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Thread: Beam and lens specifications

  1. #1
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    Default Beam and lens specifications

    Got a few spec questions about Leadlight lasers pointer modules I'd like to know the answers to.
    If any one knows the answers I'd be very happy to hear them.


    Typically.
    What are the focal lengths of the expander lens and collimating lens?
    What is the distance in millimeters from the expander lens to the first crystal
    What is the beam diameter before it enters the expander lens?
    What is the beam divergence before it enters the expander lens?

    If any one knows the answers I'd be very happy to hear them.

    Steve

  2. #2
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    Default Re: Beam and lens specifications

    Quote Originally Posted by steve001

    Typically.
    1>What are the focal lengths of the expander lens and collimating lens?
    2>What is the distance in millimeters from the expander lens to the first crystal
    3>What is the beam diameter before it enters the expander lens?
    4>What is the beam divergence before it enters the expander lens?

    If any one knows the answers I'd be very happy to hear them.

    Steve
    1> Jesus. mm's at the longest. very strong cocave lenses there. never measured it, never had to.

    2> Probably somewhere near the focal point consider a 50micron dot at the first crystal surface.

    3> expander? do you mean the plano convex collimator jobbie? .25mm ish. depends on the rocks and the walkoff. if you mean post diode pre crystalset then its probably rectangular in size and standard mrad wont work here. see intro to A4

    4> Less than 9x40. larger than a breadbox. smaller than a commercial jetliner. Depends on stages before it but i would venture a guess at 8-12mrad as that would allow for a decent 1.5 mm beam with low divergence.

    The way you state the above question implies that you want someone to do your homework.

    Its a pointer... If it works then everythings fine and further investigation to reinvent the wheel is pretty silly.

  3. #3
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    Default Re: Beam and lens specifications

    Quote Originally Posted by Spec
    Quote Originally Posted by steve001

    Typically.
    1>What are the focal lengths of the expander lens and collimating lens?
    2>What is the distance in millimeters from the expander lens to the first crystal
    3>What is the beam diameter before it enters the expander lens?
    4>What is the beam divergence before it enters the expander lens?

    If any one knows the answers I'd be very happy to hear them.

    Steve
    1> Jesus. mm's at the longest. very strong cocave lenses there. never measured it, never had to.

    2> Probably somewhere near the focal point consider a 50micron dot at the first crystal surface.

    3> expander? do you mean the plano convex collimator jobbie? .25mm ish. depends on the rocks and the walkoff. if you mean post diode pre crystalset then its probably rectangular in size and standard mrad wont work here. see intro to A4

    4> Less than 9x40. larger than a breadbox. smaller than a commercial jetliner. Depends on stages before it but i would venture a guess at 8-12mrad as that would allow for a decent 1.5 mm beam with low divergence.

    The way you state the above question implies that you want someone to do your homework.

    Its a pointer... If it works then everythings fine and further investigation to reinvent the wheel is pretty silly.

    The way you state the above question implies that you want someone to do your homework
    No, this is not a homework question. There is an applet here[ http://www.lightmachinery.com/gausbeam.html] that I use and I wanted to know some specs that are not readily known. I posted these questions before I removed the module. Upon inspection, it appears that the PCV lens is spaced about 1mm from the MCA. I have no way of measuring the beams diameter as it enters the PCV lens but I loosely estimate it to have a diameter of about .1mm. Divergence of the beam prior to entering the PCV lens is unknown.
    As for focal length of the PCV and PCX, I estimate the PCV lens has a focal length of -6mm, worldwide that is common for off the shelf optics. The focal length for the PCX to 15-18mm. Knowing these numbers precisely would help with the above mentioned applet.
    You mentioned A4. What is that?

  4. #4
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    Default

    Heh, one thing that'll put a crimper on that is that the actual diodes change
    per batch, so a number that works for one won't work for the other... The
    key indicator is that the optics and the crystal are all threaded with a fine
    pitch, and they hand calibrate each unit individually. The design allows
    for a kinder gentler sloppiness in the manufacturing tolerances...

    What are you doing? It may be best to spec your own pump diode, and
    reuse the casix crystals. I know I'm definitely not too fond of the collimating
    lenses on the pointers so I'd personally get my own set of those too...
    Now that I think about it, I'm not a fan of the casix laminates either...

  5. #5
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    Default

    I just add one simple question in here as we speak about lense and optics...

    Can i focuse my laser "beam" into a more tighter beam ?!
    Yeas I talk about my laser I did buy from spec..

    I wonder what lense i need to make the spot tiny tiny tiny
    (hmm yes so I can try to burn something :twisted: )

    I know it will be hard to get it tight like 1000 feet away, but what about a distance of only 1 meeter ?

  6. #6
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    Yes, any convex optic will allow you to focus it to a very tiny spot nearby
    It'd be just like burning stuff with the sun...

    However, if you want that spot collimated over a distance, then there are
    physical constraints due to the size of the original die and the rayleigh
    length of the wavelength... Though I do hear that once negative index of
    refraction optics (i.e. "deep magic") makes it into the visible spectrum, there's
    a possibility they may be able to break some of the old rules...

  7. #7
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    Default

    Quote Originally Posted by yaddatrance
    Heh, one thing that'll put a crimper on that is that the actual diodes change
    per batch, so a number that works for one won't work for the other... The
    key indicator is that the optics and the crystal are all threaded with a fine
    pitch, and they hand calibrate each unit individually. The design allows
    for a kinder gentler sloppiness in the manufacturing tolerances...

    What are you doing? It may be best to spec your own pump diode, and
    reuse the casix crystals. I know I'm definitely not too fond of the collimating
    lenses on the pointers so I'd personally get my own set of those too...
    Now that I think about it, I'm not a fan of the casix laminates either...
    Using the aforementioned applet I wanted to know what the beam divergence was now that I installed new lenses for a Galilean beam expander. The question was not about the lens(es) that focuses the IR onto the first crystal. With a little juggling of the input numbers I was able to figure out what the beams divergence is approximately

  8. #8
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    Quote Originally Posted by liteglow
    I just add one simple question in here as we speak about lense and optics...Can i focuse my laser "beam" into a more tighter beam ?!
    Yeas I talk about my laser I did buy from spec..

    You need to expand the beam first than focus the beam when you do that you can do this
    http://www.olympusfluoview.com/theor...aserintro.html
    It is important to note that extremely high power densities are achieved at the focal point of a concentrated laser beam. A 10-milliwatt beam focused to a diffraction-limited spot 0.22 micrometers in diameter results in a power density of approximately 30-million watts per square centimeter. Such high energy levels can rapidly degrade or destroy lens and filter coatings, as
    I wonder what lense i need to make the spot tiny tiny tiny
    (hmm yes so I can try to burn something :twisted: ) I know it will be hard to get it tight like 1000 feet away, but what about a distance of only 1 meeter ?
    If you do this then, you can do this. you could burn something if your output is great enough
    [/quote]You'll need a 4 cm diameter lens to have a green beam collimated* for 1000 m. The Gaussian spot size** must be 1.3 cm at the lens, and it is customary to use lenses at least 3 times larger than the spot size, hence the 4 cm diameter requirement. **The spot size is the beam radius at 1/e^2 of the center beam intensity. *Actually, an initially collimated Gaussian beam will expand by the square-root-of-2 in that distance, for 532 nm and a 1.3 cm spot size. Alternatively, if you focus that same beam on a point 500 m from the lens, then at 1000 m it will have the same diameter as it does at the lens. Look up Gaussian beam propagation in most any book on lasers, for example A. E. Siegman, Lasers, section 17.1 Milonni & Eberly, Lasers, section 14.5 Mark

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