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Apparatus and methods for transmitting electrical signals indicative of optical interactions between a light beam and a flowing suspension of particles

  • US 5,883,378 A
  • Filed: 07/30/1996
  • Issued: 03/16/1999
  • Est. Priority Date: 07/30/1996
  • Status: Expired due to Fees
First Claim
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1. Apparatus for detecting an optical signal representing optical interactions between a light beam and a flowing stream of particles and transmitting a low gain electronic output representative of the optical interactions, comprising:

  • a first circuit board including a high gain amplifier having an input and an output;

    a cable having a characteristic impedance, a first end and a second end, the first end being coupled to the high gain amplifier input; and

    a second circuit board including;

    a first amplifier having a current output;

    a photodetector connected to said first amplifier current output, the photodetector having an optical input and an electrical signal output responsive to an optical signal intensity at the optical input;

    a second amplifier coupled to said photodetector electrical signal output having a first amplified voltage output;

    an RC filter having as an input the first amplified voltage output and having a filtered voltage output corresponding to the filtered first amplified voltage output; and

    a third amplifier having as an input said filtered voltage output, and a second amplified output coupled to the second end of the cable, the second amplified output having a low impedance output to match substantially the characteristic impedance of the cable.

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