Diffractive optical element including a diffractive grating pattern
AssigneeAsahi Kogaku Kogyo Kabushiki Kaisha
InventorsTakashi Iizuka, Masato Noguchi, Tsutomu Sato
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Abstract
Disclosed is a diffractive optical element which includes a diffractive grating pattern on a base plate. The diffractive grating pattern includes a plurality of phase gratings arranged in parallel lines extending along a predetermined direction to cause diffraction of an incident beam. Each of the plurality of phase gratings has an asymmetrical phase pattern. There is a phase gap, ΔP, representing a phase difference (in radians) between an end point and a beginning point of each phase pattern. The phase gap, ΔP, is substantially equal for each of the plurality of phase gratings and satisfies the relationship. 0.7π<|ΔP|<1.2π.
Claims6
A diffractive optical element, comprising a cylindrical surface provided with a diffractive grating pattern, said diffractive grating pattern including a plurality of phase gratings arranged in parallel lines extending along a circumference of said cylindrical surface to cause diffraction of an incident beam, wherein a beam incident on said diffractive grating pattern is divided into and emitted as a plurality of diffracted beams;
- and
- wherein said plurality of phase gratings are of equal width and each of said plurality of phase gratings has an asymmetrical phase pattern and a continuous, nonlinear surface with a starting point and an ending point, such that a position of an ending point of one phase grating coincides with a position of a starting point of an adjacent phase grating in a direction of arrangement of the gratings, said plurality of phase gratings causing phase differences in a wave front of said incident beam, and
- wherein, a phase gap ΔP, representing a phase difference between an end point of each of said plurality of phase patterns and a beginning point of each of said plurality of phase patterns, in radians, is substantially equal for each of said plurality of phase gratings and satisfies:
- 0.7π<|ΔP|<1.2π.
A diffractive optical element, comprising a cylindrical surface provided with a diffractive grating pattern, said diffractive grating pattern including a plurality of phase gratings arranged in parallel lines extending along a circumference of said cylindrical surface to cause diffraction of an incident beam, wherein a beam incident on said diffractive grating pattern is divided into and emitted as a plurality of diffracted beams;
- and
- wherein said plurality of phase gratings are of equal width and each of said plurality of phase gratings has a continuous nonlinear surface with a starting point and an ending point, such that a position of an ending point of one phase grating coincides with a position of a starting point of an adjacent phase grating, in a direction of arrangement of the gratings, said plurality of phase grating causing phase differences in a wave front of said incident beam, said phase grating being arranged so that a predetermined number of diffracted beams having substantially a same intensity are emitted, and no additional beam having a substantial intensity is emitted.
A diffractive optical element, comprising a cylindrical surface provided with a diffractive grating pattern, said diffractive grating pattern including a plurality of phase gratings arranged in parallel lines extending along a circumference of said cylindrical surface to cause diffraction of an incident beam having a predetermined wavelength, wherein a beam incident on said diffractive grating pattern is divided into and emitted as a plurality of diffracted beams;
- wherein said plurality of phase gratings are of equal width and each of said plurality of phase gratings has a continuous nonlinear surface with a starting point and an ending point, such that a position of an ending point of one phase grating coincides with a position of a starting point of an adjacent phase grating, in a direction of arrangement of the gratings, said plurality of phase gratings causing phase differences in a wave front of said incident beam;
- wherein each of said plurality of phase gratings has an asymmetrical phase pattern, and
- wherein, a phase gap ΔP, representing a phase difference between an end point of each of said plurality of phase patterns and a beginning point of each of said plurality of phase patterns, in radians, is substantially equal for each of said plurality of phase gratings and satisfies:
- 0.7π<|ΔP|<1.2π.
Dependencies are inferred from the claim text.