Lot of 2 Coherent D3 Directly Doubled Diode Lasers. 1 Low Power, 1 Broken, RARE

Description

This listing is for a pair of laser assemblies from the Coherent D3 Directly Doubled Diode laser.
The Coherent D3 (which actually should be D
3
but that's kind of a pain to do everywhere!) uses a single mode 860 nm laser diode feeding an external resonant doubling cavity to generate a perhaps up to 30 mW of output at a wavelength of 430 nm. According to the specifications, the output is single frequency (single longitudinal mode) with a coherence length of around 6 meters, making it suitable for holography and other similar applications.
The D3 was developed in the late 1990s when there were no low cost (relatively speaking!) ways of generating 430 nm. This must be the most complex low power laser ever attempted and apparently never worked quite right. It must have also cost a fortune to develop and then technology passed it by since it's now possible to obtain 430 nm directly from a GaN laser diode, or from a frequency doubled optically or electrically pumped external cavity vertical surface emitting laser diode, both of which are considerably simpler technologies to reproduce (once all the hard research and development has been completed!).
For a long time I believed the D3 never went into production at all, but apparently it did, or almost did as I have a couple samples that are definitely beyond the prototype stage - nice control electronics with no cuts and jumpers on the PCBs, and an optics construction technique that is very similar to that of the C532.
The complexity arises from the need to precisely match the doubler cavity resonance to the wavelength of the 860 nm laser diode as well as phase matching the doubling crystal as well as mode-matching the diode beam into the main cavity and maintaining all of this stable for a useful amount of time! Of the 2 of these I know of that work, both are temperamental.  This was a laser designed by geniuses who never had to contemplate actually building the things. ;-)
But apparently no more than a couple dozen were every built and there will never be any more.  So these are very rare and definitely rate a place in any true laser nerd's collection. ;-)
One of the pair in this listing is fully intact and did lase when acquired many years ago, but at perhaps only 3-5 mW.  (I believe they were rated around 12 mW.)  It has now been retested and appears to be in similar condition.  But your mileage may vary.  See second photo.
Note that there was original excessive scatter in the beam so an AR-coated window has been attached to the original window with index-matching cement.  The original window could be replaced but that would require breaking the cavity environmental seal, which is not desirable.  The only downside of how it is now is a 5-10 percent reduction in power.
The other laser is quite dead and may have a fractured glass optics platform/baseplate.  Its optics platform would be great for show and tell. ;-)
This listing is for the D3 laser assemblies as shown.  The outer cases are NOT included - I never had them.
To reiterate, these are the ultimate Laser Nerd Lasers but only one does anything. ;-)
More information is available at Sam's Laser FAQ under "Diode Lasers", "Coherent D3 (Directly Doubled Diode) 430 nm Laser".  Google will find it.
The last photo is the annotated interior of the D3 Optics Box.
Sold as-is, no returns unless not as described (such as it lases at 30 mW).  Included are the four power packs and wiring harness used for testing so that the working D3 should lase out of the box,  and the Coherent operation/installation manual.
Thanks for looking,
--- sam