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Steve Koch 22:37, 5 March 2010 (EST): Hey Pranav -- thank you for starting to use the wiki! I, or hopefully Anthony, can show you a bit about how to more easily use it for taking notes (where to put things, etc.). For now, I'll comment here: 10^-7 ... is tough! Hopefully Mr. Gunn's contacts have a good idea. We do have a beam choppper. Maybe that could help, sweep a pinhole or strip through the beam and use the QPD w/ KG filters to profile the beam? I'm not sure where the beam chopper is, but sounds promising (because then you wouldn't worry about the KG distorting the beam. Maybe some google searching and / or talking to experts to see if beam chopper + photodiode is good method for high power beam profiling?
Our e-mail conversation over beam-profiling (03/09/2010-03/03/2010)
I talked to Kevin at Ophir-Spiricon, LLC. Ophir-Spiricon, LLC Mr. Daniel L. Ford Southwest Southern CA, AZ, NM, and Las Vegas
Toll Free: +866-755 5499 Cell: +480-650 1103 Fax: +480-718 7721
He gave me the price for Beam Tap I-$575 and II-YAG-$995 with 5% university discount. I asked him to send me a final quote.
For AR coated blanks: 45 degree cold mirror-Cold Mirror
■ Angle of Incidence: 45°
■ Transmission: >85% Average
from 750-1200 nm
■ Reflection: >90% Average
from 420-630 nm
FM03 $ 32.20 45° 1.0 mm 25.4 mm (1") Cold Mirror
FM203 $ 71.90 45° 1.0 mm 50.8 mm (2") Cold Mirror PR
AR coated blanks should have almost no beam distortion -- just make sure they have a decent flatness specification, which I imagine almost all of them will.
That link took me to a beam tap, which would probably work on a collimated portion of your optical path -- it's up to you to figure out if the power numbers make sense for you. The benefit of that device is that you could set up a beam profiler on the tapped light, and use the main beam for the optical tweezer. If you want to measure the optical profile directly at the trapping location, then you have another problem, since you would need to insert this device in your setup in such a manner that the low power tap proceeds to your focusing lenses. Another way would be to place a beam pick, or AR reflector after the focusing lens of the tweezer, and use a relay system to project that mode onto a beam profiler, but this might be a little more advanced of an approach than you need.
It will be more expensive to do it this way, but probably faster than putting it together yourself with the blanks.
Best of luck,
Dear Mr. Gunny, Thanks for helping us with this, our lab sincerely appreciate your effort. Mr. William told me that it is OK if i contact you directly. I have a question in the same line: Would AR coated blanks accurately represent the beam, because it looks like that we most probably have to use 2 of them? And also do you think this kind of a system: http://www.ophiropt.com/laser-measurement-instruments/beam-profilers/products/industrial-applications/the-accessories---beam-profiling/beam-tap-i--ii-ya can be a good match in solving our problem? Thanks once again for your time Mr. Gunn. Best, Pranav CHTM-UNM
Thanks for looking into this, Pranav! The antireflection coated blank is a possibility, but I worry about whether that would accurately represent the beam. Did you find any blogs or other “how to” sites out there that may talk about beam profiling with AR blanks? We’d only need two of those (10^-3)^2 probably.
· Pricing on above system (and the others)
· Pricing on very flat AR coated blanks
· A little blog searching (blogsearch.google.com) to see if you can find any very good “how to” articles on our issue.
-( http://news.thomasnet.com/fullstory/558749 http://www.youtube.com/watch?v=xGtuNCMghNM (i just love this one) http://www.ophiropt.com/laser-measurement-instruments/beam-profilers (expensive one) http://www.newport.com/Laser-Beam-Profiler/318103/1033/catalog.aspx this all info will be on wiki also soon |:-(|) PR
Thanks in millions Mr. Gunn. The information is really help-full, I am working on it right now. Can i get back to you if i have some questions. Thank you, Pranav CHTM - UNM
--- On Fri, 3/5/10, William Gunn <firstname.lastname@example.org> wrote:
On Fri, Mar 5, 2010 at 1:49 PM, Cary Gunn <email@example.com> wrote:
I'd bounce the beam off of a few pellicles,
That way you don't pick up distortions related to transmission through a thick ND filter. If the attenuation is not enough, you can use lower reflectivity mirrors, like a simple quartz blank (R<4%), an anti-reflective coated blank at that wavelength (R<0.1%), like this:
On Fri, Mar 5, 2010 at 11:05 AM, William Gunn <firstname.lastname@example.org> wrote:
A graduate student working for a friend of mine at UNM had some simple questions about beam profiling, and I thought you'd probably know the answer off the top of your head, so I thought I'd put you in touch.
Forwarded message ---------- From: PRANAV RATHI <email@example.com> Date: Thu, Mar 4, 2010 at 7:54 PM Subject: Beam profiling at higher powers To: firstname.lastname@example.org