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I can make transmision gratings all day long. For $100 I could easily make 20 2.5 x 2.5" transmision gratings at around 800 lpi. They would fade over time but it would be a cheap way to go. If you cut each piece into 4 gratings you would have 80 gratings for $100. My film goes up to 2000 LPI but that would take some experimentation.

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Then I assume - from the way this thread developed subsequently - that this statement was just a typo: That you had meant to say 880 lpmm and 2000 lpmm, and not lpi?

If so, I withdraw all the questions I had asked when you first wrote this.

Gene

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That is correct. I can interfer two 532nm laser beams and record the interference as either a reflection or transmision grating. The efficiency on the reflection gratings is quite low. I might be able to hit 30%. By changeing the angles of the laser beams I can vary the spacing. My films thereotical limit is 2000 lpmm. I know people who can make DCG reflection gratings with much higher efficiencies at in shorter wavelengths. I have seen gratings made this way to 8000 lpmm.

My friend Ed wrote this for one of my sites:

http://www.holowiki.com/index.php/Holography_Transmission_Equations_Part_I#Spatial_Frequency

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Mahalo,
Colin Kaminski

Coulter 10.1" Dobsonian
TV-76/Baader Film White Light
LS60T/DS50/FT/BF1200
LDX-75
AT Voyager

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