Three-dimensional ladar module with alignment reference insert circuitry

Abstract

A 3-D LADAR imaging system incorporating stacked microelectronic layers is provided. A light source such as a laser is imaged upon a target through beam shaping optics. Photons reflected from the target are collected and imaged upon a detector array though collection optics. The detector array signals are fed into a multilayer processing module wherein each layer includes detector signal processing circuitry. The detector array signals are amplified, compared to a user-defined threshold, digitized and fed into a high speed FIFO shift register range bin. Dependant on the value of the digit contained in the bins in the register, and the digit's bin location, the time of a photon reflection from a target surface can be determined. A Ttrigger signal defines the reflection time represented at each bin location by resetting appropriate circuitry to begin processing. A reference insert circuit inserts data into the FIFO registers at a preselected location to provide a reference point at which all FIFO shift register data may be aligned to accommodate for timing differences between layers and channels. The bin data representing the photon reflections from the various target surfaces are read out of the FIFO and processed using appropriate circuitry such as a field programmable gate array to create a synchronized 3-D point cloud for creating a 3-D target image.