Synchronous wavelength drive and data acquisition conversion for a sequential spectrophotometer
First Claim
1. A sequential spectrophotometer system having a light source, a scanning monochromator device having a movable prism, a stepper motor coupled to the monochromator for periodically changing the monochromator device wavelength, a photomultiplier for detecting the intensity of the output light from the monochromator device and providing an electrical signal corresponding thereto, data acquisition means responsive to the electrical signal from the photomultiplier for measuring same, and a recording device for providing indicia representative of the measured electrical signal, the improvement comprising:
- means for effecting a data acquisition during a prism displacement.
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Accused Products
Abstract
A sequential spectrophotometer system having a light source, a scanning type monochromator, a stepper motor means for changing the monochromator wavelength over a light spectrum being scanned, a photomultiplier for measuring the intensity of light absorption or passage through a sample being tested and generating a signal corresponding thereto, data acquisition means for compiling data corresponding to said signals and means for recording such data generally as a function of light measured for each wavelength, the improvement comprising:
a method and means to effect the data acquisition conversion at or about each desired wavelength during a respective stepper motor rotor displacement period, i.e., during each corresponding period of diffraction grating vibration or oscillation following a stepper motor disposition thereof to another wavelength position angle.
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Citations
12 Claims
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1. A sequential spectrophotometer system having a light source, a scanning monochromator device having a movable prism, a stepper motor coupled to the monochromator for periodically changing the monochromator device wavelength, a photomultiplier for detecting the intensity of the output light from the monochromator device and providing an electrical signal corresponding thereto, data acquisition means responsive to the electrical signal from the photomultiplier for measuring same, and a recording device for providing indicia representative of the measured electrical signal, the improvement comprising:
means for effecting a data acquisition during a prism displacement. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A sequential spectrophotometer system being powered from a line frequency power source comprising:
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means responsive to the line frequency for providing a plurality of harmonic signal frequencies of the line frequency; means responsive to said harmonic signal frequencies for providing a plurality of control signals; means responsive to a respective one of said control signals for providing a drive signal; stepper motor means being synchronized to the line frequency and responsive to said drive signal for incrementally rotating its rotor; a source of light; means responsive to said light and the rotational disposition of the rotor for providing a diffracted light generally corresponding with the rotational disposition of the rotor; means responsive to said diffracted light for providing a corresponding electrical signal; means synchronized to the line frequency and responsive to said control signals and said electrical signal for providing a data acquisition conversion signal representative of said diffracted light during a rotor displacement; and means responsive to said data acquisition conversion signal for providing an indicia representative thereof; whereby data acquisition conversion being effected during a rotor displacement. - View Dependent Claims (10)
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11. A synchronous wavelength drive and data acquisition conversion circuit network for a sequential spectrophotometer system being operated from a line frequency power source, said spectrophotometer having a plotter-scriber, a stepper motor, a monochromator having a prism, a source of light and a photomultiplier, comprising:
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data acquisition means coupled to the photomultiplier for providing data conversion synchronized to the line frequency; and control mans for synchronizing the data conversion with prism displacement of the monochromator prism to effect data conversion during a line frequency synchronized relatively small portion of the prism displacement occurring shortly after a wavelength change and within a respective cycle time of the line frequency.
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12. A method of synchronizing the data conversion of a spectrophotometer system having a diffraction prism and a stepper motor operatively coupled to the diffraction prism with the line frequency, comprising the steps of:
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providing a plurality of drive pulses to the stepper motor each being synchronized to a first corresponding portion of each respective cycle of the line frequency; providing a plurality of data conversion command pulses to the data acquisition means of the spectrophotometer system each being synchronized to a second corresponding portion of each cycle of the line frequency; and effecting a respective data conversion in response to each data conversion command pulse during a corresponding portion of a respective prism displacement.
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Specification