Catoptric and catadioptric imaging system with pellicle and aperture-array beam-splitters and non-adaptive and adaptive catoptric surfaces

Abstract

An interferometric system including: an interferometer that directs a measurement beam at an object point to produce a return measurement beam, focuses the return measurement beam to an image point in an image plane, and mixes the return measurement beam with a reference beam at the image point to form a mixed beam; a beam combining layer located at the image plane which is responsive to the mixed beam and produces an optical beam therefrom, wherein the layer comprises a thin film with an array of transmissive openings formed therein and further comprises a fluorescent material associated with each of the openings of the array of openings; a detector that is responsive to the optical beam from the beam combining layer; and an imaging system that directs the optical beam from the beam combining layer onto the detector.

1 . An interferometric system comprising: 
 an interferometer that directs a measurement beam at an object point to produce a return measurement beam, focuses the return measurement beam to an image point in an image plane, and mixes the return measurement beam with a reference beam at the image point to form a mixed beam;    a beam combining layer located at the image plane which is responsive to the mixed beam and produces an optical beam therefrom, wherein said layer comprises a thin film with an array of transmissive openings formed therein and further comprises a fluorescent material associated with each of the openings of the array of openings;    a detector that is responsive to the optical beam from the beam combining layer; and    an imaging system that directs the optical beam from the beam combining layer onto the detector.    
   
   
       2 . The interferometric system of  claim 1 , wherein the beam combining layer comprises a first layer in which the array of openings is formed and a second layer behind the first layer and comprising the fluorescent material.  
   
   
       3 . The interferometric system of  claim 1 , wherein the beam combining layer further comprises third layer comprising an array of microlenses, each of which is aligned with a different one of the openings in the array of openings.  
   
   
       4 . The interferometric system of  claim 1 , wherein the fluorescent material is in each of the openings of the array of openings.  
   
   
       5 . The interferometric system of  claim 1 , wherein each of the openings in the array of openings is conically shaped.  
   
   
       6 . The interferometric system of  claim 1 , wherein the fluorescent material comprises lumogen.  
   
   
       7 . The interferometric system of  claim 1 , wherein the fluorescent material is sensitive to UV or VUV.  
   
   
       8 . The interferometric system of  claim 1 , wherein the fluorescent material is responsive to radiation at a first wavelength and the detector is responsive to light at a second wavelength, wherein the first and second wavelengths are different.  
   
   
       9 . The interferometric system of  claim 8 , wherein the fluorescent material is responsive to radiation in the UV or VUV region and the detector is responsive to light in the visible region.  
   
   
       10 . The interferometric system of  claim 1 , wherein the fluorescent material absorbs radiation at a first wavelength and emits radiation at a second wavelength, wherein the second wavelength is longer than the first wavelength.  
   
   
       11 . The interferometric system of  claim 1 , wherein the imaging system is a low power microscope.  
   
   
       12 . The interferometric system of  claim 1 , wherein the interferometer comprises a catadioptric imaging system.  
   
   
       13 . The interferometric system of  claim 1 , wherein the interferometer comprises: 
 a beam splitter positioned to receive the return measurement beam from the object point and separate each of a plurality of rays into a transmitted portion and a reflected portion, the transmitted portions defining a first set of rays and the reflected portions defining a second set of rays; and    a reflecting surface positioned to receive one of the sets of rays from the beam splitter and focus that set of rays towards the image point via the beam splitter.    
   
   
       14 . The interferometric system of  claim 1 , wherein the beam splitter has an array of transmitting apertures formed therein and wherein said one set of rays travels along a path contacting on one end the beam splitter and on another end the concave reflecting surface and at least most of which passes through a gas or vacuum.  
   
   
       15 . The interferometric system of  claim 13 , wherein the interferometer comprises an array of independently positionable reflecting elements forming the reflecting surface.  
   
   
       16 . The interferometric system of  claim 15 , wherein the reflecting surface is positioned to receive the first set of rays and reflect the first set of rays back to the beam splitter, and wherein the beam splitter is positioned to reflect at least a portion of each ray received from the reflecting surface to the image point.  
   
   
       17 . An imaging system for imaging an object point to an image point, the system comprising: 
 a beam splitter positioned to receive light rays from the object point and separate each of a plurality of rays into a transmitted portion and a reflected portion, the transmitted portions defining a first set of rays and the reflected portions defining a second set of rays; and    an optical structure forming a concave reflecting surface positioned to receive one of the sets of rays from the beam splitter and focus that set of rays towards the image point via the beam splitter,    wherein the beam splitter has an array of transmitting apertures formed therein and wherein said one set of rays travels along a path contacting on one end the beam splitter and on another end the concave reflecting surface and at least most of which passes through a gas or vacuum.    
   
   
       18 . The imaging system of  claim 17 , wherein the beam splitter is a self-supporting structure.  
   
   
       19 . The imaging system of  claim 17 , wherein the beam splitter comprises a thin reflective layer in which the array of transmitting apertures are formed.  
   
   
       20 . The imaging system of  claim 19 , wherein the thin reflective layer is highly reflective.  
   
   
       21 . The imaging system of  claim 19 , wherein the thin reflective layer comprises aluminum.  
   
   
       22 . The imaging system of  claim 17 , wherein the beam splitter comprises a pellicle on which the thin reflective layer is formed.  
   
   
       23 . The imaging system of  claim 17 , wherein the beam splitter comprises a first pellicle and a second pellicle with the thin reflective layer sandwiched between the first and second pellicles.  
   
   
       24 . The imaging system of  claim 22 , wherein the pellicle comprises a refractive material.  
   
   
       25 . The imaging system of  claim 24 , wherein the refractive material is from the group consisting of UV grade fused silica, F—SiO 2 , CaF 2 , and LiF.  
   
