Diffraction grating apparatus and method of forming a surface relief pattern in diffraction grating apparatus
First Claim
1. A phase diffraction grating having a surface relief pattern formed therein such that, when a monochromatic plane wave of light is transmitted to said grating, light is transmitted from said surface relief pattern to form an array of N spots, where N is an even integer and said N spots are substantially equally spacedwhere said surface relief pattern comprises two levels and has a set of transitions between said two levels, said set of transitions comprising a plurality of periods of length P, each period comprising a plurality of transitions between said two levels,such that when said plane wave of light is of wavelength λ
- , and said N spots are formed by passing said transmitted light through an objective lens of focal length f, the substantially equal spacing S of said N spots is given by ##EQU50##
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Accused Products
Abstract
A phase diffraction grating apparatus which is usable to generate an array of N spots, where n is an even integer, and the N spots are substantially equally spaced. The generation of an even number of spots is achieved using a translation symmetry in the grating design. Illustratively, the intensities of the N spots are substantially equal. Binary, multi-level, and continuous phase grating embodiments are disclosed. In the case of the multi-level and continuous embodiments, the uniform intensity is obtained using a reflection symmetry in the grating design.
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Citations
35 Claims
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1. A phase diffraction grating having a surface relief pattern formed therein such that, when a monochromatic plane wave of light is transmitted to said grating, light is transmitted from said surface relief pattern to form an array of N spots, where N is an even integer and said N spots are substantially equally spaced
where said surface relief pattern comprises two levels and has a set of transitions between said two levels, said set of transitions comprising a plurality of periods of length P, each period comprising a plurality of transitions between said two levels, such that when said plane wave of light is of wavelength λ - , and said N spots are formed by passing said transmitted light through an objective lens of focal length f, the substantially equal spacing S of said N spots is given by ##EQU50##
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A phase diffraction grating having a surface relief pattern formed therein such that, when a monochromatic plane wave of light is transmitted to said grating, light is transmitted from said surface relief pattern to form an array of N spots, where N is an even integer and said N spots are substantially equally spaced,
where said surface relief pattern comprises L levels, L being a positive integer greater than two, said surface relief pattern having a set of transitions between ones of said L levels, said set of transitions comprising a plurality of periods of length P, each period comprising a plurality of transitions between ones of said L levels such that when said plane wave of light is of wavelength λ - , and said N spots are formed by passing said transmitted light through an objective lens of focal length f, the substantially equal spacing S of said N spots is given by ##EQU51##
- View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A phase diffraction grating having a surface relief pattern formed therein such that, when a monochromatic plane wave of light is transmitted to said grating, light is transmitted from said surface relief pattern to form an array of N spots, where N is an even integer and said N spots are substantially equally spaced
where said surface relief pattern comprises a continuous surface comprising a plurality of periods of length P such that when said plane wave of light is of wavelength λ - , and said N spots are formed by passing said transmitted light through an objective lens of focal length f, the substantially equal spacing S of said N spots is given by ##EQU53##
- View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28)
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29. Optical spot-generating apparatus comprising
means for generating a monochromatic plane wave of light of wavelength λ - ,
an objective lens of focal length f, and a phase diffraction grating responsive to said plane wave of light and having a surface relief pattern comprising a plurality of periods of length P for transmitting light from said surface relief pattern through said lens to form an array of N spots, where N is an even integer and said N spots are substantially equally spaced at a spacing S given by ##EQU54##
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30. Apparatus comprising
an objective lens of focal length f, and a phase diffraction grating responsive to a monochromatic plane wave of light of wavelength λ - , said grating having a surface relief pattern comprising a plurality of periods of length P for transmitting light from said surface relief pattern through said lens to form an array of N spots, where N is an even integer and said N spots are substantially equally spaced at a spacing S given by ##EQU55##
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31. A method of forming a surface relief pattern in a phase diffraction grating such that when a monochromatic plane wave of light is transmitted to said grating, light is transmitted from said surface relief pattern to form an array of N spots, where N is an even integer and said N spots are substantially equally spaced, said method comprising
forming first half periods of a plurality of periods of length P which comprise said surface relief pattern, and forming second half periods of said plurality of periods, said second half periods obtained by a translation of said first half periods and having a phase offset substantially equal to π - with respect to said first half periods.
- View Dependent Claims (32, 33, 34, 35)
Specification