SYSTEM AND METHOD FOR REDUCING STRAY LIGHT INTERFERENCE IN OPTICAL SYSTEMS
A method for reducing optical interference in an optical sensor including detecting, by an optical sensor device comprising a plurality of pixel sensors, a signal with a reflected light component and a stray light component, estimating, by a processor, a stray light intensity in each pixel of the plurality of pixel sensors using a point spread function obtained by emitting a reference light signal and measuring intensities detected by the plurality of pixel sensors, identifying, by the processor, at least one pixel associated with a relatively high intensity from the plurality of pixel sensors of the optical sensor device, wherein the identified pixel is considered to be associated with a retroreflector or a bloom causing object, adjusting, by the processor, a noise probability for the signal using the estimated stray light intensity and an unbiased noise intensity, and adjusting, by the processor, a signal confidence score using the adjusted noise probability.
1 . A method for reducing optical interference in an optical sensor comprising:
detecting, by an optical sensor device comprising a plurality of pixel sensors, a signal with a reflected light component and a stray light component;
estimating, by a processor, a stray light intensity in each pixel of the plurality of pixel sensors using a point spread function obtained by emitting a reference light signal and measuring intensities detected by the plurality of pixel sensors;
identifying, by the processor, at least one pixel associated with a relatively high intensity from the plurality of pixel sensors of the optical sensor device, wherein the identified pixel is considered to be associated with a retroreflector or a bloom causing object;
adjusting, by the processor, a noise probability for the signal using the estimated stray light intensity and an unbiased noise intensity; and
adjusting, by the processor, a signal confidence score using the adjusted noise probability.
2 . The method according to claim 1 , further comprising using the adjusted signal confidence score to control autonomous operations of a robot.
3 . The method according to claim 1 , wherein identifying further comprises classifying points in a point cloud as bloom points, the point cloud being generated based on outputs from the optical sensor device.
4 . The method according to claim 3 , wherein the classifying comprises identifying points of the point cloud that have range values within a given range tolerance defined by the minimum range and maximum range associated with a pixel considered to possibly be associated with an object causing bloom.
5 . The method according to claim 4 , wherein the classifying further comprises filtering the point using heuristics or confidence thresholding.
6 . The method according to claim 1 , wherein the noise probability is adjusted by adding the estimated stray light intensity to the unbiased noise intensity or by multiplying a first number derived using the unbiased noise intensity and a second number derived using the estimated stray light intensity.
7 . The method according to claim 1 , wherein the adjusted signal confidence score is a function of a span count and a trial count in addition to the adjusted noise probability.
8 . The method according to claim 1 , further comprising adjusting an intensity of the reflected light using the adjusted noise probability and a photon detection efficiency.
9 . The method according to claim 1 , further comprising filtering points from a point cloud based on a comparison of the adjusted signal confidence score to a threshold value.
10 . The method according to claim 1 , wherein the estimating further comprises estimating a relationship between stray light distribution and pixel indices of the optical sensor device, and
wherein a normalized stray light intensity distribution is compared to a pixel index in the point spread function.
11 . A system, comprising:
an optical sensor device comprising a plurality of pixel sensors and configured to detect a signal with a reflected light component and a stray light component;
a processor; and
a non-transitory computer-readable storage medium comprising programming instructions that are configured to cause the processor to implement a method for operating a system, wherein the programming instructions comprise instructions to:
estimate a stray light intensity in each pixel of the plurality of pixel sensors using a point spread function obtained by emitting a reference light signal and measuring intensities detected by the plurality of pixel sensors;
identify at least one pixel associated with a relatively high intensity from the plurality of pixel sensors of the optical sensor device, wherein the identified pixel is considered to be associated with a retroreflector or a bloom causing object;
adjust a noise probability for the signal using the estimated stray light intensity and an unbiased noise intensity; and
adjust a signal confidence score using the adjusted noise probability.
12 . The system according to claim 11 , wherein the programming instructions further comprise instructions to classify points in a point cloud as bloom points, the point cloud being generated based on outputs from the optical sensor device.
13 . The system according to claim 12 , wherein identified points have range values within a given range tolerance defined by the minimum range and maximum range associated with a pixel considered to possibly be associated with an object causing bloom.
14 . The system according to claim 13 , wherein the identified point are filtered using heuristics or confidence thresholding.
15 . The system according to claim 11 , wherein the noise probability is adjusted by adding the estimated stray light intensity to the unbiased noise intensity or by multiplying a first number derived using the unbiased noise intensity and a second number derived using the estimated stray light intensity.
16 . The system according to claim 11 , wherein the adjusted signal confidence score is a function of a span count and a trial count in addition to the adjusted noise probability.
17 . The system according to claim 11 , wherein the programming instructions further comprise instructions to adjust an intensity of the reflected light using the adjusted noise probability and a photon detection efficiency.
18 . The system according to claim 11 , wherein the programming instructions further comprise instructions to filter points from a point cloud based on a comparison of the adjusted signal confidence score to a threshold value.
19 . The system according to claim 11 , wherein the programming instructions further comprise instructions to estimate a relationship between stray light distribution and pixel indices of the optical sensor device, and
wherein a normalized stray light intensity distribution is compared to a pixel index in the point spread function.
20 . A non-transitory computer-readable medium that stores instructions that, when executed by at least one computing device, will cause the at least one computing device to perform operations comprising:
estimating, by a processor, a stray light intensity in each pixel of the plurality of pixel sensors using a point spread function obtained by emitting a reference light signal and measuring intensities detected by the plurality of pixel sensors;
identifying, by the processor, at least one pixel associated with a relatively high intensity from the plurality of pixel sensors of the optical sensor device, wherein the identified pixel is considered to be associated with a retroreflector or a bloom causing object;
adjusting, by the processor, a noise probability for the signal using the estimated stray light intensity and an unbiased noise intensity; and
adjusting, by the processor, a signal confidence score using the adjusted noise probability.