Make: Magazine came up with a great name for our hologram film – Hella Fast Holograms! We call it LitiHolo Instant Hologram Film, but we’re thinking about changing the name now.
“Holograms are fun to view, and recently they’ve become a lot more fun to make.”
Because they are targeting the DIY community of makers, they went old-school and built most of the setup from scratch, but used LitiHolo film and lasers. After you read the whole article, we think you’ll understand why we prefer to use one of our Hologram Kits to make things easier (see the part where they have to make a vibration isolation table with a steel plate, a tire, and some carpet). Here’s the full article…
Hella Fast Holograms: Use a laser and special film to create your own instant 3D images
Holograms are fun to view, and recently they’ve become a lot more fun to make. Previously, shooting white-light reflection holograms – the kind you can view under ordinary light – could only be done using high-resolution holographic film that required development using chemicals. Not anymore. Now there’s instant holographic film that doesn’t require development, chemical or otherwise. Couple this film with the availability of inexpensive laser diodes, and it has never been easier to create holograms – it’s really a shoot-and-see process!
- Time required: 1-2 hours
- Difficulty: Intermediate
- Cost: $80-$100
- Materials: Laser diode (4-5mW), Instant hologram film plates (2″x3″), LED safelight, scrap of carpet or foam or towel (12″x12″), ferrous metal plate (12″x12″x1/8″), paint (flat black), inner tube (8-12″ diam), cardboard squares (one black, one white), bar magnets, rectangular magnets, steel plate (2 1/2″x1″x1/16″), quiet and dark place
What are holograms?
Holograms are true three-dimensional pictures that capture the depth of a scene. True 3D pictures allow you to angle the hologram horizontally or vertically to get a different view of the subject, unlike standard 2D pictures which just create a foreshortened view of the same flat image when angled.
Holography doesn’t record an image onto film the same way photography does. Instead, holography records the interference pattern of light, generated from a reference beam and reflected light from the subject (called the object beam). The light source required must be monochromatic (a single light frequency) and coherent (wavelengths in phase). A laser fits the bill.
Why 5 milliwatts?
A quick search for 650 nm “focusable” laser diodes will show availability of much higher-powered laser diodes from Amazon and eBay, from 20 mW to 200 mW. You can use these, but I suggest a 4mW-5mW diode because they’re safer – beaming yourself in the eye with on is less harmful.
Modifying the laser diode
You want to purchase a focusable laser diode because the “focusable” lens is typically removable. This lens focuses the laser light into a beam, which produces a dot, but we want the laser light from the diode to spread out evenly, covering our holographic plate and the object we’re shooting behind the plate. To make it so, remove the lens from the diode.
Making an isolation table
When shooting holograms, vibration must be eliminated as much as possible. Vibrations too subtle for us to feel, such as those caused by music or ceiling fans, can prevent a hologram from forming. Holographers shoot holograms on an isolation table. As its name implies, an isolation table “isolates” the holographic setup from vibration.
A simple isolation table I use consists of three components: a piece of carpet (or soft foam, or thick cloth like a towel) a small 12”-diameter inner tube, and a 12”x12”x 1/8” thick ferrous metal plate.
Fill the inner tube with just enough air for it to be full but still soft and easy to squeeze. The 12”x12” metal plate needs to be thick enough to support itself and a few lightweight components without flexing or bending, and it needs to be a ferrous metal so that our magnetic mount will stick to it. Paint the stell tabletop flat black. This will help cut down on unwanted laser light reflection to improve the quality of your holograms.
You’ll want to set all this up in a place that is dark and quiet.
Mounting the laser
For our basic single-beam setup you’ll only need a few mounts and components.
You can create mounts using small permanent magnets, the metal isolation table surface, and small steel plates or binder clips. The magnets can either be ceramic or high-strength neodymium.
I typically hot-glue the object I’m going to create a hologram of onto a small steel plate, 1” x 2 ½” x 1/16”. When you secure the plate or binder clip to the steel isolation table using a magnet, it allows for easy repositioning.
Binder clips with magnets are also useful for holding the holographic film, white setup card, black shutter card, and laser diode. The entire diode fits into a medium sized binder clip, which also serves a heat sink.
Mounting the film
To secure the glass holographic film plates to the table, you’ll place the film in a medium binder clip, secured to the table with a magnet to prevent vibration.
Safelight
When handling the holographic film, you’ll darken the room and use a safelight to see what you’re doing. The film is sensitive to red, green and blue light. Liti Holographics suggests using a single-diode blue LED safelight, which can be fabricated from a battery, series resistor, and a darkroom-safe LED (I used a green one because I have them from my other holography work). Use your safelight as little as possible to prevent fogging your film.
