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Control apparatus for spectrophotometer

  • US 4,293,222 A
  • Filed: 02/09/1979
  • Issued: 10/06/1981
  • Est. Priority Date: 02/27/1978
  • Status: Expired due to Term
First Claim
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1. A control apparatus for use with a dual beam spectrophotometer of the type in which light from a light source is split into two beams which are directed along respective first and second optical paths to a photosensitive device, the first optical path passing through a reference station and the second optical path passing through a sample station, and of the type which includes means for changing the wavelength of the light from a light source over a predetermined time period through a span of at least 75 nanometers and up to 600 nanometers or some segment thereof, starting at a wavelength of 200 nanometers or greater and proceeding up to a wavelength of 825 nanometers or less, means associated with the wavelength changing means for producing an output signal indicative of a particular wavelength of the light beams at any point in time and signal generating means coupled to the photosensitive device for subtracting the log of each signal generated by the light received by the photosensitive device from the second optical path from the log of each signal generated by light received by the photosensitive device from the first optical path and then producing a log difference signal indicative of absorbance, said control apparatus comprising electric circuit means including control, processing and memory circuits adapted to be coupled to the spectrophotometer for receiving and storing signals therefrom, said electric circuit means including first memory circuit means and second memory circuit means for receiving and storing the varying log difference signals, control and processing means for manipulating the data comprised of signal values stored in said memory circuit means, said manipulations including transferring data in one memory circuit means to the other memory circuit means, adding data from one to the data of the other, subtracting data in one from data in the other and taking the derivative of data stored in one of the memory circuit means, wavelength digital display means, absorbance digital display means, and said control and processing circuit means being coupled to a recorder in the spectrophotometer and being operable to cause movement of a pen of the recorder to plot a spectrum of wavelength v. absorbance on the recorder from a spectrum of varying log difference signals which are related to absorbance and which are stored in said one of said memory circuit means, and said control and processing means including control means coupled to said one of said memory circuit means for causing a cursor operation on the curve plotted on the recorder, said cursor being seen as a holding of the pen at a particular point on the curve and said control and processing means being operable to cause a display on said respective wavelength and absorbance digital display means of the wavelength and absorbance at the particular position of the pen on the curve plotted on the recorder and said control means including means for moving said pen in increments along the curve plotted on the recorder.

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