Looks like there’s an MIT class ring behind that glass slide…
Nope! It’s “just” a hologram of an MIT class ring!
Now, behold! HoloGIF!
Description
I present to you a novel approach to real-time holographic displays, my final project is inspired by devices such as a zoetrope, classic reflection holograms, and the up-and-coming Holographic Video Monitor (MIT/BYU). My original interests and inspirations for this project from my passion obsession for Star Wars, the Marvel Cinematic Universe, and various other sci-fi works in which 3D displays are at the forefront of their futuristic technology. Then, mix that with some other inspirations that helped shape the sci-fi world that I created, such as the “Butlerian Jihad” from Dune and whole steampunk idea/aesthetic of creating advanced technology with more less modern components. Put all that together and you have my new device: HoloGIF.
A classic zoetrope
An example of a hologram
Mark V Holographic Video Monitor (BYU/MIT)
The device I have created is essentially a zoetrope turned on its side, and instead of single frames of an animated scene, there are exposed holographic plates of a scene that was altered using stop-motion techniques. Twenty individual plates on a wheel spun around at one revolution per second (60rpm) creates the visual effect of a moving image within the hologram. Only for this display, any individual frame can be paused and will still have 3D characteristics in isolation from the others. Below, you will find the bill of materials to create this project, the build process, and how it ties in to my science fiction world (https://scifab.pubpub.org/pub/ryl9rxi3).
Before talking about my set up for recording my holograms, let me give a brief overview of what an actual hologram is and how it is made. Holograms are physical recordings of the optical wave front of an object that can be played back by recreating the original wave front of the object to display what appears to be a 3D image. When recording, a coherent laser source is typically split into two beams. One beam will be directly onto the film and is called the reference beam. The other beam hits the object and the light that bounces off of it then hits the film and is called the object beam. Those beams interfere and physically change the holographic film to record the interference patterns. After the exposure and development of the film, the holograms can be “played back” by shining a light through the plate, which will recreate the image of the object, even without the object there, preserving all of the 3D information of the actual object. A couple of important things to keep in mind is that when recording the holograms, the room must be dark so that the only light present is the object and reference beams, or else the film will get overexposed. Also, vibrations need to be kept to a minimum because even a small shift in the interference pattern can ruin the sharpness of the hologram due to the extremely small wavelengths of the light that is being used. More information on creating your own holograms can be found from a variety of sources, but one of the best for beginner is the “Holography Handbook” by Fred Unterseher (can be found in the MIT Library).
One thing of note is that with these LitiHolo holographic plates that I was using, they are somehow extra resistant to light exposure and vibrations, and they are special in the fact that the plates develop as they are exposed, so no chemicals are required for the development process. LitiHolo sells these plates individually or in a kit that comes with a laser and stands for everything to keep them aligned. With all of those modifications and extra tools, it enables anyone to pick up a kit and make their own holograms without the need for fancy optical equipment such as optics tables and mounts.
With that being said, to get the best results for my holograms, I used the Modern Optics Lab in building 38 to do my hologram recordings since I had access to it from my 6.637 Optics class. Within this lab, I used a variety of optics mounts to position the laser, microscope objective, aperture, holographic plates, and object, all on top of the floating vibration resistant optics table. Below is a photo of my set up.
Hologram recording set up
Another batch of these plates were available and I tested them a couple of times to get my set-up right, as well as the exposure time and laser power. I ended up going with 7 minute exposures at 10mW. The process is as follows: make sure the laser is off or blocked, turn off the light, get a single plate out from the packaging, insert it into the plate holder, wait for vibrations to settle, then turn on or unblock the laser. After the 7 minute exposure, you can then turn the lights back on.
Exposure in progress
Choosing the right object is important with making holograms because you want to be able to see the object well in the plate. The ring I used was pretty reflective, but only at certain angles off of the detailed faces. Therefore, when thinking out how to make the GIF-like animation, I decided to make the ring rotate about its center a full 90 degrees, then go back to the center, 90 degrees the other way, then back to the center again. This was because the back side of the ring wasn’t as reflective or interesting as the front side.After determining the motion, I divided the motion into 20 frames worth of angles and made sure I rotated the ring accordingly before each exposure (exposures at 0, 18, 36, 54, 72, 90, 72, 54, 36, 18, 0, -18, -36, -54, -72, -90, -72, -54, -36, and -18 degrees makes 20 frames that loop together nicely). If you look back at the picture of my set up, you will notice that the ring is mounted to the table on a rotational mount. I also needed to secure the ring to the optical mount, so I took a wooden dowel slightly larger than the inner diameter of the ring, sanded it down to fit, painted it black, then drilled the proper hole through it for the mounting screw.
