45 results about "Rayleigh length" patented technology

The invention discloses an optical nonlinearity measuring device and a measuring method for nonlinearity thick photonics materials, and belongs to the technical field of nonlinearity photonics materials and nonlinearity photonics measurement. Tophat type laser pulses serve as probe light, a reference standard sample with the suitable thickness is selected according to the thickness of a sample to be measured, the reference standard sample and the sample to be measured are subjected to Z scanning measurement respectively, energy of incident light is adjusted to obtain the same normalization transmittance peak-to-valley values, and a nonlinearity refraction coefficient of the sample to be measured is obtained by data processing. The optical nonlinearity measuring device and the measuring method for nonlinearity thick photonics materials are suitable for nonlinearity photonics materials of which the thicknesses exceed a Rayleigh length.

A distributed resonator laser system using retro-reflecting elements, in which spatially separated retroreflecting elements define respectively a power transmitting and a power receiving unit. The retroreflectors have no point of inversion, so that an incident beam is reflected back along a path essentially coincident with that of the incident beam. This enables the distributed laser to operate with the beams in a co-linear mode, instead of the ring mode described in the prior art. This feature allows the simple inclusion of elements having optical power within the distributed cavity, enabling such functions as focusing / defocusing, increasing the field of view of the system, and changing the Rayleigh length of the beam. The optical system can advantageously be constructed as a pupil imaging system, with the advantage that optical components, such as the gain medium or a photo-voltaic converter, can be positioned at such a pupil without physical limitations.

This is an efficient nuclear decontamination device using the laser light to remove the radioactive substance from the polluted parts of the radioactive object sample in the nuclear devices and facilities. In the nuclear decontamination device, the laser source (11) of the oscillator and amplifier system is used to irradiate on the surface (20) of the decontamination object sample through the condensing optics (12). The controller (13) optimizes the laser energy density on the surface by using both of the laser sources (11) and condensing optics (12). In the optimization, the energy density per pulse is controlled by optics system (12) of condensing within the range of 1 J / cm2-1000 J / cm2 in the surface of the decontamination object sample (20). Minimum beam spot size and Rayleigh length are chosen to keep the energy density per pulse in the above-mentioned range of the energy density.

An ignition facilitated electrodeless sealed high intensity illumination device is configured to receive a laser beam from a continuous wave (CW) laser light source. A sealed chamber is configured to contain an ionizable medium. The chamber has an ingress window disposed within a wall of a chamber interior surface configured to admit the laser beam into the chamber, a plasma sustaining region, and a high intensity light egress window configured to emit high intensity light from the chamber. The CW laser beam is producible by a CW laser below 250 Watts configured to produce a wavelength below 1100 nm. The device is configured to focus the laser beam to a full width at half maximum (FWHM) beam waist of 1-15 microns2 and a Rayleigh length of 6 microns or less, and the plasma is configured to be ignited by the CW laser beam.

A mode-locked solid-state laser apparatus having a resonator which includes a solid-state laser medium, a saturable absorption mirror, and a negative group dispersion element therein, in which the solid-state laser medium and the saturable absorption mirror are disposed at a distance not greater than twice a Rayleigh length which is determined by the beam radius of oscillation light formed at the saturable absorption mirror. The apparatus further includes a dichroic mirror in the resonator that reflects excitation light inputted from a direction crossing the optical axis of the resonator toward the solid-state laser medium and transmits oscillation light.

The invention discloses a method for determining the laser defocusing amount in the femtosecond laser polishing process of an optical element, which belongs to the technical field of mechanical precision manufacturing engineering, and comprises the following steps of: outputting laser wavelength and focusing spot radius by using a femtosecond laser, and calculating Rayleigh length of a light beam;calculating the energy density when the laser reaches the surface of the material by utilizing the output pulse energy of the laser to focus the spot radius and the defocusing amount; calculating theablation depth of the surface of the energy material by using a femtosecond laser ablation rate mathematical model; solving the ablation depth of the femtosecond laser to the material under differentdefocusing amounts according to the laser ablation rate mathematical model; measuring the average value of the surface of the to-be-polished optical element, and determining the optimal polishing defocusing amount by substituting the height difference of the wave crest and the wave trough into calculation. The defocusing amount of femtosecond laser polishing can be rapidly, efficiently and accurately determined, the cost is low, the efficiency is high, and the accuracy is high.

