Spectrometer apparatus for self-calibrating color imaging apparatus

Claim 2

Spectrometer apparatus for measuring the spectral characteristics of color imaging apparatus of the type including a solid state image sensor having multiple pixels, and optical apparatus for projecting light, transmitted via a color image, along an optical axis for illuminating pixels of said image sensor, said spectrometer apparatus comprising: (a) a light source; (b) a member, defining an optical slit, positionable on the optical axis between said light source and the optical apparatus in a plane occupied by a color image when it is illuminated; and (c) a diffraction grating positionable on the optical axis between the optical apparatus and the image sensor to disperse light, projected by the optical apparatus, onto the image sensor, the magnitude and the location of the light impinging upon the image sensor varying as a function of optical characteristics of the color imaging apparatus including the spectral content of said light source and the spectral transmissivity characteristics of the optical apparatus and the image sensor.

Claim 3

Spectrometer apparatus as defined in claim 1 wherein said light source produces light of a predetermined wavelength.

Claim 4

Spectrometer apparatus as defined in claim 2 wherein said light source is selected from the group consisting of a spectral lamp, a fluorescent lamp, a light emitting diode, or a laser.

Claim 5

Spectrometer apparatus for measuring the spectral characteristics of color imaging apparatus of the type having a source of polychromatic light for illuminating a color image, a solid state image sensor having multiple pixels, and optical apparatus for projecting polychromatic light transmitted via the color image along an optical axis for illuminating pixels of said image sensor, said spectrometer apparatus comprising: (a) a member, defining an optical slit, positionable on the optical axis between the light source and the optical apparatus in a plane occupied by a color image when it is illuminated; and (b) a diffraction grating positionable on the optical axis a given distance from the image sensor to disperse spectral components of the polychromatic light, transmitted by the optical apparatus, onto individual pixels of the image sensor, the respective magnitudes of the spectral components varying as a function of optical characteristics of the color imaging appratus including the spectral content and sensitivity of the light source and the spectral transmissivity characteristics of the optical apparatus and the image sensor.

Claim 6

Spectrometer apparatus for measuring the spectral characteristics of color imaging apparatus of the type having a source of polychromatic light for illuminating a color image, a solid state image sensor having multiple pixels, and optical apparatus for projecting polychromatic light transmitted via the color image along an optical axis for illuminating pixels of said image sensor, said spectrometer apparatus comprising: (a) a member, defining an optical slit, positionable on the optical axis between the light source and the optical apparatus in a plane occupied by a color image when it is illuminated; and (b) a diffraction grating positionable on the optical axis a given distance from the image sensor to disperse spectral components of the polychromatic light, transmitted by the optical apparatus, onto individual pixels of the image sensor, the respective magnitudes of the spectral components varying as a function of optical characteristics of the color imaging appratus including the spectral content and sensitivity of the light source and the spectral transmissivity characteristics of the optical apparatus and the image sensor.

Claim 7

Spectrometer apparatus for calibrating a color image scanner of the type having a source of polychromatic light for illuminating a color image to be scanned, a solid state image sensor having multiple pixels, and lens apparatus for projecting polychromatic light transmitted via the color image along an optical axis for simultaneously illuminating pixels of said image sensor, said spectrometer apparatus comprising: (a) a member, defining a narrow optical slit, positionable on the optical axis during a calibrating mode of operation between the light source and the lens apparatus in a plane occupied by a color image when it is scanned; and (b) a diffraction grating positionable on the optical axis during the calibration mode of operation a given distance from the image sensor to disperse spectral components of polychromatic light, projected by the lens apparatus, onto individual pixels of the image sensor, the respective magnitudes of the spectral components varying as a function of the optical characteristics of the color image scanner including the spectral content and sensitivity of the light source and the spectral transmissivity characteristics of the lens apparatus and the image sensor.

Claim 8

Spectrometer apparatus for calibrating a color image scanner of the type having a source of polychromatic light for illuminating a color image to be scanned, a solid state image sensor having multiple pixels, and lens apparatus for projecting polychromatic light transmitted via the color image along an optical axis for simultaneously illuminating pixels of said image sensor, said spectrometer apparatus comprising: (a) a member, defining a narrow optical slit, positionable on the optical axis during a calibrating mode of operation between the light source and the lens apparatus in a plane occupied by a color image when it is scanned; and (b) a diffraction grating positionable on the optical axis during the calibration mode of operation a given distance from the image sensor to disperse spectral components of polychromatic light, projected by the lens apparatus, onto individual pixels of the image sensor, the respective magnitudes of the spectral components varying as a function of the optical characteristics of the color image scanner including the spectral content and sensitivity of the light source and the spectral transmissivity characteristics of the lens apparatus and the image sensor.

Claim 9

Spectrometer apparatus as defined in claim 5 wherein said member comprises a film having an optical slit defined by a transparent needle-shaped zone.

Claim 10

Spectrometer apparatus as defined in claim 6 wherein the image sensor is a linear sensor and said film has an optical slit oriented so that it is non-orthogonal to the axis of the image sensor.

Claim 11

Spectrometer appratus as defined in claim 7 wherein the color image scanner includes a drum on which an image to be scanned is mounted, and said film is mounted on the drum co-planar with an image to be scanned.

Claim 12

Spectrometer apparatus as defined in claim 8 wherein during the calibration mode the drum is sequentially rotated to position the optical slit in a plurality of discrete predetermined positions relative to the image sensor, each position of the optical slit changing the respective locations at which corresponding spectral components of the light are imaged onto the image sensor.

Claim 13

Spectrometer apparatus as defined in claim 5 wherein the image sensor is a linear sensor and said member comprises a film having a plurality of optical slits arranged in a row aligned with the axis of the image sensor.

Claim 14

Spectrometer apparatus as defined in claim 10 wherein the optical slits are spaced relative to each other to cause each slit to image first-order spectra onto the image sensor that are non-overlapping with respect to the first-order spectra imaged by each of the other optical slits.