All 20 plates after exposure
Once all of the plates are exposed, they will finish developing under the light, and they are ready to be attached to the rest of the device. Handle the plates with care, making sure to place the little pieces of paper included in the packaging in between each plate to protect the film on each plate.
I will also quickly note that I did not choose the number of frames (20) arbitrarily. After consulting with someone with more experience in film, especially in stop-motion, they determined that at minimum, I should do 15 frames, but the best would be 24-30. Since the LitiHolo plates came in packs of 10, I opted to get two packs, thinking that 20 frames would be a good number. I knew that there were some extra plates in the lab that I could use to test. Even then, I still made a mistake on two of the plates that I used for the final results. Like I said, recording holograms can be a tricky process for beginners, and for people with a little more experience.
Wheel Structure
After determining the best way to build this structure based off of materials and tools I had available, I decided that I would lay the plates on top of two sheets of aligned acrylic cut into a 20-sided polygon. With that basic idea in mind, I used SolidWorks to design the CAD model of not only the wheel, but the entire structure. After tweaking designs a couple of times due to new measurements of materials or new ideas for the structure, I had a design that I was happy with and used it to laser cut the acrylic.
CAD drawing of one side of the wheel structure
Laser cutter in action
The LitiHolo plates are approxiately 2” x 3”, so I made the sides of the polygon 2.5” so that there would be some room between plates to work with. After cutting both sides of the wheel, I cut the Delrin rod into eight 3” supports that would go in the holes between the sides of the wheel, as well as one 9.5” shaft to go through the whole wheel structure. I hot glued the supports in place to add some extra security even though the tight fit was holding most of them in pretty well. I used Delrin because of its strength, and the fact that it is “slippery” enough to not require bearings of some sort to make the wheel turn easily.
Note the little groove in the center hole of the wheel structure. It was originally to be used in conjunction with some other grooved circles so that I could insert a sort of peg into the shaft. That peg was going to be able to go through the whole wheel structure, be rotated, then pulled back into the groove to secure it even better to allow it to rotate the wheel better. However, after testing the wheel structure with the plastic shaft, the tightness of the fit and friction were good enough to not require the extra complexity of that work.
I then cut one more piece of Delrin (about 5”) for the crank shaft handle. In order to connect this piece to the shaft of the wheel, I used SolidWorks again to create a connector piece for the hand crank. I then 3D printed that piece and attached it to the rest of the wheel structure. At that point, part of the base structure had also been completed, so I inserted the wheel into the base to make sure the rotation would work well. I was pleased with the results!
CAD model of the hand crank handle connector
Hand crank in action
Now it was time to attach the hologram plates to the wheel structure. A lab mate had an idea to cover the structure with black paper to give a better contrast of a background for the holograms. I used the railroad paper and cut it into 2.5” x 3” rectangles, then taped them to the wheel and trimmed them. The next step was to attach the plates. I tested how the would hold on some excess pieces of the paper and determined that hot glue would be sufficient to keep them in place, even with the rotation. The tricky part here was to make sure that the image was exactly aligned up in each plate to the next so that there wouldn’t be any jumping around of each image. Luckily, when recording the holograms, the plate holder had a very specific way that the plates needed to be inserted, and so that made a sort of built-in alignment system. The edge that the plates were pressed up against during recording becoming the new edge to be aligned with the wheel structure for gluing. That was pretty straightforward minus a mistake at the very beginning, but still shouldn’t be too big of a deal.
Finally, there were still little strands of hot glue everywhere. I attempted to clean them all up, but due to using clear acrylic for the sides of the wheel structure, I could still see all of the mess of the hot glue that was used for the supports. I wasn’t very successful in cleaning them up, so I instead had the 20-sided polygon shape cut out in the same black railroad paper, but without the support rods holes. I hot glued those pieces on either side and it looked so good!
Wheel structure with holograms attached and covered in black paper
I then cut the silicone tubing into four 1” pieces to add in as spacers before and after each piece of wood in the base support structure. These spacers make it so that the wheel stays in the same position as it rotates. Now that this is all done, it can be transferred into the base structure.
