How to Make an Almost Perfect Ice Lens Not being satisfied with the previous jig, I went off and designed/built a bunch of things.

I wanted to feed my lens machine with cylinders of ice. A cylinder is already circular in two dimensions - a good start. I took a tin can and soldered a piece of steel strapping to the open end. I cut teeth into the strapping. The strapping isn't hardened, but for ice it's just fine. This picture shows an ice cylinder "drilled" out with the modified can. Beside the ice is a piece out of an old disk-drive that I used to hold the ice cylinder.

This picture shows the "machine." It works on the same principle as the "field jig." There is an arm which "rotates" about a pivot point. On the arm is a rotary tool with a coarse bit. The base assembly holding the ice in its frame can move up and down as well as rotate. (The base assembly can also slide back and forth for experiments with plano-convex lenses.) The ice lens can be removed along with the frame and then inverted to machine the other side. The frame also provided a convenient way of holding the lens without melting it.

This is a close-up of the "business" portion of the machine

Did it work? A picture with smoke is better than any words. :-) Note - this lens wasn't as aggressive in it's curvature - but the compensating factor was the optical quality.

Another view with the lens removed from its frame.

This picture and the next were taken with the same camera position. The first picture (to the left) shows pine needles with some burned tinder fungus. The second picture (below) was taken with the ice lens placed in front of the camera lens. This shows the magnification of the ice lens. Due to melting, I rushed this lens so the optical quality is not the best. So why try to make an optically perfect ice lens? Stay tuned....

Eureka - it was always staring me in the Face! From my first day playing with ice lenses, the word "sphere" kept coming up. If we think about a double convex lens, it is just a sphere with its middle removed. Why not use the whole sphere for an ice lens? It certainly has a very aggressive curvature and as long as the ice isn't cloudy, the extra ice in the middle doesn't do any harm. I tried it. Wow.

I started with a block of ice. Using a small hand saw, I first carved a cylinder. I then started to round out the top and bottom of the cylinder. In about 20 minutes I had something that looked like a sphere.

A bit of hand polishing...

Some more hand polishing. The advantage of making a sphere is that "everyone" knows what a sphere looks like. Imperfections are pretty obvious. In a double convex lens, it's far more difficult to identify flaws. The technique for hand polishing is similar to packing a snowball, or making meatballs. The constant "packing" and rotating motion of the hands tends to improve the geometry of the sphere. This picture shows the very short focal point for this lens.

Did it work? The tinder lit so quickly that I had to be fast on the camera shutter! If You Don't Read Any Other Text on this Page, Read this: One very important feature of an ice sphere is that it contains an "infinite" number of lenses. Why is this important? Let's think about a normal double convex lens. Once you are done, there is only one "optical axis." As soon as you tilt the lens in one direction or another, you aren't taking full advantage of the lens. (For a variety of reasons.) Now, here's the beauty of an ice sphere: you can rotate the lens as much as you want. If the sphere were perfect in shape, then any rotation would have no effect. Given that these hand-made spheres are not perfect, we can rotate the sphere and look for the sharpest focus or dot. It is surprising how what I thought was a pretty good sphere worked extremely well in certain orientations and poorly in others. Given the ease of construction and the flexibility in use, I am quite convinced that an ice sphere is an excellent candidate - if not the best - for an ice lens.

My next question was to find out how small of an ice sphere will still work and how quickly I could make one. I gave myself a 15 minute time limit and started with a "random" chunk of ice. The picture on the left shows what I came up with. Did it work? The proof is in the smoke in the next photo (below).

It was quite a journey for me to make fire from ice. I hope you have gained some insights from reading about my discoveries and hope you will share some of your thoughts or experiences. Email Rob.