Birefringent device with application specific pupil function and optical device

Abstract

A birefringent device, which is configured to be mounted in an optical path of an optical system, has an effective area in a pupil plane. The birefringent device affects different polarization states differently and position-dependently. The birefringent device realizes a first pupil function assigned to a first polarization state and a second different pupil function assigned to a second polarization state. The pupil functions may be optimized to achieve various specific optical properties like extended depth of field.

1 - 36 . (canceled) 
     
     
         37 . A birefringent device configured to be arranged in an optical path of an optical system and having an effective area to be arranged in a pupil plane of the optical system, comprising:
 a first pupil function assigned to a first polarization state; and   a second pupil function assigned to a second polarization state.   
     
     
         38 . The birefringent device of  claim 37 , wherein
 the second polarization state is orthogonal to the first polarization state.   
     
     
         39 . The birefringent device of  claim 37 , wherein
 the first pupil function is the complex conjugate of the second pupil function.   
     
     
         40 . The birefringent device of  claim 37 , wherein
 the slope of the pupil functions is not zero at least in a portion of the effective area.   
     
     
         41 . The birefringent device of  claim 37 , wherein
 the first and second pupil functions are determined to increase the depth of focus of the optical system.   
     
     
         42 . The birefringent device of  claim 37 , wherein
 the first and second pupil functions are point-symmetric with respect to a symmetry point of the birefringent device.   
     
     
         43 . The birefringent device of  claim 37 , further comprising:
 a birefringent element made of birefringent material,   wherein an orientation of an extraordinary axis of the birefringent material changes in a plane perpendicular to an optical axis of the optical system.   
     
     
         44 . The birefringent device of  claim 43 , wherein
 the direction of the extraordinary axis of the birefringent element is changing laterally within the plane perpendicular to the optical axis of the optical system to form a pattern defining the pupil functions for the first and second polarization states.   
     
     
         45 . The birefringent device of  claim 43 , wherein
 a thickness of the birefringent element is changing laterally within the plane perpendicular to the optical axis of the optical system to form a pattern defining or contributing to a definition of the pupil functions for the first and second polarization states.   
     
     
         46 . The birefringent device of  claim 43 , wherein
 a difference between an extraordinary and an ordinary refractive index of the birefringent element is changing laterally within the plane perpendicular to the optical axis of the optical system to form a pattern defining or contributing to a definition of the pupil functions for the first and second polarization states.   
     
     
         47 . The birefringent device of  claim 43 , wherein
 the birefringent element comprises a circular section and at least one annular section encompassing the circular section,   wherein the directions of the extraordinary axes of the birefringent material in adjacent ones of circular and annular sections change alternately.   
     
     
         48 . The birefringent device of  claim 47 , wherein
 at least one of the circular and annular sections does not comprise birefringent material.   
     
     
         49 . The birefringent device of  claim 43 , wherein
 the birefringent material is a liquid crystal, an orientation of the liquid crystal being aligned by an alignment layer.   
     
     
         50 . The birefringent device of  claim 43 , wherein the orientation of the alignment layer is fixed by linear photopolymerization. 
     
     
         51 . The birefringent device of  claim 43 , wherein
 the birefringent material is a liquid crystal polymer and the orientation of the liquid crystal polymer is fixed by curing the polymer with UV light.   
     
     
         52 . The birefringent device of  claim 43 , wherein
 the birefringent material is a nano grating formed on a surface of a substrate having an extraordinary refractive index parallel to the surface.   
     
     
         53 . The birefringent device of  claim 52 , wherein
 the nano grating is formed by a nano imprinting method.   
     
     
         54 . The birefringent device of  claim 37 , further comprising:
 a first and a second sub-device,   wherein the first sub-device realizes the first pupil function and the second sub-device realizes the second pupil function.   
     
