 Objective lens for optical pick-up head of optical disk drive |
| It is therefore the principle object of the present invention to provide an objective lens for ... |
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| Optical head |
| For solving the problem of the prior art, an optical head of the present invention comprises, light ... |
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| Compound objective lens having two focal points |
| A first object of the present invention is to provide, with due consideration to the drawbacks of ... |
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| Polarizing plate and liquid-crystal display containing the same |
| What is claimed is: 1. A polarizing plate comprising: a protective film, 5 to 150 μm thick, ... |
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| Polarization independent wavelength tunable filter based on birefringence compensation |
| It is an object of the present invention to provide a tunable, polarization independent wavelength ... |
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| Wavelength division multiplexer and demultiplexer |
| This invention is based on the observation that many filters have the characteristic property that ... |
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| Tunable filtering device for optical communications |
| To solve the above problems, it is an objective of the present invention to provide a tunable ... |
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High resolution imagery systems and methods
| Details |
Inventors: Whitney, Theodore R.;
Assignee:
Primary Examiner: Sugarman; Scott J.
Assistant Examiner: Robbins; Thomas
Attorney, Agent or Firm: Merchant, Gould, Smith, Edell, Welter & Schmidt
The current limits of resolution of multi-element optical systems are exceeded by reducing the number of elements while introducing at the critical aperture a blazed transmission grating having grating rings of low bending power defined by multiple plateaus. By illuminating the optical train with monochromatic light that constitutes a multiplicity of distributed sources having a substantial temporal coherence but spatial incoherence and by varying the slopes and widths of the grating rings, local phase delays are introduced that adjust aberrations in the optical system, providing an aligned composite wavefront. The system and method may be used for presenting an image, as for a wafer stepper, or for viewing an image, as in a microscope. |
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DETAILED DESCRIPTION Systems and methods in accordance with the invention dispose at least one holographic areally distributed transmissive grating element in the optical train of a refractive optical system, one of the elements usually being at the aperture stop.
The grating element and other components are illuminated monochromatically by a multiplicity of distributed spatially incoherent but temporally coherent sources in such manner as to introduce incrementally varying phase retardation.
These incremental variations vary nonlinearly but in controlled fashion throughout the illuminating field, forming a composite wavefront which compensates for selected aberrations.
In an optical imaging system the compensation is not only for predetermined spherical aberration but also predetermined chromatism in the refractive optics.
Wave retardation is effected by a transmission grating having segments defined by multiple plateaus varying by fractional wavelength increments that provide high efficiency diffraction.
A real organization of the segments may include phase reversals and transmissivity changes to modify the wavefront component interactions so as to create a number of interrelated pupils whose composite effect can be, for example, increased depth of field, better contrast, and improved resolution.
In one general example of an imaging system, an illuminator is employed that comprises a monochromatic light source, means for distributing the beam evenly throughout an extended beam area and means for establishing temporal coherence of the waves at above a predetermined minimum, but with spatial coherence effectively eliminated.
The phase plate in this instance comprises a light transmissive element having a plurality of concentric rings, each having multiple plateaus varying by incremental wavelength fractions, the plateaus of a ring together providing low angle bending of the local wavefront.
The phase plate is disposed at the aperture stop of a refractive optics system, the design of which is integrated with the phase plate and thereby simplified
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Optical Systems 
