Dynamic beam splitter for direct time of flight distance measurements

A coaxial beam scanner, comprising:

• a transmitter configured to transmit a transmit light beam along a transmit beam path;
• a scanning structure configured to rotate about at least one scanning axis, the scanning structure configured to receive a portion of the transmit light beam from the transmitter, direct the portion of the transmit light beam into a field of view, receive, from the field of view, a receive light beam that corresponds to the portion of the transmit light beam, and direct the receive light beam along a receive beam path;
• a photodetector array configured to receive a portion of the receive light beam that is deflected by the scanning structure;
• and
• a time-of-flight (ToF) optical beam splitter arranged in the transmit beam path between the transmitter and the scanning structure and in the receive beam path between the scanning structure and the photodetector array,
• wherein the ToF optical beam splitter comprises:
• a main body having a first reflectivity and comprising a main surface facing the scanning structure, wherein the main surface includes a first region and a second region;
• and
• a reflective coating disposed on the main surface at the first region and excluded from the main surface at the second region, wherein the reflective coating has second reflectivity that is greater than the first reflectivity,
• wherein the ToF optical beam splitter has a time variable splitting ratio with respect to the receive light beam, the time variable splitting ratio being is dependent on a ToF of a round trip light beam comprising of the transmit light beam and the receive light beam, and
• wherein the ToF optical beam splitter is configured to receive the receive light beam from the scanning structure and deflect the portion of the receive light beam towards the photodetector array.

A coaxial Light Detection and Ranging (LIDAR) system, comprising:

• a transmitter configured to transmit a transmit light beam along a transmit beam path;
• a scanning structure configured to rotate about at least one scanning axis, the scanning structure configured to receive a portion of the transmit light beam from the transmitter, direct the portion of the transmit light beam into a field of view, receive, from the field of view, a receive light beam that corresponds to the portion of the transmit light beam, and direct the receive light beam along a receive beam path;
• a photodetector array configured to receive a portion of the receive light beam that is deflected by the scanning structure;
• and
• a time-of-flight (ToF) optical beam splitter arranged in the transmit beam path between the transmitter and the scanning structure and in the receive beam path between the scanning structure and the photodetector array,
• wherein the ToF optical beam splitter comprises:
• a main body having a first reflectivity and comprising a main surface facing the scanning structure, wherein the main surface includes a first region and a second region,
• wherein the first region and the second region share at least one boundary,
• wherein the at least one boundary corresponds to a ToF threshold of a ToF;
• and
• a reflective coating disposed on the main surface at the first region and excluded from the main surface at the second region, wherein the reflective coating has second reflectivity that is greater than the first reflectivity,
• wherein the ToF optical beam splitter has a time variable splitting ratio with respect to the receive light beam that is dependent on a ToF of a round trip light beam comprising of the transmit light beam and the receive light beam.