     
         55 . The birefringent device of  claim 37 , wherein
 the birefringent device comprises a first structure in which the refractive index effective for the first polarization state changes with increasing distance to the symmetry point and a second structure in which the refractive index effective for the second polarization state changes with increasing distance to the symmetry point.   
     
     
         56 . An optical device comprising:
 a lens unit;   an image sensor unit arranged in the image plane of the lens unit; and   the birefringent device of  claim 37 , wherein the birefringent device is arranged with a symmetry point of the pupil functions on an optical axis of the optical device.   
     
     
         57 . The optical device of  claim 56 , wherein
 the first pupil function is assigned to a first point spread function and the second pupil function is assigned to a second point spread function, the first point spread function being symmetric to the second point spread function with respect to an image plane of the optical system.   
     
     
         58 . The optical device of  claim 56 , wherein
 the birefringent device comprises a plurality of spatially separated sub-devices realizing different pupil sub-functions, the different sub-functions resulting in the first and second pupil functions, wherein the sub-devices are arranged in the optical path of the optical system.   
     
     
         59 . The optical device of  claim 58 , wherein
 the birefringent device comprises a first sub-device realizing the first pupil function and a second sub-device realizing the second pupil function.   
     
     
         60 . The optical device of  claim 58 , wherein
 at least one of the sub-devices is formed as a coating on an element of the lens unit.   
     
     
         61 . The optical device of  claim 60 , wherein
 the coating has a refractive index gradient defining or contributing to a definition of the respective pupil function.   
     
     
         62 . The optical device of  claim 60 , wherein
 the coating has a thickness variation gradient defining or contributing to a definition of the respective pupil function.   
     
     
         63 . An optical device, comprising:
 a lens unit;   an image sensor unit arranged in the image plane of the lens unit; and   the birefringent device of  claim 43 , wherein the birefringent device is arranged with a symmetry point on an optical axis of the optical device and   comprises two carrier substrates arranged in parallel and a liquid crystal material filling a gap between the two carrier substrates, at least one of the carrier substrates comprising an alignment layer for defining an alignment direction of a crystal axis of the liquid crystal, an orientation of the alignment layers defining or contributing to a definition of the pupil functions.   
     
     
         64 . The optical device of  claim 63 , further comprising:
 transparent electrodes on at least one of the carrier substrates; and   a control unit configured to control an orientation of the crystal axis of the liquid crystal continuously.   
     
     
         65 . The optical device of  claim 63 , further comprising:
 transparent electrodes on at least one of the carrier substrates; and   a control unit configured to switch an orientation of the crystal axis of the liquid crystal between a first orientation and a second orientation different from the first orientation.   
     
     
         66 . The optical device of  claim 63 , further comprising:
 transparent electrodes on at least one of the carrier substrates; and   a control unit configured to switch an orientation of the crystal axis of the liquid crystal out of a plane parallel to surfaces of the carrier substrates.   
     
     
         67 . The optical device of  claim 63 , further comprising:
 transparent electrodes on at least one of the carrier substrates; and   a control unit configured to switch an orientation of the crystal axis of the liquid crystal parallel to a plane parallel to surfaces of the carrier substrates.   
     
     
         68 . An optical device comprising:
 a lens unit;   an image sensor unit arranged in the image plane of the lens unit; and   the birefringent device of  claim 37 , wherein the birefringent device is arranged close to the aperture stop of the lens unit.   
     
     
         69 . The optical device of  claim 56 , wherein
 the birefringent device is formed as a coating on an element of the lens unit.   
     
     
         70 . The optical device of  claim 69 , wherein
 the coating has a refractive index gradient defining or contributing to a definition of the pupil function.   
     
     
         71 . The optical device of  claim 69 , wherein
 the coating has a thickness variation gradient defining or contributing to a definition of the pupil function.   
     
     
         72 . The optical device of  claim 69 , wherein
 the coating comprises a birefringent material, the extraordinary axis of the birefringent material changing laterally to form a pattern defining or contributing to a definition of the pupil function.