The procedures described in the sections Setting up, and
Exposure/Development are adaptations from methods taught by Dr.Mac Rugheimer of
Montana State University to countless students, teachers, and amateur holographers in
his "no prerequisites" holography class, his hologram exhibits, and numerous
presentations to K-12 students and teachers. He is a pioneer of amateur
holography.
Introduction:
This page will provide you with a clear idea of what holography is by showing you how it can done simply with a minimum of resources. If you are only interested in getting acquainted with holography, click WHAT IS HOLOGRAPHY in the menu below. Also, go to RELATED LINKS to visit some very interesting commercial holography sites. If you are interested in MAKING holograms, you will find here a very simple, inexpensive, and complete procedure for making very nice holograms. ENJOY the tour!
IMPORTANT UPDATES (After 2000):
1. Holographic films and plates available
Most of the presentation that follows was prepared when amateur holography
was based almost exclusively on AGFA 8E75 film and plates.
Since the fall of 1997, AGFA abandoned its holography product line. The holographic plate processing described below is based on my experience with AGFA material.
The Russian company
Slavich has come up with AGFA equivalents,
plates and film. Information on the complete Slavich line of materials
can be found at the Slavich site
or at the site of their main distributor
Geola. Geola provides detailed information for processing Slavich
recording materials.
The Slavich plates can be developed using developers recommended by the manufacturer or the ones formerly used with AGFA 8E75 such as Integraf's JD-3.
Slavich distributors in the United States incude:
Another important recent development in amateur holography is the use of inexpensive laser diodes in the place of He-Ne gas lasers to make holograms. The links below deal with this important development:
The Integraf Holography site
Integraf Laser Pointer Holography Note--Integraf is an important source of film, plates, developing chemicals, and holography kits.
Frank DeFreitas, Alan Rhody, and Steve Michael's
Shoebox Hoolography book ($16.95)
The original contents that follow, are still useful in understanding the basic procedures. Changing to a different type of film/plate, and from a gas laser to a diode laser involves minor adjustment in procedure.
It is a light wave interference pattern recorded on photographic film (or other
suitable surface) that can produce a 3-dimensional image when illuminated properly.
How is a hologram made?
A laser beam is split into two beams: {see diagram above}
The reference beam is spread by a lens or curved mirror and aimed directly
at the film plate
The object beam is spread and aimed at the object. The object reflects some
of the light on the holographic film-plate. The two beams interact forming an
interference pattern on the film. This is the hologram. Laser light is needed
because it is made of coherent waves (of same wavelength and phase). The principle of
holography was discovered in Britain by Dennis Gabor in 1948. He was awarded the
Nobel price for this discovery in the early 70's.
How is a hologram viewed?
When the hologram is illuminated from the original direction of the reference
beam, a 3-dimensional image of the object appears where the object was
originally. Some holograms must be viewed with laser or monochromatic (single
color) light, and others with white light.
What are the main types of holograms?
Transmission Holograms: Viewable with laser light. They are made with both
beams approaching the film from the SAME side.
Reflection (White Light) Holograms: Viewable with white light from a
suitable source such as spotlight, flashlight, the sun, etc. They are made with
the two beams approaching the holographic film from OPPOSITE sides.
Multiple channel holograms: Two or more images are visible from different
angles. There are different types of multiple channel holograms:
Simple ones with 2, 3, or a few images each viewed from a different angle.
Multiplex: A large number of "flat" pictures of a subject viewed from different
angles are combined into a single, 3-dimensional image of the object. A COMPOSED
hologram.
Rainbow holograms: The same image appears in a different color when viewed from
different angles.
Real Image Holograms (H-2's)
These are usually reflection holograms made from a transmission original (H-1). The
image dramatically projects IN FRONT OF THE PLATE toward the viewer. Most
holograms in holography museums are of this type. The procedure for making them is
quite elaborate and demands precise control of angles.
Mass-Produced Holograms
Embossed--Made by stamping on foiled backed mylar film using a metal master (most
common method).
Polymer--Made from light sensitive plastic. The Polaroid Corporation mass
produces holograms by this method.
Dichromates--Very vivid holograms on jewelry, watches, etc. They are recorded on
a light sensitive coating of gel that contains dichromate.
What are some applications of holography?
Holographic Art--Holography museums, advertising, postage stamps, jewelry,
etc.
Security from Forgery--Credit cards, tickets, etc.
Optical Devices--Holographic lenses, diffraction gratings, etc.These are
holograms in which the "object" is a mirror or a lens.A flat mirror as an object
produces a diffraction grating. A lensor a concave mirror as the object produce a
hologram that behaves LIKE A LENS! These HOLOGRAPHIC LENSES are lighter than
traditional lenses and mirrors and they can be designed to perform more specialized
functions such as making the panel instruments of a car visible in the windshield
for enhanced safety.
