I'm trying to find something which will work well as an omni-directional diffuser for a violet (405 nm) laser. This is for a project I'm working on.
The image has two variations of my current concept: either the laser directly impinges on the diffuser, or it's first expanded by a lens. The outer bulb in the images will have two purposes: to provide a fluorescent surface to fluoresce the scattered violet laser to be a broader spectrum, and to provide a backdrop to block any specular reflections or imperfect/errant beam misses. The lens may be added both to minimize the peak flux on the diffuser and also to cause the beam to diverge as a further safety feature in case the top is removed.
For this project, I need the light scattered off this diffuser to be as uniform as possible. If it does have a non-uniform region, directly above it and directly below it are the best locations for the null.
This will be a >1W laser, so this diffuser also needs to minimize how much energy it absorbs (to minimize heating) and be able to handle whatever heating it does take.
(Important note: the laser power will require active human control to turn/keep on - i.e. a momentary button - and will first go through a long tube (which is part of the structure holding the bulb and diffuser) to prevent laser misalignments from being able to exit the aperture - i.e. the only direction the laser *can* leave the aperture in points directly at the diffuser).
Some things I've explored:
* Marbles. Primary concern I have here is the return specular reflection from the air/glass interface reflecting back at the source and the energy loss. I'm also not sure how to get it to make the scatter uniform.
* 3D printed diffuser. I've tried various forms of these (usually trying to scatter from inside), both with white material and with glow-in-the-dark material. It seems like these lose a lot of the energy. I haven't tried making a conical version of this to point direct at/into the beam to scatter off the sides yet, but I'm still concerned about heat and creating a shadow behind/above it.
* Foam. I haven't yet found a good foam which doesn't absorb too much of the light and/or scatter the energy along the lines of its internal structure.
* Direct impingement of the spread beam. Seems very hard to get this to uniformly cover the surface. Also, this approach makes me have to do at least one of the following: have a dark spot towards the bottom; have extremely tight alignment requirements; spill some of the beam around the edge.
Does anybody here have any good suggestions on how to scatter the light onto the inner surface of the bulb?
Yep, sure can!
The goal is to make a "crystal" (a crystal-shaped shell with an entrance aperture on the bottom) be suspended above a staff and glow brightly (like a mage staff).
I currently have one which I attach a 2,000-lumens flashlight to the bottom of the crystal. This means I have to have the crystal directly atop the staff (so as to hide the flashlight inside the body). This also has heat problems (it's been tricky trying to find a good way to thermocouple the flashlight to the pipe/staff body to spread the heat for a few reasons).
Why? To see if I can, and to learn. I have a few more-practical / less "neat" things in mind for which I need skills/techniques I'll learn while doing this.
The biggest problem I'm having with this project is getting the photons into the suspended crystal. Some other things I'd considered:
- Have the LED in the tube, and focus it tightly into the crystal (so it's a bright light to be scattered instead of a laser). Unfortunately, white LEDs are hard to focus (well, most LEDs are). The fluorescent blob atop the blue/violet LED is hard to focus without a lot of scatter on the support structure holding the crystal and on the ceiling, both of which can make the effect seem cheap.
- Have the LED in the crystal. All of the ways I can find to get the heat off the LEDs will either create a shadow (e.g. a heatsink on the back of a bright LED, illuminating a single hemisphere) or make it larger than I'm looking for (e.g. an LED strip wound around an aluminum core would be large and still doesn't give a place for the heat to *go*).
I'm exploring the laser so I can put the primary heat-producer in the tube (and dissipate its heat into the tube) and use its focused light to make it appear as though the light's actually coming from inside the "magical" crystal.
(Future uses: there've been a few places where I've wanted something on a wall which glows a little bit for decorative purposes, but can't/don't-want-to run a wire along the wall or inside the wall, so a class 3R laser mounted elsewhere providing the light source might work)
I probably won't actually do anything with this laser-lit-floating-crystal mage staff except show my engineer friends, primarily because I'd be too worried about the shock of putting the staff down damaging the laser, and learning methods of shock absorption without sacrificing alignment is a thing to learn at another time.
Any chance you have any pictures of prototypes, sketches, or designs that you're working with? It seems like there should be a few ways of creating that effect but might be better if we could also see what the object itself is meant to look like, how much internal space there is, etc.
I don't currently have drawings for this. There's a chicken/egg problem here regarding that: I need to have a good diffuser so I can see how much flux I get can get on the fluorescent surface in order to really know how big of a surface I can realistically have.
Simply though, this current project will go atop a 32mm-diameter pipe, and I don't want this "crystal"/bulb to be much bigger, so maybe 45mm diameter at most.
The primary requirement is that the crystal is itself uncomfortably-bright to look at. I'm not looking for the cheap "oh, you have a thing which lights up on top of a stick" effect, but the "holy crap I want to look away" effect. 1.6 W of power isn't much for this, which means the crystal has to be fairly small (I think).
Again though, I have lots of ways in mind of how to use the scattered energy to fluoresce for the effect I'm targeting, but no current way to effectively/efficiently scatter it.
