What is the adverse optical effect inhibiting production of generic ip65 housings?

[FallingGirl]

This is my first post on this forum but I’ve been a longtime grateful lurker.

Anyway, I was wanting to know what effect a secondary transparent medium (such as projecting a quality 5w RGB FB4/ILDA fully built out of box laser’s beam through a window on a waterproof housing) has on the clarity/sharpness/output/etc of the light’s final rendering when it reaches its destination of focus (wall/screen/etc) .

[** Let’s put heat issues aside and just address the optical constraints of adding a second occlusive barrier through which a diode’s beam would need to pass before reaching its final intended point of focus, such as a wall or screen.]


I am a laser hobbyist and enjoy assembling my own show lasers to accompany my Eurorack music performances. But I am far from an engineer and even further from a physicist. And the reason why I ask this question is because there must be some problem with adding a second “transparent” solid medium to a beam’s path or I would expect to see untold numbers of waterproof laser and DMX moving head transparent housings for sale on Amazon/ebay. I believe that one of Pangolin’s brands offers a true weatherproof housing (as opposed to a cheap vinyl rain cover) for its lasers. But the catch is the price. Not only is the price of the housing more expensive than my Prius, the laser designed to fit into this custom housing costs more than i probably earn in a year.


Sorry for the long post (and please comment if I have made my post too wordy as I want to learn proper Photonlexicon forum etiquette).


ALSO, if you know this additional answer, can you please let me know if the same constraints that inhibit the ability to properly render the final output of a laser that is placed in a housing ALSO APPLY TO VIDEO PROJECTORS AND DMX MOVING HEADS?


Thanks so much for any insight you are willing to share 🙏

THE FALLING GIRL

[mixedgas]

Unless the AR coated glass is thicker, there should be almost no difference in clear weather with a clean window. In IP65 it is generally difficult to keep the electronics cool.

Steve

[buffo]

As Steve said, from an optical perspective there's nothing stopping you from building a generic weather-proof enclosure for a laser projector. It would be best to use a thin AR-coated glass window for the aperture portion of the enclosure, but even a thin sheet of ordinary acrylic will work with minimal distortion. I would not recommend enclosing an entire projector in plastic, as that will likely lead to serious overheating issues as Steve mentioned, but if you can design a means to transfer heat out of the case without letting rain and dust in, you should be fine.

The reason you don't see such enclosures for sale for laser projectors is because the market is so tiny, and because there's no such thing as a "standard" laser projector case. Instead, most laser projector manufacturers will offer their own custom, IP65-rated versions of their more popular, higher power units. (Since the higher power units are more likely to be used outdoors.) Also, these outdoor-rated projectors are built to be weatherproof from the start, rather than just being encased in an external weatherproof housing.

Extending your question to video projectors and other non-coherent light sources, you can easily project light from these devices through a glass or plastic case as well. Here again, for best results you'll want to use a thin AR-coated glass window as your aperture, but if you're willing to put up with some loss in optical brightness, you can use standard plexiglass. You'll see a little "fuzz" in a video image that is projected through plastic, just as you may notice some blooming of the spot size from a par-can or moving head fixture, but this effect can be minimized if your window is clean and thin.

Just as laser projector manufacturers sell IP65-rated versions of some of their projectors, lighting manufacturers sell outdoor-rated fixtures too. Because intelligent lighting fixtures come in a wide variety of shapes, sizes, and power ranges, it's easier to weatherproof the fixture itself, rather than trying to stuff it into a generic weatherproof box. (There's also the issue of heat dissipation if you try to enclose it in an external housing.)

Finally, I noted that you mentioned you are building your own laser projectors to accompany your live music shows. Just wanted to remind you that if there's any commerce involved in these events (even indirect commerce, where you are not getting paid for the performance but there is a business that is benefitting from the crowd that is drawn to the performance), then the CDRH has jurisdiction and you'll need to have a laser light show variance *and* you'll have to be using US-legal laser projectors that have been certified under a laser product manufacturer's variance. Enjoying the vibe with some college classmates in a dorm room is fine, but performing at the local watering hole down the street (even for free) places you under federal jurisdiction (along with all of the legal liability if you are found to be non-compliant).

Getting your laser light show variance is not very hard. However, trying to certify a laser projector that you have built is quite difficult. It is possible to apply for a laser product manufacturer's variance, and if you are granted one, you would be able to self-certify your projectors as being US-Legal, but this is a very daunting proposition that will involve a great deal of work (especially when it comes to filing the laser product report). If your goal is to perform laser shows for the general public, it's much easier to start with a US-Legal, certified projector.

Adam

[kecked]

I do recommend installing the window on an angle so the back reflection can’t find the scanners a second time and make a ghost. Ask me how I know……

[mixedgas]

An easy source of Antireflection Coated Float Glass in the US is Hobby Lobby of all places. They charge a cutting fee (not cheap) and X$ per square inch, back in the framing department. They will have an artistic name for it like "museum grade" glass. Be aware that it reflects near UV, so might not be great for 440 nm diodes.

It was cheaper to buy a large sheet and cut it down myself. Even with AR coated glass you still want a few degrees of tilt.

Not the place I'd normally go, but I was pressed for time.

Steve

[swamidog]

why not edmund optical?

https://www.edmundoptics.com/f/high-...windows/12261/

hobby lobby is.... problematic.

An easy source of Antireflection Coated Float Glass in the US is Hobby Lobby of all places. They charge a cutting fee (not cheap) and X$ per square inch, back in the framing department. They will have an artistic name for it like "museum grade" glass. Be aware that it reflects near UV, so might not be great for 440 nm diodes.

It was cheaper to buy a large sheet and cut it down myself. Even with AR coated glass you still want a few degrees of tilt.

Not the place I'd normally go, but I was pressed for time.

Steve

[mixedgas]

QUOTE "hobby lobby is.... problematic.[/QUOTE]

Yeah, but my usual industrial optics and camera shop sources were out of the size I needed, holiday weekend, and sometimes you got to do what you got to do. Getting snow in the galvos is unpleasant.

The projector in question needed a big, oblong, window.

It's very nice glass with good coatings on both sides and cuts easily. My alternative was diamond sawing a thick hunk of coated Pyrex.

Steve

[buffo]

Getting snow in the galvos is unpleasant.

LOL! Your comment reminded me of a Christmas show I did with Jeff (rgb-gas) years ago in Kentucky. He had some Kvant 6 watt RGB projectors that used 532 nm for green. It was so cold outside that we started to lose the green in the projectors! (Yeah, the KTP was getting cold enough to kill the frequency doubling gain.) Ended up running out to Walmart to buy some heating pads and blankets to keep the projectors warm. Crazy times...


I do agree with Marc's suggestion to angle the window a bit so any reflection will miss the galvos though. And really, you don't need a huge window, assuming the projector's aperture is positioned close to the window.

I'll also admit that I never would have thought of looking in a Hobby Lobby store for AR-coated glass!

Adam