Base/Viewing Window Structures
For the base, I chose MDF because it’s durable, soft, easy to cut, and was available to me. I cut it into a 12” x 22” base board piece, and then two 5” x 12” beams. I then drilled a 1/2” hole into the beams 2.5” from the top and in the center of the sides. This raises the center of the wheel structure 9.5” off of the base board, giving it a good 1-1.5” of clearance.
I painted all of those pieces black, then aligned them with the wheel structure by inserting the shaft through the first board, then the wheel, then the other board. After marking where the most structurally sound and centered placement was, I took the wheel structure off and mounted those boards in place with some large L-brackets. The structure up to that point has already been shown in the above photos of the wheel structure.
For the viewing window, I decided on a viewing angle of 30 degrees. Rather than trying to do a bunch of complicated geometry which would inevitably turn out to be wrong, I just cut out the viewing window and two support legs out of 1/4” plywood with the laser cutter. I purposely made the legs long so that I could have some freedom to where I wanted to place the window with the rest of the structure. I lined it up where I wanted the window, made a mark of how much lower that was from the top of the legs, then cut that much off of the legs to shorten the window to the appropriate height. Because the legs are on the outside, I didn’t need to worry about the wheel hitting the legs, and so I just made sure that the window was far enough from the plates to not get hit, but close enough to be able to see one isolated frame at a time well with the light source.
CAD drawing of the viewing window and support legs
I painted those pieces black, then attached them to the rest of the base using some smaller L-brackets. With the base and viewing window in place, the strobe light circuit can be incorporated into the design.
Many photos of the base structure are in the previous section so that the wheel could rest on it, and photos of the viewing window will be included in the strobe light section.
Strobe Light Circuit
While each individual hologram plate can be viewed with a light source, I wanted to get the sense of animation/motion between the frames. The viewing window helps so you only see one frame at a time, but the light source cannot be continually on, or else your vision blends everything into a streaky mess. I therefore needed to implement a sort of strobe light that flashed once per frame.
I tested this by downloading an app to my phone that flashed at 20 Hz, but matching that pace with the hand crank. So, as a proof of concept, it kind of worked, but in order to see the full thing, I needed to get the strobe light working.
To build the circuit, I needed a power supply, as well as a power regulator to step the power down to manageable levels for the circuit. During the testing phase, I then had the circuit go straight through a resistor and then an LED to test positioning of the LED and which LED would work the best for my circuit. I ended up choosing a super bright white LED (NTE30059) for the display.
With the correct LED in place, I opted to use a photo interrupter to achieve the strobe effect. However, the photo interrupter I had on hand sent a high signal when there was nothing obstructing the optical path of the photo interrupter, and a low signal when there was an obstruction. This could still work, but I would need to make some sort of appendage to the display that would have slits where the frame needed light on it. I thought it would be easier to only make little notches for when the light needed to be on, and so I needed to find a way to invert the operation of my circuit.
I solved this problem, and another problem of the photo interrupter draining most of the current in the circuit by sending the photo interrupter signal to drive the gate of a transistor. The base would be directly connected to the power, and the emitter would run through the resister and LED. Now the photo interrupter would “turn on” the transistor circuit and therefore light up the LED whenever there was an obstruction to the optical path.
Designing the circuit on the breadboard
Schematic of strobe light circuit
With all of the circuitry set, I replaced the wires with some more solid wires that would stick better, tested the circuit again, then hot glued it all down. I then soldered some wire to the LED so I could have the rest of the circuit down below the wheel structure, while the LED would be mounted behind the viewing window. I then hot glued the battery pack that was acting as my power supply and the circuit breadboard to one of the legs of the base, making sure to align the photo interrupter horizontally next to the wheel.
I put something in to obstruct the optical path of the photo interrupter so I could have the light on, and I went frame by frame determining the best positioning of the frame, then marked where exactly along the wheel was the photo interrupter. I then cut small strips of electrical tape, folded them over, and attached them to the side of the wheel at the marked locations. I oriented them so they would slide right through the optical path. Electrical tape was nice because it sticks well and is flexible, so if something got off slightly, no damage would be done to the device, and the tape would still pass through the photo interrupter.
Strobe circuit mounted to the base of the display with tape strips to activate photo interrupter
Now, it was time to clean everything up and test the device!!!
Final Results
It worked!!!! I could see the ring rotating back and forth, and each frame still has all of the freedom of movement within the 3D scene that holography provides!
