produce, so don't be put off by the massive
amount of discussion below. I'm just trying to
cover all bases.
Q: I DON'T UNDERSTAND HOW TO MAKE THEM!
A: Follow the instructions on the top page, but also take a look at the
1. Make curved scratches as shown above
Your first hologram should be something very simple. How about the letter
First draw the little "V" as a guide. Draw it near the bottom edge of
your piece of plastic. Next, use the dividers to make lots of curved
scratches above the "V". For each scratch, place the point on a different
spot on the "V." Each scratch should be a quarter-arc or even a
half-circle. Don't change the distance between the metal points.
Make about twenty scratches. Even more is better.
2. Make LOTS more scratches on the plastic plate
Each scratch will create a single glowing dot in the finished hologram.
That means you should make lots and lots of curved scratches. If you just
few scratches, your hologram will look like a collection of sparks. If
you make enough scratches (spaced closely like the grooves of a vinyl
record album), the rows of sparks in the hologram will start to look like
glowing white lines.
IMPORTANT NOTE: Each scratch must look dark and shiny. If they
dusty, then your hologram won't work. If the sharp point of the compass
makes a squeeking noise, then that scratch is useless. Make your
scratches slowly, so the compass point doesn't squeek.
3. Cut the little picture off the bottom of the plate
The scratches ARE the hologram. If you wish, you can cut your little "V" drawing off the bottom of the plastic plate. If people only see the plastic plate with "sandpaper marks", they won't know what the picture looks like until they see the actual holographic image.
Q: I TRIED IT AND IT DIDN'T WORK!"
A: 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.B) PROBLEMS WITH VIEWING ANGLE
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 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:
___----___ two little / \ highlight / (O) reflections | | | . | | | | | (O) / \ / ---____---
C) FAULTY HOLOGRAM
Use a sturdy, expensive compass. I tried the $2 kind, and it didn't work. It wobbled and changed spacing. A drafting compass from an art supply store works best. 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. [WARNING! Always verify that the second metal point can actually be clamped in place of the pencil! I've encountered compasses where the supplied metal point was the wrong size and could not be used. ]
Try holding the compass tilted, so the point trails across the plastic and doesn't dig in and bounce.
Q: WHAT IS THE THEORY BEHIND THIS?
See my SPIE Paper for details
Q: 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.
Q: HOW DID YOU DRAW THAT CUBE IN TRUE 3D?
Q: I'd just like to know what's going on with your '3D' cube hologram. According to my understanding, if I follow the instructions in your article I will generate a flat 2D image of a 2D original, but which appears to float above or below the surface as determined by the divider spacing. So how did you generate an apparently 3D image on one plate??My very first 3D object was a big nasty job because I changed the spacing of the compass in order to change the depth of every single point. Every single point required a different radius. It took me hours.
Q: 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 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.
- You can't!! Well, it's nearly impossible to see the image unless the room is dark, and unless you use just the right light source. If your hologram doesn't seem to work, you'd better view it outdoors in the sunlight. ALWAYS view your first hologram in sunlight. That, or use a slide projector or overhead projector (or a video projector displaying a bright white field.) You can even use a streetlight outdoors at night. Once the angles of light are correct and you can "find" the image, then later you can try using a single distant light bulb indoors.
- Of the types of plastic I've tried, styrene and polycarbonate seem to work best, but acrylic is the most easy to find. Polycarbonate is "Lexan(tm)" or "Tuffak(tm)", the bulletproof plastic. Acrylic is "Plexiglas(tm) or Lucite(tm), perspex and others. Acrylic can be found at glass shops and large hardware stores. Styrene is commonly found on the "jewel box" cases of music and computer CDs, the plastic covers of framed photos, etc. Softer plastic works a bit better, and tends not to make the "crunchy white" scratches that sometimes happen with acrylic. Slightly greasy plastic is best.
Oh yeah? See Why I Call It 'Holography'. The short answer is: if these are not holograms, then neither are Benton Rainbow Holograms. Abrasion holograms employ the same optics as the holograms found on credit cards. Mine just have larger spaces between the zoneplate fringes. All white-light holograms require size-independent zoneplates in order to reconstruct sharp images using broad-spectrum light.
see http:// amasci.com/freenrg/secret.txt for my thoughts on this.
- I received several messages saying things like "I thought it was a hoax, but I tried it and it worked!" Huh. It never occurred to me that people would think it was a hoax. Unfortunately it is impossible to convince a "disbeliever" of anything. Anything I could say would just be part of the hoax, right? They'll have to try it themselves. This behavior is called Pathological Skepticism, and is covered on my page about Closeminded Scientists.