Optical system

Abstract

An optical system includes an oriented polymeric multilayer optical film having a first reflection band, and a light source configured to produce light in an output band and/or a sensor configured to receive light in an input band. The light source and/or sensor is in optical communication with the oriented polymeric multilayer optical film. In some cases, the first reflection band overlaps the input and/or output band at normal incidence, but not at an oblique incidence angle. In some cases, the first reflection band overlaps the input and/or output band at an oblique incidence angle, but not at normal incidence. The optical system can further include a non-birefringent optical filter having a first blocking band where the first blocking band overlaps the first reflection band for at least one of normal incidence or an oblique incidence angle.

What is claimed is: 
     
         1 . An optical system comprising:
 an oriented polymeric multilayer optical film having a first reflection band;   a non-birefringent optical filter having a first blocking band, the first blocking band overlapping the first reflection band for at least one of normal incidence or an oblique incidence angle; and   a light source configured to produce light in an output band, the light source in optical communication with the oriented polymeric multilayer optical film and with the non-birefringent optical filter,   
       wherein either:
 the first reflection band overlaps the output band at normal incidence, but not at the oblique incidence angle; or 
 the first reflection band overlaps the output band at the oblique incidence angle, but not at normal incidence. 
 
     
     
         2 . The optical system of  claim 1 , wherein the first reflection band overlaps the output band at normal incidence, but not at the oblique incidence angle. 
     
     
         3 . The optical system of  claim 1 , wherein the first reflection band overlaps the output band at the oblique incidence angle, but not at normal incidence. 
     
     
         4 . The optical system of  claim 1 , wherein the oblique incidence angle is 60 degrees. 
     
     
         5 . The optical system of  claim 1 , wherein the first blocking band is entirely contained in the first reflection band at normal incidence and is not is entirely contained in the first reflection band at the oblique incidence angle. 
     
     
         6 . The optical system of  claim 1 , wherein the first reflection band and the first blocking band do not overlap at normal incidence and do overlap at the oblique incidence angle. 
     
     
         7 . The optical system of  claim 1 , wherein the output band has a full-width at half-maximum of no more than 40 nm. 
     
     
         8 . The optical system of  claim 1  further comprising a sensor in optical communication with the oriented polymeric multilayer optical film, the non-birefringent optical filter, and the light source. 
     
     
         9 . An optical system comprising:
 an oriented polymeric multilayer optical film having a first reflection band;   a non-birefringent optical filter having a first blocking band, the first blocking band overlapping the first reflection band for at least one of normal incidence or an oblique incidence angle; and   a sensor configured to receive light in an input band, the sensor in optical communication with the oriented polymeric multilayer optical film and with the non-birefringent optical filter,   
       wherein either:
 the first reflection band overlaps the input band at normal incidence, but not at the oblique incidence angle; or 
 the first reflection band overlaps the input band at the oblique incidence angle, but not at normal incidence. 
 
     
     
         10 . The optical system of  claim 9 , wherein the first reflection band overlaps the input band at normal incidence, but not at the oblique incidence angle. 
     
     
         11 . The optical system of  claim 9 , wherein the first reflection band overlaps the input band at the oblique incidence angle, but not at normal incidence. 
     
     
         12 . The optical system of  claim 9 , wherein the oblique incidence angle is 60 degrees. 
     
     
         13 . The optical system of  claim 9 , wherein the first blocking band is entirely contained in the first reflection band at normal incidence and is not is entirely contained in the first reflection band at the oblique incidence angle. 
     
     
         14 . The optical system of  claim 9 , wherein the first reflection band and the first blocking band do not overlap at normal incidence and do overlap at the oblique incidence angle. 
     
     
         15 . The optical system of  claim 9 , wherein the input band has a full-width at half-maximum of no more than 40 nm. 
     
     
         16 . A method of modifying a first reflection band of an oriented polymeric multilayer optical film, the method comprising:
 providing the oriented polymeric multilayer optical film having the first reflection band, the first reflection band having a band edge at a first wavelength at normal incidence;   determining a desired normal incidence band edge wavelength;   selecting a non-birefringent optical filter having a first blocking band, the first blocking band having the desired normal incidence band edge wavelength and including the first wavelength at normal incidence; and   positioning the non-birefringent reflector in optical communication with the oriented polymeric multilayer optical film.   
     
     
         17 . The method of  claim 16 , wherein the non-birefringent optical filter is a non-birefringent reflector and the first blocking band is a second reflection band, and wherein selecting the non-birefringent optical filter comprises selecting different first and second materials such that a stack of alternating layers of the first and second materials provides the second reflection band. 
     
     
         18 . The method of  claim 17 , wherein the positioning step comprises depositing the stack of alternating layers directly onto the oriented polymeric multilayer optical film. 
     
     
         19 . The method of  claim 18 , wherein the depositing step comprises depositing the stack of alternating layers through a mask resulting in a spatially variant non-birefringent reflector. 
     
     
         20 . The method of  claim 18 , wherein the depositing step comprises one or more of atomic layer deposition, sputtering, chemical vapor deposition, and layer-by-layer self-assembly.