Up to HOLOGRAM | SCIENCE HOBBYIST
ABRASION HOLOGRAMS FAQ                               (c)1996 William Beaty

billb@eskimo.com                          SCIENCE HOBBYIST webpage
www.eskimo.com/~billb/amasci.html

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These holograms aren't extremely hard to produce, so don't be put off by
the massive amount of discussion below.  I'm just trying to cover any
eventuality.
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1. "I TRIED IT AND IT DIDN'T WORK!"

If your hologram doesn't work, the problem could be from three main
sources: the illumination, the viewing angle, or the hologram itself.

A) ILLUMINATION PROBLEMS

- Holograms are sometimes hard to view, so at the start, USE SUNLIGHT
OUTDOORS.  The bright light will make your holographic image easy
to recognize.  If sunlight is lacking, then use an overhead street
light outdoors at night.  The dark background and the small bright
light source gives good results.  Once you know that your holograms
are working and you can see them under sunlight, you can try bare
lightbulbs indoors.  Even flourescent tubes will work somewhat if you
stand so the tube is lined up perpendicular to the hologram.  But
avoid light bulbs and flourescent tubes at the start, they make the
hologram too hard to see.

- When illuminating holograms indoors, avoid using a bulb in a fixture
that has a white reflector, or one that is very close to the white
ceiling.  These will make the hologram image blurry.  The ideal
light source will look like an intense pinpoint having a black
background.  A small clear lightbulb hanging from a wire in a
darkened room is best. If your only lamp has some sort of reflector,
you might consider painting the reflector black.  A frosted bulb will
work OK if it is about 5 ft or more from your hologram.  A transparent
light bulb is preferred.

- These holograms work best when the reflected background is dark,
so try shading the windows and turning off all room lights except the
one used for illumination, or try viewing them at night.

B) PROBLEMS WITH VIEWING ANGLE

- Stand so you are facing the light source, or with the light source
will only operate over a very small range of viewing angles, and the
correct angle might be hard to find.)

- Hold the hologram so the scratches are humped upwards in the center.
If you hold it so the scratches are bowl-shaped (humped downwards)
then the image will be upside down, and the depth will be inside-out!

- While looking at the scratches, tilt the top edge of the hologram
slowly farther away from you and slowly back again.  Try tilting
the hologram until you see the reflection of the light source in the
plastic surface, then tilt it back again so the light source appears
to move up a few inches above the scratches.  You should see a
collection of highlights in the scratches.  The highlights ARE the
holographic image.

- If you still cannot produce a hologram, then as a last resort, try
drawing a single circular scratch on plastic like so:

___----___
/            \
/                \
|                  |
|          .         |
|                    |
|                  |
\                /
\            /
---____---

Hold this scratch in the sun, and you should see two little highlight
reflections which move around along the scratch.  The highlights
will be on opposite sides of the circle, like so:

___----___
/            \    little highlight reflections.
/               (O)
|                  |
|          .         |
|                    |
|                  |
(O)               /
\            /
---____---

These little reflections ARE THE HOLOGRAMS.  They are holograms of
a single dot.  When you make a complete hologram plate, every single
scratch should have a little highlight when you hold the plastic
plate in the sun.  The little dots of highlight-reflections form
the hologram (of the letter V, for example.)

If you don't see these little moving reflections, then there is
something wrong with the scratch.  You may have pressed too hard
with the compass point, or swept the point along too fast and
produced a white scratch with a shredded internal surface.  Or
your compass may be too wobbly, since the scratched line must
be very straight and smooth.  If it has little wiggles, it won't
produce holographic images.

C) FAULTY HOLOGRAM

- Use a sturdy, expensive compass.  I tried the \$2 kind, and it didn't
work.  It wobbled and changed spacing.  What works best is a drafting
compass from an art supply store.  Expect to pay between \$10 and \$15.
It must have a screw adjustment which sets the spacing between the
points.  It must have an extra metal point which can be put in
place of the pencil lead in order to change the compass into
"dividers."  When set to a particular spacing, you should feel no
"play" or wiggling if you try to move the compass arms together and
apart.

- Draw one object, and LOTS of circular scratches, from lots of points
on your object. For example, if you were to only draw scratches from
the tips of the letter "V", your hologram would appear as three
glowing dots, and would be very hard to see.  Instead, draw the
scratches with your compass placed upon at least nine different places
spread across the "V."  The more scratches, the more dots will be in
the final hologram.

- Use a sturdy plastic plate, like a piece of Plexiglas 1/16in thick
or thicker.  I found that polycarbonate "Lexan" works a little
better than acrylic because the plastic is softer.  Someone recently
had good success using the clear plate that came with a small picture
frame.  For your first hologram try to get some acrylic or
polycarbonate (Plexiglas or Lexan.)  Try other materials later, once
you succeed in producing holograms.

