Compact high resolution grating spectrometer
AssigneeCymer, Inc.
InventorsAlexander I. Ershov, Gamaralalage G. Padmabandu, Palash P. Das
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Abstract
A compact high resolution grating spectrometer. A beam of expanding light from a light source is collimated and the collimated beam is expanded with a beam expander before illuminating a reflecting grating. The expansion of the beam permits high resolution in a small package. In preferred embodiments mirror arrangements are provided to produce double reflections off the reflecting grating to further improve the resolution of the spectrometer.
Claims12
A spectrometer for measuring intensity of light in a light source at various wavelengths comprising:
- A) a beam expansion optic for producing an expanding beam from said light source;
- B) a reflecting grating;
- C) a collimating optic for collimating said expanding beam from said light source to produce a first collimated beam;
- D) a beam expander for expanding said first collimated beam to produce a second collimated beam for illumination of said reflecting grating;
- E) a photometer for measuring light intensity in light reflected from said reflecting grating at a plurality of spacial locations.
A spectrometer for measuring intensity of light in a light source at various wavelengths comprising:
- A) an entrance slit for producing an expanding beam from said light source;
- B) a reflecting grating;
- C) a collimating optic for collimating said expanding beam from said light source to produce a first collimated beam;
- D) a beam expander for expanding said first collimated beam to produce a second collimated beam for illumination of said reflecting grating;
- E) a maximum reflection optic, positioned, along with said reflecting grating, to reflect back to said reflecting grating light at a selected range of wavelengths reflected from said reflecting grating at an angle such that light at the selected range of wavelength will pass back through said beam expander and exit said beam expander along a path generally opposite a path defined by said first collimated beam;
- F) a photo diode array for measuring light intensity in light reflected from said reflecting grating at a plurality of spacial locations;
- G) a focusing lens positioned for focusing light on to said photo diode array;
- and
- H) a beam splitter positioned across said first collimated beam to reflect light-reflected back through said beam expander to said photo diode array.
A spectrometer for measuring intensity of light in a light source at various wavelengths comprising:
- A) an entrance slit for producing an expanding beam from said light source;
- B) a reflecting grating;
- C) a collimating optic for collimating said expanding beam from said light source to produce a first collimated beam;
- D) a beam expander for expanding said first collimated beam to produce a second collimated beam for illumination of said reflecting grating;
- E) a partially reflecting mirror positioned across said second collimated beam and positioned, along with said reflecting grating to reflect back to said reflecting grating light at a selected range of wavelengths such that a portion of the light at said selected range of wavelengths will reflect a second time from said reflecting grating then pass through said partially reflecting mirror and back through said beam expander and exit said beam expander in a direction generally opposite a path defined by said first collimated beam;
- F) a photo diode array for measuring light intensity in light reflected from said reflecting grating at a plurality of spacial locations;
- G) a focusing lens positioned for focusing light on to said photo diode array;
- and
- H) a beam splitter positioned across said first collimated beam to reflect light-reflected back through said beam expander to said photo diode array.
Dependencies are inferred from the claim text.