Spectrophotometer and method
AssigneeMutoh Industries Ltd.
InventorsChris Brown, Brain T. Pridham, John Peter Coales
Life of this patent
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Abstract
A spectrophotometer includes a plurality of LEDs arranged in a circular array, each having a calibrated power input determined by the use of pulse width modulation and each having a unique wavelength band determined by the utilization of a unique fluorescent phosphor coating or lens. At least one of the LEDs comprising a phosphor-free high energy UV LED. Light reflected to the spectrophotometer is divided into predetermined wavelength ranges through the utilization of a linear variable filter and photo detectors wherein the analog signal from a photo detector is converted to a digital value through the use of auto-ranging gain technique.
Claims27
In a spectrophotometer having a light source to be directed upon a reflective sample for measuring the spectral reflectance of a sample surface, an improved light source comprising:
- (a) a plurality of LEDs arranged in an array;
- and
- (b) each LED individually adjustably energized to vary the LED output intensity.
In a spectrophotometer having a light source to be directed upon a reflective sample for measuring the spectral reflectance of a sample surface, an improved light source comprising:
- (a) a plurality of LEDs arranged in a circular array and connected to be simultaneously energized;
- (b) each LED individually adjustably energized to vary the LED output intensity;
- and
- (c) each LED having a predetermined spectral bandwidth with a different center wavelength.
In a spectrophotometer having a light source to be directed upon a reflective sample for measuring the spectral reflectance of a sample surface, an improved light source comprising:
- (a) a plurality of LEDs arranged in a circular array and connected to be simultaneously energized;
- (b) each LED individually adjustable energized by a pulse width modulated signal to vary the LED output intensity;
- and
- (c) each LED having a different predetermined spectral bandwidth.
In a spectrophotometer having a light source to be directed upon a reflective sample for measuring the spectral reflectance of a sample surface, an improved light source comprising:
- (a) a plurality of electrofluorescent illuminants each having a different emission spectra;
- and
- (b) each illuminant individually adjustably energized by a pulse width modulated signal.
In a spectrophotometer having a light source to be directed upon a reflective sample for measuring the spectral reflectance of a sample surface, an improved light source comprising:
- (a) a plurality of LEDs arranged in an array;
- and
- (b) a corresponding plurality of electrofluorescent illuminants each corresponding to a different one of said LEDs and each positioned to intercept emitted light energy from a corresponding different one of said LEDs and re-emit light energy at a different wavelength.
In a spectrophotometer having a light source to be directed upon a reflective sample for measuring the spectral reflectance of a sample surface, an improved light source comprising:
- (a) a plurality of LEDs arranged in a circular array and connected to be simultaneously energized;
- (b) a corresponding plurality of electrofluorescent illuminants each corresponding to a different one of said LEDs and each coated on a corresponding different one of said LEDs to intercept emitted light from the LED and re-emit light energy at a different wavelength.
In a spectrophotometer having a light source to be directed upon a reflective sample for measuring the spectral reflectance of a sample surface, a method for determining spectral reflectance comprising:
- (a) directing light upon a reflective surface to generate reflected light;
- (b) directing said reflected light through an interference filter onto a plurality of photo detectors arranged in an array to generate electrical analog signals corresponding to photonic energy present at each photo detector;
- (c) directing said electrical analog signals to an analog-to-digital converter (ADC);
- (d) selecting at least two reference values for comparison in said ADC to said analog signals to derive digital signals corresponding thereto, one reference value corresponding to a low or zero gain and a second reference value corresponding to a high gain;
- and
- (e) sampling the electrical analog signal at each photo detector twice, alternately using said one reference value and said second reference value.
In a spectrophotometer, a method for determining spectral content of light to be measured, comprising:
- (a) directing said light through an interference filter onto a plurality of photo detectors arranged in an array to generate electrical analog signals corresponding to photonic energy present at each photo detector.
- (b) directing said electrical analog signals to an analog-to-digital converter (ADC);
- (c) selecting at least two reference values for comparison in said ADC to said analog signals to derive digital signals corresponding thereto, one reference value corresponding to a low or zero gain and a second reference value corresponding to a high gain;
- and
- (d) sampling the electrical analog signals at each photo detector twice, alternately using said one reference value and said second reference value.
In a spectrophotometer, for determining the spectral content of light entering an input aperture to be measured, having a light path including a light path geometry converter and having a spectral sensor, an improved light path geometry converter comprising:
- (a) a plurality of fiber optic strands positioned in parallel and in contact with each other to form a predetermined cross-sectional combined shape at a light input end thereof corresponding to said input aperture;
- and
- (b) said fiber optic strands extending from the light input end to form a different cross-sectional shape at a light output end corresponding to said spectral sensor.
In a spectrophotometer having a light source to be directed upon a reflective sample for measuring spectral reflectance of a sample surface, and having a light path for directing reflected light on a spectral sensor, the improvement comprising:
- (a) an interference filter wedge formed of multiple bandpass filter coating layers;
- (b) a collimating faceplate comprising an array of holes or capillaries, said faceplate positioned to collimate light in said reflected light path prior to said interference filter.
In a spectrophotometer having a light source to be directed upon a reflective sample for measuring spectral reflectance of a sample surface, and having a light path for directing reflected light on a spectral sensor, the improvement comprising:
- (a) an interference filter wedge formed of multiple bandpass filter coating layers;
- and
- (b) a collimating faceplate comprising an array of optically transparent plastic or glass fiber elements positioned to collimate light in said reflected light path prior to said interference filter.
Dependencies are inferred from the claim text.