Prisms for 445nm diode front surface knife edging

[dnar]

What! I just found this thread!

Something else to empty my wallet? Oh goody!

Looking forward to seeing the results with these.

[LaNeK779]

you should not complain wayne.
just assume that you were still smoking and all that money was going to waste!

by the way, nice avatar . hehehehehe!!

[planters]

Got an idea.

After looking at the laser profile images, I think you can estimate the significance of any chamfer/skiff. Set up the prism to cut the beam near it's edge, but sufficiently into the beam that there is spill of unreflected light past the prism. Measure the two resulting beams and sum them. This sum vs. the laser power when reflected from a central position on the prism would be a conservative estimate of the loss. You could also carefully slide the prism just to the point where no light passes and measure the total reflected light and compare. This should be a little more realistic as only the edges of these beams are usually compromised by the edges of the reflector.

The power profile is not flat topped and so an estimate of the physical dimension of the chamfer by comparing percentage power loss to the total beam height will not be accurate. However, you might try to profile the reflected and unreflected beams at the same distance from the prism. The missing segment will be the chamfer and its approximate dimension will be the ratio of the missing segment to the measurable beam height at the profiler's distance to the diode.

[lasertack]

@planters

In theory it sounds pretty easy but what you seem to forget is that prisms are only 5x5mm. It is very tricky to align. Futhermore, the beam profile is extremely sensitive to any kind and intensity of light. There is no chance to make a clear picture to determine the uncoated part. However I´ll try to make some other beam profile pictures and get back to you in a few minutes

[planters]

I understand. Not all ideas are good ones. Many fall in the face of a reality check. See what you think/can do.

[lasertack]

Here are additional two pictures. One picture was taken by 100% reflection from the prism surface. The other picture shows the profile, where the beam was cut off by the half at the hypotenuse of the prism. As you can see, there is no chance to say at the XY coordinate the coating ends. The beam profiler is too sensitive.



@planters

Your idea was very good and worth a try but at the end it does not show the desired result
Solarfire should get his prisms today. Let us wait for his first test and the test of daniel. It will tell us much more than the beam profiler pictures.

[danielbriggs]

I think you are overcomplicating something that doesn't need to be. However I will never stop anyone from a thought experiment.

[lasertack]

Hi guys!

I´ve also a source for PBS cubes for red an blue lasers. Size is 10x10mm and the price is 26€ (excl. VAT) Any interest?

Alex

[Solarfire]

Hi guys!

I´ve also a source for PBS cubes for red an blue lasers. Size is 10x10mm and the price is 26€ (excl. VAT) Any interest?

Alex

Got any data on coatings, transmission/reflection?

[lasertack]

Will ask the factory for the transmission curve. But as I remember the transmission is >95% and the reflection is <0,5%.

@Solarfire

Did you receive the prisms?