This paper presents a design of single photon avalanche diode(SPAD)light detection and ranging(LiDAR)sensor with 128×128 pixels and 128 column-parallel time-to-analog-merged-analog-to-digital converts(TA-ADCs).Un...This paper presents a design of single photon avalanche diode(SPAD)light detection and ranging(LiDAR)sensor with 128×128 pixels and 128 column-parallel time-to-analog-merged-analog-to-digital converts(TA-ADCs).Unlike the conventional TAC-based SPAD LiDAR sensor,in which the TAC and ADC are separately implemented,we propose to merge the TAC and ADC by sharing their capacitors,thus avoiding the analog readout noise of TAC’s output buffer,improving the conversion rate,and reducing chip area.The reverse start-stop logic is employed to reduce the power of the TA-ADC.Fabricated in a 180 nm CMOS process,our prototype sensor exhibits a timing resolution of 25 ps,a DNL of+0.30/−0.77 LSB,an INL of+1.41/−2.20 LSB,and a total power consumption of 190 mW.A flash LiDAR system based on this sensor demonstrates the function of 2D/3D imaging with 128×128 resolution,25 kHz inter-frame rate,and sub-centimeter ranging precision.展开更多
Coherent rainbows can be formed by focusing white-light laser into liquids.They are bilaterally symmetric interference rings with various shapes.Such interference rings arise from the temperature distribution of the l...Coherent rainbows can be formed by focusing white-light laser into liquids.They are bilaterally symmetric interference rings with various shapes.Such interference rings arise from the temperature distribution of the liquid induced by laser heating,i.e.,thermal lens effect,which changes the refractive index locally and thus the optical path difference.The up-down asymmetry of the interference rings is caused by convection in the liquid.With the increase of the viscosity,the interference rings change their shape from oval to circular shape.After a shutter is opened and the laser shines into the liquid,the interference rings are circular at the beginning.As time goes on,they gradually turn into an oval shape.Let the liquid go a free-fall at the beginning,the interference rings remain circular.All the three experiments have confirmed that the asymmetric interference rings are due to convection in the liquid associated with thermal lens effect.We also numerically simulate the two-dimensional heat conduction with and without convection,whose results agree well with our experimental observations.展开更多
基金supported by National Science and Technology Major Project(Grant No.2021ZD0109801)in part by the Beijing Municipal Science and Technology Project(Grant No.Z221100007722028)in part by the National Natural Science Foundation of China(Grant No.62334008).
文摘This paper presents a design of single photon avalanche diode(SPAD)light detection and ranging(LiDAR)sensor with 128×128 pixels and 128 column-parallel time-to-analog-merged-analog-to-digital converts(TA-ADCs).Unlike the conventional TAC-based SPAD LiDAR sensor,in which the TAC and ADC are separately implemented,we propose to merge the TAC and ADC by sharing their capacitors,thus avoiding the analog readout noise of TAC’s output buffer,improving the conversion rate,and reducing chip area.The reverse start-stop logic is employed to reduce the power of the TA-ADC.Fabricated in a 180 nm CMOS process,our prototype sensor exhibits a timing resolution of 25 ps,a DNL of+0.30/−0.77 LSB,an INL of+1.41/−2.20 LSB,and a total power consumption of 190 mW.A flash LiDAR system based on this sensor demonstrates the function of 2D/3D imaging with 128×128 resolution,25 kHz inter-frame rate,and sub-centimeter ranging precision.
基金Project supported by the National Key Research and Development Program of China(Grant No.2016YFA0301202)the National Natural Science Foundation of China(Grant Nos.11674311 and U20A20205)。
文摘Coherent rainbows can be formed by focusing white-light laser into liquids.They are bilaterally symmetric interference rings with various shapes.Such interference rings arise from the temperature distribution of the liquid induced by laser heating,i.e.,thermal lens effect,which changes the refractive index locally and thus the optical path difference.The up-down asymmetry of the interference rings is caused by convection in the liquid.With the increase of the viscosity,the interference rings change their shape from oval to circular shape.After a shutter is opened and the laser shines into the liquid,the interference rings are circular at the beginning.As time goes on,they gradually turn into an oval shape.Let the liquid go a free-fall at the beginning,the interference rings remain circular.All the three experiments have confirmed that the asymmetric interference rings are due to convection in the liquid associated with thermal lens effect.We also numerically simulate the two-dimensional heat conduction with and without convection,whose results agree well with our experimental observations.
