APPARATUS FOR GENERATING BACKSCATTER HISTOGRAM DATA FOR DETERMINING A DIFFUSE BACKSCATTER DURING AN OPTICAL RUNTIME MEASUREMENT AND A METHOD

Abstract

An apparatus for generating backscatter histogram data for determining a diffuse backscatter during an optical runtime measurement, comprising:

At least one histogram accumulation unit, which has several signal inputs, so as to receive time-correlated histogram data; and wherein the histogram accumulation unit is set up to generate backscatter histogram data based upon the time-correlated histogram data received at the signal inputs.

Claims

1. An apparatus for generating backscatter histogram data for determining a diffuse backscatter during an optical runtime measurement, comprising: At least one histogram accumulation unit, which has several signal inputs, so as to receive time-correlated histogram data, wherein the histogram accumulation unit is set up to generate backscatter histogram data based upon the time-correlated histogram data received at the signal inputs.

2. The apparatus according to claim 1, wherein the histogram accumulation unit generates the backscatter histogram data by adding together the received time-correlated histogram data.

3. The apparatus according to claim 1, wherein the histogram accumulation unit calculates an arithmetic mean from the received time-correlated histogram data, so as to generate the backscatter histogram data.

4. The apparatus according to claim 1, wherein the histogram accumulation unit accumulates the received time-correlated histogram data of several time intervals in one time interval, so as to generate the backscatter histogram data.

5. The apparatus according to claim 1, wherein the histogram accumulation unit is further set up not to consider received time-correlated histogram data of time intervals exceeding a specific time threshold for generating the backscatter histogram data.

6. The apparatus according to claim 1, wherein the histogram accumulation unit is further set up to weight the received time-correlated histogram data for generating the backscatter histogram data.

7. The apparatus according to claim 1, wherein the histogram accumulation unit is further set up to output the backscatter histogram data for determining the backscatter.

8. The apparatus according to claim 1, further comprising: A receiving matrix with several light-detecting receiving elements, wherein each of the light-detecting receiving elements is configured to detect light and generate an electrical signal in response thereto.

9. The apparatus according to claim 8, wherein each of the light-detecting receiving elements can be activated and deactivated.

10. The apparatus according to claim 8, wherein the light-detecting receiving elements in the receiving matrix are arranged in columns and rows, wherein the same number of light-detecting receiving elements is provided in each row.

11. The apparatus according to claim 10, further comprising: Several evaluation units, wherein a respective evaluation unit is connected with the light-detecting receiving elements in a column, or a respective evaluation unit connected with the light-detecting receiving elements in a row.

12. The apparatus according to claim 11, wherein each of the evaluation units is set up to generate the time-correlated histogram data based upon the electrical signals of the light-detecting receiving elements.

13. The apparatus according to claim 12, to the extent it depends on claim 9, wherein only the light-detecting receiving elements that are activated are considered for generating the time-correlated histogram data.

14. The apparatus according to claim 1, wherein each signal input is connected with one of the evaluation units, so that the time-correlated histogram data are transmitted from the evaluation unit to the corresponding histogram accumulation unit.

15. A method of generating backscatter histogram data for determining a diffuse backscatter during an optical runtime measurement, comprising: Receiving several time-correlated histogram data; and generating backscatter histogram data based upon the received time-correlated histogram data.

Description

[0062] Exemplary embodiments of the invention will now be exemplarily described with reference to the attached drawing, in which:

[0063] FIG. 1 illustrates a diagram of an exemplary embodiment of an apparatus;

[0064] FIG. 2 shows time-correlated histogram data received by two evaluation units in two histograms (upper left and lower left), and the backscatter histogram data generated therefrom in a histogram accumulation unit in a histogram (right); and

[0065] FIG. 3 illustrates a flowchart of an exemplary embodiment of a method.

[0066] FIG. 1 illustrates a diagram of an exemplary embodiment of an apparatus 1.

[0067] The apparatus 1 has a receiving matrix 2, which has arranged on it several light-detecting receiving elements (ENxM, in this exemplary embodiment E0,0 to E127,255) in rows (Z0 to Z127) and columns (S0 to S255). M=256 light-detecting receiving elements (E0,0 to E127,255) are arranged in each of the N=128 rows (Z0 to Z127) (corresponding to M=256 columns (S0 to S255)). In this exemplary embodiment, the light-detecting receiving elements (E0,0 to E127,255) are SPADs.

