- This is a hologram that I made by hand. This is also a handmade hologram, but as you can see, it was made by someone who actually knows what they're doing. Both holograms were made
using the same technique, and this one and this one, the technique is deceptively simple. You just make scratches
in a shiny surface. I made my holograms on sheets of black
acrylic using a divider, basically a compass where
both ends are pointy. These aren't like traditional
holograms like this one, but these types of holograms
you get on credit cards are the same as these handmade ones. It's just that the
etching is much smaller. One thing that's hard to appreciate on video is that this thing is 3D. It appears to hover
below the acrylic plate. I can give you a sense of
that by tilting the thing in front of the camera or
moving the camera side to side, but to really appreciate it. Here's a cross view stereogram. If you're able to go cross eyed
until the two images overlap with each other, it should
pop out as a 3D image. You know, while we're doing
the crossview stereogram thing why don't I show you this
traditional hologram as well? It's pretty cool, isn't it? And here are those other etch holograms. To show you how etch holograms
work and how to make them. We'll start with a really simple just a floating point of light and then we'll work up to
something as complex as this. To create a floating point of light all you have to do is gently score an arc into the acrylic sheet. Now, if I put the camera
here and a light source here then you can see that the light
glint off the etched line. But what decides the
position of the glint? Because look, as the camera
moves, the glint moves as well. Well, the simplest way to think about it is that the etched groove is like a curved trough shaped mirror. I was gonna try and figure
out how to build a large one of those so that you could
see what was going on. But actually it pretty much acts the same as a shiny tube like this one. And this has the added benefit of being able to change how bent it is. See when the tube is straight,
the glint is always directly in front of the light source,
wherever I put the camera. But when the tube is curved the glint doesn't travel as far and the same thing happens
with the etch on the arc. And that's really the
key to the whole thing because your left eye sees this image and your right eye sees this image. And if your brain makes the assumption that the glint is in fact an object then your eyes will move so
as to converge on that object. Just like how if you hold your
finger in front of your face you'll see two fingers
until your eyes move inwards they converge on your finger. Then you see one finger
and two backgrounds and the same thing is happening with the glint except in
the opposite direction. Your eyes have to move apart
to get the glint to overlap. And of course, your
brain uses the position of your eyes to figure out
how far away objects are. So if your eyes have to move apart to bring the two glints together then that tells your brain
the glint is further away than the surface of the acrylic. The opposite happens when you turn the arc upside down actually and the glint appears to be
hovering above the acrylic. If you want to make a more complex object then you simply draw out your
shape and then create lots and lots of points around your drawing, creating an etch for each point. You'll notice that the image is distorted compared to the original. And the distortion of the
image actually depends on the location of the
light source and the camera. From what I can tell, if it was possible to have the
light source exactly parallel with the mirror, you might
get a proper rendition of the image, but at that angle you get basically no glint at all. So there's a trade off, and if
I was gonna do this properly I would pre warp the image
in the opposite direction so that when the image became warped by the viewing experience, it would undo the pre-applied warp and the image would look normal. This is all well and good,
but you might be thinking, "Hold on a second, this thing is flat." Yes, it's floating below the acrylic, but it's all at the same depth and the drawing itself is two dimensional. So how can we make this
hologram more interesting by creating lines at different depths and maybe even lines that plunge
in and out of the acrylic? Well, one clue is to be found
in accidental etch holograms that you may have
witnessed in your own life like when you've run out of wiper fluid but you use the windscreen wiper anyway, the top of that bright line
appears to be further away than the bottom of the bright line. Similarly, if a metal
surface has been worked in a circular motion
like this source panel then you'll have a glint line that appears to be
touching the metal surface at the center of the circular work pattern and move away as the light
glint moves outwards. And that's because, well, it turns out that the tighter the arc, the closer the glint appears to be, and the straighter the
arc, the further away the glint appears to be. And that makes sense because if the arc was perfectly
straight at one extreme well that's analogous to the straight tube that I was holding in front of the lights. And in that situation the glint is always directly