Holographic Interferometry--A very precise technique for measuring
changes in the dimensions of an object. Useful in industrial stress analysis,
quality controll, etc.
Pattern Recognition--Using electro-optical devices with computers to
interpret what is "seen" by a machine. Peace-time and military application of lasers
and holographic optical devices.
Medical Applications--Combining CAT scans into a 3-dimensional image, A
multiplex. Ultraound holography, etc.
Other--Holographic computer memory storage, holographic microscopy,
holographic radar, etc.
NOTE: This list does not include a sand-table which is cumbersome to
construct. For the simplest type of holography, single-beam reflection
type, a sturdy table or bench will do fine.
Laser Hazards
(I) A laser power supply is typically 2500 volts or more. If you
do your own wiring for an EXTERNAL power supply ordinary insulation is not
adequate. A qualified person must do it. Better yet, buy a self contained
laser or one with cable to the power supply included. (II). The laser beam
is an EYE HAZARD if one looks directly into it or a reflection of it from
a shiny object. After the beam is spread the danger is diminished
Lasers, accessories, and recording material
A helium-neon laser, 1-10 milliwatt (the higher the better)
A lens or concave mirror (10X to 20X / FL15 to 20mm)
A small object (model). Pewter figurines work well
Holographic film or plate: Agfa 8E75 is the amateur's choice(2.5in
x 2.5in glass plates would be best for a beginner. Film is less expensive
but more difficult to use. It must be clamped between glass plates
to keep it flat)
A sturdy table and sturdy bases and mounts for the laser, the optical
components, the model, and the holographic plate. Concrete blocks
make good bases. Lenses and mirrors should be mounted on rods or clamps
which, in turn, are mounted on short ring stands with a triangular bases.
Other mounts can be used as long as they are firm. [Diagram 4]
A room WITHOUT too much air movement or too much ventilation noise
or other kinds of vibration, that can be darkened. It should have a
uniform stable temperature.
One or more GREEN safe-lights 25 watts or less. They should not shine
directly onto the light sensitive surface.
Chemical Hazards
MOST CHEMICALS LISTED HERE ARE EITHER TOXIC OR HAZARDOUS TO EYES
AND SKIN. THE SOLUTIONS SHOULD BE MADE BY {OR UNDER THE SUPERVISION
OF} A PERSON EXPERIENCED IN THE USE OF HAZARDOUS CHEMICALS
Developing and bleaching solutions:
DEVELOPER (Discarded after using once)
Solution A: Pyrogallol 10.0 grams/Liter
Solution B: Sodium carbonate 60 g/L
Solutions A and B are mixed at equal volumes just before development.
ALTERNATE DEVELOPER (Reusable for one day)*
Solution A: 20 grams catechol, 10 grams ascorbic acid,
10 grams sodium sulfite, and 75 grams urea in one liter
of distilled water.
Solution B: 60 g sodium carbonate per liter
Solutions A and B are mixed at equal volumes just before development.
*A newer developer named "JD-3" is available from The Photographers'
formulary.
See SOURCES of materials. It is reported to be less hazardous.
Bleach (RE-USABLE)
4.0 g. potassium dichromate and 8 mL sulfuric acid per
liter
Photo-flow solution to avoid spots
Darkroom utensils
*3, 5in x 7in darkroom trays any color (White preferred)
*Disposable plastic gloves (cafeteria type)
*Small darkroom tongs (plastic or stainless steel)
*Green safe-lights (NOT red or orange)
A hair drier.
Should be used with caution to dry the hologram without scorching
it.
This is the easiest type of holography for amateurs. In its simplest
form, it requires only a laser, a lens, a holographic plate, and some
darkroom supplies. A sturdy table and firm supports for the laser, the
lens, the holographic model and the film or plate are necessary.
Freedom from vibrations within millionths of a centimeter must be assured.
Air currents, ventilation noises, changes in temperature (that causes
movement), walking, making any contact with the table during exposure,
guarantee failure. The greater the number of optical components (beam
splitters, mirrors etc.), the greater the destructive effect of vibrations.
Diagram 2
NOTE: This "single-beam" set-up actually generates a second beam as
some of the light going to the object through the plate reflects back
to the plate. The original and the reflected beams form an interference
pattern on the holographic plate which is recorded to produce a hologram:
Diagram 3
It is desirable for the plate to make contact with the object so that
if there is any movement they will move together. In that case, there
is no motion of one beam relative to the other. This is the next best
thing to having no motion at all.
The assembly on the previous page is the simplest but it is difficult
to align, it requires a very long table or two tables, and the angle at
which the laser-beam strikes the plate-object combination cannot be controlled.
also using a lens without a spatial filter produces a "dirty" beam--full
of interference patterns because of dust particles. Using a front-surface
coated concave mirror with a focal length of 15 to 25 mm and a flat mirror
(also front-coated) alleviates these problems.
