ABRASION HOLOGRAMS FAQ                               (c)1996 William Beaty

billb@eskimo.com                          SCIENCE HOBBYIST webpage

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


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


  - 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.


  - Stand so you are facing the light source, or with the light source
    directly overhead.  (If the light source is behind you, your hologram
    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.


  - 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

  - 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.



    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.



  - 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
    of your face, about 1ft from your eyes, and hold it so you look
    *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
    any light-colored wall or lampshade.



  - 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.

    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

Created and maintained by Bill Beaty. Mail me at: billb@eskimo.com.
If you are using Lynx, type "c" to email.