400 mW DPSS Blue Laser


Acquisition Date: April 2012
Date of Manufacture:2004
Country of Origin: California, USA
List Price (when new): $30k (?)
Purchase Price: $6500

Provenance: I bought it from Phil Bergeron and Laser Sam, where they go it from I have no idea. I needed a deep blue emitter for shooting photo-resist, and this one was the only thing in the used market vailable.

BLD stands for Blue Laser Dual, that last word meaning that there are a pair of beams emitted! Actually there are more like 6, 2 equally strong ones with a couple of hundred milliWatts in each, and a few others that must be caused by some internal reflections. The one that comes in 3rd place, a few 10's of mW's, has enough oomph to drive the Scanning Fabry Perot Interferometer Spectrum Analyzer to monitor the spectral purity of the output, which is helpful, as the laser does get off track once in a while. A restart usually fixes that.

A Major Issue:
The pump laser diode gets quie hot, so the laser is cooled by forced air. A rather strong fan is attached to the end of the laser, and shakes the shit out of the vibration isolation table, according to my fringe stabilizer..

I solved the problem by removing the from the laser housing, and mounted it on something like a microphone stand on the floor.  A paper shroud keeps the wind flowing through the cooling fins under the laser head and transmits little, if any vibration to the laser on the table.


There is enough slack to in the laser head's cabling to allow this.  You would be surprised by how much the fan stand vibrates, and wonder who thought that putting a fan on a laser that is capable of having each of its 2 beams running single longitudinal mode and mutually coherent was a good idea?

This arrangement doesn't seem to bother the laser, maybe because there is plenty of cooling power overkill built into the design of the radiator fins.  The software for this laser monitors the critical temperatures, and they are seen to be stable with this new mounting.

Here's a close up of the paper shroud entering the laser.  Or perhaps exiting is the proper word, as the air flow is out the rear end.  Because the room air enters at the front of the emitter, a paper tube connecting the laser head to the hole in the Styrofoam laser enclosure isolates the beams from the entering turbulence.

BLD Fan2

This laser is guaranteed to be Single Longitudinal Mode, and not only are all the beams of that nature, they are coherent with each other! Here is research to back that up!

This laser is still lasing, although the best I can wring out of it using its software to change temperature settings is only 140 mW! Time for a new pump diode?

Operator's Manual
In pdf format

This is one laser that has useful software, as the output can be peaked by varying the diode and crystal temperatures; however, one needs to resurrect an antique computer with Windows XP or earlier to run the program, with an RS232 port! Clickng on the link above will download MG_GUI.exe, and you can have my word for it that it is flakey, but not malware.

The password is foo:bar, (with a colon in the middle) a variation of FUBAR, and you know what that means.  Enter it into Password in the Controller pull-down menu, then Factory Settings appears on the toolbar, open it, re-enter the password, and you can see all the important temperatures!

Manufacturer’s Current Web Page
There really is no Manufacturer's Current Web Page since Melles Griot came under the umbrella of the fustercluck known as Idex. But clicking on the link right up above will bring you to Laser Sam's FAQs, which shows what's inside these things!

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