There are a few photodiodes made with built in filters to render a sensitivity versus wavelength resembling that of the eye. (The glass on the ones I have is greenish in tint.) There also is a Wratten gelatin filter (I believe #106, but check a data book) which converts normal diode sensitivities in the same way as that glass. It is probably cheaper to buy a diode already equipped with a filter! I don't have the data at hand, but I can imagine such a diode having specs given in microampere per lumen.
I doubt diodes give a single value of mV per microwatt. Current into a short circuit will be linear with incident power (or lumens), but not voltage. The latter normally has a log variation of voltage with power and with a non-trivial temperature dependence.
Bob
At 20:52 17.01.03 -0500, you wrote:
Getting uniform lighting over a large area with a homebrew fluorescent source may take some effort...I have an idea to follow some day.I am working on my homebrew spotmeter idea. Silicon photodiodes have typical sensitivity rating in mV per uW/cm^2. I see that as meaning voltage as a function of optical power density. The number of dimensional units involving illumination and luminance and all the physical variations and unit systems are confusing. I've charted luminances vs. EV numbers, shutter speeds and apertures. Now I need to relate luminance and the above-described photodiode sensitivity. I have the sensor area for a couple different size sensors if that is needed. I'm having a hard time figuring out the dimensional analysis (what physical parameters are missing or needed). Any help appreciated. Murray --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.391 / Virus Database: 222 - Release Date: 9/19/02 _______________________________________________ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
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