Hologram Hump Day – Ask a Hologram Expert

Another Wednesday, and more of your hologram questions answered by our hologram expert. Happy Hologram Hump Day! Now to the questions:

Hologram Questions, Hologram Answers!

Q: If I was to make a hologram of another already made hologram would I see it move in the hologram I’m making?

A: There are many ways to make copies of holograms, but one of the simplest is called “contact copying.”

You need to determine where the original reference beam or illumination beam is coming from (angle and distance for best reconstruction).

For a transmission hologram (laser illumination often from behind the film plate with the viewer on the opposite side and the image “transmitting” through the plate), the copy plate (sensitive film) goes against the original hologram with the copy plate on the opposite side of the original hologram from the laser source. In this way, the light straight from the laser source hits the original hologram first (illuminating the hologram and creating the object beam), and then the remainder of the light going through the original hologram and hitting the copy plate creates the reference beam.

For a reflection hologram (illumination typically from the front side of the hologram with the viewer on the same side, and the image “reflecting” off and back to the viewer), the copy plate goes on top of the original hologram between the laser source (creating the new copy) and the original hologram. In this configuration, the laser light straight from the source hits the copy plate creating the reference beam, and then the remainder of the laser light passes through hitting the original hologram and reflecting back the hologram image, which creates the object beam.

Q: Why don’t you offer larger film sizes? I am guessing that there are some technical issues, such as the laser power needed would be too high. Am I correct?

A: Larger holograms typically require more stability and more laser power, so yes, mostly correct. There is also a lot to do with getting larger sizes and avoiding defects. With smaller plates, we can just cut around the defects with only small waste, but bigger plates take a lot of work (and often expense), with potential for more waste. Our regular sizes are 2″x3″, 4″x5″, and 6″x8″, but we also do custom sizes and have done a variety of custom runs including 8″x10″, 10″x12″, and 12″x16″. There is usually a minimum charge for these custom runs.

Q: What are the challenges to overcome to create a color holoprinter, or give the one that exists the ability to do color?… Besides flooding that is.

A: Appreciate your point that flooding is a major problem! (For those of you new to LitiHolo, see the video of our office flood that happened last year, and that we are still charting our recovery from.)

Color holograms for the 3D Hologram Printer are exactly where we wanted to go, and where we thought we would be before the flood. Our first 3D Hologram Printer is red-only, but really a stepping stone to prove the concept and basic principles. Full-color is already available in our hologram film sensitivity (which is across the visible), and we’ve got Full-Color Hologram Kits for analog holograms in color. For the 3D Hologram Printer, it is a matter of adding green and blue to the existing red. With the right investment (investor?), we could be doing it tomorrow!

Q: Definitely interested in how you achieve adequate stability with the simple setup of the kit! Do tell.

A: Here’s a fun one! And a little secret behind what we do and how we do it: split-beam holography is hard, single-beam holograms are much easier!

All holograms need a reference beam (light straight from the laser source) that interferes with the light from the object beam (light reflecting off the object). The interaction between these two beams is the wave interference that creates the hologram, and the interference pattern captured for the hologram has dimensions that are on the order of the wavelength of the light used, so we’re talking about a few hundred nanometers. Classic hologram setups almost always use split-beam holography, with a beamsplitter separating the 2 beams, and relative movement between the 2 beams on the order of nanometers can affect the hologram (or destroy it). Our Hologram Kit setups use single-beam techniques, which hugely reduce the sensitivity. For our setups, the main concern is the relative movement between the film plate and the object, which are often in close proximity and even touching each other. The stability of the laser before it hits the film plate or object doesn’t matter, only the relative movement between the two. We’ve made holograms with this technique without the standard vibration isolation tables and other extreme measures that usually typify holography, including holograms on folding tables, classrooms desks, and even a Starbuck!

Q: I remember hearing about holography of a telescope and somehow the “telescope lens” worked? I’m curious if this was a particularly elaborate holographic image, if it worked because it captured the light coming through the lens, or if somehow a holograph of an optical lens actually can alter light passing through it?

A: This is a classic! The hologram with a telescope or binoculars, and you are just drawn to put your eyes up to the eyepiece (like it was real!), and you look through it and see the resulting image! If you’ve seen this hologram, you remember it!

Take a look at our video of a Hologram of a Lens for how we did this with our Hologram Kits setup. Holograms can capture and replay the full nature of lenses and other optical elements in the hologram. Holographic Optical Elements can often recreate the effects of complex lenses, all in a single thin lightweight piece of film.

The actual holograms involved in the classic telescope, microscope, or binoculars images had some simplified optics and images (they weren’t staring at the moon), but the effect is very real and a unique advantage of what holograms can capture.

Thanks!

Thanks for all your questions, and feel free to leave more questions for our hologram experts below in the comments. Happy Wednesday!

– LitiHolo