power measurement for a 300 nm UV LED

runcyclexcski

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Mar 5, 2008
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I have a 300 nm UV LED rated at 30 mW power output. Is there a decent sensor (to within 25% error) that I could use to measure the power of the light I managed to collect, without having to spend thousands on a high-end sensor? Some details are below:


LED: https://shop.boselec.com/products/vpc1a1-300-smd-c


Power output 30 mW
Forward current 500 mA
Forward voltage 6.0 V
Peak wavelength 300 +/- 5 nm
Spectrum FWHM (typ.) 15 nm
Viewing angle (half power) 130 deg.


I drive it at 6V (getting about 0.12A, which is 4x less than the 500 mA rating... does it mean that I should be getting, at best, 30 mW/4 = 7.5 mW???). I collect the light using a 6mm silica lens (>95% transmission in UV), 6 mm focal length, and re-focus into a diffraction spot using another silica lens (10/10). A laser power meter gives readings 10x less than the 30 mW that I expect (?). Of course, this might be due to incomplete collection of light, but I do not think I lose 90% of light. The power meter gives good readings with a 'non-exotic' 532 laser line (within 20% of expeceted value).
 
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MeMeMe

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Aug 27, 2018
Messages
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I have a 300 nm UV LED rated at 30 mW power output. Is there a decent sensor (to within 25% error) that I could use to measure the power of the light I managed to collect, without having to spend thousands on a high-end sensor? Some details are below:


LED: https://shop.boselec.com/products/vpc1a1-300-smd-c


Power output 30 mW
Forward current 500 mA
Forward voltage 6.0 V
Peak wavelength 300 +/- 5 nm
Spectrum FWHM (typ.) 15 nm
Viewing angle (half power) 130 deg.


I drive it at 6V (getting about 0.12A, which is 4x less than the 500 mA rating... does it mean that I should be getting, at best, 30 mW/4 = 7.5 mW???). I collect the light using a 6mm silica lens (>95% transmission in UV), 6 mm focal length, and re-focus into a diffraction spot using another silica lens (10/10). A laser power meter gives readings 10x less than the 30 mW that I expect (?). Of course, this might be due to incomplete collection of light, but I do not think I lose 90% of light. The power meter gives good readings with a 'non-exotic' 532 laser line (within 20% of expeceted value).

It sounds like you should have a much higher current at that Vf, but perhaps there is an error in your measurement.

That said, you have an ~ 1mm square, i.e. 1.4mm diagonal emission surface, with an emission over about 140 degrees. You have 0.7mm from the front of the LED to the front of the glass. A 6mm lens would need to up against the glass of the emitter and even then, your collection efficiency is likely limited. You may even run into critical angle issues.

Do you have any optical simulation S/W?

If your laser power meter has sensitivity at 300nM, you can probably get the specs for it and correct the power. If it is pyroelectric (most common), then it should have high responsivity at 300nm, probably more than at 532nm.
 
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