HolographyHolography

Gilbert CollinsGilbert Collins& &

Billy HatfieldBilly Hatfield

Physics 173Physics 173

What is a Hologram?What is a Hologram?-A Hologram is a three dimensional image-A Hologram is a three dimensional image

-While standard photography records color and intensity -While standard photography records color and intensity

information, a hologram encodes phase and intensity.information, a hologram encodes phase and intensity.

-A Holographic Image is created using a coherent light source to -A Holographic Image is created using a coherent light source to

create an interference pattern on a film or plate. create an interference pattern on a film or plate.

-When reconstructed, an observer can view a virtual image beyond -When reconstructed, an observer can view a virtual image beyond

the film that contains all possible perspectives of the object that the film that contains all possible perspectives of the object that

available according to the placement of the film.available according to the placement of the film.

Basic EquipmentBasic Equipment-Basic Holograms require just a few basic components:-Basic Holograms require just a few basic components:

••Light Source:Light Source: The light source generally a laser, which provides The light source generally a laser, which provides

monochromatic and coherent light. Different colors of lasers can monochromatic and coherent light. Different colors of lasers can

be used according to the film. be used according to the film.

••Spatial Filter:Spatial Filter: This is a combination of an objective lens and a This is a combination of an objective lens and a

pinhole. The light is focused into a pinpoint by the objective and pinhole. The light is focused into a pinpoint by the objective and

then passes through the pinhole. This creates modes.then passes through the pinhole. This creates modes.

••Aperture:Aperture: The aperture is closed or opened The aperture is closed or opened

accordingly to select the central mode, which accordingly to select the central mode, which

is the bright area in the center the pattern is the bright area in the center the pattern

created by the spatial filter. created by the spatial filter.

--Film:Film: (we’ll get there) (we’ll get there)

Types of HologramsTypes of Holograms-Transmission Holograms:-Transmission Holograms: Use two beams to create the Use two beams to create the

interference pattern recorded on the film.interference pattern recorded on the film.

••A beam splitter divides the laser beam into two parts. One A beam splitter divides the laser beam into two parts. One

becomes the reference beam and the other, the object beam.becomes the reference beam and the other, the object beam.

••The reference beam needs only go to the film. Generally, it is The reference beam needs only go to the film. Generally, it is

suggested that the reference beam intensity be around 3:1 or 4:1 suggested that the reference beam intensity be around 3:1 or 4:1

so use of an ND filter may be necessary. so use of an ND filter may be necessary.

••The object beam passes reflects off of the object before hitting the The object beam passes reflects off of the object before hitting the

film.film.

-Reflection Holograms:-Reflection Holograms: Place the film between the light source and Place the film between the light source and

the object, thus effectively creating two light sources, and an the object, thus effectively creating two light sources, and an

interference pattern.interference pattern.

Advantages/DisadvantagesAdvantages/Disadvantages-Transmission Holograms:-Transmission Holograms: They take up more space, require more They take up more space, require more

equipment, and require more adjustments and fine tuning to equipment, and require more adjustments and fine tuning to

acquire a good hologram. However, the freedom to adjust many acquire a good hologram. However, the freedom to adjust many

more parameters in a transmission hologram makes them a more more parameters in a transmission hologram makes them a more

powerful tool.powerful tool.

-Reflection Holograms:-Reflection Holograms: These are much simpler to create, and These are much simpler to create, and

require little setup and equipment. They are limited in their ability require little setup and equipment. They are limited in their ability

to change relative intensities, and require transparent film. Plates to change relative intensities, and require transparent film. Plates

will not work for reflection holograms. will not work for reflection holograms.

FilmFilm-Holographic film, like photographic film uses a chemical emulsion-Holographic film, like photographic film uses a chemical emulsion

to capture light information. to capture light information.

-There are a variety of holographic films for difference colors of -There are a variety of holographic films for difference colors of

laser light. laser light.

-The particular film used in our experiments is Slavich PFG-01, -The particular film used in our experiments is Slavich PFG-01,

which is red light sensitive. which is red light sensitive.

