New oclaro 700mw diode

[planters]

OK, I measured the dual P73 module more carefully and the beam that exits the projector, measured at the scanner position, is actually 6mm wide by 3.2mm high. At a baseline of 17.7M, the spatially filtered beam is 14mm by 4mm. The beam should spread to 6/5 x 14mm or 16.8mm if it had been truly 5 mm in width. That calculates to 0.67mrad in the worst axis.

I discovered an interesting phenomenon however. The spatial filter uses a 1 power telescope with two symmetrical 75mm PCX lenses. This should not effect the near field beam dimensions and it does not. This should also not effect the far field divergence, but it does. Maybe the long FL lenses are easier to position to remove residual defocus out of the diodes that requires too fine an adjustment of the 4mm FL Optima collimators. Maybe the spherical lens pair introduces some spherical aberration that counteracts some over correction in the aspherical collimators. I actually think it might be some of both because it cleans up the beam as well and this is before the spatial filter blades are moved into position.

[logsquared]

That's truly strange. If the lenses are flat to flat or curved facing curved they should cancel each others aberrations. I wish I new more about optics. The thing I think would be most worth investigating/ learning is the aspheric constant and how it applies to collimation of the diode. Ever try using a spherical 4mm as a collimator ? It doesn't work. Not even close. You end up with an hourglass shaped spot with airy disks. Also, I have tried odd aspherical lens from ebay and surplus, etc. And most don't work?

[planters]

The thing I think would be most worth investigating/ learning is the aspheric constant and how it applies to collimation of the diode.

I believe that almost universally, the aspheric modification of the lens is calculated to cancel the spherical aberration when the lens is placed at its FL from a point source and so would produce an aberration free collimated beam. The laser emitter is not a point source and the beam that exits has structure and divergence dependent on the cavity. So, the aspheric is a good approximation, but I now think it can be improved to decrease the aberration from other sources in the optical train as well as any residual from the collimator.

I believe you are right about the symmetrical lenses, but I am not looking to avoid spherical aberration, but to counter the aberration already there by orienting the lenses asymmetrically. That is why the best situation so far has been the modification of the cylinders. I think most of the aberration is in one axis. These don't cancel because they are of significantly different FL's.

Take a look at my thread about improving red beams in advanced tech discussions.

[planters]

With all the precise measurements for the P73 diode, that I just posted in the advanced tech thread, I ordered some Oclaro diodes from DTR. I will retrofit these into the same set up as I just tested and see how they compare. I will also check wavelength and power while I'm at it.

Also logsquared, look at the table I am including regarding lens shape. The curve does not seem to be perfectly symmetrical. It's close, but this is probably due to the effect of the finite thickness of the glass in the lens.


http://hyperphysics.phy-astr.gsu.edu...oopt/aber.html

[vjernst]

I'm very curious about the results.
Last week i bought some oclaro diodes from DTR and i'm planning to built a few modules with them
I have Dave's 2 mm lenses and the telescopic sets also