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Illumination angle control using dichroic filters

  • US 8,054,553 B2
  • Filed: 06/12/2008
  • Issued: 11/08/2011
  • Est. Priority Date: 06/12/2008
  • Status: Active Grant
First Claim
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1. A method of controlling the illumination angle onto a target, comprising:

  • illuminating onto the target with light from at least two light sources of pre-selected wavelengths;

    wherein each point on the target is illuminated by light from the light sources with a respective maximal illumination angle relative to a main illumination axis extending from substantially the center of the at least two light sources to the target;

    selecting a dichroic filter that transmits light from the at least two light sources as a function of the angle of incidence upon the filter; and

    positioning the dichroic filter between the at least two light sources and the target to limit the transfer of light to light of the pre-selected wavelengths;

    wherein said dichroic filter is selected to limit the maximal illumination angle illuminating each point on the target;

    wherein said dichroic filter does not form a right angle relative to the main illumination axis; and

    wherein the angle of the dichroic filter is user controllable.

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