Jacob_Norman
Newly Enlightened
- Joined
- Jun 13, 2017
- Messages
- 5
Hello all,
I am a researcher at a US university, and my adviser has instructed me to come up with a solution to a lighting issue we're having. "Shadowgraph" is a technique used for high-speed imaging, gas and density-based research. For example, shadowgraphs are commonly used to view the blast front of an explosion, due to the change in air density associated with said blast front being visible in the shadowgraph images.
This technique requires a fairly significant amount of light from what is functionally a point-source, and definitely not a distributed series of point-sources. Typically, we use an arc-lamp with a series of lenses appropriate to the task at hand, giving us a relatively bright light, focused onto a finger-tip sized area. My adviser suggested I look into using the "100W LED panels" that Amazon sells, as we already have several of those laying around. (This one: https://www.amazon.com/dp/B00CZ75TWA/?tag=cpf0b6-20) One of these with an appropriate power supply is quite bright, significantly more so than an HID headlight, but it's not enough.
What I'm looking for is suggestions on how to combine several of these LED chips into a singular beam of light that functions as a point source, not as several notably distinct sources of light. I have 4 ideas so far:
1. An old attempt from a colleague of mine, strikingly similar to this old article from '06: http://spie.org/newsroom/0197-non-imaging-optics-combine-leds-into-one-bright-source I saw an older thread on this site from a decade ago discussing this same topic, and involving this article here: http://www.candlepowerforums.com/vb...mbining-multiple-LEDs-to-a-point-source/page2 My colleague assembled a simple 2-D dome shape out of acrylic sheets in 6 layers, flat at the base and covered in reflective mylar plastic. The "top" of the dome was flat and frosted, and light could be seen "seeping" out of the "sides" of the dome, likely due to not properly observing refraction math.
2. A far more expensive option of individually collecting the light from the LED chips into fiber-optic cables, perhaps requiring collimation first, then using a laser splitter the "wrong-way 'round" to merge the light beams into one, then de/focusing it to the correct diameter upon exiting the fiber-optic.
3. A far more machining-intensive design where the LED chips would not be mounted co-planar, but in a ring facing into each other, then using mirrors to aim the light "out" of the ring, perhaps with a reflector around that ring to help aim the light, then even an additional lens after that reflector.
4. I have seen the Lambda 421: https://www.sutter.com/IMAGING/lambda421.html and while I could possibly construct something "homemade" in a similar fasion, it would require collimation, the same drawback #2 has. I am at the moment unaware of any simple tools or strategies for collimating light that exist on the common market, so this certainly seems like a challenge and a drawback to me.
Any feedback you gentlemen could provide me on these ideas or your own LED combination strategies would be helpful in this pursuit.
I am a researcher at a US university, and my adviser has instructed me to come up with a solution to a lighting issue we're having. "Shadowgraph" is a technique used for high-speed imaging, gas and density-based research. For example, shadowgraphs are commonly used to view the blast front of an explosion, due to the change in air density associated with said blast front being visible in the shadowgraph images.
This technique requires a fairly significant amount of light from what is functionally a point-source, and definitely not a distributed series of point-sources. Typically, we use an arc-lamp with a series of lenses appropriate to the task at hand, giving us a relatively bright light, focused onto a finger-tip sized area. My adviser suggested I look into using the "100W LED panels" that Amazon sells, as we already have several of those laying around. (This one: https://www.amazon.com/dp/B00CZ75TWA/?tag=cpf0b6-20) One of these with an appropriate power supply is quite bright, significantly more so than an HID headlight, but it's not enough.
What I'm looking for is suggestions on how to combine several of these LED chips into a singular beam of light that functions as a point source, not as several notably distinct sources of light. I have 4 ideas so far:
1. An old attempt from a colleague of mine, strikingly similar to this old article from '06: http://spie.org/newsroom/0197-non-imaging-optics-combine-leds-into-one-bright-source I saw an older thread on this site from a decade ago discussing this same topic, and involving this article here: http://www.candlepowerforums.com/vb...mbining-multiple-LEDs-to-a-point-source/page2 My colleague assembled a simple 2-D dome shape out of acrylic sheets in 6 layers, flat at the base and covered in reflective mylar plastic. The "top" of the dome was flat and frosted, and light could be seen "seeping" out of the "sides" of the dome, likely due to not properly observing refraction math.
2. A far more expensive option of individually collecting the light from the LED chips into fiber-optic cables, perhaps requiring collimation first, then using a laser splitter the "wrong-way 'round" to merge the light beams into one, then de/focusing it to the correct diameter upon exiting the fiber-optic.
3. A far more machining-intensive design where the LED chips would not be mounted co-planar, but in a ring facing into each other, then using mirrors to aim the light "out" of the ring, perhaps with a reflector around that ring to help aim the light, then even an additional lens after that reflector.
4. I have seen the Lambda 421: https://www.sutter.com/IMAGING/lambda421.html and while I could possibly construct something "homemade" in a similar fasion, it would require collimation, the same drawback #2 has. I am at the moment unaware of any simple tools or strategies for collimating light that exist on the common market, so this certainly seems like a challenge and a drawback to me.
Any feedback you gentlemen could provide me on these ideas or your own LED combination strategies would be helpful in this pursuit.