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Surplus Shed Green Dichroic Filter
Surplus Shed is one of my favorite sources for optics.
The $2.50 green dichroic 2x2 was too good a target to pass
up, and I have access to a HP CCD spectrometer at work and a pretty good one at home too.
Call this thing the "poor man's slightly angle sensitive combiner"
So here goes. Transmission at 0" incidence random polarization
common laser wavelengths
457 .627%
477 1.55%
488 4.42%
504 7.87%
514 21.16%
532 71.07 %
peak is at 543 @ 93 %
A second peak is @ 568 KR yellow, 98%
I'd say the 3 Db points are 515 and 580 looking at the plot.
however, tilt this beast about 30' and 532 goes up to 85%
@ 45', 620-670 nm reflection is greater then 98.5%, and you loose maybe
8% green
So if your green beam can come in at ~35' off your red beam and your @ 45, this is a winning combiner @ a mere 2.50 , some 1mm deep spots in the coating at the edges, nothing to complain about in the central 95% of the glass.
At a 0' green beam and a 45' red beam, your not loosing any red at all.
if you have more green then you need for color balence and are low on red, this is a Winner.
If you own a all lines krypton or white light and want to pass only the 568 yellow line and the 530 nm green line, but block the red and blue, this is a WINNER !
I'm gonna use mine with a mercury lamp to pass the mercury green line for testing optics, but hey, at this price, who cares.
So its a nice classic angle tunable filter
For those who ask, the shift in wavelength is a cosine function. All dichros have it to some extent.
Sadly it has a 80% transmission at 808 nm. What do ya want for 2.50 and shipping.
Surplus Shed part number is M2147
Next week, I'll review the zero loss at maxy's red, 1% loss at green 45' dichro from Ealing Electro-Optics currently serving as my yellow projector combiner. Its a Ealing SWP 660 designed for 0', but ran at 45.
Steve Roberts
Last edited by mixedgas; 12-19-2007 at 15:18.
Reason: I got a D in typing in high school when teacher covered my keys
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nice. thanks for the details!
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