in front of the light source. So when your eyes move to line up the glint in that
scenario, they will converge at the same depth as
the light source itself. And then at the opposite end, if the arc was so tight that
it was basically just a dot, well the glint wouldn't
move at all relative to the surface of the acrylic. So it should appear to be at
the surface of the acrylic. And so curvatures in
between those two extremes will give you depths in between. Here, for example I've created a tilted
square where the top edge of the square is further away. So the top edge is created
with straighter arcs. The sides of the square were much trickier because each point along the
line was at a different depth. So I had to adjust the divider and change the position of the pivot point as I went down the line. By specifying where the
arcs start and stop. You can have objects that
appear and disappear, depending on the viewing angle, and
if you get it just right, that means you can create opaque
objects with other objects behind that you can only see
by looking around the corner. Because the opaque square in
this hologram is quite close to the surface of the acrylic. In other words, I was
using quite short arcs. You can actually see the
pivot points that I used for the divider, because it's created all these
little dots in the surface and there are various techniques
you can use to prevent that from happening, but it makes
the whole process a lot slower. The final thing I wanted
to try was a hologram of the corner of a cube sticking out. This is a lot harder, because all the lines are
changing death along their length and it was really mind bending to try and work out pivot position and divider adjustment
for every single point. I also wanted to see if I
could have the actual tip of the cube poking out from
the surface of the acrylic, which meant having some
arcs that were upside down. In the end, I made a bunch of mistakes and it was so hard to get to this point that I just rage quit on this particular hologram. So this is as much as you get of this one. This is actually my attempt
to copy William J Beaty. He discovered the divider
method independently. Though he does mention that he found some prior
literature on this subject. Actually, he has some great advice on things like etching
technique and stuff like that. I'll leave a link to his website. Actually, his YouTube
channel is brilliant too. There's a link to that in
the description as well. But anyway, as you can see,
I got part of the way there. The bits that stick out from
the acrylic behave weirdly and the glints are quite long. I think that's an artifact of
the arcs being upside down. I thought it would be
really cool to have a way for people to be able to
share their own creations like if you end up making
your own etch hologram. So on my Discord server, I've created a channel
specifically for that. I've called it Science Fair Project. So if you do end up
making an edge hologram do hop over to my Discord server. The link is in the description. Now here's the question. How do you get from this to this? Well, this one was
created by Matthew Brand. He really helped me to
understand what's going on, linked to all his stuff
in the description. Some of his creations
are for sale, in fact. So one issue you may have
realized with these holograms that you don't get with this hologram, is the image warps and bends in weird ways as you
change your viewing angle. Matthew explained that that's because actually an
arc is the wrong shape. In fact, most people
creating etch holograms aren't using the right shape. They're all approximations
to the correct curve. Matthew figured out what
that curve should be. I won't go into the equations
or anything like that but look, he kindly sent me this animation of how you might create the correct curve. So it's possible to do it mechanically with the right linkages. But actually what Matthew
did was create a CNC process. So he defines the 3D shape
that he wants in software, and then his code converts that into the appropriate etching. The etching is then carried
out by the computer. It's really interesting to just look at the etches themselves because there would be no way of knowing just looking at this mess
here, that this would pop out into a 3D shape with an
appropriate light source. This is a depiction of
Borromean rings, by the way. So here's a quick tangent about that, because they're really cool. It's possible to link
three closed loops together in such a way that no two
loops are linked together meaning if you break any
one of the three loops the other two come apart,
and that's Borromean rings. What about those vinyl records? Well, earlier I said that the arc of a circle is not the right shape for the etch because it
causes warping and distortion, except under very specific
circumstances where the arc of a circle is the right
shape for the edge line. And that specific circumstance
is when the etch goes in a full circle and the image rotates once for
every rotation of the circle. And that fact has been used beautifully in these commemorative
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