Embodiments of the disclosure provide a receiver in an optical sensing system. The exemplary receiver includes a movable detector configured to receive optical signals reflected or scattered from an object scanned by the optical sensing system. The receiver further includes an actuator configured to move the movable detector. The receiver also includes a controller configured to determine a plurality of target positions of the movable detector for receiving the optical signals. The controller is further configured to control the actuator to move the movable detector to the plurality target positions according to a movement pattern.