Building a low-power, multi-wavelength, laser array?

The goal of this experimental idea is to identify the wavelengths of paranormal anomalies (ghosts). The idea is take various wavelength lasers from 355nm (UV) to 808nm (IR) and place them in an array that will project onto a flat surface. These will then be monitored via video for refraction and/or distortion. I don't want anything dangerous (requiring me to equip all my team members with goggles), so I'm looking at keeping everything 5mW and under.

A) Is this even possible given the limited maximum power requirements. I've seen plenty of 5mw red and green diodes, but what about the other wavelengths? I'm looking at getting as many different wavelengths as I can to cover as much of the visible and invisible spectrum as posible.

B) What about the yellow/orange range? It seems like these are not generally available as laser diodes or are VERY expensive if they are.

If you are seeking a broad range of wavelengths you are looking at serious expenditure even for low powers of certain wavelengths.

As you span whatever part of the spectrum you need, what kind of spacing between wavelengths are you after? There are many wavelengths where no easily acquired laser exists..

ElektroFreak said:

If you are seeking a broad range of wavelengths you are looking at serious expenditure even for low powers of certain wavelengths.

As you span whatever part of the spectrum you need, what kind of spacing between wavelengths are you after? There are many wavelengths where no easily acquired laser exists..

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Well, I was hoping to get each color of the light spectrum...so it varies. Some bands such as yellow and orange are 20nm and 30nm wide, respectively. Green, on the other hand, is 75. As indigo, yellow and orange are probably out, I was thinking of going something like this...

355nm
Delta of 50
405nm
Delta of 68
473nm - if I can get a low power blue, otherwise a Delta of 127
Delta of 59
532nm
Delta of 103
635nm
Delta of 173
808nm

Red and green being the widest bands, hence the biggest delta between wavelengths. I'd really like something in the near infrared, as well, say around 770nm.

At this point, I'm not figuring in price (within reason) .

Well I think what your trying to achieve is going to be difficult, considering you can only achieve red, IR and 405nm colours through diodes, green is a DPPS system, which consists of an IR pumped set of crystals which changes the light to green (532nm.)

I think the best option for you would to do a bit of research on the forum, and look at sightfx's seven colour build kit, it basically consists of 3 heatsinks which can hold a green, violet and a red module, these are then ran through a set of optics from a PHR sled and the 3 beams are combined to one.

You could modify this build slightly, so that each laser runs through a pot and allows you to adjust all the lasers power, this way you can get all the way through the visible spectrum practically.

Then for the IR spectrum you could go for an IR diode, as for below 405nm I've never herd of any completely UV diodes (below 390nm) since they can cause cancerous cells.

To do the multi colour sled build at low powers your looking around 200-250$ and then a cheap IR diode costs nearly nothing, but you'll also need a driver for around $25.

It might be worth you looking into some other light source for what your trying to do... "hunt ghosts"

Hope this helps.

What about using a prism to difract white light?

Why you need the light to be coherent?

The sled idea is an interesting thought, but I would have to build several of them to shoot multiple wavelengths at once....short of cycling them with a microcontroller and datalogging the wavelength to a timestamp on the video...which is WAY too complicated. The main reason I'm looking at this approach is because a) I would have set wavelengths for reference and b) can do multiple beams at one time.

You wont get any other wavelenghts than 405nm,532nm or 650nm out of these builds. You would only mix the wavelenghts to a colour...

why lasers? you can get 1w leds in almost every color. 400nm, deep blue, cyan, green, yellow, orange, red, deep red, infrared. with a lens, you can collimate it pretty well, having a several inches "dot" after a meter. perhaps an aperture somewhere in between for a nice clear dot. plenty of power. with UV, it will be difficult and expensive, both for lasers and leds. expect 200$ for a led, but these go down to 250nm. i would stick to 400nm as the lower end, though..

interesting project, for sure! ;-)

manuel

EPRSEric said:

355nm
Delta of 50
405nm
Delta of 68
473nm - if I can get a low power blue, otherwise a Delta of 127
Delta of 59
532nm
Delta of 103
635nm
Delta of 173
808nm

Click to expand...

Pretty much all of those wavelengths are available, 808 is very easy to get, 635 isn't hard to get, and cheap, 532 is very cheap and very easy to get, 473nm is somewhat expensive, 405 can be done with any kind of blu-ray diode, 355nm I believe would be the hardest to get out of all these, you may need to contact a few companies like CNI etc.


The wavelength of the lasers wont be exact, as they can drift slightly with temperature etc, but for what you are trying to do they should be respectable.

Green is available as a diode, however it's wavelength is around 515nm and it would be very, very expensive.

Krutz said:

why lasers? you can get 1w leds in almost every color. 400nm, deep blue, cyan, green, yellow, orange, red, deep red, infrared. with a lens, you can collimate it pretty well, having a several inches "dot" after a meter. perhaps an aperture somewhere in between for a nice clear dot. plenty of power. with UV, it will be difficult and expensive, both for lasers and leds. expect 200$ for a led, but these go down to 250nm. i would stick to 400nm as the lower end, though..

interesting project, for sure! ;-)

manuel

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There's something I hadn't thought about! I don't know if I could get beam tight enough, though. I'm looking at covering distances across rooms of all sizes, as well as down long hallways. A place we investigated last weekend was 109,000 sf...big! So, unless I spaced the LEDs far apart, there would be crossover between the colors...not exactly ideal for my application. However, on a smaller scale, this could work quite nicely.

Oh my goodness ....you never want to "CROSS the BEAMS" !

It can be done. Here is the array I would use:
405 Diode
430 D3
457 DPSS
473 DPSS
488 OPSL
515 DPSS
532 DPSS
577 OPSL
593 DPSS
629 OPSL
660 Diode
700 Diode

^Hope the OPs a millionaire..

EPRSEric said:

The goal of this experimental idea is to identify the wavelengths of paranormal anomalies (ghosts). The idea is take various wavelength lasers from 355nm (UV) to 808nm (IR) and place them in an array that will project onto a flat surface. These will then be monitored via video for refraction and/or distortion. I don't want anything dangerous (requiring me to equip all my team members with goggles), so I'm looking at keeping everything 5mW and under.

Click to expand...

On my 355nm unit, you can remove the harmonic separator and IR filter to get a combination of 808nm, 1064nm, 532nm and 355nm in one dot. I'm not sure how you'd separate the dots though; perhaps a diffraction grating of some sort? Anything in the UV region is not eyesafe, you run the risk of cataracts if you don't wear appropriate goggles. Also, the cheapest I can see you doing this whole setup for is about 6k-10k. BTW, you wouldn't happen to be the same guy who wanted to point a laser a "UFOs", would you?

digital_blue said:

BTW, you wouldn't happen to be the same guy who wanted to point a laser a "UFOs", would you?

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No, but now that you mention it... j/k