Woods glass filter for UV light.

Today I finally got my wood's glass filters. As people here with 365nm led experience know the led's themselves emit a small amount of whitish light. This tends to obscure some of the fluorescing effect of the led. Well after going to a local stained glass place and having them cut out a glass circle from the 2"x2" piece, I have to say it vastly improves the quality of the UV light output.

From my driver's license to the colored stripes glowing on various denominations of dollar bills, the contrast is greatly improved. For anyone with a 365nm UV light I highly recommend getting a wood's glass filter made.

Very interesting, thanks for sharing. I will soon order my first 365nm light and will test the visible light output to see how much comes out of it.

Did you get the Rosco 2x2" filter?

I just got one of the Rosco 2" x 2" filters. Even though the website said it was Woods Glass, and so does the packaging t hat it came in, it's actually a dichroic filter and has a silver mirrored appearance.

I'm wondering if I can cut this type of filter to shape with conventional glass cutting techniques without disturbing the properties of the filter.

Cutting Dichroic "Wood's Glass" from Rosco

PhotonWrangler said:

I just got one of the Rosco 2" x 2" filters. Even though the website said it was Woods Glass, and so does the packaging t hat it came in, it's actually a dichroic filter and has a silver mirrored appearance.

I'm wondering if I can cut this type of filter to shape with conventional glass cutting techniques without disturbing the properties of the filter.

Click to expand...

Yes, I purchased one of the 2"x2" filters just last week from B&H and using an ordinary hand cutter, I scored it and broke it easily. You can just barely see your score mark because it is like a front surface mirror on both sides, but it cuts like ordinary glass, not plate or pyrex. I made two clean cuts with NO problem at all, and used my Wizling grinder to prepare a 1" diameter blank to replace the clear lens in my UV LED flashlight. It works wonderfully. I have tried working with the glass from fluorescent BLB bulbs without much luck. I suppose if you broke an incancescent BLB bulb and used your nippers to get a convex piece, then took a grinder to it, you would be in luck.

But for me, it worked out GREAT to cut up the Rosco filter and grind a circular blank!


-- Nightcrawler

Re: Cutting Dichroic "Wood's Glass" from Rosco

ok, well i've been looking for as cheap as possible woods glass and have come to no avail unless i get it from china, and they want a fortune for what i need. it needs to be 4" dia for my spotlight, anyone here know where i can find such a piece?

Re: Cutting Dichroic "Wood's Glass" from Rosco

Nighcrawler said:

Yes, I purchased one of the 2"x2" filters just last week from B&H and using an ordinary hand cutter, I scored it and broke it easily. You can just barely see your score mark because it is like a front surface mirror on both sides, but it cuts like ordinary glass, not plate or pyrex. I made two clean cuts with NO problem at all, and used my Wizling grinder to prepare a 1" diameter blank to replace the clear lens in my UV LED flashlight. It works wonderfully. I have tried working with the glass from fluorescent BLB bulbs without much luck. I suppose if you broke an incancescent BLB bulb and used your nippers to get a convex piece, then took a grinder to it, you would be in luck.

But for me, it worked out GREAT to cut up the Rosco filter and grind a circular blank!


-- Nightcrawler

Click to expand...

Nightcrawler, thank you for this information. I have a regular glass cutter so I will try this. The dual-sided evaporated coating was scaring me off but if you've had good success with this technique I will try it also.

Re: Cutting Dichroic "Wood's Glass" from Rosco

Here's one way to get a good quality woods glass filter - buy a used Blak-Ray B100 fixture.

I just got a Solarforce UV dropin, and have the same question -- is cutting down a larger Wood's Glass filter still the only good way to filter out the visible part of the spectrum, for a regular flashlight?

hank said:

I just got a Solarforce UV dropin, and have the same question -- is cutting down a larger Wood's Glass filter still the only good way to filter out the visible part of the spectrum, for a regular flashlight?

Click to expand...

EDIT: this looks partway toward what I want, in a filter gel: http://www.rosco.com/CFFileServlet/_cf_image/_cfimg6513053213413912437.PNG
That's Permacolor P4200 Deep Purple
Transmission: 89%

found using their graphic search tool: http://www.rosco.com/mycolor/mycolor.cfm

If it's an LED drop-in, you can try some gel filters. Here's a site that recommends a combination of Rosco R383 Congo Blue and R375 Cerulean Blue. Look up a theatrical lighting supply shop and obtain a RoscoGel sample swatch book to test it.

If it's an LED light already, and you arn't planning on using it for anything else, I'd go with an LED drop in rather than filter.
UV incan is virtually useless.
UV hid is awesome but need a thick filter to withstand the heat. I use the filter from a magnaflux lamp on my maxabeam, but it's a little thick to try and cut.
I've found high power UV leds to be quite impressive!

Eagletac has a 365nm drop in for the T20C2. I really like mine.