any affordable despecklers out there?

[widaxi]

I am looking for an affordable laser despeckler (speckle reducer) to use with a laser scanning pico projector module.
The only one I found is 3x the price of the pico projector, that can never be commercialized.
Would want something that is $50 for few hundred piece order at least.
is there any?

(I don't know what technology goes inside these so if the price I am looking for is unrealistic now you know why)

[VDX]

... you can feed the laser beam into/through a fiber ...

Viktor

[kecked]

How does this thing work? Tried looking it up but just find buy my stuff ads with no explaination. I get it destroys coherence but how.

[VDX]

... some are moving/oscillating "diffusors", others uses glass fibers to "homogenize" a laser beam.

Here a sample description:

An adjustable despeckler is formed by combining two optical fibers (710, 718) in parallel and adjusting the amount of light in each path with the help of a rotatable waveplate (704) and a polarizer (706) as a beam splitter.
The smoothed image data is then selectively sharpened using variable contrast mapping that provides overshoot-free variable-sharpening and despeckling.

Viktor

[Eidetic]

A desplecker for a laser beam is a "holy grail". No current technology will do it on such a small scale, and there's certainly nothing that'll cost less than $50. One can use an LCoS display random diffuser functions, but that won't work with scanning beam projectors. I think you're gonna' have to live with the speckle.

[Photonbeam]

I did a service call on a laser fingerprint detection system bought by the Dallas County Sheriffs Dept. in the late '70's. It was a Spectra Physics 164 4W argon launched into a fiber optic. A loop of the fiber was taped to an aquarium pump which vibrated the fiber enough to homogenize the light and eliminate the speckle. Crude but effective. There must be better ways now with current technology.

[mixedgas]

I did a service call on a laser fingerprint detection system bought by the Dallas County Sheriffs Dept. in the late '70's. It was a Spectra Physics 164 4W argon launched into a fiber optic. A loop of the fiber was taped to an aquarium pump which vibrated the fiber enough to homogenize the light and eliminate the speckle. Crude but effective. There must be better ways now with current technology.

.

Put one of your fold mirrors on a piezo fed with its resonant frequency exclusive "ORed" or otherwise gated or mixed with a narrow band white noise (at most a few KHz) from a shift register noise generator. You'll have to find the assembly's first resonance, because once a mirror is on there, that frequency is inevitably going down. Its not a great despeckle, it is some times a however a "good enough" despeckle. You can even try to do it with a thin AR coated plate on a piezo. Both of these will inevitably have less energy on the screen and all you can achieve is say 1/4 or 1/2 wave of shift at the defracting optic by moving the beam sideways. But you will have to some how actively find that resonance, because it is narrow.
.



For one application I used a rotating transmissive disk that had been ever so lightly etched by acid, but that is only good in a thin beam, macro application.

.

If I really had to do it, I would have the diode moving in wavelength a few nanometers. There are ways to do that in a lab, but probably a Littman Metcalf cavity or a moving tilted thin glass etalon slide feeding about 4% power back into the diode is way too complicated and/or too much loss for your situation.
~
The commercial laser projector guys were looking at very short pulse width fiber lasers to get the bandwidth up at one time, or to lase one or more lasers at Raman shifted frequencies, then combine them, but that won't work with direct diodes.
`
You can't mount the diode laser's rear cavity mirror on a piezo or noise gen, so your very limited in what you can do.
`
I agree with Eidetic, your in between a rock and a hard place....

Steve

[Eidetic]

I've seen a green laser operating here with a 4nm bandwidth, but the project was shelved over a year ago.