Abstract: A lidar device includes a laser source configured to emit a transmit beam, an optical scanner that has at least one lens and is configured to transmit a first portion of the transmit beam towards a target and receive a receive beam reflected by the target, and a transmission medium configured to provide a propagation path for the transmit beam and the receive beam. The lidar device also includes a target detection module that is configured to determine a range and/or a velocity of the target based on the receive beam and a second portion of the transmit beam reflected at a media-air interface defined at an end of the transmission medium where the first portion of the transmit beam is launched into air towards the at least one lens of the optical scanner.

Abstract: An apparatus for cancellation of scattered light in lidar sensors is provided. In some embodiments, the apparatus includes a lidar device with a transmitter configured to transmit optical signals and a receiver configured to receive return signals based on the optical signals. The receiver includes a first photodetector configured to receive a first return signal and a second return signal, and generate a first electrical current in response to the first return signal and the second return signal. The receiver further includes a second photodetector configured to receive the first return signal but not the second return signal, and generate a second electrical current in response to the first return signal. The receiver also includes an amplifier configured to receive a third electrical current equal to a difference between the first electrical current and the second electrical current.

Abstract: Systems and methods of signal processing for sensors are disclosed. Signal processing methods and systems demodulate the optical interference phase of cascaded individual optical fiber intrinsic Fabry-Perot interferometric sensors in a coherent microwave-photonic interferometry distributed sensing system. The chirp effect of an electro-optic modulator (EOM) is used to create a quasi-quadrature optical interference phase shift between two adjacent pulses which correspond to two adjacent reflection points in the time domain. The phase shift can be controlled by adjusting the bias voltage that is applied to the EOM. The interference phase is calculated by elliptically fitting the phase shift. The interference phase change is proportional to the optical path difference (OPD) change of the interferometer, and the sign can be used to differentiate the increase or decrease of the OPD. The approach shows good linearity, high resolution, and large dynamic range for distributed strain sensing.