Positioning your model
For your first model, choose something rigid and hard that won’t bend, droop, or move during exposure. If the object is dark, paint it white. Ideally the complete object will fit behind the 2”x3” film plate. For beginners I recommend a small, light-colored seashell.
To create the brightest viewable hologram, position the model close to the film plate without touching.
Setting up your holography table
I use a side-lighted, single-beam holographic setup. To understand what this means, trace the spread beam from the laser diode to the holographic plate.
With this side-lighting setup, the point where the spread beam first touches the plate is labeled T because it will be the top of the holographic image when viewed later under a white light. Therefore the top of your model when placed behind the plate should be oriented to the T side of the plate.
To make sure your laser light is correctly oriented, test it by placing a 2”x3” piece of white cardboard where you will place the film. Use a binder clip secured with a magnet to keep it in position. Direct the spread laser light onto the white card, making sure the light strikes at a 45°-60° angle. Position the diode so that laser light fills the white card as evenly as possible.
Next, position the model behind the white card. Remove the white card, leaving behind the binder clip and magnet. With the white card removed, the laser light will be illuminating the object. Look at the object from the laser side. This will be the view of your finished hologram.
Shutter, exposure, hologram!
Use a 2 ½” X 2 ½” piece of matte black cardboard as a shutter, propped up with a binder clip. Don’t use magnets on this binder clip, because you’ll need to lift the shutter card. Turn all the lights off and remove a film plate from its light-tight box. Hold the plate by its edges, turn on your safelight, and place the film I the binder clip that was holding the white card. To ensure maximum stability, make sure the bottom edge of the plate and the binder clip are flush with the surface of the table.
To expose the holographic film, lift the card off the table to unblock the laser light. The exposure takes 10 minutes, and then you can place the shutter back down in front of the laser.
The exact exposure time varies with the diode’s power output, and how wide the laser light is spread. Litiholo recommends using a 5-10 minute exposure time using a 5mW laser diode, and that it’s better to overexpose then to underexpose.
To develop the film, just turn on the room lights.
Admire your work
Now it’s time to take a look at your hologram. The hologram you shot is a white light reflection hologram (viewable in standard white light). You can obtain the sharpest image by using a point light source above, and a black background behind the hologram. The sun, tungsten halogen spots, and bright white LEDs work well. Incandescent lamps can be used, but the image quality will suffer.
To view the hologram, the point light source must illuminate the hologram at the same angle as the laser bean did during exposure. So you may have to rotate the hologram a couple of times and vary the angle until the light strikes the plate correctly. If you’re holding the holographic plate upside down (in reference to the angle of the laser light used to make the hologram) or sideways, you may not see any image at all.
To improve the appearance of the image, place something black behind the hologram.
Troubleshooting:
While shooting holograms is easy, shooting good holograms takes a little practice. I have over 20 years’ experience, and have written numerous articles and two books on the subject. Here are some common complications that can arise when shooting holograms.
No Image – Ensure there is nothing that can vibrate the table during exposure: music, a running fan, drafts, etc. This is the primary reason holograms don’t form. You can also try a longer exposure time; again, it’s better to overexpose than underexpose.
Laser Diode – It’s possible that the particular diode you purchased may not produce a hologram. Two manufacturers sell laser didoes that have already been tested to produce holograms: Midwest Laser and Litiholo.
Tip: during the long exposure time, your laser diode may mode hop. This creates an interesting echo effect in the resulting hologram, almost like the image was shot multiple times. Hard to explain, but if you see if, you’ll say “Oh yeah, that’s it.”
Mode hopping is when the laser diode changes its light output frequency slightly, due to heat and current fluctuations in the crystal cavity and such. The only simple way to reduce mode hopping is to under-power the laser diode. So if the diode is rated at 5V, give it about 4.5 volts. It helps, but it’s not a cure.
Faint Image – Can be caused by stray light fogging the film. Make sure there are no other light sources besides the laser. Use your safelight as little as possible, and do not hold it close to the holographic film. When viewing, make sure the holographic film plate is oriented properly with reference to the point light source.
Going further
After you’ve practiced your holography skills using this single-laser setup, you might be interested in trying full-color holograms. Litiholo has developed a full-color kit that uses the same instant film but require three lasers (red, blue, and green) to shoot the hologram. The process is a little more complicated but the results are even more lifelike.
The article “Hella Fast Holograms: Use a laser and special film to create your own instant 3D images” was written by John Iovine in June/July 2018 for Make: Vol. 63. You can learn more about this issue of Make: Magazine on their website.