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Extreme lasers GBS-100 (modifications and review)


Well-known member
Sep 12, 2007
I tried the pricey route with Wicked Lasers... not the best plan. I tried the cheap route with Extreme Lasers... even worse.

I bought the green 100mW from the eBay seller "Extreme lasers" the beginning of this year for $130. The auction claimed the unit came with an on/off switch but I saw nothing of the sort, only the TTL contacts. I Emailed the guy asking about it and received no response. Oh well. I thought about installing a Switch, but thought it easier to just unplug it.

The beam was round at the aperture but had one hell of a fast axis. The diameter has a ratio of 3 to 1 in size at a distance. The divergence is an appalling 2.7mRad - quite a ways above the claimed <1.5. I disassembled it last night, curious if anything could be done about the divergence. Indeed there was a threaded cavity in which the expanding lens was sitting, yet the collimating lens was at a fixed position. Perhaps it's glued from the inside? I twisted the thing for quite a while and finally decided at a certain point the dot wasn't going to get any smaller with these optics. I measured the divergence again - about 1.8mRad! Not exactly stellar, but better than my X-105. The dot is now almost round as a bonus. It seems to me these guys buy the parts in bulk and throw them together, not bothering with much alignment or adjustment. The beam exits the aperture (before and after tampering) at about 15 degrees above where it should. Before I played with it, it was also exited 10 degrees to the right.

The power output at room temp starts out at 45mW and slowly climbs as it warms up. After 15 minutes warm up time it reaches a very stable 68mW. Only once has it measured 100mW. This was after it had been outside (in 40 F weather) and even then, it dropped to 60 after 5 seconds..

The power supply warms up 10 times faster than the head. The head has a fan and TEC, but the power supply has no cooling means whatsoever. The wires are just soldered in place and look fragile. I built an enclosure for it out of a radio shack project box and a spare heat sink which has thus far done the job quite well.

Overall, I'd give this 3/10. But if you're willing to pay $100+ for a 50mW laser with terrible divergence, "more power to ya" ::)

Head disassembled:

Angle of beam:

Compared to X-105: