources, like cameras, Energy monitors, AD-

converters. It is the main task of the PTU 9 to guarantee, that all data in

a multiframe DaVis image come from the same trigger. This is more than a

trivial task, because cameras typically have an internal image memory stack of

model dependent size. When you simply send a trigger from your home-made

electronics to a bundle of different devices, you have to make sure, that all

data reported back to the software are from the same trigger pulse. The PTU

9 can maintain this feature without a loss of speed!

Example: Your system consists of one PIV camera, one LIF camera, oneAD-converter and one Energy monitor. It will be triggered from an external

source, e.g. a running engine. With the PTU 9 you will get a multiframe image

with two PIV frames, one LIF image frame, the full AD-converter data trace

over the entire engine’s cycle and the Energy monitor readout from the LIF

laser, all in a single DaVis image file plus a microsecond precise time stamp.

4.10.2 Flexible independent reference times (optional)

With LaVision ’s advanced Intelligent Imaging Systems you can simultaneously

combine different techniques for your measurement task. This could mean that

you have to measure at several independent times or phase angles at the same

event.

Example: You want to measure a flow field in an early stage of an automotive

fuel injection with stereo PIV and a bit later with LIF the resulting flame in

the same engine cycle. Both events are independent of each other, so your

PIV is somewhere just after the system trigger and the LIF must come later,

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4 PTU 9

but both are from the same main trigger. The PTU 9 supports this indepen-

dent timing behavior with the reference times feature. You can upgrade your

PTU according to your model to up to 8 independent events (reference times)

per trigger. The software allows you to easily combine your devices with the

reference times.

In the example above, you would go for three reference times. The 1st reference

time (T1) will be bound to the PIV camera and the PIV laser, while the

2nd reference time (T2) is for the LIF camera, the Energy monitor and the

LIF laser. The 3rd Reference Time (T3) allows to start the AD-converter

independently from the rest of the system.

4.10.3 Phase trigger

All PTU versions support a phase angle based trigger, when the trigger source

has a frequency (internal or external trigger). This means that you can set a

trigger not only on the time scale, like in milliseconds, but also as a phase, like

’trigger at 120◦ and 180◦’. For use with engines you can also define whether

360◦ is a full cycle or 720◦ for 4-stroke engines.

An optional fully integrated hardware rotary decoder allows to increase the

phase trigger precision in case of an uneven running machine, like engines

typically are.

4.10.4 Multiple device control (optional)

The PTU 9 takes care of all trigger issues in a LaVision Intelligent Imaging

System. The main purpose is to synchronize all system devices such as cameras

and lasers, but also other components like Energy monitors and AD-converters.

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The PTU 9 can control:

• up to six Cameras

• up to four Lasers

• Image Intensifiers

• AD-converter

• up to four Energy monitors

• Laser Shutter and/or Camera Shutter

• User Defined Trigger Lines

• and many more...

4.10.5 User defined trigger (optional)

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4 PTU 9

Additional to the trigger lines reserved for the laser system devices (e.g. camera

and laser trigger) you can add up to eight programmable lines (restricted by

the total number of lines, which is 16, including the device trigger lines), each

with the full precision of the PTU 9 (10 ns). Each user trigger line can be

bound to any reference time with an offset and a burst of up to five pulses.

A burst consists of up to five pulses which are defined with respect to the

reference time and an offset, freely programmable in its delay and length and

polarity.

In order to add a user defined trigger line go to the DaVis hardware setup and

highlight the Recording entry in the device tree. Use the Add button, select

the PTU User Trigger 1 and confirm with OK. You may enter a name for

the user trigger that is then also used in the Device settings of the Record-

ing dialog. Using the Inverted trigger line option you may determine the

polarity of the trigger signal (off is positive 0V→5V, on is negative 5V→0V).

Use the Initialize button and make sure that the user trigger has been added to

the device list. On the Timing Setup card you may select to which reference

time the user trigger signal should be phase logged to.

After the user trigger has been added to the hardware setup you may select

the parameter for the user trigger on the Device settings in the Recording

dialog.

