Pseudo-split beam technique by Tom B.
the transfer, I had my uncollimated laser (with cylinder lens to square up the
elliptical beam) at one end of table pointing up at 8" f/5 collimating mirror on
tripod at other end (not on table). The collimated beam bounced down to the
transfer setup at the Brwster angle, and was fat enough to serve as a reference
beam for H2 (with a large 4x5 ND filter over it to reduce intensity, and to
directly illuminate H1, another 4x5 reflection holo about 6 inches away.
H1 was made with a similar overhead
setup, ND filter over plate, objects positioned far enough away not to be
shadowed. The object gets moved into the film plane during the transfer. A
master bigger than the final H2 would have been better to increase the useful
I'd been meaning to mention this unusual technique
sometime, but never got around to it. There's a lot of limitations, but it's
nice not to have to worry about dealing with high-power collimated beams,
spatial filters, etc.
The table is 14" x 28" x 1/4" steel plate sitting on 1/4" bubble-pack on
a concrete basement floor. I can pound the floor next to it and see no fringe
movement (other than from air currents etc.) Settling time from tapping the
table is very fast - a second or less. For a while, I had the table coupled to
the floor through plasticene balls, but found that bubble pack worked just as
well, if not better because of the broad area mushy coupling of the bubble pack
which might be helping to suppress resonances in the steel plate. It helps of
course to have a very stable concrete floor to play on.
Overview of setup.
8" f/5 mirror on plywood mount and transfer setup, power supply
Dual plate holder made from used Canon auto bellows and angle
iron. The obligatory porcelain kitty is helping to hold up
the black cardboard barrier that blocks stray light from the
Home-made diode laser mount with cylinder lens on wee
A nice hologram!
From Tom: "(H2) so
cute I could puke, a sure sign of greatness."
"(H2) Space Kitty fondles shiny ornament, get unpleasant
photographing reflection holograms:
I used an elderly Kodak 1.2 megapixel digicam on a mini-tripod and overhead
halogen lighting. I think I used macro mode. The film was carefully cleaned and
squashed under clean glass, then tilted back for best brightness from the
camera's point of view. Since the flash can't be used, exposures would be too
long for hand-held shooting, hence the tripod. To keep reflections from the
camera body out of the image, I cut a hole in a piece of 8x11 black card stock
(painted black to make it darker) just big enough for the camera lens to stick
through. Some care was needed when pressing the shutter button to avoid jiggling
the camera and blurring the image. Images were cleaned up using PaintShop Pro V6
or 7. I probably ended up removing a few distracting dust specks from the
images. Contrast and brightness were adjusted for best looking image without
misrepresenting the appearance of the hologram.
Feb 25, 2004
Author: Tom Burgess Feb 24/04
Medium: BB-640 4x5 plate, 3% TEA pretreatment
Setup: single beam Denisyuk reflection
Laser: Panasonic LNCQ05 660 nm diode, cylinder lens for 8 degree
X and Y divergence
Exposure: 15 seconds at 100 microjoules/cm2
Chemistry: Metol/Ascorbic acid developer, Brilland bleach
Lighting for pics: OptiLeds Amber LED at about 3 feet
Camera: Kodak DC3400
Fish credits: Tub o' Ocean Animals Inc.
Cat artist: Lesley Anne Ivory
The stereo pair is meant for the "cross-eyed" viewing method. Zoom the image
size to a couple of inches across, get close to the
monitor and try to merge the pair. Being nearsighted helps.
March 29, 2004
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