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Tony Brock-Fisher

The idea behind what I’ve been working on is basically a small holocamera. I originally came upon the idea as something I can teach for middle school grades (5-8) at my sons’ school. It’s turned out to be very useful for general (small scale) hobby holography at home too. I don’t have space available for a regular darkroom setup - the holography project has to share space in our high-tech family room, which is home to many other hobbies (4 computers total, 3 ham radio stations, model rocket building, etc.) all in a 16x24’ room.

The critical ingredients for a daylight holocamera, besides providing a stable optical setup, are the ability to set up the mirrors, object, film position, and laser in room light, then close the box and allow the film to be exposed.

I built a small table (1' x 2') using 4 cinder blocks,

that are topped with a piece of plywood. A large cardboard box sits on the plywood, and the rest of the table is built inside the box.

 

Vibration isolation is provided by  13” bicycle inner tubes next to each other underneath a 12” x 24” x 4” cast slab of concrete with smooth marble floor tiles on top for a flat surface

The cardboard box is not mounted to the table - the inner tubes and table are inside the box. The box has a tight-fitting lid.

I worked out a way to mount a piece of film in a glass sandwich inside an old 5 x 7 cut film holder. 4” x 5” PFG-01 film is sandwiched between 4” x 6” pieces of glass, which is held in a modified 5x7 sheet film holder

 

The film is loaded in the dark (a bathroom with no windows) and the dark slides are inserted to exclude light.

There's a cutout section on the side of the box. I used 8 layers of black plastic trash bags to make a vibration-isolated light-blocking 'window' where the plate holder can be inserted

I made a metal guide for the film holder to fit thru which is mounted in the plastic ‘window’

The plastic ‘window’ provides light blocking while also allowing relative movement between the box which is non-isolated and the slab on the inner tubes which is isolated.

I built a shelf out of steel angle which holds the film holder and the object

This can be used frontwards

or backwards

for transmission and reflection holo’s.

The film holder is inserted in the guide and clamped to the object holder with small clamps

Other optical components are mounted on 3/*’ IPT pipe flanges and nipples. I epoxied a 2” square piece of plexiglass to the bottom of each stand for a stable surface to the marble.

For the laser I use a small 5mw diode laser powered by 2 AA batteries. To keep everything small so it fits inside the setup, I’ve assembled the laser diode, a 20x microscope objective, and a Radio Shack meter type shutter together onto a single stand

Because the beam is expanded right at the laser, I have to use large mirrors (4”x5”) mounted on the optical stands. I have one that serves as a beam splitter - it’s about 70% reflective. Here’s a typical setup for a transmission holo:

 


I set up everything inside the box, put the cover on, then remove the dark slides from the film holder. I use a switchbox with a long cable to time the exposure with the Radio Shack type meter shutter. After the exposure's done, I slip the dark slides back in. Then I can open the box and remove the film holder.

I do daylight processing as well, using a color print drum. I load the film into the drum in a dark (bath)room, then process in daylight using D-19. I use a stop bath step, after which the rest is done in daylight. I use the JD-2 bleach, which seems to last forever.
 


October 21, 2003

I took some digital pictures of a hologram I made with the holocamera setup. This is one of my best. It's a ceramic 'Minnie Mouse Blowing a Kiss' (purchased in DiIsney World). The kiss™ is mounted on a tiny wire spring. I thought it was likely to move and apparently it did. Although the kiss is red, and bright when viewed in laser light, it came out black in the holo. If you look closely at the spring, and follow it down to the rest of the statuette, you can see where the spring changes from black to shiny silver! Very interesting effect!

It was exposed for 136 seconds. This is a split beam transmission hologram on PFG-01 developed with JD-2. The resultant density was 1.27.

 


November 23, 2003

Wireless Shutter for Holography

Recently I’ve been making holograms with diode lasers and helium neon lasers in the 5-10 mw range. I’ve developed a technique for making holograms without a darkroom (see my pictures posted at http://www.dragonseye.com/holography/guests/tonybrockfisher/). A critical component for this is a remotely activated shutter. I made electric shutters in the usual way from a Radio Shack meter (#270-1754). The process for making a shutter from this meter is documented elsewhere. I had this connected to a small project box with a battery, current limiting resistor, and switch. The control box was connected with small wire to the shutter itself which sits on the optical bench.

This system worked, but the wire was always a hassle. First, I worried about it transmitting vibrations to the table. Second, I was always tripping over it. And finally, it was always getting tangled up. I definitely wanted to find a way to ‘Go Wireless’.

My solution was found cheaply in the form of the miniature Radio Control cars that are so popular. Priced from around $20 or less, these little cars have a transmitter unit and a 2-channel receiver in the little car. Here’s how to adapt the circuit from the car to the shutter. The car I bought was only $12, and was called ‘microEnergizers’. It had a red LED inside the car that lit up anytime the car was moving.

The first thing is to put batteries in the toy and play with it a while to make sure it works - have some fun! Remove the car body. This reveals a clear plastic cover which hold the postage-stamp sized circuit board in place. Carefully pry the clips that hold the clear lid in place to remove it. With the cover removed, the circuit board can also be removed carefully - it has many wires attached to it. Before removing any of the wires, make some notes to yourself so you know where the wires are attached. You should find 2 wires that go to the motor, 2 very fine copper wires that go to the steering solenoid in the front, and two wires that go to the tiny rechargeable battery. My car also had 2 wires going to the small LED. Remove the battery - it should pop out. Using a low-wattage soldering iron, unsolder the battery wires at the contact clips (remember which is (+), it is usually red and goes to the button end of the battery). Also unsolder the fine copper wires for the steering and the motor from the circuit board. If there’s a LED, unsolder it but leave the wires.

In my setup, I used the LED output to drive the meter. This was convenient because the LED goes on whenever the forward or reverse buttons are pushed. If you have a car without the LED, you’ll have to choose either the motor circuit or the steering circuit to drive the meter.

Whichever circuit you choose, connect it to the meter, using the 15K resistor that comes with the meter. Connect a small battery (AAA or 1.5v N cell) holder to the battery connections on the circuit board, observing proper polarity. You can then stick the battery holder to whatever type of mount scheme you have using double-sided foam tape.





Insert a battery into the battery holder (observe proper polarity) and test the unit. When you press the appropriate button (depends on whether you used the motor circuit or the steering circuit), the meter/shutter should open.

The car circuit draws very little current, so it should last quite a while - but remove the battery between shooting sessions.
 

 


March 21, 2004

These are my 'latest works', H2 reflection copies. 11 mw Hene, PFG-01 and 8E75 (varied) processed in D-19. These were done on my 1'x2' table. Originals are 4"x5".