On the User trigger card you can select when the user trigger should be

send. This can be either always or only during recording. And you can

select the frequency of the user trigger. This can be with trigger rate or

with recording rate. Find an example of the resulting sequence for the user

trigger below.

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trigger rate (18Hz)

camera trigger (9Hz)

laser trigger (9Hz)

user rigger modes:

start recording of 4 images

On the User trigger card you can select the delay with respect to the selected

reference time and up to five delay-gate pairs.

4.10.6 Device delay control

The trigger signal for each device connected to the PTU 9 can be fine tuned

in 10 ns steps in order to compensate for intrinsic delays or different cable

lengths.

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4 PTU 9

4.10.7 Graphical Connector Interface (GCI)

To simplify the connection of your devices, such as camera, laser, A/D-

converter, DaVis configures your connectors graphically. You attach a con-

nector to a PTU 9 port in hardware, and make the same connection graphi-

cally in DaVis . The PTU 9 automatically generates the proper signals at the

connector’s output lines.

4.10.8 Frequency strategies (optional)

Besides the typical standard trigger, which means that one trigger makes one

measurement, the PTU 9 supports also advanced trigger situations, where the

trigger rate and the measurement rate are different to each other. Also the

very challenging case of a variable external trigger during the measurement

using fixed frequency lasers is covered by the sophisticated dynamic frequency

strategy.

All calculations are done automatically. You do not have to take care aboutmaximum camera or laser rate, it’s the job of the PTU 9 to make this opti-

mization for you. Although the PTU 9 always gets the optimized recording

speed, you can also manually overwrite the settings. This is the case when you

want to force the laser system to run at a speed lower or different to the fastest

possible setting, e.g. in fuel injection test chambers.

• Static frequency strategy: The static frequency strategy optimizes

the recording speed of the laser system, when triggered by an arbitrary

constant rate.

Example 1: This could be an external trigger source, like an engine

running at constant speed, which is different to the laser system speed.

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The PTU 9 calculates the optimum trigger scheme in order to get the

highest possible recording rate.

Example 2: You run an automotive fuel injector test chamber and

measure with a fixed frequency laser. The laser needs 10 Hz trigger but

your injector should fire at 1 Hz. This is simply made just by entering

the target recording rate of 1 Hz, the rest is automatically done by the

PTU 9.

• Dynamic frequency strategy: This advanced feature allows to mea-

sure an accelerating or decelerating trigger with a fixed frequency laser(but cannot be combined with multiple reference times).

Example: An automotive engine running at continuously changing

speed (engine test cycle), but the laser system has a fixed frequency

laser like some large Nd:YAG lasers are (i.e. the flashlamp needs to be

triggered within a narrow range). The PTU 9 permanently optimizes the

laser system trigger during a running measurement in order to match the

varying engine speed to the fixed laser frequency for maximum recording

rate.

Frequency Strategy Features

none 1 ext-trig = 1recording trigger

trigger rate = recording rate

static ext-trig = arbitrary constant

different recording rate

dynamic dynamic ext-trig = variable

on-line frequency calculation for

fixed frequency laser

4.10.9 Software controlled TTL Lines (PIO)

Additionally to the high-accuracy sequencer lines, the PTU 9 provides up to 16

software controlled TTL output-lines and four input-lines from a PIO (parallel-

input-output). These lines are not affected by the triggering logic, but can be

set by commands written in DaVis ’ unique macro language.

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4 PTU 9

4.10.10 Time scan capability

The entire system can be triggered with respect to an external event or to an

additional trigger output. The time scanning module of the DaVis software

allows to record a certain number of images at different times automatically.

4.10.11 Rotary Decoder and Phase Scan (optionally)

Integrated rotary decoder for trigger generation at user defined rotation angle

(N-degree) on rotary machines (engines, turbines, etc.). Decodes cycle trigger

and increment signal (e.g. 1°) to generate the user selectable N◦ trigger.

In combination with DaVis the LaVision (laser) imaging system locks to a

certain phase (e.g. engine’s crank angle). The scanning module allows to

record a certain number of images for a preselected range of phase angles.

