Diffractive optical element
First Claim
1. A diffractive optical element, comprising two diffraction gratings composed of materials differing in dispersion from each other, and which are laminated with a separation between the gratings, which allows for enhancing diffraction efficiency for a particular design order throughout a predetermined wavelength region, wherein edges of at least part of corresponding grating portions of said two diffraction gratings are shifted from each other in a direction of grating pitch of each diffraction grating, and a grating thickness of one of the gratings in one period thereof increases monotonically along one direction of the grating pitch.
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Abstract
A diffractive optical element is composed of a plurality of diffraction gratings which differ in dispersion from each other and are laminated while being spaced to enhance diffraction efficiency for a particular order (design order) throughout an entire usable wavelength region, wherein edges of at least part of corresponding grating portions of the plurality of diffraction gratings are shifted from each other in a direction of arrangement of grating portions of each diffraction grating.
28 Citations
32 Claims
- 1. A diffractive optical element, comprising two diffraction gratings composed of materials differing in dispersion from each other, and which are laminated with a separation between the gratings, which allows for enhancing diffraction efficiency for a particular design order throughout a predetermined wavelength region, wherein edges of at least part of corresponding grating portions of said two diffraction gratings are shifted from each other in a direction of grating pitch of each diffraction grating, and a grating thickness of one of the gratings in one period thereof increases monotonically along one direction of the grating pitch.
- 4. A diffractive optical element, comprising two diffraction gratings composed of materials differing in dispersion from each other and which are laminated with a separation between the gratings, which allows for enhancing diffraction efficiency for a particular design order throughout a predetermined wavelength region, wherein grating pitches of at least part of corresponding grating portions of said two diffraction gratings are different from each other, and a grating thickness of one of the gratings in one period thereof increases monotonically along one direction of the grating pitch.
- 12. A diffractive optical element, comprising two diffraction gratings composed of materials differing in dispersion from each other and which are laminated with a separation between the gratings, wherein, with respect to at least two wavelengths, a maximum optical path length difference is made equal to integer times each of the wavelengths, and wherein edges of at least part of corresponding grating portions of said two diffraction gratings are shifted from each other in a direction of grating pitch of each diffraction grating, and a grating thickness of one of the gratings in one period thereof increases monotonically along one direction of the grating pitch.
- 15. A diffractive optical element, comprising two diffraction gratings composed of materials differing in dispersion from each other and which are laminated with a separation between the gratings, wherein, with respect to at least two wavelengths, a maximum optical path length difference is made equal to integer times each of the wavelengths, and wherein grating pitches of at least part of corresponding grating portions of said two diffraction gratings are different from each other, and a grating thickness of one of the gratings in one period thereof increases monotonically along one direction of the grating pitch.
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27. A diffractive optical element, comprising two diffraction gratings composed of materials differing in dispersion from each other, and which are laminated with a separation between the gratings, which allows for enhancing diffraction efficiency for a particular design order throughout a predetermined wavelength region, wherein edges of at least part of corresponding grating portions of said two diffraction gratings are shifted from each other in a direction of a grating pitch of each diffraction grating;
wherein the grating pitch of each of said two diffraction gratings is gradually varied, and the shifting of edges between corresponding grating portions of said two diffraction gratings becomes larger accordingly as the grating pitch of each grating portion becomes smaller.
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28. A diffractive optical element, comprising two diffraction gratings composed of materials differing in dispersion from each other and which are laminated with a separation between the gratings, which allows for enhancing diffraction efficiency for a particular design order throughout a predetermined wavelength region, wherein grating pitches of at least part of corresponding grating portions of said two diffraction gratings are different from each other;
wherein a grating pitch of each of said two diffraction gratings is gradually varied, and a difference of the grating pitches between corresponding grating portions of said two diffraction gratings becomes larger accordingly as the grating pitch of each grating portion becomes smaller.
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29. A diffractive optical element, comprising two diffraction gratings composed of materials differing in dispersion from each other and which are laminated with a separation between the gratings, wherein, with respect to at least two wavelengths, a maximum optical path length difference is made equal to integer times each of the wavelengths, and wherein edges of at least part of corresponding grating portions of said two diffraction gratings are shifted from each other in a direction of a grating pitch of each diffraction grating;
wherein the grating pitch of each of said two diffraction gratings is gradually varied, and the shifting of edges between corresponding grating portions of said two diffraction gratings becomes larger accordingly as the grating pitch of each grating portion becomes smaller.
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30. A diffractive optical element, comprising two diffraction gratings composed of materials differing in dispersion from each other and which are laminated with a separation between the gratings, wherein, with respect to at least two wavelengths, a maximum optical path length difference is made equal to integer times each of the wavelengths, and wherein grating pitches of at least part of corresponding portions of said two diffraction gratings are different from each other;
wherein a grating pitch of each of said two diffraction gratings is gradually varied, and a difference of the grating pitches between corresponding grating portions of said two diffraction gratings becomes larger accordingly as the grating pitch of each grating portion becomes smaller.
Specification