Optical pulse counting imager and system

An imager comprising:

• a matrix array of light responsive elements (pixels), formed on a common integrated circuit substrate, arranged in rows and columns with at least one row conductor per row of the matrix and at least one column conductor per column of the matrix for selectively accessing each pixel and
• each pixel of the matrix array including:
• (a) a photodetector for detecting light pulses incident on the pixel and producing an output signal indicative of an incident light pulse;
• (b) signal processing circuitry coupled to the photodetector and responsive to its output signal for generating a corresponding electrical pulse having a rising edge and a falling edge and a pulse width corresponding to each incident light pulse, said signal processing circuitry including means responsive to at least one of said rising edge, falling edge and pulse width having at least a minimum condition for producing an output pulse indicative thereof;
• and (c) counting circuitry coupled to said signal processing circuitry for counting the number of said output pulses produced during a sampling interval and thereby counting the incident light pulses and storing information corresponding to the count.

A system for sensing light pulses comprising:

• a matrix array of light responsive elements (pixels), formed on an integrated circuit substrate, arranged in rows and columns with a row conductor per row of the matrix and a column conductor per column of the matrix for selectively accessing each pixel;
• each pixel of the matrix array including:
• (a) a photodetector for detecting light pulses incident on the pixel and producing an output signal indicative of an incident light pulse;
• (b) signal processing circuitry coupled to the photodetector and responsive to its output signal for generating a corresponding electrical pulse having a rising edge and a falling edge and a pulse width corresponding to each incident light pulse, said signal processing circuitry including means responsive to at least one of said rising edge, falling edge and pulse width having at least a minimum condition for producing an output pulse of fixed value indicative thereof;
• and (c) counting circuitry coupled to the signal processing circuitry for counting the number of said output pulses produced during a sensing interval and for storing information indicative of the number of light pulses incident on the photodector during said sensing period;
• and
• row and column decoders respectively coupled to the row and column conductors of the matrix array for:
• (a) selectively operating the pixels of the matrix array in a sensing mode during which each pixel of a row detects light pulses incident on the pixel during the sensing mode and stores information corresponding thereto;
• and (b) for operating the matrix array in a readout mode during which information stored in the pixels of the array are read out a row at time.