Multiplexed light detection and ranging apparatus

A multiplexed light detection and ranging (LiDAR) system for measuring a distance from the multiplexed LiDAR system to features on an object, comprising:

• a coherent light source ;
• a modulating controller in communication with the coherent light source and configured for generating and controlling a control signal that is transferred to the coherent light source for modulating the coherent light source to generate a pulsed wavelength-modulated coherent light beam, for creating a scan pattern for measuring a surface of the object;
• at least two LiDAR modules connected with the coherent light source for receiving the pulsed wavelength-modulated coherent light beam and comprising:
• an interferometer, comprising:
• an optical splitter for dividing the pulsed wavelength-modulated coherent light beam into at least two pulsed wavelength-modulated coherent light beams;
• a hybrid scanner in communication with the at least two LiDAR modules to receive the pulsed wavelength-modulated coherent light beams and configured to scan a surface of the object with the pulsed wavelength-modulated coherent light beams to trace the scan pattern on the surface of the object for measuring the distance from the multiplexed (LiDAR) system to the features of the object, wherein a fraction of each of the pulsed wavelength-modulated coherent light beams is back reflected to the hybrid scanner and to each interferometer of the at least two LiDAR modules wherein each of the at least two LiDAR modules further comprises a balanced detector to convert the back reflected pulsed wavelength-modulated coherent light beams electrical;
• wherein, the hybrid scanner comprises a plurality of collimators, and each of the plurality of collimators comprise:
• one or more graded-index fiber rods, where in each fiber rod is formed with a separate lens in contact with the graded-index fiber rod to provide the low numerical aperture as required of the graded-index fiber rod and the engineered graded-index lens for long-distance illumination and the higher numerical aperture required for receiving back-reflected pulsed wavelength-modulated coherent light from the object;
• a signal processor in communication with a photodetector array within the balanced detector of the LiDAR modules to receive the electrical signals and convert the electrical signals to digitized electrical signals;
• and
• a computer system configured programmed to calculate the time delay determined by the digitized electrical signal from the signal processor and generates a displayed imaging range based on the distance from the target.

A method for determining an object's distance comprises the steps of:

• generating a coherent light beam;
• modulating the coherent light beam with a pulsed wavelength-modulating signal;
• polarizing the pulsed wavelength-modulated light beam by adjusting the polarization states of the pulsed wavelength-modulated light beam and maximizing the amplitude of optical interference signals;
• optically splitting the pulsed wavelength-modulated light beam into at least two pulsed wavelength-modulated light beams;
• coupling each of the at least two pulsed wavelength-modulated light beams to one of at least two LiDAR Modules for creating a sampling pulsed wavelength-modulated light beam and a reference pulsed wavelength-modulated light beam;
• transferring the at least two pulsed wavelength-modulated light beams to a hybrid scanner module for establishing a scan pattern for each of the pulsed wavelength-modulated light beams;
• scanning the at least two pulsed wavelength-modulated light beams at an object whose distance from a source of the wavelength-modulated coherent light beam is to be measured;
• receiving the back-reflected portion of the at least two pulsed wavelength-modulated light beams from the object to be measured;
• coupling each back-reflected portion of each of the at least two pulsed wavelength-modulated light beams to a corresponding LiDAR module of the at least two pulsed wavelength-modulated light beams to form an electrical signal representing each of the at least two pulsed wavelength-modulated light beams;
• forming a hybrid scanner by the steps of
• forming a plurality of optical collimators by configuring the optical collimators such that one sampled pulsed wavelength-modulated coherent light beam is transferred to each collimator of the plurality of optical collimators;
• wherein forming each optical collimator of the plurality of optical collimators to contain one or more graded-index fiber rods, by forming each fiber rod with a separate lens in contact with the graded-index fiber rod for providing a low numerical aperture as required of the graded-index fiber rod and and forming the engineered graded-index lens for long-distance illumination and the higher numerical aperture required for receiving back-reflected pulsed wavelength-modulated coherent light from the objective;
• digitizing the electrical signals;
• detecting an envelope of each of the digitized electrical signals for determining the envelope of each of the digitized electrical signals;
• determining the times of rising or falling edges of the envelope of the digitized electrical signal;
• determining the time difference between the rising or falling edges of the envelope of the digitized interference signal;
• calculating a distance to the object to be measured is calculated;
• and
• forming a two-dimensional ranging image based on all distance measurements scanned by the at least two pulsed wavelength-modulated light beams across the object to be measured.