Photon counting device and photon counting method

Patent metadata

Field	Value
Publication number	US-11835667-B2
Application number	US-202117501398-A
Country	US
Kind code	B2
Filing date	Oct 14, 2021
Priority date	Nov 24, 2017
Publication date	Dec 5, 2023
Grant date	Dec 5, 2023

Abstract

A photon counting device includes a plurality of pixels each including a photoelectric conversion element configured to convert input light to charge, and an amplifier configured to amplify the charge converted by the photoelectric conversion element and convert the charge to a voltage, an A/D converter configured to convert the voltage output from the amplifier of each of the plurality of pixels to a digital value and output the digital value, a correction unit configured to correct the digital value output from the A/D converter so that an influence of a variation in a gain and an offset value among the plurality of pixels is curbed, a calculation unit configured to output a summed value obtained by summing the corrected digital values corresponding to at least two pixels, and a conversion unit configured to convert the summed value output from the calculation unit to a number of photons.

First claim

The invention claimed is:

1. A device for photon counting device comprising:
a CMOS image sensor including a plurality of pixels and an A/D converter, each of the plurality of pixels including i) a photoelectric conversion element configured to convert input light to charge, and ii) an amplifier configured to amplify the charge converted by the photoelectric conversion element and convert the charge to a voltage, and the A/D converter configured to convert the voltage output from the amplifier of each of the plurality of pixels to a digital value, wherein a readout noise of the CMOS image sensor is equal to or less than 0.4 e-rms; and
a computer configured to correct the digital value output from the A/D converter so that an influence of a variation in a gain and an offset value among the plurality of pixels is curbed, output a summed value obtained by summing the corrected digital values in at least two pixels, and convert the summed value to a number of photons by referring to reference data,
wherein the reference data is threshold value data for distinguishing between adjacent numbers of photons.

2. The device according to claim 1 , wherein the computer is configured to convert the digital value of only the pixels of which the readout noise is equal to or less than 0.4 e-rms.

3. The device according to claim 1 , wherein the readout noise of the CMOS image sensor is equal to or less than 0.2 e-rms.

4. The device according to claim 1 , wherein the readout noise of the CMOS image sensor is equal to or less than 0.15 e-rms.

5. The device according to claim 1 , wherein the computer is further configured to create a two-dimensional image indicating the number of photons in each pixel based on the number of photons.

6. The device according to claim 1 , wherein the computer is further configured to create a histogram that is a plot of the number of pixels with respect to the number of photons.

7. The device according to claim 1 , wherein the A/D converter is provided in each pixel.

8. The device according to claim 1 , wherein the computer is configured to divide an average number of electrons for each pixel by a quantum efficiency to obtain an average number of photons.

9. The device according to claim 1 , wherein the reference data is held as a table.

10. A method for photon counting the method comprising:
converting light input to respective photoelectric conversion elements of a plurality of pixels of a CMOS image sensor to charge;
amplifying, by an amplifier constituting each of the plurality of pixels, the converted charge and converting the charge to a voltage;
converting, by an A/D converter, the voltage output from the amplifier to a digital value and outputting the digital value;
correcting the digital value output from the A/D converter so that an influence of a variation in a gain and an offset value among the plurality of pixels is curbed;
outputting a summed value obtained by summing the corrected digital values in at least two pixels, and
converting the summed value to a number of photons by referring to reference data,
wherein the reference data is threshold value data for distinguishing between adjacent numbers of photons, and
wherein a readout noise of the amplifier is equal to or less than 0.4 e-rms.

11. The method according to claim 10 , wherein the converting converts the digital value of only the pixels of which the readout noise is equal to or less than 0.4 e-rms.

12. The method according to claim 10 , wherein the readout noise of the CMOS image sensor is equal to or less than 0.2 e-rms.

13. The method according to claim 10 , wherein the readout noise of the CMOS image sensor is equal to or less than 0.15 e-rms.

14. The method according to claim 10 , further comprising:
creating a two-dimensional image indicating the number of photons in each pixel based on the number of photons.

15. The method according to claim 10 , further comprising:
creating a histogram that is a plot of the number of pixels with respect to the number of photons.

16. The method according to claim 10 , wherein the A/D converter is provided in each pixel.

17. The method according to claim 10 , further comprising:
dividing an average number of electrons for each pixel by a quantum efficiency to obtain an average number of photons.

18. The method according to claim 10 , wherein the reference data is a table.

19. A computer comprising:
a data processor configured to correct a digital value output from an A/D converter of a CMOS image sensor so that an influence of a variation in a gain and an offset value among the plurality of pixels is curbed, output a summed value obtained by summing the corrected digital values in at least two pixels, and convert the summed value to a number of photons by referring to reference data,
wherein the reference data is threshold value data for distinguishing between adjacent numbers of photons.

20. A non-transitory computer-readable storage medium storing a program, the program causing the computer to:
correct a digital value output from an A/D converter of a CMOS image sensor so that an influence of a variation in a gain and an offset value among the plurality of pixels is curbed, output a summed value obtained by summing the corrected digital values in at least two pixels, and convert the summed value to a number of photons by referring to reference data,
wherein the reference data is threshold value data for distinguishing between adjacent numbers of photons.

Assignees

• Hamamatsu Photonics Kk

Inventors

• Maruno Tadashi
• Toda Eiji
• NAKAJIMA Mao
• Takahashi Teruo
• Higuchi Takafumi

Classifications

• H04N25/78

  Readout circuits for addressed sensors, e.g. output amplifiers or A/D converters · CPC title

• H04N25/773

  comprising photon counting circuits, e.g. single photon detection [SPD] or single photon avalanche diodes [SPAD] · CPC title

• H10F39/803

  Pixels having integrated switching, control, storage or amplification elements · CPC title

• H04N25/77

  Pixel circuitry, e.g. memories, A/D converters, pixel amplifiers, shared circuits or shared components · CPC title

• H04N25/671

  for non-uniformity detection or correction · CPC title