Instructable for building a proper light-tight box?

I tried searching for "dark box," "light box," "film box," "film processing," even for pinhole cameras. I couldn't find an I'ble which directly teaches how to make a high-quality light-tight box (felt lined, gasketed locking lid, etc.). Did I just choose poor keywords? Do any of the photo-gurus here know whether such an I'ble exists? For a couple of single-photon Physics I'bles I'm working on, I've realized that asking people to seal up a whole room and make it totally light-tight is ridiculous and impractical. I ought to get the same effect with a dark-box using a good viewport and head shroud. Rather than writing a whole I'ble myself, I'd rather cross-reference something which already exists.

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bertus52x116 years ago
What is the min / max dimension you require?
kelseymh (author)  bertus52x116 years ago
I was envisioning something maybe half a meter on a side. That gives enough projection distance to get naked-eye visible interference fringes, but not so big as to be unweildy. I'm not in a position to make and document such a thing myself, so I was hoping someone might already have an I'ble for it that I could just reference.
Maybe a long shot, but I was thinking about PVC tubing (larger sizes).
It is easy to cut, it is rigid to attach stuff, there are many blind caps and T-pieces and there are x-overs available to build whatever you like...
FlavorD6 years ago
Without the box, I just discovered that two razor blade slits in paper about 3.8in apart will give a very nice interference pattern from my video projector on a wall about 8 feet away.
kelseymh (author)  FlavorD6 years ago
Really? That's impressive. You put the slits about 10-15 cm away from the projector lens? I knew those bulbs were bright, but I didn't realize they put that much light out. A setup like that would be awesome for a classroom demonstration of interference and diffraction.
Thanks!
Sorry, I meant 3/8in., not over 3in.

I also discovered you can get the effect with two fingers. I think the light is spreading out from the different sides of the gap between the fingers and causing the interference pattern.
kelseymh (author)  FlavorD6 years ago
If there's only a single slit, it's a diffraction pattern. Visually, the two look quite similar, but they're quantitatively different (and you can extract different information from the patterns).

Thanks for the clarification on dimensions. For my projects (see my profile) I think you still need a light-tight box, because the intensity is designed to be extremely low (single photons). Nevertheless, this is a great demonstration.
NachoMahma8 years ago
. How about a cardboard box, head-size hole cut in the bottom of one end, "drape" around head hole?
kelseymh (author)  NachoMahma8 years ago
That's what I'm starting to imagine. My concern is how to mount the laser pointer (and eventually the double-slit grating and camera) and keep everything nicely aligned.
. It may need to be large/long enough that it will have to be set on a table, with the access hole hanging over the edge. Or view from the end, a la old glass-plate cameras. Someone in one of the sewing groups should be able to design the "drape" for you.
. Mounting it to a table will help with stability. Or piece of plywood for the bottom.
. Cardboard can usually be obtained free, so size shouldn't add to the expense. If one has enough space, one could build a cardboard box big enough to crawl inside of. Seal the entry with opaque tape from the inside. Remember to come out for air. ;)
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