A method is disclosed for controlling a pulse repetition rate of pulsed laser beam 1 created by pulsed laser oscillator 100, includes generating beam 1 by oscillator 100, splitting beam 1 into first pulsed split beam 1a and second pulsed split beam 1b, time-delaying split beam 1a relative to split beam 1b by optical delay device 220, generating timing baseband signal Sc including a timing jitter of the pulse repetition rate based on split beam 1a and second split beam 1b by timing detector device 230, generating feedback signal Sf based on timing baseband signal Sc, and applying feedback signal Sf on oscillator 100 and controlling the pulse repetition rate of beam 1 based on the feedback signal Sf. Furthermore, repetition rate control apparatus 200 for controlling a pulse repetition rate of pulsed laser oscillator 100 and pulsed laser oscillator 100, comprising repetition rate control apparatus 200 are described.

A PIC has first, second and third elements fabricated on a common substrate. The first element includes a structure supporting efficient coupling of one or more free-space optical modes of incident light into one or more waveguide guided optical modes. The second element includes an on-chip interferometer having an input optically coupled to the waveguide guided optical modes; one or more arms; one or more outputs; and a phase tuner configured to change optical path length in one or more of the arms. The third element includes one or more light detecting structures optically coupled to the one or more outputs of the second element, such that variation in optical power in the one or more outputs is detected, allowing an assessment of coherence characterizing the light incident on the first element of the PIC to be provided.

The ability to rapidly identify symmetry and anti-symmetry is an essential attribute of intelligence. Symmetry perception is a central process in human vision and may be key to human 3D visualization. While previous work in understanding neuron symmetry perception has concentrated on the neuron as an integrator, the invention provides the coincidence detecting property of the spiking neuron can be used to reveal symmetry density in spatial data. A synchronized symmetry-identifying spiking artificial neural network enables layering and feedback in the network. The network of the invention can identify symmetry density between sets of data and present a digital logic implementation demonstrating an 8×8 leaky-integrate-and-fire symmetry detector in a field-programmable gate array. The efficiency of spiking neural networks can be harnessed to rapidly identify symmetry in spatial data with applications in image processing, 3D computer vision, and robotics.

The present application relates to a light pulse signal processing system. A to-be-measured signal light source generates a to-be-measured signal light pulse, and the to-be-measured signal light pulse is transmitted to a cylindrical lens. The to-be-measured signal light pulse is converted into a to-be-measured signal light pulse having a spatial angle chirp by the cylindrical lens, and is outputted and is incident into a pair of long mirrors at different angles. The to-be-measured signal light pulse incident at different incident angles is delayed by the pair of long mirrors. A cluster of to-be-measured signal light pulses with a corresponding repetition rate is outputted to a beam combining mirror, and is combined with a cluster of reference light pulses by the beam combining mirror. A light signal analysis device analyzes the combined cluster of light pulses.

The present application relates to a light pulse signal processing system. A to-be-measured signal light source generates a to-be-measured signal light pulse, and the to-be-measured signal light pulse is transmitted to a cylindrical lens. The to-be-measured signal light pulse is converted into a to-be-measured signal light pulse having a spatial angle chirp by the cylindrical lens, and is outputted and is incident into a pair of long mirrors at different angles. The to-be-measured signal light pulse incident at different incident angles is delayed by the pair of long mirrors. A cluster of to-be-measured signal light pulses with a corresponding repetition rate is outputted to a beam combining mirror, and is combined with a cluster of reference light pulses by the beam combining mirror. A light signal analysis device analyzes the combined cluster of light pulses.

Provided are a time and frequency control method and system for optical comb. The method includes: controlling an optical comb measuring system to start and to generate an optical comb; obtaining monitoring data, wherein the monitoring data comprises a working temperature, a mode-locked frequency and a light pump power, wherein the mode-locked frequency comprises a repetition frequency and a carrier envelope phase locked at the end of starting the optical comb measuring system; determining whether an offset of the mode-locked frequency exceeds a self-feedback adjustment range of a hardware adjustment circuit; and in response to any of the repetition frequency and the carrier envelope phase exceeds the self-feedback adjustment range, adjusting the working temperature and the light pump power until the mode-locked frequency returns back into the self-feedback adjustment range.

The invention discloses an optical system for generating arbitrary-order optical vortex arrays and finite optical lattices with defects, comprising a laser, a collimating and beam-expanding system, a spatial light modulator, a 4-f lens system, and an image detector which are disposed according to a light path. After passing through the collimating and beam-expanding system, the linearly-polarized Gaussian beam emitted by the laser is radiated to the spatial light modulator to be modulated in complex amplitude; the first-order diffraction beam of the emergent light generates an arbitrary-order alternating optical vortex array on the back focal plane of the first 2-f lens system, and an adjustable finite optical lattice with defects on the back focal plane of the second 2-f lens system. The topological charge value of each vortex and the spacing between vortices, in the generated arbitrary-order alternating optical vortex array, can be precisely controlled.

The invention discloses an optical system for generating arbitrary-order optical vortex arrays and finite optical lattices with defects, comprising a laser, a collimating and beam-expanding system, a spatial light modulator, a 4-f lens system, and an image detector which are disposed according to a light path. After passing through the collimating and beam-expanding system, the linearly-polarized Gaussian beam emitted by the laser is radiated to the spatial light modulator to be modulated in complex amplitude; the first-order diffraction beam of the emergent light generates an arbitrary-order alternating optical vortex array on the back focal plane of the first 2-f lens system, and an adjustable finite optical lattice with defects on the back focal plane of the second 2-f lens system. The topological charge value of each vortex and the spacing between vortices, in the generated arbitrary-order alternating optical vortex array, can be precisely controlled.

Techniques for detecting pulsed radiation. A CMOS sensor array being irradiated across at least a portion of the array with pulsed radiation is addressed using a rolling shutter operation. The sensor array is read to extract the integrated energy from each sensor element and convert the integrated energy into a pixel value for a pixel in a radiation image. A pulse detection operation is then applied to the radiation image to obtain a pulse repetition frequency of the pulsed radiation. The pulse detection operation includes of extracting a beat signal, calculating a beat frequency and peak to trough ratio from the beat signal, and determining the pulse repetition frequency therefrom. Particularly suited to the technical field of pulsed laser detection. Also relates to a pulse detector for the same.

The present disclosure provides a method for determining a direction to a geodetic target from a geodetic instrument. The method includes emitting an optical pulse from the geodetic target, capturing a first image and a second image of the geodetic target using a camera arranged at the geodetic instrument, obtaining a difference image between the first image and the second image, and determining a direction to the geodetic target from the geodetic instrument based on the position of the optical pulse in the difference image. The method further includes synchronizing the geodetic instrument and the geodetic target for emitting the optical pulse concurrently with the capturing of the first image and nonconcurrently with the capturing of the second image. The present disclosure also provides a geodetic instrument, a geodetic target and a geodetic surveying system.