Teaching Holography in Classrooms
Making Holograms with PFG-03M Plates with JD-4
By T. H. Jeong, Riley Aumiller, Raymond Ro, (Lake Forest College)
and Jeff Blythe (University of Cambridge)
Edited by Alec Jeong
Copyright © 2003-2005
This paper is useful for teaching holography workshops in classrooms as well as in makeshift locations such as museums, businesses, and homes. The target audience is very general, young children to adults of any profession, all of whom have no prior experience in making holograms. A typical number of participants is twenty-five, but can vary depending on space and personnel availability.
A central original contribution of this paper is the discovery of a new chemical processing regime for the Slavich PFG-03M holographic plates using what is now called the JD-4 developer kit. These silver halide plates have the highest resolution of its kind and some of the world’s best holograms have been recorded on it for several decades. Due to its low sensitivity and long developing time (12-15 minutes if using GP-2 developer, accompanied by natural drying), this material has historically been excluded from use in workshops.
Our new processing regime JARB (first letters of the authors’ last names) has makes PFG-03M possible for classroom use. JARB has the following advantages: It (1) increases the sensitivity of PFG-03M emulsion ten-fold without sacrificing resolution; (2) hardens the emulsion during processing without significant shrinkage; (3) has a ten- to twenty-second development time; (4) is quick drying using squeegee and warm air; and (5) allows the finished hologram to be viewable with laser or incandescent light. Other advantages of JARB are (1) low toxicity, (2) low volatility, (3) non-staining, (4) low cost, and (5) long shelf life.
Keywords: holography, beginner holography, teaching holography, silver-halide processing, PFG-03M, JD-4
It has been well recognized that holography is a valuable subject for introducing young students to all the major topics of modern optics. These topics include light propagation, interference, diffraction, polarization, scattering, and photochemistry. Some of the major problems that prevent greater acceptance of holography in middle and high schools include expense, laser and chemical safety, lack of darkroom facilities, and time limitations in class and laboratory periods.
Thee above problems are addressed in another article by the same authors entitled "Simple Holography". In this current article, we will see that PFG-03M with JD-4 developer (JARB) further minimizes these pracitical limitations.
PFG-03M has been used in Russia and elsewhere for making the highest quality exhibition holograms for several decades. One can simply develop such plates in one step using the GP-2 formula. However, this combination is not suitable for school use because of the following factors: (1) the sensitivity of PFG-03M is 1.5 millijoules per square centimeter (mJ/cm2); (2) the development time is 12 - 15 minutes; and (3) the holograms must be dried naturally by evaporation, which may require one hour or longer depending on the humidity.
These problems prevent schools from using PFG-03M with GP-2 because (1) the low sensitivity means lasers with greater outputs are needed, presenting an eye safety dilemma; (2) longer exposure time is required, presenting a mechanical stability problem; and (3) the time required for the hologram to dry exceeds the duration of a class or laboratory period.
The application of JARB on PFG-03M resolves all of these problems.
2. APPLICATION OF JARB (JD-4) ON PFG-03M
The discovery of using JARB for quick processing of holograms recorded on Slavich PFG-03M plates and film was made by Tung H. Jeong, Riley Aumiller, Raymond Ro, and Jeff Blyth; thus it is called the JARB processing regime. Commercially, the chemical developer used is now called called JD-4.
JARB is ideal for making holograms during a lecture demonstration, or for laboratory exercises or workshops where many students must make holograms in a limited time. The advantage of JARB is that it effectively increases the sensitivity of PFG-03M ten times, from 1.50 to 0.15 millijoues/cm2. Thus the exposure time for holograms is one-tenth as long as when processed in GP-2. The typical development time is 20 seconds. Finally, drying time is drastically reduced by using warm air (from a hair dryer) because the JARB development hardens the emulsion. The total processing time using JARB can be as short as three minutes, from developing to drying!
The composition of JARB is a modified version of what was originally intended for processing “BB” plates manufactured in Germany (Birenheide, R., “The BB Emulsion Series: Current Standings and Future Developments”, SPIE Volume 3358: 28-30 (1997), ed.Jeong). It is mixed using three glass (or plastic) containers marked “A,” “B,” and “Bleach”, each with 1 liter of distilled or de-ionized water. Exercise extreme caution in labeling the bottles and keeping them out of the reach of children to prevent accidental ingestion of the contents).
Commercially, the chemical developer used is now called called JD-4, and contains the following.
Developer Part A--makes 1 liter solution
Developer Part B-- 1 liter
Bleach-- 1 liter
For detailed instructions on making reflection and transmission holograms, see the article "Simple Holography" on this website.
Using PFG-03M film or plate, expose the hologram so that each square centimeter area receives 0.15 to 0.4 millijoules of energy (there is batch-to-batch variation). For example, if a 5 milliwatt diode laser without a lens is location 40 cm from the plate, the exposure time is approximately 5 to 7 seconds.
Preparation before processing:
Have the following items on hand:
Let's review for a moment. So, we now have our "assembly line" of trays placed in the following order: developer, rinse, bleach, rinse, wetting agent. To view the finished holograms, we recommend an incandescent spot light. A good and inexpensive light is a Phillip 45 Watt “narrow spot” flood light that operates on 110 volts and sold in hardware stores. The best lamp is ESX(20MR16) run on a HATVS12-60WD transformer sold by lighting companies.
After the holographic plate is exposed, hold it by the edges with your gloved hand, with the emulsion side (sticky side) facing upward.
The hologram is finished except for drying. The best way to dry the hologram is to stand it against a vertical surface with the bottom edge resting on a hand-towel or tissue paper. Best results are obtained when it dries naturally in clean air. However, if time is limited, the hologram can be quick-dried by holding it vertically and blow warm air across it with a hair dryer. For a reflection hologram, the image can be viewed, after thorough drying, using the laser light that exposed it or an incandescent spotlight.
3. PRACTICAL CONSIDERATIONS FOR WORKSHOPS
In this section, we will present practical ways of setting up and operating workshops in makeshift locations using commonly available equipment.
“Darkroom” preparation and system setups
Ideally, the space used should be an interior room with no windows. When the lights are turned off, the room should be dark with the exception of light from existing exit signs. Several night lights (5-Watts) can be plugged into electrical sockets to provide low ambient light. For every four or five students, there should be one setup as explained in "Simple Holography". The laser light from each setup must be shielded so that it will not reach into the vicinity of another setup. Also, when one setup is being used, the commotion and vibrations must not be transmitted to other setups. For this reason, each setup should occupy its own table.
If an interior room is not available, then all exterior windows need to be blocked by black plastic sheets, making certain that there is no fire code violation.
Layout for chemical processing
It is to be understood that the above information is like instructions for a theatrical stage play. A basic rehearsal is recommended with the students is recommended before you start.
Assuming the reader has read "Simply Holography", he/she should practice privately the making of reflection holograms using the above additional guidelines. The next step is to make holograms in front of an audience. With the experience thus gained, workshops can be offered to a broad range audiences.