F-Sin (theta) lens system and method of use of same

Abstract

An optical system for focusing an incident light so as to obtain a linear output (as a function of the wavelength, or of the order of diffraction, or of the grating spacial frequency or of the inverse of the index of refraction) comprises a diffraction grating and a lens, or a group of lenses, having a f-Sin(θ) characteristic, where f is the effective focal length of the lens, or group of lenses, and θ is an output angle of the light exiting from the diffraction grating. Therefore, a light incident on the diffraction grating reaches the lens, or the group of lenses, and results in a linear output. Using the present invention in a spectrometer reduces the time consuming calibration process required and renders it easier because of the linear output between wavelength and pixels positions. The lens, or group of lenses, has a diffractive, refractive or reflective property, or any combination thereof. The incident light can be a collimated, converging or diverging beam. The diffraction grating can be a plane, concave or convex grating.

1 . An optical system for obtaining a linear output from an incident light, comprising a diffraction grating and a lens having a f-Sin(θ) characteristic, where f is the effective focal length of said lens and θ is an output angle of the light exiting from said diffraction grating, wherein a light incident on said diffraction grating reaches said lens and results in a linear output.  
     
     
         2 . An optical system as defined in  claim 1 , wherein said lens has at least one of diffractive, refractive and reflective properties.  
     
     
         3 . An optical system as defined in  claim 1 , wherein said incident light is one of a collimated beam, a converging beam and a diverging beam.  
     
     
         4 . An optical system as defined in  claim 1 , wherein said diffraction grating is one of a plane grating, a concave grating and a convex grating.  
     
     
         5 . An optical system for obtaining a linear output from an incident light, comprising a diffraction grating and a group of lenses having a f-Sin(θ) characteristic, where f is the effective focal length of said group of lenses and θ is an output angle of the light exiting from said diffraction grating, wherein a light incident on said diffraction grating reaches said group of lenses and results in a linear output.  
     
     
         6 . An optical system as defined in  claim 5 , wherein said group of lenses has at least one of diffractive, refractive and reflective properties.  
     
     
         7 . An optical system as defined in  claim 5 , wherein said incident light is one of a collimated beam, a converging beam and a diverging beam.  
     
     
         8 . An optical system as defined in  claim 5 , wherein said diffraction grating is one of a plane grating, a concave grating and a convex grating.