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FrozenGate by Avery

Lbo






I think that is the wrong crystal :)

That part number is a THG LBO for a Coherent AVIA 355-5. It should be 14mm long and 2.5x2.5mm clear aperture. Another good indication that that is not an LBO crystal is the arrow pointing to one side, that indicates that it is a mirror. Additionally, Coherent puts an individual serial number on every crystal.

If that was a crystal, it would say 0174-425 on one side and 17 on the other.

I am guessing that the optic is a pickoff or a wave plate. It is hard to say for sure.
 
Not necessarily
James Harper At Coherent hand picked 5 of these for me and the arrow shows the direction. these are not your ordinary production crystals.
 
DSCF6184.jpg
 
Looks nice.. Someone will get a sweet deal, no doubt..

Off topic: I see you're in St. louis.. What part or town? I live very close to forest park.
 
Didn't know there were any other laser people on here from the area. Nice to finally meet one..

Ordinarily I would buy that LBO for sure since I could pick it up from you directly, but I haven't had much time lately for experimenting with DPSS..

If you're familiar with PL it might not hurt to post it there too.
 
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Diode-pumped solid-state (DPSS) lasers are solid-state lasers made by pumping a solid gain medium, for example, a ruby or a neodymium-doped YAG crystal, with a laser diode.

DPSS lasers have advantages in compactness and efficiency over other types, and high power DPSS lasers have replaced ion lasers and flashlamp-pumped lasers in many scientific applications.
Contents


* 1 Coupling
o 1.1 Some numbers
* 2 Common DPSS processes


Coupling

The wavelength of the laser diodes is tuned by means of temperature to produce an optimal compromise between the absorption coefficient in the crystal and energy efficiency (low as possible pump photon energy). As waste energy is limited by the thermal lens this means higher power densities compared to high-intensity discharge lamps.

High power lasers use a single crystal, but many laser diodes are arranged in strips (multiple diodes next to each other in one substrate) or stacks (stacks of substrates). This diode grid can be imaged onto the crystal by means of a lens. Higher brightness (leading to better beam profile and longer diode lifetimes) is achieved by optically removing the dark areas between the diodes, which are needed for cooling and delivering the current. This is done in two steps:

1. The "fast axis" is collimated with an aligned grating of cylindrical micro-lenses.
2. The partially-collimated beams are then imaged at reduced size into the crystal. The crystal can be pumped longitudinally from both end faces or transversely from three or more sides.

The beams from multiple diodes can also be combined by coupling each diode into an optical fibre, which is placed precisely over the diode (but behind the micro-lens). At the other end of the fiber bundle, the fibers are fused together to form a uniform, gap-less, round profile on the crystal. This also permits the use of a remote power supply.
Some numbers

High power laser diodes are fabricated as bars with multiple single strip laser diodes next to each other.

Each single strip diode typically has an active volume of:
1 µm 2 mm 100 µm
Height Depth Width
fast axis optical axis slow axis

and depending on the cooling technique for the whole bar (100 to 200) µm distance to the next laser diode.

The end face of the diode along the fast axis can be imaged onto strip of 1 µm height. But the end face along the slow axis can be imaged onto a smaller area then 100 µm. This due to the small divergence (hence the name: 'slow axis') which is given by the ratio of depth to width. Using the above numbers the fast axis could be imaged onto a 5 µm wide spot.

So to get a beam which is equal divergence in both axis, the end faces of a bar composed of 5 laser diodes, can be imaged by means of 4 (acylindrical) cylinder lenses onto an image plane with 5 spots each with a size of 5 mm x 1 mm. This large size is needed for low divergence beams. Low divergence allows paraxial optics, which is cheaper, and which is used to not only generate a spot, but a long beam waist inside the laser crystal (length = 50 mm), which is to be pumped through its end faces.

Also in the paraxial case it is much easier to use gold or copper mirrors or glass prisms to stack the spots on top of each other, and get a 5 x 5 mm beam profile. A second pair of (spherical) lenses image this square beam profile inside the laser crystal.

In conclusion a volume of 0.001 mm³ active volume in the laser diode is able to saturate 1250 mm³ in a Nd:YVO4 crystal.
[edit] Common DPSS processes

The most common DPSS laser in use is the 532 nm wavelength green laser pointer. A powerful (>200 milliwatt) 808 nm wavelength infrared laser diode pumps a neodymium doped yttrium orthvanadate (Nd:YVO4) crystal which produces 1064 nm wavelength light. This is then frequency doubled using a nonlinear optical process in a KTP crystal, producing 532 nm light. Green DPSS lasers are usually around 20% efficient, although some lasers have been reported to be 35% efficient. In other words, a green DPSS laser using a 2.5 W pump diode would be expected to output around 500 mW of 532 nm light.

Blue DPSS lasers use an extremely similar process, except that the 808 nm light is being converted to 946 nm light, which is then frequency-doubled to 473 nm. Because of the lower gain for the materials, blue lasers are relatively weak, and are only around 3% efficient.



