Frequency modulated scanning LIDAR with 360 degrees field of view

A method for scanning a transmitted beam through a 360° field-of-view (FOV) and processing beams reflected off of a target in a light detection and ranging (LIDAR) system to determine a distance between the LIDAR system and the target and a velocity of the target, said LIDAR system including a transmitter sub-system and a receiver sub-system, said method comprising:

• generating a laser beam to be transmitted by the transmitter sub-system at a first frequency;
• determining a temperature of optical and electro-optical components in the transmitter and/or receiver sub-systems;
• adjusting the first frequency of the laser beam to compensate for changes in the temperature of the optical and electro-optical components in the transmitter and/or receiver sub-systems;
• directing the laser beam to a spiral phase plate resonator (SPPR) device in the transmitter sub-system having opposing reflective surfaces that reflect the laser beam back and forth in the SPPR device, wherein one of the reflective surfaces includes a spiral step index that causes multiple internal reflected beams having different phases to be combined as the transmitted beam emitted from one side of the SPPR device and having a coherent superposition of optical vortex intensity patterns and a processing beam emitted from an opposite side of the SPPR device and having a coherent superposition of optical vortex intensity patterns;
• directing the transmitted beam from the SPPR device onto a conical mirror to direct the transmitted beam at a certain angle therefrom depending on the first frequency of the laser beam;
• shifting the optical frequency of the laser beam to a second frequency to change the angle that the transmitted beam is directed from the conical mirror;
• frequency modulating the laser beam at the second frequency over a frequency modulation range;
• receiving a reflected beam from the target at the receiver sub-system;
• mixing and correlating the processing beam and the reflected beam;
• calculating a fast Fourier transform of signals representing the mixed processing and reflected beams;
• determining beat frequencies in the mixed and transformed signals;
• identifying intermediate frequencies in the beat frequencies;
• estimating a time delay between the transmitted beam and the reflected beam from the beat frequencies to determine the distance to the target;
• determining a Doppler shift frequency from the beat frequencies to determine the velocity of the target;
• shifting the optical frequency of the laser beam to a plurality of other frequencies to change the angle that the transmitted beam is directed from the conical mirror over a complete 360° scan;
• and
• repeating the steps of frequency modulating, receiving a reflected beam from the target, mixing and correlating, calculating a fast Fourier transform, determining beat frequencies, identifying intermediate frequencies, estimating a time delay and determining a Doppler shift frequency for each separate optical frequency.