[0068] The apparatus 1 further has several evaluation units (A0 to A127), wherein a respective evaluation unit (A0 to A127) is connected with the light-detecting receiving elements (E0,0 to E127,255) of a row (Z0 to Z127) by a multiplexer (not shown). In each row (Z0 to Z127), only the two light-detecting receiving elements (E0,0 and E0,1 to E127,0 and E127,1) are activated in the columns S0 and S1 at any given time (illustrated by the second circle within the light-detecting receiving elements (E0,0 and E0,1 to E127,0 and E127,1)). When light is detected, the activated light-detecting receiving elements (E0,0 and E0,1 to E127,0 and E127,1) generate electrical signals, from which time-correlated histogram data are generated with the help of a time-to-digital converter (not shown) in each of the evaluation units (A0 to A127). In this exemplary embodiment, the time-correlated histograms of the two activated light-detecting receiving elements (E0,0 and E0,1 to E127,0 and E127,1) are added in the evaluation units (A0 to A127), so as to generate and output time-correlated histogram data. In other exemplary embodiments, any desired number of the M=256 light-detecting receiving elements (E0,0 to E127,255) can be activated in each row, e.g., E0,0 to E0,10, E1,0 to E1,10, E2,0 to E2,10, . . . , E127,0 to E127,10.

[0069] The apparatus 1 further has several histogram accumulation units (HA0 to HAX). Each histogram accumulation unit (HA0 to HAX) has P=16 signal inputs (not explicitly shown), wherein each signal input is connected with a respective evaluation unit (A0 to A127). In this exemplary embodiment, X=N/P=8 histogram accumulation units are thus required at N=128 rows (Z0 to Z127), which accumulate the time-correlated histogram data of P=16 evaluation units (A0 to A127) accordingly. The time-correlated histogram data output by the evaluation units (A0 to A127) are transmitted to the histogram accumulation units (HA0 to HA6X), so that these are received at the signal inputs. Based upon the received time-correlated histogram data, the histogram accumulation units (HA0 to HAX) generate backscatter histogram data. In this exemplary embodiment, the time-correlated histogram data received at each signal input are added together, so as to generate the backscatter histogram data.

[0070] FIG. 2 exemplarily shows the time-correlated histogram data (ZHD0 to ZHDP) received by two evaluation units (A0 and A1) for two of 16 histograms (upper left and lower right), and shows the backscatter histogram data (RHD0) generated therefrom in a histogram accumulation unit (HA0) in a histogram (right).

[0071] The apparatus 1 in this exemplary embodiment is configured analogously to the apparatus 1 on FIG. 1.

[0072] FIG. 2 illustrates how the time-correlated histograms (ZHD0 to ZHDP) generated by 16 evaluation units (A0 to A15) are accumulated.

[0073] The horizontal axis is the time axis, which is divided into several identical time intervals (“bins”), and the event is allocated to one of the time intervals depending on the time the light was detected (“event”). The number of events detected within the time interval is illustrated by the height of a bar on the vertical axis. The number of events in each time interval of the time-correlated histogram data (ZHD0 to ZHDP) is added together, so as to generate the backscatter histogram data (RHD0).

[0074] The large bar in the fifth time interval of the time-correlated histogram data (ZHD0) from the first evaluation unit (A0) here corresponds to a small object, which is only recorded in a small area of the visual field. However, the contribution of diffuse backscatter is present in the entire visual field before the object at short distances, and thus also present in the two exemplary time-correlated histogram data (ZHD0 to ZHDP). Adding the 16 time-correlated histogram data (ZHD0 to ZHDP) together increases the SNR in the backscatter histogram data (RHD0) in comparison to the contribution by objects and ambient light. This makes the backscatter histogram data (RHD0) better suited for determining a diffuse backscatter during an optical runtime measurement.

[0075] FIG. 3 illustrates a flowchart for an exemplary embodiment of a method 20.

[0076] Several time-correlated histogram data are received at 21, as stated herein.

[0077] Backscatter histogram data are generated at 22 based upon the received time-correlated histogram data, as stated herein.

TABLE-US-00001 Reference List  1 Apparatus  2 Receiving matrix 20 Method 21 Receiving several time-correlatedhistogram data 22 Generating backscatterhistogramdatabased upon the received time- correlated histogram data A0 to A127 Evaluation units ENxM, E0,0 to E127,255 Light-detecting receiving elements HA0 to HAX Histogram accumulation units RHD0 Backscatter histogram data S0 to S255 Columns Z0 to Z127 Rows ZHD0 to ZHDP Time-correlatedhistogram data