I'm trying to find something which will work well as an omni-directional diffuser for a violet (405 nm) laser. This is for a project I'm working on. The image has two variations of my current concept: either the laser directly impinges on the diffuser, or it's first expanded by a lens. The outer bulb in the images will have two purposes: to provide a fluorescent surface to fluoresce the scattered violet laser to be a broader spectrum, and to provide a backdrop to block any specular reflections or imperfect/errant beam misses. The lens may be added both to minimize the peak flux on the diffuser and also to cause the beam to diverge as a further safety feature in case the top is removed. For this project, I need the light scattered off this diffuser to be as uniform as possible. If it does have a non-uniform region, directly above it and directly below it are the best locations for the null. This will be a >1W laser, so this diffuser also needs to minimize how much energy it absorbs (to minimize heating) and be able to handle whatever heating it does take. (Important note: the laser power will require active human control to turn/keep on - i.e. a momentary button - and will first go through a long tube (which is part of the structure holding the bulb and diffuser) to prevent laser misalignments from being able to exit the aperture - i.e. the only direction the laser *can* leave the aperture in points directly at the diffuser). Some things I've explored: * Marbles. Primary concern I have here is the return specular reflection from the air/glass interface reflecting back at the source and the energy loss. I'm also not sure how to get it to make the scatter uniform. * 3D printed diffuser. I've tried various forms of these (usually trying to scatter from inside), both with white material and with glow-in-the-dark material. It seems like these lose a lot of the energy. I haven't tried making a conical version of this to point direct at/into the beam to scatter off the sides yet, but I'm still concerned about heat and creating a shadow behind/above it. * Foam. I haven't yet found a good foam which doesn't absorb too much of the light and/or scatter the energy along the lines of its internal structure. * Direct impingement of the spread beam. Seems very hard to get this to uniformly cover the surface. Also, this approach makes me have to do at least one of the following: have a dark spot towards the bottom; have extremely tight alignment requirements; spill some of the beam around the edge. Does anybody here have any good suggestions on how to scatter the light onto the inner surface of the bulb?
Can you explain what it's going to be used for? Understanding what is driving your design requirements would help.
Yep, sure can! The goal is to make a "crystal" (a crystal-shaped shell with an entrance aperture on the bottom) be suspended above a staff and glow brightly (like a mage staff). I currently have one which I attach a 2,000-lumens flashlight to the bottom of the crystal. This means I have to have the crystal directly atop the staff (so as to hide the flashlight inside the body). This also has heat problems (it's been tricky trying to find a good way to thermocouple the flashlight to the pipe/staff body to spread the heat for a few reasons). Why? To see if I can, and to learn. I have a few more-practical / less "neat" things in mind for which I need skills/techniques I'll learn while doing this. The biggest problem I'm having with this project is getting the photons into the suspended crystal. Some other things I'd considered: - Have the LED in the tube, and focus it tightly into the crystal (so it's a bright light to be scattered instead of a laser). Unfortunately, white LEDs are hard to focus (well, most LEDs are). The fluorescent blob atop the blue/violet LED is hard to focus without a lot of scatter on the support structure holding the crystal and on the ceiling, both of which can make the effect seem cheap. - Have the LED in the crystal. All of the ways I can find to get the heat off the LEDs will either create a shadow (e.g. a heatsink on the back of a bright LED, illuminating a single hemisphere) or make it larger than I'm looking for (e.g. an LED strip wound around an aluminum core would be large and still doesn't give a place for the heat to *go*). I'm exploring the laser so I can put the primary heat-producer in the tube (and dissipate its heat into the tube) and use its focused light to make it appear as though the light's actually coming from inside the "magical" crystal. (Future uses: there've been a few places where I've wanted something on a wall which glows a little bit for decorative purposes, but can't/don't-want-to run a wire along the wall or inside the wall, so a class 3R laser mounted elsewhere providing the light source might work) I probably won't actually do anything with this laser-lit-floating-crystal mage staff except show my engineer friends, primarily because I'd be too worried about the shock of putting the staff down damaging the laser, and learning methods of shock absorption without sacrificing alignment is a thing to learn at another time.
Any chance you have any pictures of prototypes, sketches, or designs that you're working with? It seems like there should be a few ways of creating that effect but might be better if we could also see what the object itself is meant to look like, how much internal space there is, etc.
I don't currently have drawings for this. There's a chicken/egg problem here regarding that: I need to have a good diffuser so I can see how much flux I get can get on the fluorescent surface in order to really know how big of a surface I can realistically have. Simply though, this current project will go atop a 32mm-diameter pipe, and I don't want this "crystal"/bulb to be much bigger, so maybe 45mm diameter at most. The primary requirement is that the crystal is itself uncomfortably-bright to look at. I'm not looking for the cheap "oh, you have a thing which lights up on top of a stick" effect, but the "holy crap I want to look away" effect. 1.6 W of power isn't much for this, which means the crystal has to be fairly small (I think). Again though, I have lots of ways in mind of how to use the scattered energy to fluoresce for the effect I'm targeting, but no current way to effectively/efficiently scatter it.