# US 11,079,479 B2 · Device for measuring a distance and method for measuring said distance

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- Number: US 11,079,479 B2
- Document ID: US11079479B2
- Status: Granted
- Kind: B2
- Application number: 16/031,640
- Filed: 2018-07-10
- Published: 2019-01-17
- Granted: 2021-08-03
- Earliest claimed: 2017-07-11
- Assignees: Fondazione Bruno Kessler
- Applicants: Fondanzione Bruno Kessler
- Inventors: Daniele Perenzoni; David Stoppa; Leonardo Gasparini; Matteo Perenzoni; Nicola Massari; Ulrich Zwölfer; Kai Waslowski; Alexander Bohli; Michael Albert; Friedhelm Wiethege
- Web page: https://patentgrep.com/patent/US11079479B2

## CPC

- G01S 7/4865: Time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak (peak detection in noise, signal conditioning G01S7/487)
- G01C 3/08: Use of electric radiation detectors
- G01C 15/002: {Active optical surveying means (optical plumbing G01C15/105)}
- G01J 1/18: using comparison with a reference electric value
- G01J 1/44: Electric circuits {(for command of an exposure part G03B7/02)}
- G01S 7/4808: {Evaluating distance, position or velocity data}
- G01S 7/4816: {of receivers alone}
- G01S 7/4861: Circuits for detection, sampling, integration or read-out
- G01S 7/4863: Detector arrays, e.g. charge-transfer gates
- G01S 7/497: Means for monitoring or calibrating
- G01S 17/10: using transmission of interrupted, pulse-modulated waves (determination of distance by phase measurements G01S17/32)
- G01J 2001/442: {Single-photon detection or photon counting}
- G01J 2001/4466: {Avalanche}
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01C: MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY (measuring liquid level G01F; radio navigation, determining distance or velocity by use of propagation effects, e.g. Doppler effects, propagation time, of radio waves, analogous arrangements using other waves G01S)
- G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N)

## Abstract

Measuring device (1) suited to measure the distance (d) of a reference object (O), configured so that it performs a plurality of measuring operations (Ai) in succession and comprising emission means (2) suited to emit a light radiation (R), receiving means (3) comprising a sensitive area (31) which is sensitive to the light radiation (R) and which is provided with a number M of sensitive units (4), each one of the sensitive units (4) being configured to generate an electrical signal (S), a first processing unit (5) comprising Ne processing elements (6), each one of said Ne processing elements (6) being configured to receive the electrical signal (S) for determining the time of impact (t) of a photon (F) on the sensitive units (4) and for calculating the value of said distance (d). The measuring device (1) comprises a second processing unit (7) configured to receive the electrical signals (S), processing the electrical signals (S) in such a way as to select a number Nu of sensitive units (4) impacted by the photons (F), associating each one of the Nu sensitive units (4) to one of the Ne processing elements (6), in such a way that, at the moment of the successive measuring operation (Ai+1), the distance (d) is determined by each one of the Nu sensitive units (4) selected.

## Claims

### Claim 1

A measuring device (1) suited to measure the distance (d) of at least a reference object (O), configured so that it performs a plurality of measuring operations (Ai) in succession and comprising:
emission means (2) suited to emit a light radiation (R) directed towards said reference object (O) during a predetermined time interval (I) for each one of said measuring operations (Ai);
receiving means (3) comprising a sensitive area (31) which is sensitive to said light radiation (R) reflected by said reference object (O), said sensitive area (31) being provided with a number M of sensitive units (4), each one of said sensitive units (4) being configured to generate an electrical signal (S) following the impact of at least one photon (F) on its sensitive surface (41), wherein each one of said sensitive units (4) comprises at least one Sinie Photon Avalanche Diode (SPAD) (81, 82);
a first processing unit (5) comprising Ne processing elements (6), where Ne <M, each one of said Ne processing elements (6) being configured to receive the electrical signal (S) generated by one of said M sensitive units (4) and to determine the time of impact (t) of said at least one photon (F) on said sensitive units (4) with respect to a reference electrical signal (clock), said first processing unit (5) being configured in such a way as to calculate, at the moment of each one of said measuring operations (Ai), the value of said distance (d) based on the time of impact (t) related to at least one of said M sensitive units (4),
wherein the measuring device further comprises a second processing unit (7) configured in such a way as to perform the following steps at the moment of each one of said measuring operations (Ai):
receiving as an input said electrical signals (S) generated by said M sensitive units (4);
processing said electrical signals (S) in such a way as to select a number Nu of sensitive units (4) impacted by the photons (F) belonging to said light radiation (R), where Nu⇐Ne;
associating each one of said Nu sensitive units (4) to one of said Ne processing elements (6), in such a way that, at the moment of the successive measuring operation (Ai+1), said distance (d) is determined by said first processing unit (5) based on the time of impact (t) of at least one of said photons (F) related to each one of said Nu sensitive units (4) selected,
wherein each one of said sensitive units (4) comprises at least two SPADs (81, 82) whose sensitive surfaces have different sizes, said second processing unit (7) being configured in such a way that, at the moment of each one of said measuring operations (Ai), said two SPADs (81, S2) of each one of said sensitive units (4) are enabled individually or jointly said time interval (I).

