Possible filters for working with fluorescence

[Lisa Thalheim]

I just came across a possible source of filters for working with
fluorescent dyes and such - Rosco E-Colour filters. They're made for
photography and they're dirt cheap, but what I found really neat is that
there's a sampler of all 180 colours that you can buy for 3,50 Euros,
and which features transmission curves - I've often had trouble coming
by this information when digging around for cheap alternatives to
high-end filters. See attached photo.

Has anyone worked with these, by chance?

[Nathan McCorkle]

That reminds me that I bought a similar 'sample pack' years ago, for
basically free as well:
http://shop.leefiltersusa.com/LEE-Swatch-Books_c4.htm

I totally forgot about them earlier this week, when I instead went and
purchased a black-light bulb to confirm my GFP subculture! Oops!
Will go dig them up and take a look.

Thanks for the reminder :)

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--
-Nathan

[John Ladasky]

Not this specific brand, but I am familiar with things like them.  Gel filters and colored-glass filters typically transmit around 1% of the light at wavelengths that are "rejected."  Is that good enough?  It depends what you need them to do.  If you are doing fluorescence work, you have a bright illumination source, and much dimmer fluorescence of a different color.

Say you were working with a DNA - ethidium bromide gel, on a blue, violet or a near-UV transmission table.  A 540 nm long-pass piece of glass can improve the contrast for your eyes a bit.  If you are working with a black-and-white camera and want to take a picture of the gel, it can also help.  How much depends how sensitive the camera is to the excitation wavelength. 

If you are doing cellular fluorescence microscopy, you need much better sensitivity.  You usually use a laser excitation source and focus it with a lens.  The scattered light off the cell is strong, and the fluorescence is weak.  You hope to achieve quantitative results -- in other words, where there's no fluorescence, you want the pixel to be as close to background levels as possible.  To do this kind of work well, you typically want < 0.001 % transmission (10^-5)of the excitation light.  You can only achieve this with the fancy interference filters made of many layers of coatings.  They typically cost a few hundred dollars each, though some very popular wavelengths can go for less.

[John Griessen]

On 03/18/2017 11:01 PM, John Ladasky wrote:
> To do this kind of work well, you typically want < 0.001 % transmission (10^-5)of the excitation light. You can only achieve
> this with the fancy interference filters made of many layers of coatings. They typically cost a few hundred dollars each, though
> some very popular wavelengths can go for less.

I used to work on a product with these kind made of furnace processed silicon/glass/metals sputtered on in high vacuum.

Won't it be nice when some self assembling nanomaterial can do this kind of light interference filtering?

[John Ladasky]

On Sunday, March 19, 2017 at 10:31:26 AM UTC-7, John Griessen wrote:

On 03/18/2017 11:01 PM, John Ladasky wrote:

>  To do this kind of work well, you typically want < 0.001 % transmission (10^-5) of the excitation light.  You can only achieve

> this with the fancy interference filters made of many layers of coatings.  They typically cost a few hundred dollars each, though
> some very popular wavelengths can go for less.

I used to work on a product with these kind made of furnace processed silicon/glass/metals sputtered on in high vacuum.

Won't it be nice when some self assembling nanomaterial can do this kind of light interference filtering?

Hey, you just gave me an idea for a project...  :^)