520, 462 diodes and wave plates anyone try it?

[logsquared]

Anyone here try the newer 462 and 520 diodes with a wave plate and cube yet? I have been getting huge losses on the beam that goes through the wave plate and is reflected in the cube. The beam that passes through the cube has only a small loss (3-4%).

I have tried a combination of Dave's and Rob's waveplates and cubes.

[Carl B]

Unless you are using a PBS cube with broad band coatings then you will lose power from one of the colours.

[logsquared]

i didn't explain that too well. I am not mixing the 462 and 520 diodes in one cube. I am having large losses with both wavelengths on independent 462 and 520 only set-ups. Only on the waveplate input side of the cube.

[norty303]

Chris, did you try the waveplate and the cube independently yet, or are they still stuck together?
It would be interesting to know if its a combination of both together or whether its particularly one element thats poor.

[logsquared]

Chris, did you try the waveplate and the cube independently yet, or are they still stuck together?
It would be interesting to know if its a combination of both together or whether its particularly one element thats poor.

Just on the blue. No better luck with them separated. I tried "angle tuning" the cube with little improvement. One thing I didn't try yet is turning the cube 90deg with out the WP to see what the losses are. This will show how well the cube reflects. Should have done that when I had it on the bench.

[lightlinked]

if you have little pieces of polarizer film, you can observe the polarization orientation

[Carl B]

I take it you know that the wave plate has to be tuned by rotating it while in position between the diode and cube.

In the case of my duel reds the wave plate is in the path of the beam that passes straight through the cube

[jors]

Are you sure waveplate is for 520nm and not 532nm? I have typical losses with laserwave wp & pbs

[logsquared]

Are you sure waveplate is for 520nm and not 532nm? I have typical losses with laserwave wp & pbs

Yes 532 and 445 waveplates. I expected some loss but seeing way more than anticipated. I have used 660 waveplates at 637 with good results.

[planters]

I remember some time ago there was a lot of discussion about various PBS cubes looking for low loss. But, an undervalued component was the wave plate. These wonk like an etalon and are designed for a specific wavelength. Low order (broadband) cemented wave plates are the most common in low cost application. What they gain in wavelength coverage they loose in higher losses. The loss manifests not as reflection or absorption, but as ineffective rotation. More of the light fails to be uniformly rotated to the best angle to pass the PBS and so when it is reflected by the PBS we tend to blame the PBS.

A high performance, air spaced, zero order wave plate and a narrow band PBS will have only a couple % loss for both beams. I have seen this and I have these in a couple of my projectors. The very best wave plates I have ever seen came from Tower Optics. They will build you one for any wavelength you want, but they will cost hundreds of dollars. The scatter is so low as well that you can't even see them in the beam when the laser is at full power.