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Thread: 445nm diode for holography?

  1. #1
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    Default 445nm diode for holography?

    Hello All!

    I am new to this forum and a first-time poster. I decided to join PL because you guys seem a bit more serious about your lasers. There's plenty of other spots on the web eager to discuss 445nm diodes, but their primary focus seems to be how many balloons the unit can pop.

    I'm interested in 445nm coherent light because I want ~50mW of it to be the "B" in my RGB holography setup.

    I've been burning holograms at 532nm for a couple of years now, and am in the process of gearing up for a couple of super-cool upgrades - the first of which is the design and construction of robotic devices that will manage the capture and exposure of source images for multiplex holography.

    The second upgrade is the move to full-color holography. My Compass 215 will soon be joined by a couple of new buddies - I need as "blue" a blue as I can get (to my eye 445nm looks great), and a nice red that I imagine will fall into He-Ne territory.

    I've heard of single-beam holograms being made with the Casio 445nm diode, but lord knows that may have been sheer luck.

    I'm hoping some of the knowledgeable laser folks here may be able to help me find an appropriate laser for this task.

    I don't need heaps of power - 50mW will be about right to get exposure times roughly similar.

    My biggest concern with a diode is mode hops. Mode hops during exposure will bone a hologram. I don't know if laser diodes are capable of single-longitudinal-mode operation, at least without costing a fortune, and I guess I could live with multimode operation, as long as those darn modes remain stable!

    I'll grant you that I've been a bit spoiled by my sweet sweet Coherent laser, with its SLM operation and incredible coherence length, but I'm prepared to work with a little less if it means I can find an affordable solution to my blue dilemma.

    Can anyone advise me on how to get a 445nm diode -with a really stable output and at least a few inches of coherence length- mounted to my table without spending a lot of money?

    Thanks for any and all help

  2. #2
    Join Date
    Dec 2007
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    Nottingham, UK
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    Default

    Justin,
    Welcome aboard!

    There is a member here on PL (redlumx I think) who wrote up some of his findings on 445's and holography here:
    http://hololaser.wordpress.com/2010/...lographer-too/
    and here:
    http://redlum.xohp.pagesperso-orange...t.html#NDB7352

    I hope that's a start to answering some of your questions...

    Best Regards,
    Dan
    Last edited by danielbriggs; 03-16-2011 at 13:35.
    - There is no such word as "can't" -
    - 60% of the time it works every time -

  3. #3
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    Mar 2011
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    Spring Hill, FL
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    Hi Daniel

    Thank you very much for your reply. The article you linked me to really brings me hope for an inexpensive solution for my project. I've got a buddy who will hopefully be willing to build me a unit to mount to my table that won't break the bank.

  4. #4
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    Hi Justin

    Welcome to the 'dark side'

    With regard to the 445, i'm not sure how you'll get on trying to get the beam through a spatial filter as it's not a TEM00 beam, rather a series of stripes.

    Cheers

    Jem
    Quote: "There is a theory which states that if ever, for any reason, anyone discovers what exactly the Universe is for and why it is here it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another that states that this has already happened.... Douglas Adams 1952 - 2001

  5. #5
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    Heya Jem!

    Well, crap. Thanks for bringing that to my attention. This sounds like it could be a real issue. Is it not possible though that focusing the beam through a pinhole could just blur all the stripes into a homogeneous spot?

  6. #6
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    Quote Originally Posted by HoloJustin View Post
    Heya Jem!

    Well, crap. Thanks for bringing that to my attention. This sounds like it could be a real issue. Is it not possible though that focusing the beam through a pinhole could just blur all the stripes into a homogeneous spot?
    I doubt it, I think you'll pretty much get out what you put in, possibly the pinhole may clean it up a bit , but I think we're clutching at straws. Maybe someone here could try it and post the results. I guess there's a good reason why they're only being used for SBR's.
    Quote: "There is a theory which states that if ever, for any reason, anyone discovers what exactly the Universe is for and why it is here it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another that states that this has already happened.... Douglas Adams 1952 - 2001

  7. #7
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    May 2009
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    what about rounding out the beam with an achromatic prism set?
    Will there be three phase!!!!

  8. #8
    Join Date
    Oct 2010
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    Athens, Greece
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    you can check this one, for some findings on the 445 diodes' use in holography

    http://holoforum.org/oldforum/viewto...=7290&start=30

    but you can also start thinking about getting a proper 473nm 50mw dpss. i know that member "raingob" here sells one at what i consider a reasonable price. you could contact him directly

    cheers
    "its called character briggs..."

  9. #9
    Join Date
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    Lightbulb

    Hi Justin,
    Have a look at this thread on laserpointerforums.

    http://laserpointerforums.com/f39/50...9-a-53553.html

    I bought a couple of these 50mW rated 445nm Nichia NDB7242E diodes for my mini RGB projector.
    I'm about a week away from powering mine up so cant vouch for the beam quality yet.

    From what I've been told they can do more power comfortable and the beam specs are much better than the harvested 445nm diodes. They are 3.8mm not 5.6mm so be prepare for some custom machining. The guys name is Gary and was good to deal with. They may all be gone but there might be people with some spare as he had a couple of hundred of them.

    I think Gary posted his email in that thread or an earlier post. Do a search for 50mw 445nm diode on LPF and you should find it. If not PM me and I'll put you in touch.

    Here is the data sheet.
    Click image for larger version. 

Name:	NDB7242E UTZ-SC0112_1.pdf 
Views:	24 
Size:	129.6 KB 
ID:	24117

    Good luck.
    Kit

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