Polychromator
AssigneeBodenseewerk Perkin-Elmer & Co., GmbH
InventorWolfgang Witte, deceased
Life of this patent
Estimating the term…
Abstract
In a polychromator, the image plane or the focus line (28) is adapted optimumly to the plane of a detector (26), e.g. to a diode-array. At the same time, an optimum linear wavelength scale is obtained on the detector (26). To this end, an arrangement having a concave grating (14), and an imaging mirror (20) is provided. An optimizing method is described by which both curves can be optimized in converging steps by alternate variation of the distance b between concave grating (14) and mirror (20) and the asymmetry measure G' of the concave grating (14).
Claims21
A polychromator comprising,
- an inlet slit for introducing a beam of light from a light source,
- a concave grating for spectrally dispersing light from said inlet slit into a wavelength spectrum,
- a locally resolving detector means for simultaneously detecting radiation at different points in a plane, said detector means defining a detection plane, and
- imaging mirror means for deflecting spectrally dispersed light from said grating to image a wavelength spectrum of slit images on said detector means,
- said grating and said mirror means being disposed to define a predetermined path of rays between said inlet slit and said detector means for imaging a wavelength spectrum of slit images on said detector means with said grating being disposed along said path between said inlet slit and said mirror means and said mirror means being disposed along said path between said grating and said detector means, and
- said grating and said mirror means being configured and relatively positioned so that the image plane of the slit images formed by said mirror means is substantially adapted to said detection plane at the wavelengths of said spectrum and the slit images are substantially linearly disposed along said detection plane relative to wavelength.
A method of optimizing the imaging of a wavelength spectrum on a detector plane in a polychromator of the type having a concave grating with an asymmetry line measure G' spectrally dispersing light from an inlet slit and a locally resolving detector defining a detection plane, comprising the steps of:
- reflecting dispersed light from the grating with an imaging mirror to image a wavelength spectrum on the detection plane with the wavelength spectrum defining a wavelength scale along the detection plane,
- varying the distance between the imaging mirror and the concave grating to a first distance which minimizes the deviation of the image plane formed by the imaging mirror from the detector plane, and
- varying the asymmetry line measure G' of the concave grating to a first G' value which minimizes the deviation of the wavelength scale on the detection plane.
A polychromator comprising
- an inlet slit for introducing a beam of light from a light source,
- a concave grating for spectrally dispersing a light beam from said inlet slit into a wavelength spectrum,
- a locally resolving detector means for simultaneously detecting radiation at different points in a plane, said detector means defining a detection plane, and
- imaging mirror means for deflecting spectrally dispersed light from said grating to image a wavelength spectrum of slit images on said detector means,
- said grating and said mirror means being disposed to define a substantially Z-shaped path of rays in tangential section from the inlet slit to the detector means with the mirror means positioned between the grating and the detector means so as to image a wavelength spectrum of slit images on the detection plane of the detector means,
- said grating having a concave surface and an axis normal to said surface,
- said grating defining a zero order reference position relative to the light beam from the inlet slit and the mirror means such that the light beam impinging on the grating would be diffracted toward said mirror means in zero order, said normal axis and said light beam defining a first reference angle therebetween at said zero order reference position of the grating,
- said grating being angularly disposed relative to said mirror means such that said normal axis and said light beam defined a second angle therebetween, said first reference angle being greater than said second angle, and
- said grating and said mirror means being configured and relatively positioned so that the image plane of the slit images formed by said mirror means is substantially adapted to said detection plane at the wavelengths of said spectrum and the slit images are substantially linearly disposed along said detection plane relative to wavelength.
Dependencies are inferred from the claim text.