CW lasers
CW Violet Blue Green Yellow Lasers Wavelength (nm) 375 405 430 442 473 488 523 527 532 542 555 561 593 Max Output(mW) 16 1000 15 500 150 20 300 300 500 200 200 200 50 CW Red TEMoo Mode Lasers Wavelength (nm) 638 642 655 656 660 671 690 785 808 830 852 914 980 Max Output(mW) 50 100 70 200 200 200 50 120 120 100 100 100 1000 CW Infrared Lasers Wavelength (nm) 780-990 946 1030 1047 1053 1064 1122 1313 1319 1338 1342 1444 1550 Max Output(mW) 100 500 200 2000 2000 3000 1000 1000 1000 1000 1500 500 1000 Q-switched lasers
Q-switched UV Blue Green Lasers Wavelength (nm) 262 266 349 351 355 440 447 473 523 527 532 555 561 Max Aver Power(mW) 50 50 150 150 150 50 50 50 1000 1000 1000 500 500 Q-switched Red and Infrared Lasers Wavelength (nm) 657 660 671 750-950 946 1047 1053 1064 1080 1313 1319 1342 1444 Max Aver Power(mW) 100 100 500 50 400 2000 2000 2000 500 500 400 750 200 Customized Options Digital TTL on/off Control and Analog Modulation
Fiber Coupling. Single mode fiber coupling and multi-mode fiber coupling
Ultra Stable Option. Output power stability 0.5% or 0.25% over 24 hours
Laser Beam Expanders. Change the laser beam size and beam divergence.
 
Forgot to mention that this is the wrong section to advertise. You should head over the the buy/sell trade section of the forum. It's kind of like the classifieds..
 
FrostyTheDadMan said:
Not necessarily
James Harper At Coherent hand picked 5 of these for me and the arrow shows the direction. these are not your ordinary production crystals.
Click to expand...

So you are saying you bought these from Coherent? I don't really believe that, and my reason for that is that this is not how the label the crystals, and the part number on the box is not for that crystal.
 
Laser_Ben said:
So you are saying you bought these from Coherent? I don't really believe that, and my reason for that is that this is not how the label the crystals, and the part number on the box is not for that crystal.
Click to expand...

Yes it is
that is how I got them from coherent
Ask them yourself I just spoke to them yesterday.

Stephen L. Knapp
Field Sales Engineer
Midwest Office
Coherent, Inc.
(847) 433-9163 Office

Here is a copy of a corespondent with James Harper
Harper, James
to me, Debra

show details 5/15/08 from: James.Harper@coherent.com


Jeff,
I received an email this morning from our optics division that you were asking to setup the LBO crystal as you were having trouble. They do not have the expertise in this, nor will anyone else in our site. However, try to polarize your 808 light and then send it back through the crystal. This is about all we can offer and good luck.
Regards
Jim Harper

Jim Harper
Manufacturing Engineering Manager
 
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It looks a lot like a LBO used for doubiling a ti sapphire laser such as a Mira. I have very similar crystals made of BBO that are the same size. The part number prefix is similar to other ti sapphire optics that go to a mira that i've seen too.

These are angle tuned and adjusted for phase angle. For true non q-switched DPSS aplications it is a tad too thin though IMHO.
 
FrostyTheDadMan said:
Yes it is
that is how I got them from coherent
Ask them yourself I just spoke to them yesterday.

Stephen L. Knapp
Field Sales Engineer
Midwest Office
Coherent, Inc.
(847) 433-9163 Office

Here is a copy of a corespondent with James Harper
Harper, James
to me, Debra

show details 5/15/09 from: James.Harper@coherent.com


Jeff,
I received an email this morning from our optics division that you were asking to setup the LBO crystal as you were having trouble. They do not have the expertise in this, nor will anyone else in our site. However, try to polarize your 808 light and then send it back through the crystal. This is about all we can offer and good luck.
Regards
Jim Harper

Jim Harper
Manufacturing Engineering Manager
Click to expand...

A few things:

A: If they donated those to you, it would have the correct part number.
B: If they donated those to you, you would have needed to sign a agreement that you would not sell them.
C: If they donated them to you, you would have proof of such, or a explanation of what they were for.
D: That emails seems like something you typed up yourself, especially by the wording of it.
E: Jim Harper is a sales manager, not an engineer
F: The way that crystal is marked is incorrect
G: LBO of that thickness cannot be used for effective SHG generation, it is too thin, and would require a very good cavity to work efficiently, it could not be used extracavity because it is too thin.
H: Were you licensing US patent #4,826,283?
I: If you put 100W of 946nm light into that crystal, you would get nothing out.
J: What are the cut angles? Surely Coherent would have told you?
K: Is it designed for Type I or Type II Phase Matching?
L: Why would you be selling this for $95 if it cost $1000?
M: Could these be the ones you bought on ebay from Hsec_Photonics on Jun-24-08?

Don't mean to be too picky, just want to get a better understanding of this amazing product!
 
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