Results 1 to 4 of 4

Thread: Cube Beam Splitters

  1. #1
    Join Date
    Feb 2005

    Default Cube Beam Splitters

    Ok,, This is a throw together of some cube Beam Splitter facts

    Some cut and paste from various sources
    And a few to look for.

    *** Polarizing Cube Beamsplitters ***
    Polarizing cube beamsplitters divide unpolarized light into two orthogonal polarized beams at 90 to each other.
    The transmitted beam is mostly polarized parallel to the plane of incidence
    (p-polarized), and the reflected beam is mostly polarized perpendicular to the plane of incidence.

    Each beamsplitter consists of a pair of precision high tolerance right angle
    prisms, which must be fixed in relation to one another by either mounting or cement.
    A multi-layer antireflective coating is then applied to each face of the beamsplitter in order to produce maximum transmission efficiency.

    There are three main types of polarizing cube beamsplitters: prism, broadband, and laser-line.

    Prism cube beamsplitters are constructed by cementing together two precision right angle prisms with the appropriate interference coating on the hypotenuse surface.
    This is the most common style of polarizing cube beamsplitters.
    Broadband cube beamsplitters operate in the visible and very near infrared (to 850 nm) with constant performance over a 200 nm range.

    Laser-line cube beamsplitters are tuned for optimum performance at specific laser wavelengths.
    They exhibit lower loss, but have a narrower operating range, typically 25 nm or less.

    Since polarizing cube beamsplitters use reflection to polarize the light, the materials from which the cubes are made are less bifringent than those used in other types of polarizers.
    The materials tend to be oriented more towards bandpass. Some of the more common materials used in the creation of polarizing beamsplitter cubes are BK7 glass, SF2 Glass, and UV grade fused silica;
    although custom and proprietary material styles can also be found. BK7 Glass is boro-crown glass (borosilicate glass).
    It has a wavelength range of 330-2100 nm. SF2 Glass is dense flint (alkaline silicate glasses with 47% wt. PbO).
    UV grade fused silica offers improved transmission in the ultraviolet region when compared to crown glass. Its wavelength range is 200-2500 nm.

    Only collimated beams of light can be used with polarizing cube beamsplitters.

    A shear plate may be used to make sure that an expanded beam is properly collimated before striking the cube.

    I have been experimenting with a few different narrowband ones...
    One in particular is a Melles Griot 03PBS094 12.7mm 670nm laserline cube

    But others to look for are Melles 03PBS 043(10mm), 045(20mm), 047 (25.4mm) ..These are for 632nm.
    I dont know about the ones for 780nm, I dont believe these may work well, They may...albeit with a lot more loss!!!
    I have not checked-out NON-Polarized Cubes as of yet...Stay tuned!!!

    The Broadband ones are kewl as you can combine different colors as well.

    Note: This assumes that the polarization of the diodes used are 100 : 1
    or most are!!!

    Most cheap Green and Blue DPSS lasers usually have much less of a ratio and contain both polarities..
    There will be more loss, But its affordable to loose some green now-a-days!!
    Blue is another story.. NOT cheap price- wise !!!

    But watchout for Polarization problems when using more than one cube!!!

    Check out these references for more infomation:
    "My signature has been taken, so Insert another here"
    *^_^* aka PhiloUHF

  2. #2
    Join Date
    Jan 2005



    thanx for all the info
    I sure have alot to learn.. :idea: :idea:

  3. #3
    Join Date
    Mar 2006


    Thanks. Good info, and just when I was about to start thinking seriously about beam combining, too.

  4. #4
    Join Date
    Mar 2006
    Ottawa, Ontario, Canada


    Heh Folks,

    Another source for polarized beam splitters are the old first generation video disc players. If you can cannibalize one, you will find a HE-NE laser built into an optical bench that contains high quality dichroic mirrors that you could adapt for combining red and green and it also contains a nice cube beam splitter + some adjustable quarter or half wave plates to fine tune the laser polarity. Also may contain some line generating optics and a diffraction grating for special effects.

    I think Mike Kenney at MWK lasers might have some If he's still in business.
    I believe one of his 2 Ebay seller Identities is "HENE1" or try doing a search for MWK lasers.

    Good Luck
    Profile Redacted by Admin @ 04.24.2010

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts