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That's fascinating. Thanks for the explanation.

I was reading a paper which suggested that "angular bandwidth" (which I assume is the number of viewing angles a hologram can be seen from, i.e., narrow angular bandwidth = restricted viewing angles) can be related to spectral bandwidth. The paper suggested that narrow spectral bandwidth i...

Thank you for maintaining the Holography Forum. It's an invaluable resource!

Thanks Dave, I'm using a Sapphire 488nm (200mW) right now. The PL 530 is becoming a popular holography laser, it's amazing how much green light is now available to holographers at low cost. By the way, I saw your 275mW green Sapphire head on eBay. I've always wondered to what extent Sapphire control...

Thanks Din. That's an interesting thought about the hair dryer, I used a new one with a ceramic heating element. Maybe the ceramic was shedding dust. If the problem persists, I'll get out the microscope.

This morning's DCG has some blank (empty) spots which I haven't seen before. P1010050.JPG On the right side of the image, there is a multitude of tiny <1mm spots which group together at the far right, then spread out more as they go to the left. They're also visible at the bottom. When coating the p...

Din, thank you for fielding my questions lately, it's been a big help. In my setup, I didn't use a side reference like you did. My plate was mostly "flat" on the table, that is, one end of the plate was raised/tilted 33 degrees off the table (90 - 57 = 33) and the laser beam (coming in fro...

I was wondering if other holographers have a preferred way to collimate a reference beam. Some of my holograms lately showed "hotspots" in the middle, which were thought to be from the Gaussian reference beam profile (in DCG maybe a better word would be "hard" spots since the mid...

An even more important reason to have an even beam is beam ratio. The beam ratio is proportional to the modulation, and modulation is the most important parameter for efficiency. However, the modulation is a non-linear function of the beam ratio*, so a small loss in beam ratio creates a larger loss...

I was wondering if other DCG holographers have a rule of thumb for measuring energy distribution across the plate, to get reasonably uniform results in the hologram. It seems that an even energy distribution in DCG is more important than in silver, since the hardening issues are so critical. Today's...