Spectrometer designs

Abstract

Various embodiments include spectrometers comprising diffraction gratings monolithically integrated with other optical elements. These optical elements may include slits and mirrors. The mirrors and gratings may be curved. In one embodiment, the mirrors are concave and the grating is convex. The mirrors and grating may be concentric or nearly concentric.

1 . A hyper-spectral imaging system, comprising:
 a housing;   a slit disposed with respect to said housing;   a detector attached to said housing; and   a monolithic Offner spectrometer positioned inside said housing.   
   
   
       2 . The hyper-spectral imaging system of  claim 1 , wherein said monolithic Offner spectrometer includes:
 a transmissive material which has:
 an entrance surface; 
 a first surface which has a first reflective coating applied thereto to form a first mirror for receiving and reflecting a beam that has passed through said entrance surface; 
 a second surface which has a second reflective coating applied thereto to form a diffraction grating for receiving, diffracting and reflecting the beam; 
 a third surface which has a third reflective coating applied thereto to form a second mirror for receiving and reflecting the diffracted beam; and 
 an exit surface for passing there through the diffracted beam reflected from said second mirror. 
   
   
   
       3 . The hyper-spectral imaging system of  claim 2 , wherein said diffraction grating has a powered surface. 
   
   
       4 . The hyper-spectral imaging system of  claim 3 , wherein said diffraction grating is configured to direct the first order of the diffracted beam to the second mirror. 
   
   
       5 . The hyper-spectral imaging system of  claim 2 , wherein said diffraction grating has a curved surface. 
   
   
       6 . The hyper-spectral imaging system of  claim 5 , wherein said diffraction grating is configured to direct the first order of the diffracted beam to the second mirror. 
   
   
       7 . A monolithic Offner spectrometer, comprising:
 a transmissive material which has:
 an entrance surface; 
 a first surface which has a first reflective coating applied thereto to form a first mirror for receiving and reflecting a beam that has passed through said entrance surface; 
 a second surface which has a second reflective coating applied thereto to form a curved diffraction grating for receiving, diffracting and reflecting the beam; 
 a third surface which has a third reflective coating applied thereto to form a second mirror for receiving and reflecting the diffracted beam; and 
 an exit surface for passing there through the diffracted beam reflected from said second mirror. 
   
   
   
       8 . The monolithic Offner spectrometer of  claim 7 , wherein said diffraction grating is configured to direct the first order of the diffracted beam to the second mirror. 
   
   
       9 . The monolithic Offner spectrometer of  claim 7 , wherein said transmissive material is suitable for infrared applications. 
   
   
       10 . A method of manufacturing a monolithic Offner spectrometer, said method comprising the steps of:
 forming an entrance surface on a transmissive material;   shaping said transmissive material to form therein a first surface and then applying a first reflective coating to form a first mirror;   shaping said transmissive material to form therein a second surface and then applying a second reflective coating to form a curved diffraction grating;   shaping said transmissive material to form therein a third surface and then applying a third reflective coating to form a second mirror;   providing an exit surface on said transmissive material.   
   
   
       11 . The method of  claim 10 , wherein said diffraction grating is configured to direct the first order of the diffracted beam to the second mirror. 
   
   
       12 . A monolithic spectrometer comprising:
 a medium comprising substantially optically transmissive material;   a first reflector;   a second reflector, said first and second reflectors disposed on portions of said substantially transmissive material; and   a curved reflective grating disposed on a surface on said medium, said first reflector and said reflective grating defining a first optical path therebetween, said first reflector and said reflective grating disposed with respect to each other and said medium such that said first optical path substantially comprises said substantially transmissive material, said second reflector configured to reflect light diffracted from said reflective grating.   
   
   
       13 . The spectrometer of  claim 12 , further comprising a slit disposed such that light propagating though said slit is reflected from said first reflector to said reflective grating. 
   
   
       14 . The spectrometer of  claim 12 , wherein said first and second reflectors are curved. 
   
   
       15 . The spectrometer of  claim 12 , wherein said first and second reflectors are concave. 
   
   
       16 . The spectrometer of  claim 15 , wherein said first reflector, said second reflector, and said reflective grating have curvatures defined by concentric centers. 
   
   
       17 . The spectrometer of  claim 12 , wherein said diffraction grating is configured to direct the first order of the diffracted beam to the second curved reflector. 
   
   
       18 . The spectrometer of  claim 12 , further comprising a detector disposed with respect to said substantially optically transmissive medium and configured to receive light reflected from the second reflector. 
   
   
       19 . The spectrometer of  claim 18 , wherein said detector comprises a sensor sensitive to IR radiation.