Cheap laser - large jump in power - normal?

[clansley]

Hi I brought a cheap 1mW 532nm laser (from odicforce) and at the time in darkness the beam was faintly visible.

Recently I've got a 5mW 532nm laser (from odicforce) which has a PowerCheck sticker of 5mW. This one also is faintly visible in darkness.

Oddly, the 1mW has jumped in it's brightness - I guess it's 3 times as bright as it used to be and as the 5mW.

Is it normal for cheap lasers to jump in power? Seems dangerous - you think you have a safe 1mW and then it changes to >5mW...

I presume for a specific make/range the 1mW to 50mW have the same components and they are graded by their output performance after manufacturing - OR does a 1mW have components that are only capable of 1mW - OR do lasers have a component that caps the laser to 1mW?

Chris.

 

[clansley]

After more research, when a laser must be less than a set power (i.e. 1mW/5mW) then a APC (Automatic Power Control) is used. I guess like the IR filter, a APC would be left out of cheap lasers.

 

[bdgreenb]

Temperature changes effect the efficiency of dpss crystal set ups like that in a 532nm laser. So depending on the ambient temp, your laser may in fact be putting out three times more green light. High quality dpss systems use active cooling like TECs to keep the crystals around optimal efficiency, do a search for 473nm rebuilds for more detailed info.