Method and apparatus for shaping electromagnetic beams
First Claim
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1. A method of shaping the intensity profile of a beam of electromagnetic waves comprising:
- positioning a diffraction grating having a centrally symmetric grating pattern in the optical path of the beam, the grating pattern itself having a generally central phase reversal transverse to the axis of the beam.
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Abstract
The intensity profile of a beam of electromagnetic waves such as a laser beam is shaped by means of a diffraction grating and/or prism in the beam path. In one embodiment, beams exhibiting Gaussian energy intensity profiles undergo an energy redistribution to approximately uniform profiles. A reflective or transmissive surface relief grating is employed with phase steps generally periodic except at the pattern center where a pattern phase reversal occurs. Prisms are cut and oriented relative to the incoming beam to operate at the Brewster'"'"'s angle for compressing or expanding the beam with minimum losses.
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Citations
15 Claims
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1. A method of shaping the intensity profile of a beam of electromagnetic waves comprising:
positioning a diffraction grating having a centrally symmetric grating pattern in the optical path of the beam, the grating pattern itself having a generally central phase reversal transverse to the axis of the beam. - View Dependent Claims (2, 3, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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4. A method of shaping the intensity profile of an electromagnetic beam by reflecting said beam off, or transmitting said beam through, a surface relief grating, said grating having a coded surface relief pattern composed of many spaced binary phase steps of height h, where h is chosen to provide an incremental wavelength path difference related to the wavelength of the light in the laser beam whose intensity profile is shaped, the spacing between said spaced binary phase steps being periodic except at the surface relief pattern center where a surface relief pattern phase reversal occurs such that the center phase step has a width twice the width of other phase steps in the pattern, the periodicity of the binary phase steps being determined on the basis of the width, divergence and wavelength of the original beam and the required profile of the beam after processing by the grating.
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