HPLD confusion

I have just recently started looking into the world of DPSS/HPLD. I came across a photo of a HPLD that totally confused me.

The laser was specified as being IR but what I can't understand is where the bright white or sometimes purple/pink glow comes from. The white glow looks really hot, like an incandescent bulb, but I didn't think diodes liked that much heat so it has totally confused me.

I have added a copy of the first picture I saw.



Please can some help shed some light on this for me? (pardon the pun)



Regards

Buffy

I believe that CCDs react to IR. The filters which determine which colour will be represented in a pixel are relatively equally transparent to IR, causing it to appear white.

Hi! Thanks for your reply.

I tested out the theory with my 50mW Green pointer which I know doesn't have an IR filter on it and the 808nm beam came out a lilac colour (which is what I have seen on the videos on YouTube). I used the pointer with "cheap" batteries so that the green beam was not as bright and got the following results....



I must try and get some sort of filter for it!!!!

Thanks again for your help!

Regards

Buffy

Hi Buffy,

Welcome to the forum! :wave:

Something to bare in mind...

Be careful when shining your 50mW green directly into the camera like that. Although 50mW of 532nm light is not likely to cause damage to your camera, the 808nm might well do. The pump diodes are several hundred mW, (even at an optomistic 20% efficiency 50mW of green needs to have a 250mW pump diode), and CCDs don't like it up 'em, (Dad's Army Stylie!). Having said this, the IR isn't usually as colimated as the green so the energy wouldn't be focused to such a tight spot on the sensor.

You can observe the same visible IR phenomenon without fear of damage by looking at the LED on any remote control for you TV, CD Player, etc, whilst pressing a button.

Welcome to photonic nirvana!

M