handbook for keck - ece.neu.edu filetable 1 signal interface connector ... (imaq) card 1408, one ni...
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Handbook for KECK
---- Control System
Version: 2.1.1
June 25, 2014
This work is contributed by Zhenhua Lai, Zetong Gu,
Stephen Karasek, James Mclean
Documented by Zetong Gu
Supervised by Charles A. DiMarzio
Handbook for KECK-----Scanning Control System
Contents
Figures and Tables .................................................................................................. 2
1 Overview .............................................................................................................. 4
2 Control System’s Layout ..................................................................................... 5
3 The Structures of control scanning system .......................................................... 7
4 Power Supply Board .......................................................................................... 10
5 Galvo Control Board .......................................................................................... 12
6 Polygon Control Board ...................................................................................... 15
7 Sensor and Filter ................................................................................................ 18
8 Cable connection in Scanning System ............................................................... 22
Figures and Tables
Figure 1 Layout of KECK control system ............................................................. 5
Figure 2 Scanning System Structure ...................................................................... 7
Figure 3 Photo of Power Supply Board ............................................................... 10
Figure 4 function illustration of power supply .................................................... 11
Handbook for KECK-----Scanning Control System
Figure 5 photo of galvo control board ................................................................. 12
Figure 6 photo of interface connector .................................................................. 13
Figure 7 Vsync signal (top) and Galvo control signal (bottom) .......................... 14
Figure 8 Photo of Polygon Control Board ........................................................... 15
Figure 9 illustration of Polygon Control Board ................................................... 16
Figure 10 Instruction of connecting signal cable to polygon ............................... 17
Figure 11 sensor cables connection ..................................................................... 18
Figure 12 illustration of sensor cables connection ............................................... 19
Figure 13 the principle of the filter ...................................................................... 19
Figure 14 the result before (yellow) and after (blue) filter .................................. 20
Figure 15 Hsync (square wave) and APD signals ................................................ 21
Table 1 signal interface connector ....................................................................... 12
Table 2 Digital Control for Pin 4 ......................................................................... 16
Table 3 Keck Cable Connections ......................................................................... 22
Handbook for KECK-----Scanning Control System
1 Overview
The Keck 3D fusion multi-modal microscope (3DFM) in the Optical Science
Laboratory (OSL) at Northeastern University was first built by Daniel J. Townsend in
2004. The 3DFM allows us to image samples with multiple modalities on the same
stage. The modalities on the 3DFM include: Brightfield Microscopy, Differential
Interference Contrast Microscopy (DIC), Epifluorescence Microscopy (EFM),
Confocal Reflectance Microscopy (CRM), Confocal Fluorescence Microscopy (CFM),
Multi-Photon Fluorescence Microscopy (MPFM), and Second Harmonic Generation
(SHG). An imaging spectrometer is integrated in the 3DFM for spectrum measurement.
The 3DFM underwent a major upgrade in the year 2013. This upgrade to 3DFM
2.0 was led by Zhenhua Lai and assisted by Zetong Gu, Stephen Karasek, and James
Mclean. The whole control system and part of the optics were redesigned. The
performance of the second generation 3DFM has been significantly improved after the
upgrade.
Handbook for KECK-----Scanning Control System
2 Control System’s Layout
The control system’s layout of the KECK system is demonstrated in Figure 1.
Figure 1 Layout of KECK control system
The KECK system consists of two computers: a 64 bit Windows 7 PC and a 32 bit
Windows XP PC., one Image Acquisition board (IMAQ) card 1408, one NI USB-6341
Data Acquisition board (DAQ), several NI USB-6008 Data Acquisition boards (DAQ)
and a branch of optical parts as well as a few cameras.
The Windows XP PC is used due to incompatibility issues between the image
acquisitions cards and the Windows 7 system. The Windows 7 computer controls the
motorized rack through RS 232 port, and the grating (SP2150, Princeton Instruments) ,
Handbook for KECK-----Scanning Control System
the NI USB-6341, Thorlabs camera as well as NI USB-6008 through USB.
The subsystem in the red rectangle is a 2-D scanning system which makes the laser
to scan in two dimensions. The Polygon and galvanometric mirror scanner (Galvo) are
responding for one dimension separately. The NI USB-6341 controls Polygon and
Galvo to let them worked together by sending the HSync, VSync, and PCLK. IMAQ
1048 receives the picture signals and sync signals.