Diagram 4
The above assembly is very compact and it provides complete control
of the angle at which the laser beam strikes the holographic plate and
the object. This is important because it ultimately determines the angle
at which the finished hologram must be illuminated by a spotlight (or
a flashlight) for comfortable viewing.
The holographic set-up is seen as shown in the diagrams. Beam alignments
and spread are done in green light. The scene is composed with the object
and a discarded holographic plate (or a glass plate of similar size)
so that everything is seated firmly without teeter-tottering. A small
white card is used to trace the path of the beam. The beam diameter
at the plate should be large enough to cover the plate.
Now the beam is blocked, all lights off except the green safe-light.
The bad plate is replaced carefully with a good unused holographic plate.
The emulsion (sticky) side is facing the object. Feel the edges for
firm seating. Remember to secure the unused plates or film in the original
box NOW! Wait a few minutes for temperature equilibrium.
No unnecessary motion now. Absolutely no contact of body parts
or clothing with the table. LIFT THE BEAM BLOCKING CARD OFF ITS SUPPORT--STILL
BLOCKING THE BEAM. WAIT WITHOUT MOVING 30 SECONDS TO 1 MINUTE. GENTLY
LIFT THE CARD OFF THE BEAM 6-10 SECONDS, THEN PUT IT IN ITS ORIGINAL
POSITION TO BLOCK THE BEAM AGAIN. (See Diagram 4)
4. Development
Now the plate is ready for development. Set up three 5 x 7 trays
labeled DEVELOPER, BLEACH, PHOTO-FLOW:
DEVELOPER--50ml developer (a), 50ml developer (b), and
50ml dist. water. Mix. Place the plate in the developer emulsion
up. Lift one end of the tray gently every few seconds for agitation.
In about 2 minutes the exposed surface will be very dark.
WASHING--Pick up with plastic disposable glove. Hold paper
towel with the other hand to catch drips. Place in a deep container
in the sink under running water for three minutes. This container
should be narrow enough so that the film or plate are not horizontal.
BLEACHING--Place 100ml or more bleach in a tray. Place
the developed plate in i t face-up and agitate gently as in the
developer. LIGHTS MAY BE TURNED ON. Continue until all the darkness
(silver coating) is gone, then 30 seconds longer.
WASHING--(Same as first washing)
PHOTO-FLOW--Dip the plate in a photo-flow solution (prepared
according to the directions on the little bottle), drain well, blot
(NO WIPING OR SQUEEGEE), with lint-free blotter. Finish drying with
a WARM hair drier using a rapid sweeping motion.
MOMENT OF TRUTH--View with a small indoor spotlight or
a flashlight to see if anything is there.....Diagram 5 shows
the relationship between illumination during exposure (a)and
illumination when viewing the finished hologram (b) & (c).
NOTE: The viewing direction, should be approximately the opposite
of
Diagram 5
the direction of the reflected light from the object when the hologram
was made. To express it a little differently, the angle between the
line of sight towards the image and the line of illumination is the
same as the angle between the reference beam and the object beam.
Diagram (a) shows the original positioning of of the plate and the
object for exposure and the directions of the two light beams. It
also shows how the plate should be illuminated by a spotlight and
how it should be viewed to see the image where the object WAS. When
the plate is rotated, the lines of illuminastion and viewing rotate
also.
{Note: You can link directly with some suppliers listed below by going
to the Society of Amateur Scientists (SAS) site looking for the discount
and surplus suppliers, list. See menu/Links to.....}
Cheap lasers and components
NOTE: For multiple beam holography, specify low beam divergence
of 1.2 mrad or less, and TEM 00. It is desirable to meet those specifications
although not required for single beam holography.
The Holography Handbook, by Fred Unterseher and co-authors
Ross Books, 1987
The Complete Hologram Book, by J. E. Kasper & S. A. Feller,
Prentice-Hall, 1987
Homemade Holograms--The Complete Guide to Inexpensive
Do-It-Yourself Holography, by John Iovine, Tab Books, 1990
Understanding Lasers, by Jeff Hecht, H. W. Sams and Co., 1988
Scientific American--Several articles since 1965. Here are some:
(a) Emmett Leith and Juris Upatnieks, Photography by Laser, June
1965. For the first time Americans hear about holography from the two University of
Michigan researchers who did it first.
(b) The Amateur Scientist, Feb 1967: Homemade Hologram
(c) The Amateur Scientist, Jyly 1971: Stability of the
Apparatus
(d) The Amateur Scientist, Nov.1972: Holograms with Sound
...Waves
(e) The Amateur Scientist, Feb 1980: Easy Way...
(f) The Amateur Scientist, Sept 1986: Rainbow Holograms
(g) The Amateur Scientist, May 1989: How to.......Make
Holograms
Viewable in White Light
Practical Holography, by C.Outwater & V.Hamersveld, Dimensional Arts,Inc.
An ONLINE textbook on holography.