In experiments requiring an external trigger for image acquisition there is a

finite system delay between reception of the external trigger and the instant

at which the image is acquired. The source of this delay is the time required

to prime (pump) the laser. For solid state flash lamp pumped lasers such as

the Nd:YAG lasers that are commonly used for PIV the solid state tube must

be pumped by a flashlamp to generate a population inversion within the laser

tube. A short delay is then required before the Q-switch may be triggered to

release the light pulse that has built up in the laser cavity due to amplification

of stimulated emission. For Nd:YAG lasers the optimum delay for maximum

laser pulse energy is typically about 200µs.

Increasing the delay to about 400 µs can be used to reduce the pulse energy in

a progressive manner without altering the flashlamp voltage and is commonly

used as a means to control pulse energy.

This inherent initial delay is thus of the order of several hundred microseconds

depending on the type and size of laser integrated in the system. In many

periodic experiments such as ic-engines or turbines an encoder is often used

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to read the phase position of the machinery and to generate a periodic signal

as a time reference for making measurements. The output from the encoder

will typically provide a master trigger output or Master Gate, which is gener-

ated once every 360 or 720 degrees and an increment trigger output which is

generated many times for every revolution of the encoder.

N°-Trigger

Increment

Master

PTU9

Camera

Laser

Figure 4.8: Read-out of a rotary encoder.

Additional hardware is available to read the encoder signal(s) and to combine

these with the known initial delay to fire the lasers Q-switch and acquire images

at a precise and user specified phase angle or delay. This functionality is

referred to as an N◦-Trigger and is implemented on counter/timer hardware.

The N◦-Trigger accepts as input the Master and Incremental triggers from

the encoder and calculates an N◦-Trigger which then feeds directly to the

PTU (Programmable Timing Unit). The PTU in turn triggers the laser(s)

and camera(s) for an acquisition at a precise phase position accounting for the

initial delay described above.

Another feature of the N◦-Trigger function relates to the limited frequency

range that the lasers and camera can operate within. The camera will have a

maximum frame rate, which is fixed. The FlowMaster2 camera has a maxi-

mum frame rate of 15 double images/s while the FlowMaster3 has a maximum

frame rate of slightly more than 4 frames/s. The Nd:YAG lasers typically used

for PIV and other planar light techniques have a minimum and maximum fre-

quency they may operate at. Depending on the frequency of the encoder signal

it will not be possible for the camera(s) and laser(s) to fire every revolution at

the appropriate phase angle. The N◦-Trigger will rather calculate a laser and

camera frequency that is an appropriate sub-multiple of the encoder Master

Trigger and that lies within the performance range of the camera and laser.

In order to deliver the Master and Incremental trigger signals to the PTU plug

the PTU Trigger adapter (4.5) to the DSub15C terminal on the slot bracket of

the PTU9 board. Use BNC T-connectors and 50Ω terminators on the Trigger

and Incremental port. Connect the master trigger (1 per revolution) to the

Trigger port and the incremental trigger (N per revolution) to the Incre-

mental port.

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4 PTU 9

P T U

Pin1: Input for master trigger

Pin3: Not used

Connect to PTUDSub15 (f)

Arming

Start

Increment

50

Trigger

50

Pin2: Not used

Pin4: Input for increment trigger

Make sure that your PTU9 board is upgraded for N◦-Trigger option. If this is

not clear please contact the LaVision service.

Then select and initialize the N◦-Trigger on the PTU card in the DaVis hard-

ware setup.

Adjust following parameter according to the values given by the used encoder:

• 1 cycle: Indicates whether a single cycle of the master gate is 360◦ or

720◦ (depends on the used encoder).

• Resolution: Resolution of increment trigger in degrees (depends on the

used encoder).

• Offset: May be used to provides an offset to correct any misalignment

of the encoder relative to 0◦-position.

• Increment pulses per cycle: Calculated absolute number of incre-

mental trigger pulses per cycle.

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The functionality of the rotary encoder readout can be used from the Timing

card in the Devices dialog.

