Method and arrangement for measuring the distance to an object

• US 8,355,117 B2
• Filed: 12/20/2006
• Issued: 01/15/2013
• Est. Priority Date: 12/21/2005
• Status: Active Grant

• Current Assignee: Ecole polytechnique fãdãrale de lausanne epfl (Schweizerische Eidgenossenschaft)
• Original Assignee: Ecole polytechnique fãdãrale de lausanne epfl (Schweizerische Eidgenossenschaft)
• Inventors: Niclass, Cristiano
• Primary Examiner(s): RATCLIFFE, LUKE D
• Application Number:
  US11/641,965
• Publication Number:
  US 20070182949A1
• Time in Patent Office: 2,218 Days
• Field of Search: 356 301- 66, 356 301- 315, 356 401- 41, 356 501- 515, 356 6- 22, 356/28, 356/28.5, 35613901-1391
• US Class Current: 356/4.01
• CPC Class Codes: G01C 3/08 Use of electric radiation detectors
• CPC Class Codes: G01S 17/36 with phase comparison between the received signal and the contemporaneously transmitted signal
• CPC Class Codes: G01S 17/894 3D imaging with simultaneous measurement of time-of-flight at a 2D array of receiver pixels, e.g. time-of-flight cameras or flash lidar
• CPC Class Codes: G01S 7/491 Details of non-pulse systems
• CPC Class Codes: G01S 7/493 Extracting wanted echo signals

Abstract

Arrangement (10) for measuring the distance to an object, comprising:

• • a photonic source for illuminating said object using a continuous modulated photonic wave,
  • a solid-state image sensor, comprising an array of avalanche photodiodes and a plurality of circuits for processing signals output by said avalanche photodiodes to yield data depending on the photonic wave reflected by said object onto said photodiodes.

The circuit may comprise a multiplexer at the pixel level arranged so as to accumulate the signal output by the avalanche photodiode during different sub-periods in different storage devices.

Claims

1. A distance measuring arrangement for measuring the distance to an object, comprising:

a photonic source for illuminating said object using a continuous modulated photonic wave, and

a solid-state image sensor, comprising an array with W×

H avalanche photodiodes with W≧

1 and H≧

1 and a circuit for processing signals output by said avalanche photodiodes to output distance data depending on a phase of the photonic wave reflected by said object onto said photodiodes, wherein said solid-state image sensor comprises one said circuit for each avalanche photodiode, and wherein said avalanche photodiodes are reverse biased above their breakdown voltage, thus operating in Geiger mode.

2. The arrangement of claim 1, wherein the continuous modulated photonic wave is free from discontinuities.

3. The arrangement of claim 1, said sensor comprising at least one said circuit for processing signals output by a plurality of avalanche photodiodes.

4. The arrangement of claim 1, wherein said photonic wave is periodically modulated, and wherein said circuit outputs data proportional to the phase and/or amplitude of said reflected photonic wave.

5. The arrangement of claim 1, wherein said solid-state image sensor is fabricated on a monolithic integrated CMOS circuit chip.

6. The arrangement of claim 1, wherein said circuit comprises at least one multiplexer, one or more storage devices, and a readout circuit,

wherein each independent multiplexer output is connected to an independent storage device,

wherein at least one selection input of said multiplexer is periodically modulated so as to accumulate into said storage devices the signal output by at least one connected avalanche photodiode during a given period of time defined as the integration time.

7. The arrangement of claim 6, wherein each storage device comprises at least one counter, and wherein each counter is connected to readout circuit allowing the contents of each counter to be read simultaneously and/or consecutively synchronously to an global clock signal or asynchronously via a read request signal.

8. The arrangement of claim 7, wherein the content of said counter is read and reset many times during each integration time so that the capacity of said counter can be reduced.

9. The arrangement of claim 7, wherein the output of said avalanche photodiode circuit and/or the outputs of said multiplexer are held to an inactive state as soon as the full capacity of one of said counters is reached, using an overflow signal provided by each counter.

10. The arrangement of claim 7, wherein said multiplexer holds its state when the avalanche photodiode circuit output is active so that only the counter connected to the multiplexer output that was selected during the photo detection is incremented on the leading edge of said digital pulse.

11. The arrangement of claim 1, said solid-state image sensor comprising an array of pixels, each pixel comprising:

(a) one of said avalanche photodiodes;

(b) one multiplexer with one common input, one selection input, and at least two outputs;

(c) at least two digital counters with an overflow output signal; and

(d) a readout circuit that allows the contents of said at least two counters to be read and reset.

12. The arrangement of claim 1, said solid-state image sensor comprising an array of pixels and means for combining the signals of two or more avalanche photodiodes within a pixel to increase the sensitivity of the pixel to the photonic wave.

13. The arrangement of claim 1, comprising a plurality of integrated focusing elements for focusing light into the light sensitive part of each photodiode.

14. The arrangement of claim 1, comprising a plurality of colour filters with different colours to generate colour intensity images.

