How to create super bright laser beams

[tribble]

http://www.maximintegrated.com/en/pr...s/MAX1968.html

?

[logsquared]

Cool chip. Its output is like a class d audio amp. Needs a lot of external components and is limited to less than 15watts. Wonder if they make a 12V version?

[planters]

Yes, I like that chip. Someone want to see if they will sell 1/2 dozen for testing or does this suggest that this "type" of chip may in fact be already available for higher cost , but in ones and twos fro say DigiKey etc?

Twixt the nog and the Christmas gooooose I machined the stainless bar. Less nasty than I feared and now done; always moving a little bit.

[tribble]

Cool chip. Its output is like a class d audio amp. Needs a lot of external components and is limited to less than 15watts. Wonder if they make a 12V version?

The 1969 goes to 24 watts but still 5v and is a lot more expensive. Perhaps there are others out there; just saw that and thought I'd toss it in to the mix here.

[planters]

I have been thinking about a point that was raised a few days ago by logsquared; the inevitable shift in the multiplexed beam as the modulation (injection current) varies. This may be small enough to ignore, but there is no way that it will not occur. I do believe that the DIFFERENTIAL shift of the "hot" diode and the "cold" diode will be small, probably very small as both are modulated from one current to another. They will both red shift as the current rises, but the current will rise in both and to the same amount especially if they are powered in series.

However, the prism does two things to the laser as it passes. It will disperse (or as we want, collimate) the beams based on the differential refractive index of the glass for the different wavelengths. This is our goal, but it will also deviate all the beams. The deviation is large, like 70 degrees and although this can be fixed by simply inserting a steering mirror to send the beam to its target, the deviation will vary with the wavelength (modulation current) as well.

I considered two solutions if this proves more than trivial and I think it will. The first is to use a single scanner/amp controlled by the same modulation voltage signal that controls the red laser. The angle will probably be only a few mrad and after asking a few experts, I'm confident this should work. The second and I believe more elegant solution it to use two prisms, each made of a different glass to create what is basically a achromatic pair. The first, high dispersion prism corrects the converging beams and the second negates the deviation without undoing the convergence correction introduced by the first. I then confirmed that prisms with the right glasses are commonly available and the cost only effects how good the compensation can be. The setup would require the first prism to over correct the incoming beams depending on the level of dispersion of the second glass and then the second prism is inserted and is adjusted to eliminate the deviation of the pair. A little back and forth experimenting will be needed, but the result should be stable and essentially perfect.

[andy_con]

I love how you've gone straight into a build like this without any r&d!

Do some r&d and you will get the answer to the above modulation question

[planters]

What is r&r?

I'm not asking a question. The red shift with current is an established fact and I have seen it myself many times with my deep cooling experiments. Its magnitude is on the order of several nm. This is of the same magnitude as the target wavelength spacing between diodes. The prism will deviate the beam inversely proportional to the wavelength and logsquared saw this effect in his test set up. Where the build comes in is in finding the significance of the several factors that limit your ability to control the beams. If the line width is broad then larger temperature steps are needed to distinguish the beams. Is the manufacturing variability from diode to diode helpful or a hassle. Can the simple open loop thermal bar provide enough temperature gradient and stability? What will be the losses of the prism(s) at angles off of Brewster's and is AR coating necessary?

[andy_con]

FFS, typo...

r&d

[planters]

OK, that makes sense, now. But, the build is the development and I've done the research. So, I agree with you.

[mixedgas]

Eric, to answer your PM, A glass wedge or flat on a galvo or piezo would possibly compensate for the shift. I'm suggesting the wedge to reduce the sensitivity of the adjustment vs a mirror. I have a UV diode based projector assembly that does this using a stepper motor , and they bias two coils to create a microstep as they increase AVERAGE power.

Steve