Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers

Laser Pointer Store

On IR leakage from green lasers



There seems to be a lack of adequate information about IR leakage from green lasers. I would like to get info from people who have actually measured/witnessed this. If you are just guessing from something you read on a forum that is not necessarily accurate info.

So you have some 1 um IR laser, pumped by an 808 nm diode. In the cavity of this there is a nonlinear crystal that converts the 1 um light to green. This process is not 100 percent efficient so there will be some 1 um light that does not get converted and pretty much identically follows the path of the green (it has to because the green light was made from it). The other sources of IR light are 808 from the pump diode that makes it all the way through without getting absorbed (has anyone checked this). The last source of IR is spontaneous emission from the gain medium that is 1 um.

So, when people say that the IR coming from a green that is unfiltered comes out like a flashlight (I am assuming they have witnessed this with something like a viewer or camera) it has to be spontaneous emission, or else it would follow the path of the green. This also means that there should be an IR beam directly on top of the green beam, these should differ only in divergence (based solely on the wavelength difference) by a factor of 2, the IR having twice the divergence of the green.

How to test this.

It should be pretty easy for someone to just shoot their green through a high pass filter that will only let through the IR and take a picture of it. Then turn off the lights and see if you can see any extremely faint red which might be 808 from the pump diode.

So, can some people help me out on this in order to clear up the misconceptions about this?