A LiDAR detection system, comprising: a plurality of optical sources disposed along a first direction for generating a plurality of output optical signals disposed along the first direction; a signal generator for generating an output signal having a variable frequency; a modulation circuit for receiving the output signal from the signal generator and applying the output signal from the signal generator to the plurality of optical sources to modulate the output optical signals such that the output optical signals are envelope-modulated output optical signals having frequency-modulated modulation envelopes; optical transmission elements for transmitting the envelope-modulated output optical signals into a region; a scanning device for scanning the plurality of envelope-modulated output optical signals over a second direction different than the first direction; a receiver for receiving return optical signals at least partially generated by reflection of the transmitted envelope-modulated output optical signals and generating receive signals indicative of the return optical signals, the receiver comprising a two-dimensional array of optical detectors; a mask disposed in proximity to the array between the region and the array, the return optical signals impinging on the mask, the mask comprising a plurality of apertures disposed along a direction aligned with a first dimension of the array, each aperture being adapted such that the mask blocks a first portion of the return optical signals from impinging on the array and the aperture allows a second portion of the return optical signals to impinge on the array, wherein the receive signals are generated for a set of detectors in the array disposed along the first dimension of the array and aligned with the apertures in the mask and exposed to the received return optical signals, wherein the receive signals are generated for one set of detectors at a time, the sets of detectors being offset with respect to each other along a second dimension of the array substantially orthogonal to the first dimension of the array, wherein each detector in a set of detectors comprises multiple regions, a first region of each detector receiving a return optical signal at a first time and a second region of each detector receiving another return optical signal at a second time later than the first time, wherein the first and second times occur during different sweeps of the array; and a processor coupled to the receiver for receiving the receive signals and processing the receive signals to generate detections of one or more objects in the region. a plurality of optical sources disposed along a first direction for generating a plurality of output optical signals disposed along the first direction; a signal generator for generating an output signal having a variable frequency; a modulation circuit for receiving the output signal from the signal generator and applying the output signal from the signal generator to the plurality of optical sources to modulate the output optical signals such that the output optical signals are envelope-modulated output optical signals having frequency-modulated modulation envelopes; optical transmission elements for transmitting the envelope-modulated output optical signals into a region; a scanning device for scanning the plurality of envelope-modulated output optical signals over a second direction different than the first direction; a receiver for receiving return optical signals at least partially generated by reflection of the transmitted envelope-modulated output optical signals and generating receive signals indicative of the return optical signals, the receiver comprising a two-dimensional array of optical detectors; a mask disposed in proximity to the array between the region and the array, the return optical signals impinging on the mask, the mask comprising a plurality of apertures disposed along a direction aligned with a first dimension of the array, each aperture being adapted such that the mask blocks a first portion of the return optical signals from impinging on the array and the aperture allows a second portion of the return optical signals to impinge on the array, wherein the receive signals are generated for a set of detectors in the array disposed along the first dimension of the array and aligned with the apertures in the mask and exposed to the received return optical signals, wherein the receive signals are generated for one set of detectors at a time, the sets of detectors being offset with respect to each other along a second dimension of the array substantially orthogonal to the first dimension of the array, wherein each detector in a set of detectors comprises multiple regions, a first region of each detector receiving a return optical signal at a first time and a second region of each detector receiving another return optical signal at a second time later than the first time, wherein the first and second times occur during different sweeps of the array; and a processor coupled to the receiver for receiving the receive signals and processing the receive signals to generate detections of one or more objects in the region.