Now, that’s not to say that it is perfect. In fact, it is not as revolutionary as I had hoped, but it’s still pretty cool. I want to go over the main reasons why it doesn’t look as great as it could.
Hologram recordings: I messed up on the first and third frames, so there are little ghost doubles of the rings on those frames. If the hologram was a little brighter and better, the overall results would be better. Had I had more time, I could have made an even more stunning scene with a better recording geometry in order to have a more convenient readout geometry.
Hologram plate placement: when putting the plates on the wheel structure, my idea to align them to the same side that there was an edge during recording was a good idea, but the vertical placement wasn’t always uniform, and I messed up entirely on one of the plates.
Strobe light triggering notches: the thinner the notch, the shorter the pulse, which helps a better image, but I also was in a hurry to attach these to the display, so they could be slightly misaligned.
LED: in order to get the best “playback” of a hologram, you want to recreate the reference beam. My LED was far from that. Phone flashlights work really well to show holograms because of how bright they are, but I needed a light that I could control well, so I had to sacrifice a bit on brightness and viewing angle/shape.
Overall mechanical “wobbling”: any slight movement the wrong way could lead to the images not showing up quite as well as would be preferred.
All of these reasons compiled made it so the display was far from perfect, but nevertheless, I am so happy that it worked! I learned so many new skills and refined some rusty skills. I’m grateful for the help I received in creating and developing this project, and I’m proud of myself for pushing to make it happen.
Finally, the moment you’ve all been waiting for….
Testing the display at various speeds. It works!
The World of 2060
In the year 2060, technology has advanced by a tremendous amount over the past few decades—for most of the world. There are those who have been chosen to be “left behind” by technology for a variety of reasons, but chief among them are the overarching belief that with each new invention, human values of being industrious and thinking for ourselves, rather than letting machines and computers do our work and thinking for us.
While most people who are “left behind” are okay with forsaking all new forms of technology, sometimes they wonder how they might enjoy some of the new inventions for themselves in their societies. This leads them to get quite creative, as they are limited to the tools created up through the year 2019 to design and create. Some won’t even touch a computer anymore, but so long as the human is doing the planning, designing, and thinking, some computer aided tools such as CAD software, 3D printers, and laser cutters, are acceptable.
Reminiscing on the days when smartphones were prominent and meme culture had only 2D displays to work their magic with, one young student was curious. After talking to his grandparents one day, he heard them arguing for the 1,071st time about the true pronunciation of “GIF” (it’s definitely pronounced like “gift” without the “t”), he investigated what was so special about this medium of communication. If a picture is worth a thousand words, how about a bunch of them in quick succession? What if you slap a few words on there? While video is quite the ubiquitous concept, our young friend wondered why these small snippets of video in their most simple and decompressed state were so popular generations ago.
He knew the rest of the world had already achieved real-time holographic (and other modes of 3D display technological) video, but that tech was forbidden. How could he recreate something like that using the tools and skills he had access to, rather than letting some computer figure it all out for him. After much research and preliminary designs, this young student gathered his supplies and got to work. He had all of the resources he needed to make a working and unique display. He took inspiration from the proper primitive technologies, as adhering to his grandfather’s generation’s obsession with nostalgia was obligatory. He then had one thing left to do—find an object worthy of such a grand invention that would hold much meaning to his grandfather.
Finding this object turned out to be much harder of a challenge than finding the supplies needed to make this contraption (some of the stuff, like the holographic plates, were just laying around in his grandfather’s workshop). However, he realized that the one item he needed was in front of his eyes the whole time—his grandfather’s MIT class ring (or “rat” as his classmates called it). As the graduating class of 2019, his grandfather was the last class to be free by the unfortunate corruptions and scandals that plagued the school until the advisory board was all but replaced with AI. The ring had much meaning to his grandfather and was one of his proudest accomplishments and was also a symbol of his commitment to stay true to the idea of creating and improving the world without sacrificing the concepts of humanity in the process. Indeed, it was the perfect object for this display.
So, after explaining his plan to his grandmother, he got a hold of the ring as his grandfather took it off to go to sleep, and proceeded to make the holograms of the ring, then promptly returning it before his grandfather woke up. He then got to work on constructing this device which was reflective of older technologies and trends and aspired to be more like newer ones. He created what is now referred to as HoloGIF. I hope you enjoy his creative retro-futuristic invention.
Creative Commons Attribution 4.0 International License (CC-BY 4.0)
