Sciencemadness Discussion Board

Laser Safety for Raman Spectroscopy

Metacelsus - 11-3-2015 at 14:05

I'm thinking about building a Raman spectroscope. What safety precautions are required for a 50 mW 532 nm laser?

What I'm planning so far:

-build an opaque, matte enclosure for the spectroscope
-test optics with a 5 mW laser, then install the 50 mW one
-wear laser absorbing goggles with optical density 5 or greater

Are these precautions adequate? Are the goggles overkill? How would the necessary precautions change if I used a higher (100 mW) or lower (25 mW) power laser?

Sulaiman - 11-3-2015 at 15:09

I have had 5 mW, 50 mW and 500 mW green DPSS lasers,

I felt quite safe with the 5 mW as the blink reflex is probably sufficient protection due to the eyes sensitivity to green light.

The 50mW I think would have been able to burn my retina if it hadn't died so quickly.

The 500 mW was fun but terrifying, I got rid of it after a very short while.

Don't forget that with the cheap laser pen types there is often a massive output in the infra red.

Sam's Laser FAQ is my first reference for such things
http://www.repairfaq.org/sam/lasersam.htm

and remember;
DO NOT LOOK AT LASER WITH REMAINING EYE.....

m1tanker78 - 11-3-2015 at 17:16

Quote: Originally posted by Cheddite Cheese  
I'm thinking about building a Raman spectroscope. What safety precautions are required for a 50 mW 532 nm laser?

What I'm planning so far:

-build an opaque, matte enclosure for the spectroscope
-test optics with a 5 mW laser, then install the 50 mW one
-wear laser absorbing goggles with optical density 5 or greater

Are these precautions adequate? Are the goggles overkill? How would the necessary precautions change if I used a higher (100 mW) or lower (25 mW) power laser?



Point #2 is a good start. You'd be surprised how a speck of dust can scatter a laser beam in unexpected ways. Treat the 5mW laser as if it were a 1/2W to build good habits from the beginning. Always wear eye protection rated for the wavelength and highest intensity + ~10% margin you'll be dealing with. If you're going to build a custom enclosure, include a safety switch at least for the sample compartment area. A computer/MCU/FPGA-controlled laser is prone to glitches. Don't trust your eyes to glitches or bugs!

Sulaiman brought up a good point about the absence of IR filters in the cheap greenies.

Marvin - 12-3-2015 at 10:10

I have a squiggle on my left eye from a 5mw green through a pinhole. I figured 200uw would be eye safe. I checked the beam for 808nm and it was much lower than the green. I wish I'd aligned those optics with a webcam.