High resolution imagery systems and methods
OwnerTheodore R. Whitneyinventor
Life of this patent
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Abstract
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.
Claims4
The method of controlling the coherence of an illumination beam during exposure of a light sensitive medium with a beam from a substantially coherent source so as to achieve improved resolution free of speckle effects and presenting an adequate number of wave sources distributed through an illumination area, comprising the steps of:
- maintaining waves from the source temporally coherent for greater than about 10,000 waves;
- sensing the partial coherence modulus in the beam prior to the illumination area and
- modifying the spatial coherence in accordance with the sensed partial coherence to randomize spatial coherence in a controlled manner without substantially affecting the temporal coherence.
Dependencies are inferred from the claim text.