cheap green light source

[opticsman]

Hi
Can any one suggest a cheap and portable monochromatic source for demonstrating Newton fringes ( or similar interference fringes ) . green light is ideal but a green laser is ruled out becuase of cost ( target under $40 ) . I could use a narrow band filter plus torch ( flashlight ) but it will not be efficient becuase it will lose a lot of light. Are there any narrow (ish) green light flashlights around LED or other? Hopefully available in the UK ? any other suggestions are welcome.
thank you in advance . Opticsman.

 

[cev]

Fluorescent bulbs have a narrowband green line - the 546 nm mercury line. Cover the bulb with an appropriate green filter (check theater lighting shops for "gels," Rosco being a likely find). You also need a diffuser, which you might also find at the theater lighting shop.

I've never tried this, but it might also work: Your CRT monitor's red phosphor is very narrowband. If you can fill the whole screen with pure red, it might make an excellent source for viewing newton's fringes.

CEV

 

[CalculatorDave]

How about just buying green LEDs and wiring it up yourself?

 

[alderetm]

Funny you ask. I'm currently working with an item a bit more expensive than you're budgeting for, $210.00. It's the Edmund Optics Monochromatic lamp, R71-780, 5461 Angstroms.
I logged onto the forum to inquire about suggestions to collimate this light onto a 1.5 inch diameter sample. As bulb life increases, the light source weakens and the fringe contrast is not so good anymore. Otherwise, this source does the trick [recommended for viewing Brewster's and Newton's fringes]. In the printed Edmund Industrial Optics catalog, see facing page on "Using Optical Flats".

Michael Alderete
Mech Packaging Engineer
DRS Technologies-Sensors & Targeting Sys
Anaheim CA

 

[IRstuff]

The source that you're quoting is a large area diffuse source, which means that there is no convenient way to "collimate" that source.

What are you planning on doing with it?

since I work in the same area, you could call my office at x1006

TTFN