Are there any bandpass filters that work with LLP besides the ThorLabs ones?  Would an exposed negative still work for this, or does that block the wrong band?

I will be getting the 780nm Lasers from Aixiz, 4 of them.

Thanks,

Alex

exposed photonegatives will still work… other wise you can always go to ebay there is this excellent seller for BP filters called Omegabob2 here is is ebay store http://stores.ebay.ca/OmegaFiltersEbuyer2

Taha

How exactly does one determine which filter to buy?
I have 880nm LEDs and I was thinking that the 880BP15 from OmegaBob2 would work but I am not sure.  Can anybody explain these filters ratings or maybe point me to a website?

Have a look at Thorlabs Catalogue
you need to filter out every light but the ir one you are lighting the screen with, the range of your ir led
How exactly does one determine which filter to buy ?
The bandpass filter will filter the light above and below your chosen Central Wavelength

Ok, that is what I thought but was not 100% sure, thank you for the link, I ordered the 880BP15 which says it has a central wavelength of 880, with a 15 range hopefully this will work, looking at thorlabs I am not inclined to spend 100 dollars on a filter

I am not inclined to spend 100 dollars on a filter

neither i am, but the difference is huge !!
that allow you to work in daily and sunny ambient light .
For my personal experience, it worth it , before i had to wait tilll the evening to work with my MT ....

davidj2k - 30 July 2008 07:03 AM

Ok, that is what I thought but was not 100% sure, thank you for the link, I ordered the 880BP15 which says it has a central wavelength of 880, with a 15 range hopefully this will work, looking at thorlabs I am not inclined to spend 100 dollars on a filter

The 15 FWHM range might be a little narrow.  I switched from a 10 FWHM to 40 FWHM and got much better results.  However, it all depends on your set up.  My issues were exacerbated by a wide angle lens, lasers and the close proximity of screen to camera.  When you test the filter, check for uniform blob brightness especially in the corners of the screen.

Has anyone tried the filters from this ebay seller?
http://cgi.ebay.ca/IR-Infrared-Filter-infra-red-780nm-30mm-30-pass-thru_W0QQitemZ120191346732QQihZ002QQcategoryZ15220QQtcZphotoQQcmdZViewItemQQ_trksidZp1742.m153.l1262

Loon - 02 August 2008 02:24 PM

Has anyone tried the filters from this ebay seller?
http://cgi.ebay.ca/IR-Infrared-Filter-infra-red-780nm-30mm-30-pass-thru_W0QQitemZ120191346732QQihZ002QQcategoryZ15220QQtcZphotoQQcmdZViewItemQQ_trksidZp1742.m153.l1262

That appears to be a long pass filter.  It won’t work much better than a film negative because it passes the full IR spectrum that the camera can capture, as opposed to a band pass filter which will only pass a band of the IR spectrum near the wavelength of your LED’s or lasers.

rdagger - 03 August 2008 11:53 AM

Loon - 02 August 2008 02:24 PM

Has anyone tried the filters from this ebay seller?
http://cgi.ebay.ca/IR-Infrared-Filter-infra-red-780nm-30mm-30-pass-thru_W0QQitemZ120191346732QQihZ002QQcategoryZ15220QQtcZphotoQQcmdZViewItemQQ_trksidZp1742.m153.l1262

That appears to be a long pass filter.  It won’t work much better than a film negative because it passes the full IR spectrum that the camera can capture, as opposed to a band pass filter which will only pass a band of the IR spectrum near the wavelength of your LED’s or lasers.

Then why are they sold in specific nm designations? Hence 780nm.

Loon - 03 August 2008 12:02 PM

Then why are they sold in specific nm designations? Hence 780nm.

Everything longer than 780nm is passed.

You can get 780nm Bandpass filters?

yeah i would assume soo they are near IR

how does this look?

http://cgi.ebay.com/IR-Optical-Filter-852BP58-25-25mm-dia-X-4mm-thick_W0QQitemZ310075053236QQihZ021QQcategoryZ15220QQcmdZViewItemQQ_trksidZp1713.m153.l1262