15. The arrangement of claim 1, comprising a circuit for compensating the effects of timing and/or amplitude shifts or timing jitter depending on the signal output by at least one reference photodiode.

16. The arrangement of claim 1, comprising a circuit for changing the modulation frequency used for modulating said photonic wave.

17. An arrangement for measuring the distance to an object, comprising:

a photonic source for illuminating said object using a continuous modulated photonic wave, and

a solid-state image sensor, comprising an array with W×

H avalanche photodiodes with W≧

1 and H≧

1 and a circuit for processing signals output by said avalanche photodiodes to yield data depending on the phase and/or amplitude of the continuous photonic wave reflected by said object onto said photodiodes,

wherein said circuit comprises at least one multiplexer, one or more storage devices, and a readout circuit,

wherein each independent multiplexer output is connected to an independent storage device,

wherein at least one selection input of said multiplexer is periodically modulated so as to accumulate into said storage devices the signal output by at least one connected avalanche photodiode during a given period of time defined as the integration time,

wherein each storage device comprises at least one counter, and wherein each counter is connected to readout circuit allowing the contents of each counter to be read simultaneously and/or consecutively synchronously to an global clock signal or asynchronously via a read request signal,

wherein said multiplexer holds its state when the avalanche photodiode circuit output is active so that only the counter connected to the multiplexer output that was selected during the photo detection is incremented on the leading edge of said digital pulse,

wherein each periodically modulated selection input of said multiplexer is connected through a digital latch, the clock signal of said latch is synchronized with the digital signal of the avalanche photodiode circuit so that when the digital pulse is at its active level, the latch is blocked and so is each multiplexer selection input.

18. A distance measuring method for measuring the distance to an object, comprising the steps of:

illuminating said object with a continuous modulated photonic wave,

determining said distance from signals delivered at the outputs of avalanche photodiodes arranged in an array on a solid-state sensor, using a circuit for processing signals output by said avalanche photodiodes, wherein one said circuit is provided for each avalanche photodiode;

wherein said distance is determined from the phase of the photonic wave reflected onto said photodiode, and wherein said avalanche photodiodes are reverse biased above their breakdown voltage, thus operating in Geiger mode.

19. The method of claim 18, wherein said photonic wave is periodically modulated.

20. The method of claim 18, comprising a step of operating a plurality of avalanche photodiodes in Geiger mode on a monolithic integrated CMOS solid-state sensor.

21. The method of claim 18, comprising the steps of:

illuminating said object with a periodic photonic wave having a period (P);

counting pulses generated by said avalanche photodiodes during each of a plurality of fractions of said period (P),

determining said distance from the amounts of counted pulses during each of said fractions of said period.

22. The method of claim 21, comprising a step of multiplexing the output of said avalanche photodiode so as to connect the output of said avalanche photodiode with different storage devices during said different fractions of said period.

23. The method of claim 22, comprising the steps of:

(a) choosing a total integration time longer than said period,

(b) dividing said total integration time into a plurality of fractions of the integration time;

(c) commanding a selection input of a multiplexer with selection signals having different phases during said fractions of the integration time,

(d) during each fraction of the integration time, separately accumulating the number of pulses generated over a plurality of periods by said avalanche photodiodes during each fraction of period.

24. The method of claim 23, wherein said integration time is divided into an even number of intervals of the integration time larger than two, the method comprising using all the odd intervals of the integration time to form a first fraction of the integration time and all the even intervals to form a second fraction of the integration time.

25. A distance measuring circuit comprising:

an integrated array of W×

H avalanche photodiodes with W≧

1 and H≧

1

a circuit connected to said array for determining a distance depending on the phase of a continuous photonic wave received by each photodiodes, wherein one said circuit for each avalanche photodiode is provided.

26. A distance measuring apparatus, comprising:

a photonic source for illuminating said object using a continuous modulated photonic wave,

a monolithic integrated CMOS circuit having an array of W×

H avalanche photodiodes operating in Geiger mode, with W>

1 and H>

1,

a circuit connected to said array, said circuit having a counter connected to the output of the avalanche photodiodes and arranged for counting a value corresponding to the number of photons received by said counter during a duration, and

processing means for determining a distance based on said value.

27. A distance measuring arrangement for measuring the distance to an object, comprising:

a photonic source for illuminating said object using a continuous modulated photonic wave, and

a solid-state image sensor comprising an array with W×

H avalanche photodiodes with W≧

1 and H≧

1 and a circuit for processing signals output by said avalanche photodiodes to output distance data depending on a phase of the photonic wave reflected by said object onto said photodiodes,

wherein, said solid-state image sensor is fabricated on a monolithic integrated CMOS circuit chip, and wherein said avalanche photodiodes are reverse biased above their break down voltage to operate in Geiger mode.