Hsync, Vsync and Pclk are signals to control the acquisition processing. (For more
information about sync signal, please refer to NI-Tutorial-3020.pdf and
NI-Tutorial-4750.pdf in reference folder)
Handbook for KECK-----Scanning Control System
3 The Structures of control scanning system
Sensor
PCLK
Vsync
Control
Signal
Hsync
IMAQ1408
NI 6341
Polygon
Reference
Signal
Galvo
Filter
Galvo
Control
Board
Polygon
Control
Board
Power Supply Board
Figure 2 Scanning System Structure
NI 6341: The NI USB-6341 is a data acquisition device as well as a programmable
signal generator that contains 16 16-bit analog input channels, 2 16-bit analog
output channels, 24 digital I/O lines, and 4 32-bit counter/timers for pulse-width
modulation. The NI USB-6341 receives real-time input laser power signal from the
power meter in analog form, and then converts and sends the sync signals to the
Windows 7 PC. A 356.7 Hz square wave signal is generated by the NI USB-6341
for controlling of the polygon mirror scanner running at a speed of 200 RPS. The
polygon mirror scanner contains 32 facets, and therefore multiplies the scanning
speed to 6.4 kHz. The polygon mirror scanner sends a Start-of-Scan (SOS) Signal
at the beginning of each optical scan. For generation of the SOS signal, a red LED
Handbook for KECK-----Scanning Control System
is placed close to the polygon mirror. The reflected red light is detected by two
closely placed photodiodes. The SOS signal is the differential signal of the two
photodiodes. The SOS signal is then processed by a bandpass filter, and turned into
6.4 kHz square waves, which is served as triggers for the NI USB-6341 to generate
HSync, the signal that synchronizes each horizontal line of an image. The HSync
also serves as the trigger for NI USB-6341 to generate VSync, the signal that
synchronizes the acquisition of each image, pixel clock (PCLK), the signal that
synchronizes the acquisition of each pixel, and the control signal that controls the
galvanometric mirror scanner. Note that a pseudo-sawtooth is used in 3DFM 2.0,
which is different from the old 3DFM. The control signal of the galvanometric
mirror scanner will be discussed later.
IMAQ 1408: The NI IMAQ PCI 1408 is a 4-channel image acquisition module
that converts analog signals into 8-bit grayscale images. The NI IMAQ PCI-1408
is connected to the Windows XP PC through a PCI slot. The following detectors
are connected to the four acquisition channels of NI IMAQ PCI-1408: CFM PMT,
CRM APD, forward SHG PMT, and MPFM or backward SHG PMT. Since each
NI IMAQ PCI-1408 contains only one A-D converter, only one channel can be
running at a time. However, multiple modalities can be taken simultaneously by
utilizing multiple NI IMAQ PCI-1408s. The number of channels is limited by the
number of PCI slots in the computer, as well as the computer resources. An
alternate solution is running different channels alternatively. e.g. we can acquire
CRM and MPFM images alternatively. Since the image acquisition time is 0.1 s,
Handbook for KECK-----Scanning Control System
the interval between the two modes is 0.1s, which results in a two-modal
acquisition at a frame rate of 5 frame/s. The above solution is referred to as
pseudo-simultaneous mode.
Power Supply Board (Charper4):Provide the power to Polygon and Galvo.
Galvo Control Board (Charper5):Control the position, speed, etc. of the Galvo.
Polygon Control Board (Charper6):Control the speed of Polygon.
Sensor (Charper7):Detect the position of Polygon and generate Hsync through
the filter.
Filter (Charper7): Change the Hsync signal from analog to digital. In order to be
received by NI 6341.
Handbook for KECK-----Scanning Control System
4 Power Supply Board
This board is the power supply of the Polygon, Galvo, APD, and the main control
board. Figure 3 display the photo of power supply board. Figure 4 demonstrates the
function and volts for each pin.
Figure 3 Photo of Power Supply Board
The red rectangle is designed for old control board which comes into disuse.
However the pins can still work so that those 5 pins can be used as others function.
The green one is designed for Galvo mirror control board. The blue rectangle is the
power source for polygon while the yellow one is used for APD to acquire CRM
image.
Handbook for KECK-----Scanning Control System
POWER SUPPLY BOARD
Old Control Board
Galvo
NC
+1
5V
-1
5V
GN
D
NC
+15V
GND
-12V
+12V
+4.8V
Polygon
+2
4.5
V
GN
D
APD
+1
2V
GN
D
-1
2V
Figure 4 function illustration of power supply
Handbook for KECK-----Scanning Control System
5 Galvo Control Board
Figure 5 photo of galvo control board
The control signal interface is provided on connector J2 located on the baseboard.
System I/O including command input, position output, status feedback, and enable are
located on this connector.
In practice, we only use the pin1, 2 and 3. Connect the pin2 and pin3 together to the
Ground. A 8-pin cable connect the control board to NI USB-6341.
