2 ms·
I suspect you do not need to use 670nm exactly, however I suspect you need to be above 650nm. Note that many red LEDs are at a lower wavelength (~630nm). So you
by cycomanic 6y ago
I suspect you do not need to use 670nm exactly, however I suspect you need to be above 650nm. Note that many red LEDs are at a lower wavelength (~630nm). So you need to search for deep red or by wavelength.
You can use a OSA, but yes they are expensive. Spectrometers are typically cheaper, but still expensive (you could go to a university optics group and ask them if they could measure it for you). That said if you buy from a reputable source you should get the right wavelength.
If you are trying this out be careful with the brightness.
- joezydeco 6y agoInstead of trying to emit 670nm, why not just use a wide spectrum source and a 670nm bandpass filter?
- cleansingfire 6y agoLike the sun and your closed eyelids. Light transmission goes up with wavelength https://www.spiedigitallibrary.org/journals/journal-of-biomedical-optics/volume-16/issue-06/067011/Measuring-and-predicting-eyelid-spectral-transmittance/10.1117/1.3593151.full?SSO=1 https://www.spiedigitallibrary.org/journals/journal-of-biome... (see figure 5.) To speculate, perhaps we have evolved to benefit from closing our eyes in the sun.
- joezydeco 6y agoThat's a great connection. If it's that simple (and explained by human evolution), that would be awesome.