- Draw your circular scratches VERY LIGHTLY to start.  Once you have
suceeded in producing good holograms, you can try drawing deeper
scratches.  Deeper circular scratches produce a brighter hologram.
But if they are a bit too deep, the surfaces inside the scratch will
be rough and the hologram won't work.

- Dull compass points work better.  If you compass is brand new with
extremely sharp points, then don't push down too hard.  The sharp
point will make a groove with a flat-sided cross section, and your
goal is instead a round-bottom cross section.  I found that sewing
machine needles work well (they have an intentionally rounded tip.)
If your compass needle is too sharp, then shallow scratches will work,
but deep ones won't.

- Avoid making white, dusty scratches, as these will not reflect light
and will not produce hologram dots.  If you sweep the compass point
too fast, or if you push it down too hard, it may chatter and produce
a dusty, non-functioning scratch.  If you make a couple white
scratches by accident, don't sweat it.  If *most* of the circular
scratches are white, then start over.

/          /
Tilted       /          /
compass    /          /
point    /          /       (Side View)
--__      /
/  /--_/
/ /
//   ---) Direction of Motion --)
_____________/______________________
|                plastic plate       |
|____________________________________|

Try holding the compass tilted, so the point trails across the plastic
and doesn't dig in and bounce.

- Start with a very simple image, like a "V" or "I" or "X"   Once you
get this working well, you can scratch your initials, etc.  If you
start out with something complicated, you may do a lot of work
yet have your first attempt fail.  It's better to do your trial-and-
error with quick and simple images.

- It's easier to see holograms having shallow virtual depth, so set your
compass to about 1 or 2 inch spacing between the points.  The
first scratch-hologram I ever made was at *fourteen* inches depth!
It was *very* hard to see, and fortunately I knew exactly how to
illuminate and view it, or I never would have seen the image.

- Compass point too sharp?  The scratches function as reflectors having
curved cross-sections, so if your compass doesn't make polished
scratches with curved bottoms, your hologram won't work.  If your
compass point is extremely sharp, then sweep it with low pressure,
otherwise it will create a deep v-shaped scratch which won't reflect
light properly.  To make a bright hologram, use a less sharp compass
point with heavier pressure when making the scratch.

_________________________________________________________________________

2. WHY IS IT REQUIRED THAT THE PLASTIC BE BLACK?

The plastic itself needn't be black, since the intent is just to
provide a dark background.  These holograms can be viewed either in
"transmission" mode by viewing a distant light source through
clear plastic, or "reflection" mode by viewing an overhead source
bounced off of opaque plastic.  I found that the "reflection"
mode gives a much brighter hologram, and using opaque black plastic
improves the contrast.  If you use clear plastic, you can place the
hologram on a dark tabletop with a light source above, or hold some
dark paper behind the plastic, or paint the back of the clear plastic
with black paint.  These are improvements, not requirements.

_________________________________________________________________________

3. CAN'T THESE HOLOGRAMS BE VIEWED IN "TRANSMISSION" MODE?

- Yes! If you use clear plastic, try viewing your hologram using a
single small light bulb in a dark room.  Hold your hologram in front
*through* the plastic at the distant light bulb.  While observing the
patch of scratches, move the plastic down so that the distant bulb
seems to be a couple inches above the scratches from your point of
view.  You should see the highlight-dots light up and form a hologram
in the pattern of scratches.
HINT: if the background near the light bulb is brightly lit, you
may have trouble seeing the hologram.  Try turning all lights off
except the single clear bulb.  Try suspending the bulb away from

_________________________________________________________________________

4. HOW CAN I VIEW THESE HOLOGRAMS USING A FLOURESCENT TUBE?

- Flourecent fixtures give VERY blurry hologram images.  However, if
you happen to be standing under a fixture that has no diffusing
plastic plate in front of it, and which has one tube or two closely-
spaced tubes, then you can use it to view a very blurry hologram.
Stand under the flourescent tube so the tube is perpendicular
to the line between your shoulders, so the tube is in a line going
forward and back.  Hold the hologram in front of you and tilt it
up and down until you see a blurry blotch.  Tilt the top edge
toward you until the hologram almost goes dark, and it will get
somewhat clearer.

5.  ARE YOU INSANE?  YOU SHOULD KEEP THIS SECRET AND SELL IT!
see  http://www.eskimo.com/~billb/freenrg/secret.txt for my
thoughts on this.

.....................uuuu / oo \ uuuu........,.............................
William Beaty  voice:206-781-3320   bbs:206-789-0775    cserv:71241,3623
EE/Programmer/Science exhibit designer        http://www.eskimo.com/~billb/
Seattle, WA 98117  billb@eskimo.com           SCIENCE HOBBYIST web page

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