Table 1 signal interface connector
Handbook for KECK-----Scanning Control System
Figure 6 photo of interface connector
Handbook for KECK-----Scanning Control System
Figure 7 Vsync signal (top) and Galvo control signal (bottom)
(For more information about Galvo Control Board, please refer to “Galvo
controller.pdf” in reference folder)
Handbook for KECK-----Scanning Control System
6 Polygon Control Board
This board is the control board of polygon. A 356.7 Hz square wave signal is
generated by the NI USB-6341 for controlling of the polygon mirror scanner running
at a speed of 200 RPS. The polygon mirror scanner contains 32 facets, and therefore
multiplies the scanning speed to 6.4 kHz.
Figure 8 display the photo of polygon control board and Figure 9 demonstrates
the function for each pin.
Figure 8 Photo of Polygon Control Board
Handbook for KECK-----Scanning Control System
POLYGON CONTROL BOARD
Connect to Polygon
Power
Supply
Board
+2
4.5
V
GN
D
Pin1 Reference Frequency Input
Pin4 Enable
Figure 9 illustration of Polygon Control Board
In practice, two pins are used for control the polygon. Pin1 is the reference
Frequency input which enables us to control the speed of polygon, while Pin4 is the
enable pin. The control value is showed below:
Pin1:
Control the speed of the polygon. We may use square wave.
Pin4:
Table 2 Digital Control for Pin 4
Pin value function
0/GND Enable
Handbook for KECK-----Scanning Control System
1/5V Unable
Figure 10 Instruction of connecting signal cable to polygon
Handbook for KECK-----Scanning Control System
7 Sensor and Filter
The mainly function of this part is generate the Hsync from the Polygon. The
polygon has 32 faces, hence the Hsync signal has 32 periods when it rotates one circle.
The polygon mirror scanner sends a Start-of-Scan (SOS) Signal at the beginning of
each optical scan. For generation of the SOS signal, a red LED is placed close to the
polygon mirror. The reflected red light is detected by two closely placed photodiodes.
The SOS signal is the differential signal of the two photodiodes. The SOS signal is then
processed by a bandpass filter, and turned into 6.4 kHz square waves, which is served as
triggers for the NI USB-6341 to generate HSync, the signal that synchronizes each
horizontal line of an image.
Figure 11 sensor cables connection
Handbook for KECK-----Scanning Control System
Power
Supply
Connect to LED
+Vcc(3.2V-3.8V)
Photodiode Output 1
Photodiode Output 2
Photodiode Output 3
Figure 12 illustration of sensor cables connection
Output 1 and Output 2 is used for generate the Hync single. The filter will change
the Hsync signal from analog to digital and eliminate the noise.
The principle of this process shows below:
Photodiode Output 1
Photodiode Output 2
Photodiode Output 3
1k
Input_A
Input_B
A
B
A-B
TTL out
Figure 13 the principle of the filter
In practice, put output1 and output2 into CH1+ and CH1- of the filter. Use the Diff
mode in CH1. (CH1: Low pass 150K Hz. Input Gain:50, Output Gain:0). Put the output
of CH1 to CH2 input. (CH2: High pass 10 Hz. Input Gain:50, Output Gain:0). Put the
Handbook for KECK-----Scanning Control System
CH2 into NI 6341 for Hsync. The input gain can change according to the different
situation. Figure 14 demonstrate the single before and after the filter. Figure 15
display the Hsync single which is the same as the blue single in Figure.14. Also, the
APD single is showed on Figure 15 for future testing convenience.
Figure 14 the result before (yellow) and after (blue) filter
Handbook for KECK-----Scanning Control System
Figure 15 Hsync (square wave) and APD signals
Handbook for KECK-----Scanning Control System
8 Cable connection in Scanning System
The cable connection instruction showed here for future maintenance. Shielded
twisted pair cable is used here in order to eliminate the noise. All the ground as well
as mental case of instruments should be connected together.
Table 3 Keck Cable Connections
Device1 and Pin Device2 and Pin Type&Note
6341 pin15(AO 0) Galvo + pin1
Shielded Twisted Pair
6341 pin16(AO GND) Galvo – pin2
6341 pin31(AO 1) 1408 pin19(Vsync+)
Shielded Twisted Pair
6341 pin32(AO GND) 1408 pin6(Vsync-)
6341 pin89(P2.4) Polygon pin1 (REF)
Shielded Twisted Pair
6341 pin88(D GND) Ground
6341 pin73 (P1.0) Polygon LED in One Shielded Wire
6341 pin91(P2.5) 1408 pin18(Hsync+)
Shielded Twisted Pair
6341 pin90(D GND) 1408 pin5(Hsync-)
6341 pin95(P2.7) 1408 pin17(Pclk+)
Shielded Twisted Pair 6341 pin94(D GND) 1408 pin4(Pclk-)