-Emulsion undergoes a chemical change when exposed to light, -Emulsion undergoes a chemical change when exposed to light,

which then is exploited by the developer and fixer. which then is exploited by the developer and fixer.

DevelopingDeveloping-Basics:-Basics: Film developing is a process that takes exposed film Film developing is a process that takes exposed film

through a set of chemical baths. In virtually all films, there is a through a set of chemical baths. In virtually all films, there is a

developer, a stop bath, a fixer, and a rinse. developer, a stop bath, a fixer, and a rinse.

••The developer causes a reaction that transforms exposed emulsion on the The developer causes a reaction that transforms exposed emulsion on the

film. film.

••The stop bath can be a water or chemical rinse that stops the developer. The stop bath can be a water or chemical rinse that stops the developer.

••Fixer removes the remainder of the unexposed emulsion on the film.Fixer removes the remainder of the unexposed emulsion on the film.

••A final rinse then removes all chemicals from the filmA final rinse then removes all chemicals from the film

••An agent such as PhotoFlo can then be used to enhance drying and An agent such as PhotoFlo can then be used to enhance drying and

decrease spotting on the film.decrease spotting on the film.

-Photographers Formulary JD-2:-Photographers Formulary JD-2: This particular developer works This particular developer works with film used for red-laser holography. It has a two-part with film used for red-laser holography. It has a two-part developer, and a bleach in place of fixer. The stop and final rinses developer, and a bleach in place of fixer. The stop and final rinses are both water.are both water.

Setup: TransmissionSetup: Transmission

Laser (635nm)

SpatialFilter (10x)

Pinhole (15µm)

Object

Holographic Film

Aperture

Silvered Mirror/ Beam Splitter

Nd1 Filter

This is a basic transmission hologram setup similar to the one we This is a basic transmission hologram setup similar to the one we

used in lab. used in lab.

-To minimize the effects of vibrations-To minimize the effects of vibrations

through the floor, we placed 4 raquetballsthrough the floor, we placed 4 raquetballs

under the optical platform to createunder the optical platform to create

a suspension system.a suspension system.

Observer

Laser (635nm)

Developed Film

Virtual Image

Image ReconstructionImage Reconstruction

Laser (635nm)

Developed Film

Virtual Image

Converging Lens

Screen

Image Reconstruction (Pt.II)Image Reconstruction (Pt.II)

Another Type of Hologram...Another Type of Hologram...

Cylindrical HologramsCylindrical Holograms-A Cylindrical hologram uses diverging lenses after the aperture to -A Cylindrical hologram uses diverging lenses after the aperture to create a rapidly diverging beam. Film is placed in the path of this create a rapidly diverging beam. Film is placed in the path of this beam in a cylindrical shape with the target object in the center of beam in a cylindrical shape with the target object in the center of this cylinder. The diverging beam hitting the film essentially this cylinder. The diverging beam hitting the film essentially creates a reference creates a reference

beam while the light beam while the light

hitting the object hitting the object

reflects onto the film reflects onto the film

creating the equivalent creating the equivalent

of the object beam.of the object beam.

-This gives you a 360°-This gives you a 360°

view of the object.view of the object.

Laser (635nm)

SpatialFilter (10x)

Pinhole (15µm)

Aperture

-50mm Lenses

Holographic Film

Object

Cylindrical SetupCylindrical Setup-We used cylinders made of cut-out Nalgene bottles or PVC pipe -We used cylinders made of cut-out Nalgene bottles or PVC pipe

with diameters 3.5”, 4.5” and 8”. with diameters 3.5”, 4.5” and 8”.

-The insides of the cylinders were either painted or covered in -The insides of the cylinders were either painted or covered in

black paper.black paper.

Results

- First Setup

- Exposure times: 3 – 90 seconds

- Different Objects

Results

- Cylindrical Setup

- Exposure times: 60 – 360 seconds

- Various Diameters

- Different Objects

- Different Film

Difficulties

- Hard to establish “controls”

- Very powerful laser needed for

projecting large holograms

Animation Attempts

Goal: To create a multiple frame holographic animation

Strategy: Expose parts of a strip of holographic film like

frames of a movie

Phase 3: Profit!