   
       26 . The imaging system of  claim 17 , wherein the beam splitter is a vertically oriented, planar structure.  
   
   
       27 . The imaging system of  claim 17 , wherein the size of the apertures is larger than the wavelength of the light rays being imaged onto the image point.  
   
   
       28 . The imaging system of  claim 17 , wherein the beam splitter comprises a grid of conducting wires which defines the array of transmitting apertures.  
   
   
       29 . The imaging system of  claim 17 , wherein the reflecting surface is positioned to receive the first set of rays and reflect the first set of rays back to the beam splitter, and wherein the beam splitter is positioned to reflect at least a portion of each ray received from the reflecting surface to the image point.  
   
   
       30 . The imaging system of  claim 29 , wherein the reflecting surface is substantially concentric with the object point.  
   
   
       31 . The imaging system of  claim 17 , wherein the reflecting surface is positioned to receive the second set of rays and reflect the second set of rays back to the beam splitter, wherein the beam splitter is positioned to transmit at least a portion of each ray received from the reflecting surface to the image point.  
   
   
       32 . The imaging system of  claim 20 , wherein the reflecting surface is substantially concentric with the image point.  
   
   
       33 . The imaging system of  claim 17 , wherein the optical structure comprises an array of independently positionable reflecting elements forming said reflecting surface.  
   
   
       34 . An imaging system for imaging an object point to an image point, the system comprising: 
 a beam splitter positioned to receive light rays from the object point and separate each of a plurality of rays into a transmitted portion and a reflected portion, the transmitted portions defining a first set of rays and the reflected portions defining a second set of rays; and    an array of independently positionable reflecting elements arranged to form a Fresnel reflecting surface that is positioned to receive one of the sets of rays from the beam splitter and focus that set of rays towards the image point via the beam splitter.    
   
   
       35 . The imaging system of  claim 34 , wherein the array of independently positionable reflecting elements form corresponding portions of the Fresnel reflecting surface and wherein the corresponding portions of the reflecting surface have a common center of curvature and different radii of curvature.  
   
   
       36 . The imaging system of  claim 34  further comprising a plurality of position control elements, each of which is connected to a corresponding one of the reflecting elements in the array.  
   
   
       37 . The imaging system of  claim 36 , wherein each of the position control elements of the plurality of position control elements comprises a transducer.  
   
   
       38 . The imaging system of  claim 37 , wherein each transducer of the plurality of transducers controls a radial position of its corresponding reflecting element.  
   
   
       39 . The imaging system of  claim 37 , wherein each transducer of the plurality of transducers controls an orientation of the corresponding reflecting element relative to an optical axis for that reflecting element.  
   
   
       40 . The imaging system of  claim 37  further comprising a servo control system which controls the plurality of transducers.  
   
   
       41 . The imaging system of  claim 34 , wherein the reflecting surface is positioned to receive the first set of rays and reflect the first set of rays back to the beam splitter, and wherein the beam splitter is positioned to reflect at least a portion of each ray received from the reflecting surface to the image point.  
   
   
       42 . The imaging system of  claim 34 , wherein the reflecting surface is positioned to receive the second set of rays and reflect the second set of rays back to the beam splitter, wherein the beam splitter is positioned to transmit at least a portion of each ray received from the reflecting surface to the image point.  
   
   
       43 . An interferometric system comprising: 
 an interferometer that directs a measurement beam at an object point to produce a return measurement beam, focuses the return measurement beam to an image point in an image plane, and mixes the return measurement beam with a reference beam at the image point to form a mixed beam; and    a detector system that generates an electrical interference signal from the mixed beam,    wherein the interferometer comprises a source for generating an input beam and an apodizing filter through which the input beams passes to generate a conditioned beam, and wherein the measurement beam is derived from the conditioned beam.    
   
   
       44 . The interferometric system of  claim 43 , wherein the interferometer further comprises a focusing optic for focusing the measurement beam as a spot on the object.  
   
   
       45 . The interferometric system of  claim 43 , wherein the apodizing filter comprises an aperture that is apodized.  
   
   
       46 . The interferometric system of  claim 43 , wherein the apodizing filter comprises an aperture and a coating that has a transmission coefficient that depends on the position within the aperture.  
   
   
       47 . An imaging system for imaging an object point to an image point, the system comprising: 
 a beam splitter positioned to receive light rays from the object point and separate each of a plurality of rays into a transmitted portion and a reflected portion, the transmitted portions defining a first set of rays and the reflected portions defining a second set of rays; and    an optical structure forming a concave reflecting surface positioned to receive one of the sets of rays from the beam splitter and focus that set of rays towards the image point via the beam splitter,    wherein the beam splitter has an array of transmitting apertures formed therein and wherein the density of apertures is such that the beam splitter is characterized by net reflection and transmission coefficients that are nominally equal at each location within a working area of the beam splitter.    
   
   
       48 . An imaging system for imaging an object point to an image point, the system comprising: 
 a beam splitter positioned to receive light rays from the object point and separate each of a plurality of rays into a transmitted portion and a reflected portion, the transmitted portions defining a first set of rays and the reflected portions defining a second set of rays; and    an optical structure forming a concave reflecting surface positioned to receive one of the sets of rays from the beam splitter and focus that set of rays towards the image point via the beam splitter,    wherein the beam splitter has an array of transmitting apertures formed therein and a central axis and wherein each aperture in the array of transmitting apertures has a dimension in a radial direction relative the central axis that is an increasing function of that apertures distance from the central axis.    
   
   
       49 . The imaging system of  claim 48 , wherein each aperture in the array of transmitting apertures has a dimension in an azimuthal direction relative the central axis that is an increasing function of that apertures distance from the central axis.