Open the Timing card and select Trigger source: External cyclic trig-

ger. The Trigger rate textbox should display the measured external cycle

frequency automatically (if the engine is running!). The unit of the external

cycle frequency can be either RPM or Hz. You may specify the Recording

rate. The system selects the nearest possible rate, please note that the Trigger

rate needs to be a multiple of the Recording rate. Specify the angle for image

acquisition in the Reference Time 1 [degree] textbox. If images are taken

using the take, grab or Start recording button each image is acquired atthe specified reference trigger position.

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4 PTU 9

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5 Imager Intense &

FlowMaster3

5.1 Precautions

For your own safety and in order to guarantee a safe operation of the camera,

please read carefully the following information prior to using the device.

• Never operate the camera at places where water or dust might penetrate.

• Place the camera on a sufficiently stable basis. Shocks like e.g. dropping

the camera onto the floor might cause serious damage to the device.Therefore exclusively the tripod attachment at the bottom side should

be used for mounting the camera.

• Always unplug the camera before cleaning it. Do not use cleaning liquids

or sprays. Instead use a dry, soft duster.

• Never insert any objects through the device’s slots. The applied voltage

inside the camera can cause short-circuits or electrical shocks.

• The slots in the camera housing (bottom and rear panel) are needed for

ventilation. In order to guarantee a proper operation and to prevent

overheating of the camera, these slots must always be kept free.

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5 Imager Intense & FlowMaster3

• Make sure that the connecting cable is in good condition and that the

link to the socket does not represent an obstacle.

• Detach the camera and contact the customer service in the following

cases:

– When cable or plug are damaged or worn-out.

– When water or other liquids have soaked into the device.

– When the device is not properly working although you followed all

instructions of the user’s manual.

– When the camera fell to the floor or the housing has been damaged.– When the device shows apparent deviations of normal operation.

5.2 Lens Mount

FlowMaster3 has a standard C-Mount or a M42 thread. An adapter to Nikon

F mount is already included.

The M42 version is optimized for light sensitive lenses and for connection to

Scheimpflug adapters or intensified relay optics. The standard lens mount

adapters are for Nikon F- Mount and C-Mount. Other adapters are availableon request.

M42 - C-mount adapter

FM3S

C-mount - F-mount adapter

F-mount camera lens

bandpass filter (M52)

The C-mount version (not supported anymore!) has a standard C-mount with

a back focal length of 17.52mm (distance between front edge of the C-Mount

and the CCD-sensor). Standard C-Mount lenses or other lenses with their

respective C-Mount adapter (e.g. photo camera lenses) can be used. The

maximum screw-in depth of a lens (or adapter) is 7.5mm. A deeper screw

could destroy the protective window of the camera.

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5.3 Camera-to-Board Connections

5.3 Camera-to-Board Connections

There is a serial data transfer between the camera and the PCI-Interface-

Board. Depending on the version, either a double-coaxial-cable or a fiber optic

cable (FOL) is used. The maximum length to use is approximately 10m for

the coaxial version or approximately 300m for the FOL. We supply 5m coaxial

or 10m FOL for every camera as standard length.

5.3.1 Coaxial Version (BNC)

Tx

POWER

Rx

Operating LED

TRIG IN

Tx

Rx

PCI-Interface-Board Camera

Figure 5.1: Coaxial camera-to-board connection.

Connect the double-coaxial-cable, which is included, with the two BNC-sockets

at the rear of the camera and the other end to the PCI-Interface-Board.

The cables must be crossed, i.e. Tx connected to Rx and Rx to Tx (Transmitter

to Receiver and vice versa). Wrong connecting is indicated by the red LED

(Display of Power Status). If other cables are used make sure they have an

impedance of 50Ω.

5.3.2 Fiber Optic Version (FOL)

POWER

Operating LED

TRIGIN

PCI-Interface-Board Camera

Figure 5.2: Fiber optical camera-to-board connection.

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Remove the black protection caps from the camera and the PCI-Interface-

Board. Remove the blue caps gently from both ends of the cable, as well. Plug

in the cable in both devices. Due to the plug shape the cables cannot be mixed

up. The plugs should slip in easily. Avoid forcing!

