How to verify a blue light filter removes 440-490 nm wavelengths

[vande060]

I volunteered to help out with a research project, and we need a solution for a way to filter out light of the blue wavelength from a light source. THe blue wavelength is the only wavelength we want to remove. I was wondering if anyone here had any suggestions? Someone from the project suggested a photographic filter, and this is a good idea, but if we bought a color filter from a photography shop how could we know that it was working? I thought we might be able to file one and put the filings in a cuvette in solution and place that in a photospectrometer to see if the peak absorbance is 440-490. Or maybe there is an optics reference book with the absorbance of materials?

 

[Andy Resnick]

I'm confused- are you looking for a notch filter (absorbs a waveband) or a pass filter (transmits a waveband)? Either way, why do you have to grind one up to measure the transmittance?

There are many companies that make filters- Omega, Hoya, Chroma, Semrock, Tiffen,... yours is probably a stock item, or close to one.

 

[davenn]

I'm confused- are you looking for a notch filter (absorbs a waveband) or a pass filter (transmits a waveband)? Either way, why do you have to grind one up to measure the transmittance?
There are many companies that make filters- Omega, Hoya, Chroma, Semrock, Tiffen,... yours is probably a stock item, or close to one.

it would seem he's looking for a low pass filter ... so from a white light source, he wants the blue end filtered out leaving all the rest to pass through.

@vande060 ... how would you know its working? easy, put a blue filter in front of the light coming out if the other filter it should be dark, ie. no blue light present to come through the blue filter

Dave

 

[cjl]

Andy: it sounds like they're looking for a notch filter to remove blue. I'm not sure if a low pass would be sufficient (it depends on whether they want to keep the UV or not).

 

[vande060]

Optical filter sites are very helpful. I just didnt really know the title of what I was looking for. Thanks for the info. I think I am looking for a notch filter. I don't want the blue light to be transmitted from the source, and I'm hoping to find a filter that will absorb it and reduce transmittance. They are pretty expensive though, maybe the photography shop has something to offer.

 

[vande060]

I actually found a list of optical properties for wratten filters(kodak company) in the crc. They are very cheap, and I have some nice quantitative data to go with them. Just in case anyone was interested, I think I'm going to suggest these to the professor.