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It worked. Incident beam had a 15 degree divergence, so used 100 cm separation distance. Photo shows zero and first order spots from 532 nm light through the grating.The grating isn't very clean; for example, you can see a defect above and slightly right of the zero order spot. But we'll track down ...

I unrolled that old bolt of black velvet. I can cut off the edges that turned brown and it should be fine. With pinhole divergence at least 40 degrees and Liti plates 7.5 cm long, then 35 cm or more separation between pinhole and plate is a reasonable work space. So we'll set up and give it a try. M...

Din wrote: Black velvet

I was afraid you'd say that. I have some, but it was stored in a hot, humid environment for years and I am afraid to unfold it. Probably should just buy new.

In effect you got two gratings: the transmission (Raman nath) grating due to the multiple reflections inside the glass, and the reflection (Bragg) grating due to the beams entering from either side of the plate. This is very helpful for understanding... shame on me for not realizing it was a reflec...

I apologize in advance for the long read. As I mentioned in another post, early this fall my son explored Ed Wesley’s method of making a diffraction grating, described in his “Seven Single Beam Projects,” as the basis for his science project. In his project, he varied the angle between plate and mir...

I, for one, am just a rank amateur willing to waste lots money on an interesting hobby. Someday I may actually produce a hologram worth showing people, but in the meantime I'm enjoying "just trying things." This is where I'm at too. Just trying stuff. For his science project, my son made ...

So this week was alignments and getting used to the feel of new pieces. Eventually I made everything work perfectly for the green laser. A glass plate tilting down in a kludged-together mount allowed me to see when I had vertical polarization. Fast axis of half wave plate at exactly 45 degrees from ...

After all, when the detector is not perpendicular to the beam, the light meter shows smaller numbers. Why is the photosensitive plate behavior different? Well, one reason may be that the ccd is flat. So, any light hitting a specific ccd site, will record normal to the surface of the ccd. In the cas...

Yes, Petr, still making single beam holograms. And not making many of those. But equipment upgrades are under way. Put together a spatial filter today. As I moved objective toward pinhole I saw... rings, brighter rings, then wonky stuff, then across one very short space there is a large patch of som...

Thanks Dave. Indeed, tracking down unwanted light is an adventure. Fortunately I have a lot of these lying around in a drawer, doing nothing. So now they have a new use, holding card stock upright. Possibly because you got a better ratio with the spurious scattered light. Yes, must remember that the...