Caution: Avoid kinking or bending it over a sharp edge (e.g. stepping on it).

This will break the core and destroy the cable. Furthermore, avoid touching

the ends with bare fingers and replace the caps on the cable or camera / board

in order to protect the sensitive optical surfaces from dust.

5.3.3 Back Focal Length Adjustment

It might be necessary to adjust the back focal length.

C-Mount: Loosen the two small sunk allen screws at the knurled steel C-

Mount insert and rotate the insert (M 50× 0.5 thread) to the desired position.

Then secure the insert again by tightening the allen screws.

M42: The focal length is adjustable by the screw in depth of the adapter into

the camera front and can be locked by the counter screw.

5.4 Functional Principle

The images, captured by the camera head, will be transferred via a high speed

data transfer to the PCI-Board in the computer. The data will be saved in the

RAM of the computer where the operator can decide what to do with them.

With the DaVis software the camera can be controlled within the windows

environment and the images can be displayed on the monitor. The maxi-

mum memory space for the recorded images depends on the RAM size of your

computer. When starting the DaVis software, the program automatically rec-

ognizes the camera type.

5.5 Data Stream

The PCI-Board gets the 12bit data from the camera and transfers it via PCI-

Bus to a 16bit array (of the PC memory). The higher 4bits are set to zero.

The 16bit data are automatically converted in a 8bit array and accessed by

the graphic board. Depending on graphic board setup display on the monitor

is effected in 8, 24 or 32 bit. The camera which acquires always 12 bit images

resolves with 4096 (2E12) gray levels between black and white.

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5.6 Timing

5.6 Timing

The FlowMaster3(S) and ImagerIntense can be operated in the ‘Standard’ and

in the ‘Double Shutter’ mode.

5.6.1 FM3S Standard Mode

In the standard mode you can make single and multiple exposures with times

between 100ns and 1ms. The multiple exposure allows you to make maxi-

mum 10 pairs of delay and exposure, free programmable. The exposure must

be started by an internal or external trigger signal (one trigger pulse for the

complete multiple exposure). The digital 12 bit image will be read out from

the CCD immediately after the exposure. If you want to write a sequence of

exposures into the allocated memory buffer, you have to trigger each single

exposure and each multiple exposure block separately. Among the free pro-

grammable delay- and exposure times there are also system times (phase in,

intrinsic, CCD readout time) which have an influence to the camera timing.

Find the detailed camera timing in overview Fig. 5.3.

Phase in Intrinsic Delay 1

Exposure 1 Exp. 2

D 2 E 2 . .. ..Exposure 1 CCD Readout

Internal / external trigger

VGA 0 ... 40ns 0 ... 1ms0 ... 40ns 0 ... 1ms

100ns ... 1ms ......100ns ... 1ms

TimeSVGA

Depending of CCD, Binning, ROIDepending of cable

Intrinsic time1.64µs at 5m double coaxial1.66µs at 10m FOL1.85µs at 50m FOL *)

*) the delay at FOL is 4.7ns/m

CCD readout timeMaximum readout time with VGA: 33 msMaximum readout time with SVGA: 121,5 ms

Figure 5.3: Timing for FM3S standard mode.

5.6.2 FM3S Double Shutter

With the Double Shutter mode you can make two separate images with full

resolution (1280 × 1024 with SVGA sensor or 640 × 480 with VGA sensor).

The minimum time between the two images is 200ns. The integration time

for the 1st image is defined by the user by setting the length of the externally

given signal TRIG IN. The characteristic range is from 1µs to 10ms. The

integration time of the 2nd image is exclusively determined by the CCD

readout time for the 1st picture. This means, the user has no direct influence on

the duration of the second integration time and thus on the second exposure.

In case a shorter exposure time is required within this time window of the

second integration time, an external control should be used, e.g. by Laser,

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flash, mechanical shutter, . . . In that case the environment light should be

darkened.

Among the free programmable delay- and exposure times there are also sys-

tem times (phase in, intrinsic, dead time, CCD readout time) which have an

influence to the camera timing. Please find the detailed camera timing in the

following overview.

Phase in

imagerintense flowmaster piv

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