28. A distance measuring arrangement for measuring the distance to an object, comprising:

a photonic source for illuminating said object using a continuous modulated photonic wave, and

a solid-state image sensor comprising an array with W×

H avalanche photodiodes with W≧

1 and H≧

1 and a circuit for processing signals output by said avalanche photodiodes to output distance data depending on a phase of the photonic wave reflected by said object onto said photodiodes,

wherein said circuit comprises at least one multiplexer, one or more storage devices, and a readout circuit,

wherein each multiplexer has an output which is connected to an independent one of said one or more storage devices,

wherein said multiplexer has at least one input which is periodically modulated so as to accumulate into said one or more storage devices a signal output by at least one connected avalanche photodiode during a given period of time defined as an integration time.

29. A distance measuring method for measuring the distance to an object, comprising the steps of:

illuminating said object with a continuous modulated photonic wave;

operating a plurality of avalanche photodiodes in Geiger mode on a monolithic integrated CMOS solid-state sensor;

determining said distance from signals delivered at the outputs of avalanche photodiodes arranged in an array on a solid-state sensor;

wherein said distance is determined from a phase of the photonic wave reflected onto said photodiodes.

30. A distance measuring method for measuring the distance to an object, comprising the steps of:

illuminating said object with a continuous modulated photonic wave,

providing at least one multiplexer, one or more storage devices, and a readout circuit,

wherein each independent multiplexer has an output connected to an independent storage device, wherein said multiplexer has at least one selection input periodically modulated so as to accumulate into said storage devices the signal output by at least one connected avalanche photodiode during a given period of time defined as an integration time;

determining said distance from signals delivered at the outputs of avalanche photodiodes arranged in an array on a solid-state sensor, wherein said distance is determined from a phase of the photonic wave reflected onto said photodiodes.

31. A method for measuring the distance to an object, comprising the steps of:

illuminating said object with a continuous modulated photonic wave, wherein the continuous modulated photonic wave is a periodic photonic wave having a period (P);

determining said distance from signals delivered at outputs of avalanche photodiodes arranged in an array on a solid-state sensor, wherein said distance is determined from a phase of the photonic wave reflected onto said photodiode;

counting pulses generated by said avalanche photodiodes during each of a plurality of fractions of said period (P);

determining said distance from the counted pulses during each of said fractions of said period;

multiplexing outputs of said avalanche photodiodes so as to connect the outputs of said avalanche photodiodes with different storage devices during said different fractions of said period;

choosing a total integration time longer than said period;

dividing said total integration time into a plurality of fractions of the integration time;

commanding a selection input of a multiplexer with selection signals having different phases during said fractions of the integration time;

during each fraction of the integration time, separately accumulating the number of pulses generated over a plurality of periods by said avalanche photodiodes during each fraction of period, wherein said integration time is divided into an even number of intervals of the integration time larger than two, the method comprising using all odd intervals of the integration time to form a first fraction of the integration time and all even intervals to form a second fraction of the integration time.

32. A distance measuring circuit, comprising:

an integrated array with W×

H avalanche photodiodes with W≧

1 and H≧

1, and

a circuit connected to said array for determining a distance depending on a phase of a continuous photonic wave received by each photodiodes, wherein said circuit is fabricated on a monolithic integrated CMOS circuit chip, and wherein said avalanche photodiodes are reverse biased above their break down voltage to operate in Geiger mode.

33. A distance measuring circuit, comprising:

an integrated array with W×

H avalanche photodiodes with W≧

1 and H≧

1, and

a circuit connected to said array for determining a distance depending on a phase of a continuous photonic wave received by each photodiodes, wherein said circuit comprises at least one multiplexer, one or more storage devices, and a readout circuit,

wherein each independent multiplexer has an output which is connected to an independent storage device,

wherein at least one selection input of said multiplexer is periodically modulated so as to accumulate into said storage devices the signal output by at least one connected avalanche photodiode during a given period of time defined as the integration time.

34. An arrangement for measuring the distance to an object, comprising:

a photonic source for illuminating said object using a continuous modulated photonic wave, and

a solid-state image sensor, comprising an array with W×

H avalanche photodiodes with W≧

1 and H≧

1 and a circuit for processing signals output by said avalanche photodiodes to yield data depending on the phase and/or amplitude of the continuous photonic wave reflected by said object onto said photodiodes, said solid-state image sensor comprising an array of pixels and means for combining the signals of two or more avalanche photodiodes within a pixel to increase the sensitivity of the pixel to the photonic wave,

wherein each pixel comprises a plurality of avalanche photodiode and a plurality of storage devices, different avalanche photodiodes and/or different storage devices of one pixel being periodically activated and deactivated at different instants of one cycle of said photonic wave.

35. The arrangement of claim 34, wherein each pixel comprises:

(a) two avalanche photodiodes;

(b) two digital counters; and

(c) one readout circuit, wherein each counter is connected to one avalanche photodiode,

wherein said avalanche photodiode outputs and/or digital counters inputs are periodically activated and deactivated in synchronization with said photonic wave via a logic gate,

wherein when one counter is activated, the other counter is deactivated.