### Claim 2 (depends on 1)

The device (1) according to claim 1, wherein said emission means (2) emit light radiation (R) of the type pulsed with a predefined number X of pulses (B) for each time interval (I) related to each one of said measuring operations (Ai).

### Claim 3 (depends on 1)

The device (1) according to claim 1, wherein said second processing unit (7) is configured in such a way that, at the moment of each one of said measuring operations (Ai), said step of processing said electrical signals (S) consists in the calculation of the number of occurrences related to the impact of at least one photon (F) belonging to said light radiation (R) for each one of said M sensitive units (4) during said pre-determined time interval (I).

### Claim 4 (depends on 3)

The device (1) according to claim 3, wherein said second processing unit (7) is configured to calculate said number of occurrences for each one of said M sensitive units (4) by performing, in sequence:
at least one first count (UP) of said occurrences during the emission of said light radiation (R) by said emission means (2);
at least one second count (DOWN) in the absence of said light radiation (R);
a subtraction calculation between said first count (UP) and said second count (DOWN).

### Claim 5 (depends on 3)

The device (1) according to claim 3, wherein said second processing unit (7) is configured in such a way that, at the moment of each one of said measuring operations (Ai) and following said calculation of said number of occurrences, it selects said number Nu of sensitive units (4) among said number M of sensitive units (4) based on the decreasing order of said number of said occurrences.

### Claim 6 (depends on 1)

The device (1) according to claim 1, wherein said second processing unit (7) is configured to enable said two SPADs (81, 82) of each one of said sensitive units (4) individually or jointly based on the quantity of photons (F) impacting on said sensitive area (31) during the previous measuring operation (Ai−1), said number of photons (F) being determined based on said electrical signals (S) generated by said M sensitive units (4) and received as an input by said second processing unit (7).

### Claim 7 (depends on 1)

The device (1) according to claim 1, wherein said Ne processing elements (6) of said first processing unit (5) are Ne TDCs (Time to Digital Converter).

### Claim 8 (depends on 1)

The device (1) according to claim 1, wherein said sensitive area (31) of said receiving means (3) comprises a number L of sensitive units (4), said device (1) comprising a storage register (9) in which it is possible to store in advance the “enabled” or “disabled” condition of each one of said L sensitive units (4), said M sensitive units (4) being only the sensitive units (4) in said “enabled” condition, where M⇐L, wherein said storage register (9) can be set during the setting of said device (1).

### Claim 9 (depends on 1)

The device (1) according to claim 1, wherein said second processing unit (7) is configured in such a way that, at the moment of each one of said measuring operations (Ai), it varies the value of the biasing voltage (Vbias) of one or more of said M sensitive units (4) in a manner which is inversely proportional to the number of photons (F) impacting said sensitive area (31) during the previous measuring operation (Ai−1), said number of photons (F) being determined based on said electrical signals (S) generated by said M sensitive units (4) and received as an input by said second processing unit (7).

### Claim 10 (depends on 1)

The device (1) according to claim 1, wherein it is configured so that, at the moment of each one of said measuring operations (Ai), it activates said M sensitive units (4) in different time instants during said pre-determined time interval (I), based on the spatial coordinates of each one of said M sensitive units (4) on said sensitive area (31) of said receiving means (3).

### Claim 11 (depends on 1)

Method for measuring the distance (d) of at least a reference object (O), said method being implemented by means of a measuring device (1) according to claim 1 and comprising the execution, in sequence, of a plurality of measuring operations (Ai), each one of said measuring operations (Ai) including the following steps:
emission of light radiation (R) directed towards said reference object (O) through said emission means (2) for a predetermined time interval (I);
generation of an electrical signal (S) through each one of said M sensitive units (4) of said receiving means (3) following the impact of at least one photon (F) on the sensitive surface (41) of said sensitive unit (4); and
determination of the value of said distance (d) by means of said first processing unit (5), based on the time of impact (t) of said at least one photon (F) on at least one of said M sensitive units (4), said time of impact (t) being determined by at least one of said Ne processing elements (6),
wherein the method further comprises the following steps for each one of said measuring operations (Ai):
processing said electrical signals (S) of said M sensitive units (4) by means of said second processing unit (7), in such a way as to select, among said M sensitive units (4), said number Nu of sensitive units (4) where at least one photon (F) belonging to said reflected light radiation (R) impacted; and
associating each one of said Nu sensitive units (4) with one of said Ne processing elements (6) in such a way that, at the moment of the successive measuring operation (Ai+1), said value of said distance (d) is determined based on the time of impact (t) of at least one of said photons (F) related to each one of said Nu sensitive units (4) selected.

