Filters for Lens or light 1

[BigCatDavo]

I was wondering if anybody had a good source or supplier for optical filters, like to remove a certain wavelenght of light from a camera? I am looking for some type of film that could be appied and removed to a plastic lends as needed.

David Sabados BSC

 

[IRstuff]

Depends on the wavelength and degree of difficulty.

Standard camera filters include UV and certain color enhancements.

Notch filters generally only come on glass. Edmund Scientific should have those.

http://www.edmundoptics.com/IOD/DisplayProduct.cfm?productid=1734

There are plastic color filters, also available from Edmund.

http://scientificsonline.com/product.asp?pn=3039417

TTFN

 

[ornerynorsk]

IRStuff made a good recommendation. Camera filters are available in a very wide variety, both wavelengths and physical sizes. Most are threaded to allow easy changeout. Best of all they're cheap.

 

[IRstuff]

If you want to get really fancy, Schott Glass makes a large selection of glass filters that are often used in military systems.

Is there a military reason for posting here as opposed to the optical engineering forum?

forum386

TTFN

 

[BigCatDavo]

Sorry, I could not find the optical forum, a moderator could move this if required, Perhaps I should clarify a little better on what I am after. It is for the camera module on an unmanned ground vehicle. The camera/lens combo we have now is not reacting well to light. It seems to swap the auto shutter and as a result, we lose video on the flat panel display. I thought that a film might be applied to the window of the camera module or a piece of plastic with the appropriate film/material could be placed in front of the window on the module to cut down on the glare during really sunny conditions (on ice) or during sunrise or sunset.

Dave

 

[IRstuff]

Sounds like someone dropped the ball on scene illuminance requirements or implementation.

Your camera should have either selectable exposure time or some sort of optical light level control. Most of the older TV systems use counter-rotating variable neutral density filters for that specific reason.

You have about something like 5 orders of magnitude of luminance at the camera lens. A single filter is going to be of marginal utility.

Your best bet is to see if there is some sort of integration time or shutter control on the camera. If that's what you're refering to as the "auto shutter", then there's a problem with the attack and decay routine for the light level control. This is a pretty arcane thing which usually needs to be tweaked.

TTFN

 

[BigCatDavo]

Thanks for the help, we have messed with the shutter speed settings and it looks like the problem is much less pronounced. In the great battle of time vs size vs capability time always wins, and now we on the ground level are trying to work with what we have. I perhaps incorrectly assumed that we could reduce the intensity of the sunlight with a sunglass type filter. Once again, thanks for your help.

Dave

 

[ornerynorsk]

A polarizing filter might also help your situation.

 

[simultaneity]

I agree with the light polarization option and suggest that by using simple polarized light filters which do come on plastic film you can reduce glare and adjust the angles more readily, especially if you are having moderate success by adjustments. Polarization filters will also be an asset because you will retain your depth of field which is all important under tactical conditions. By adjusting your aperture you will also run the risk of blinding your panel from sudden air burst, so I think your original direction is the simplest route to the cure. If your conditions do not exist on other like units then you need to go in for maintenance, because if there is a circuitry issue you may also be generating random electronic signature outward which may, on the slight probability of actual occurrence, allow a degree of random non-passive-ness and /or illuminating.

 

[ChrisMcLean]

This is a little bit out there but I have some experience of working with a silica research group. One of the applications we worked on (which did attract military interest) is in the use of sol-gel glasses for optical applications, i.e. including specific matrix dopants to absorb specific radiation wavelengths. The advanatages of this system are primarily the long term stability of the sample (in comparison with, for example, glass calibration stanadards for UV-VIS spectrometry) and the cost - producing sol-gels is way cheaper than the traditional glass alternatives.

This obviously only becomes a critical factor if the lens filters are expected to be a part that will suffer attrition in use.

Several research groups have been working on this and I think that work is almost certainly in the public domain through some chemistry journals, particularly the materials chemistry ones.