Laser and smoke update

April 08, 2019  •  Leave a Comment

So few blog posts back I did a little piece on photographing smoke being "cut" by a flat laser beam. My experimentation with that was only partially successful. While the lenses (for the laser) I purchased did create a flat beam they also really weakened the output of the light and didn't create a nice clean flat beam. I presume that because the lenses are made of polycarbonate, are dirt cheap, and not designed to fit any of my lasers specifically that I'm getting suboptimal results with the beam.

I keep coming back to trying to find a better lens to put in my lasers to create the flat beam and I've now decided to abandon the idea of using a lens at all. There are a number of reasons for this.

1) Any lenses that I can buy in a small quantity seem to be of poor quality

2) Any lenses that are made of glass (or a higher quality of material than the ones I have) are not sold in small batches. I don't have the budget to spend $400-$600 on a hundred or more Powell lenses.

3) With the blue laser in particular, I'm worried about having a lens made of anything other than glass in the path of the beam. I already have a small scorch mark on the ceiling of my office (it's not noticeable unless you know exactly where to look for it) when I accidentally pressed the button on the laser and turned it on (probably why these things come with a lock!). The laser was on for a second, maybe, but it was long enough to heat the paint on the ceiling to slightly discolor it. In other words, I don't want to melt the lens inside the laser, start a fire, or permanently damage the laser itself (or all three).

4) I really need a nice clean, bright line to do these photographs.

A couple of days ago I came across polygon mirrors. If you have ever looked inside the barcode scanner housing at the grocery store you can see motors spinning something that generates a flat line. I always wondered what those motors were doing. They are spinning a polygon mirror at around (I think) 10,000 RPM which take a red laser point and create a very fine and clean red line. These mirrors are made from a metal. I'm assuming probably a highly polished aluminum. The metal doesn't matter though. My blue laser will never heat it enough to actually damage it. Just in case, I do plan to test this in my garage here in the near future just to make sure it won't mar or pit the surface of aluminum. The test won't be a true test but it will be extreme enough that I'll know if there's any chance of damaging aluminum. While I suppose I could figure out a way, I won't be spinning a soda can at 10,000 RPM. If I hold the beam on a static can for several minutes and there's no visible damage then I'll be satisfied that there is pretty much zero risk to damage an actual spinning mirror.

Now comes a new problem, though. It appears that I'm not going to be able to order a polygon mirror that I can just plug in and start using. More likely (and If I'm going to keep this on a budget), I'll have to find a polygon mirror, motor, circuit board assembly that I'll have to figure out how to power, put in some kind of protective housing, and give me an easy way to set it up for aligning it with the laser (like clamping it down). A soldering iron has always been on my list of things I should have in the house but I still haven't prioritized buying one. I suppose this would be a good excuse to do so but that leads to the next problem. I don't know what I'm doing. I need to connect a power source to the board, have the right power supply, figure out how to house it, etc. All things I could eventually figure out but that's also time I'm not spending on photography and I'm starting to run out of content to post as it is. I just don't have time to invest in creating the tools for this particular project. I need to be out creating new works; but that doesn't mean I have to give up on this idea either.

So now I'm looking for an accomplice that can help me with creating the solution now that I've found one. I've already reached out to one person but if you're reading this and you know someone (or you, yourself) are good with electrical engineering, electronics, etc. I'd love a hand at this.


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