### Claim 12

A measuring device (1) suited to measure the distance (d) of at least a reference object (O), configured so that it performs a plurality of measuring operations (Ai) in succession and comprising:
emission means (2) suited to emit a light radiation (R) directed towards said reference object (O) during a predetermined time interval (I) for each one of said measuring operations (Ai);
receiving means (3) comprising a sensitive area (31) which is sensitive to said light radiation (R) reflected by said reference object (O), said sensitive area (31) being provided with a number M of sensitive units (4), each one of said sensitive units (4) being configured to generate an electrical signal (S) following the impact of at least one photon (F) on its sensitive surface (41);
a first processing unit (5) comprising Ne processing elements (6), where Ne <M, each one of said Ne processing elements (6) being configured to receive the electrical signal (S) generated by one of said M sensitive units (4) and to determine the time of impact (t) of said at least one photon (F) on said sensitive units (4) with respect to a reference electrical signal (clock), said first processing unit (5) being configured in such a way as to calculate, at the moment of each one of said measuring operations (Ai), the value of said distance (d) based on the time of impact (t) related to at least one of said M sensitive units (4),
wherein the measuring device further comprises a second processing unit (7) configured in such a way as to perform the following steps at the moment of each one of said measuring operations (Ai):
receiving as an input said electrical signals (S) generated by said M sensitive units (4);
processing said electrical signals (S) in such a way as to select a number Nu of sensitive units (4) impacted by the photons (F) belonging to said light radiation (R), where Nu⇐Ne;
associating each one of said Nu sensitive units (4) to one of said Ne processing elements (6), in such a way that, at the moment of the successive measuring operation (Ai+1), said distance (d) is determined by said first processing unit (5) based on the time of impact (t) of at least one of said photons (F) related to each one of said Nu sensitive units (4) selected,
and wherein said sensitive area (31) of said receiving means (3) comprises a number L of sensitive units (4), said device (1) comprising a storage register (9) in which it is possible to store in advance the “enabled” or “disabled” condition of each one of said L sensitive units (4), said M sensitive units (4) being only the sensitive units (4) in said “enabled” condition, where M⇐L, wherein said storage register (9) can be set during the setting of said device (1).

### Claim 13 (depends on 12)

The device (1) according to claim 12, wherein it is configured so that, at the moment of each one of said measuring operations (Ai), it activates said M sensitive units (4) in different time instants during said pre-determined time interval (I), based on the spatial coordinates of each one of said M sensitive units (4) on said sensitive area (31) of said receiving means (3).

### Claim 14

A measuring device (1) suited to measure the distance (d) of at least a reference object (O), configured so that it performs a plurality of measuring operations (Ai) in succession and comprising:
emission means (2) suited to emit a light radiation (R) directed towards said reference object (O) during a predetermined time interval (I) for each one of said measuring operations (Ai);
receiving means (3) comprising a sensitive area (31) which is sensitive to said light radiation (R) reflected by said reference object (O), said sensitive area (31) being provided with a number M of sensitive units (4), each one of said sensitive units (4) being configured to generate an electrical signal (S) following the impact of at least one photon (F) on its sensitive surface (41);
a first processing unit (5) comprising Ne processing elements (6), where Ne <M, each one of said Ne processing elements (6) being configured to receive the electrical signal (S) generated by one of said M sensitive units (4) and to determine the time of impact (t) of said at least one photon (F) on said sensitive units (4) with respect to a reference electrical signal (clock), said first processing unit (5) being configured in such a way as to calculate, at the moment of each one of said measuring operations (Ai), the value of said distance (d) based on the time of impact (t) related to at least one of said M sensitive units (4),
wherein the measuring device further comprises a second processing unit (7) configured in such a way as to perform the following steps at the moment of each one of said measuring operations (Ai):
receiving as an input said electrical signals (S) generated by said M sensitive units (4);
processing said electrical signals (S) in such a way as to select a number Nu of sensitive units (4) impacted by the photons (F) belonging to said light radiation (R), where Nu⇐Ne;
associating each one of said Nu sensitive units (4) to one of said Ne processing elements (6), in such a way that, at the moment of the successive measuring operation (Ai+1), said distance (d) is determined by said first processing unit (5) based on the time of impact (t) of at least one of said photons (F) related to each one of said Nu sensitive units (4) selected,
and wherein said second processing unit (7) is configured in such a way that, at the moment of each one of said measuring operations (Ai), it varies the value of the biasing voltage (Vbias) of one or more of said M sensitive units (4) in a manner which is inversely proportional to the number of photons (F) impacting said sensitive area (31) during the previous measuring operation (Ai+1), said number of photons (F) being determined based on said electrical signals (S) generated by said M sensitive units (4) and received as an input by said second processing unit (7).

### Claim 15 (depends on 14)

The device (1) according to claim 14, wherein it is configured so that, at the moment of each one of said measuring operations (Ai), it activates said M sensitive units (4) in different time instants during said pre-determined time interval (I), based on the spatial coordinates of each one of said M sensitive units (4) on said sensitive area (31) of said receiving means (3).