Lighting LED Quality Control using bandpass filter lens

I remember learning about bandpass filters in college physics so I understand the underlying theory and can definitly say it is not a bunch of hocus pocus. I think this could prove as a good measure of whether your newly purchased 660 nm leds are to good spec!

https://www.google.com/search?q=660...m=93&ie=UTF-8#q=660+band+pass+filter&tbm=shop

A bandpass filter is exactly what the name says. A filter that only lets a given band of wave lengths pass through. You'll notice the first bandpass filter on the list claims it is 660nm +-2nm.

If you look at an led through one of these bandpass filters and it does not appear very bright you immediately know that it does not emit any wave lengths you want it to emit. If it does appear bright then it is good to go!

I may personally purchase one of these filters and let you all know how well it works. It could serve as a very good/quick means of checking the quality of a led (or an ordinary light bulb for that matter) before you integrate it into your build!

They have all sorts of wave length band pass filters by the way. So whatever wavelength your interested in checking, theoretically you can just look it up wave length you want online and buy it.

 

You bring a very good point about the money saved by going with a $35 iPhone spectrometer and you're correct in the fact that you will get transmittance between roughly 655-665.

BUT you will not get full transmittance at 655 or 665, you'll get half. So if you buy an LED with a peak at 655 nm, it is going to look quite a bit more dim through the lens than if it had a peak at 660nm (and the same for 665. Actually it would be less than half as bright as a led right at 660nm.

Also, the spike in the absorbance spectra for Chlorphyll A is just about 660 with just about a FWHM of 10 nm....so I would imagine that this lens would allow you to see the world in terms of what algae likes.

Anyways, if I buy one I'll be sure to let the world know whether or not I wasted another $100....seems to be the trend for my ATS related purchases....