A thermal lens detection apparatus comprising: i) an optical cell for containing at least one target analyte present in a carrier liquid, ii) a probe beam having a pre-determined wavelength, iii) an excitation beam having a pre-determined wavelength shorter than that of the probe beam and a Rayleigh length approximately equal to the radius of said optical cell, the beam axis of said probe beam and the beam axis of said excitation beam being at an angle to each other but both the probe beam and excitation beam being focusable so that their beams overlap in the interior portion of the optical cell, iv) a signal photo-detector for receiving at least a portion of said probe beam signal after its passage through said optical cell, and iv) an optical cutoff filter which blocks the excitation beam from impinging on said signal photo-detector.

The invention discloses a system and method for generating teraHertz waves by using flight focusing, wherein the system for generating the teraHertz waves by using the flight focusing comprises a chirped signal generating device and a flight focusing device, wherein the chirped signal generating device is used for generating chirped laser pulse; the flight focusing device uses a diffraction element for focusing the chirped laser pulse so as to stimulate and generate air plasma and to further generate the teraHertz waves. The chirped laser pulse and the diffraction element are combined by the system and method for generating teraHertz waves by using flight focusing provided by the invention, so that the moving speed of the peak value intensity of the laser focus point region is controlled;the propagation of the laser light beams in the focusing regions can be controlled; in addition, the propagation length is many times of the Rayleigh length. Compared with the existing method for generating the teraHertz waves by the air, the method provided by the invention has the advantages that the intensity of the teraHertz waves generated by the method is greatly enhanced; the blank in the technical field of the existing high-intensity teraHertz wave generation is filled; high scientific research and practical application values are realized.

A distributed resonator laser system using retro-reflecting elements, in which spatially separated retroreflecting elements define respectively a power transmitting and a power receiving unit. The retroreflectors have no point of inversion, so that an incident beam is reflected back along a path essentially coincident with that of the incident beam. This enables the distributed laser to operate with the beams in a co-linear mode, instead of the ring mode described in the prior art. This feature allows the simple inclusion of elements having optical power within the distributed cavity, enabling such functions as focusing / defocusing, increasing the field of view of the system, and changing the Rayleigh length of the beam. The optical system can advantageously be constructed as a pupil imaging system, with the advantage that optical components, such as the gain medium or a photo-voltaic converter, can be positioned at such a pupil without physical limitations.

A piercing processing method and a laser processing machine capable of carrying out a piercing processing on a thick plate in short time are provided. It is a processing method for carrying out a piercing processing on a metallic material by laser beams with wavelengths in 1 μm band, where the piercing processing is carried out by maintaining a range of 8≦Zr / d≦12 when a condensed beam diameter of the laser beams is set to be d and a Rayleigh length of the laser beams is set to be Zr. At that time, a focal position of the laser beams is set to be on a surface of a workpiece or an external of the workpiece. Then, a beam profile of the laser beams is such that the laser beams of a single mode are converted into a bowler hat shape by a beam quality tunable device.

Apparatus for laser processing a material (11), which apparatus comprises an optical fibre (2), at least one squeezing mechanism (3), and a lens (4), wherein: the optical fibre (2) is a multimode optical fibre; the optical fibre (2) is such that laser radiation (13) is able to propagate along the optical fibre (2) in a first optical mode (21) and in a second optical mode (22); the squeezing mechanism (3) comprises at least one periodic surface (6) defined by a pitch (7); and the periodic surface (6) is located adjacent to the optical fibre (2); and the apparatus is characterized in that: the pitch (7) couples the first optical mode (21) and the second optical mode C(22) together; the first optical mode (21) is defined by a first mode order (24), and the second optical mode (22) is defined by a second O mode order (25) which is higher than the first mode order (24); the squeezing mechanism (3) is configured to squeeze the periodic surface (6) and the optical fibre (2) together with a squeezing force (12), thereby coupling the first optical mode (21) to the second optical mode (22); the lens (4) is defined by a front focal plane (14) and a rear focal plane (15); the first optical mode (21) is defined by a Rayleigh length (217); and the lens (4) is located within two of the Rayleigh lengths (217) from the distal end (16) of the optical fibre (2).

The invention relates to an ultraviolet nanosecond laser direct-writing micro-fluidic chip preparation system and method. The micro-fluidic chip preparation system comprises an ultraviolet nanosecondlaser, an electrically controlled diaphragm, a laser beam expander, a light beam converter, a light beam rotator, a lens, a dichroscope, a laser cutting head, a three-dimensional moving platform and acontrol device. The light beam converter composed of a binary phase plate and an axicon is adopted, a smooth high-quality zero-order and large-Rayleigh-length Bessel laser can be effectively generated, a first-order aperture outside zero-order light in the center of a zero-order Bessel light beam is effectively erased, and therefore the processing quality of the Bessel light beam is effectively improved. Processing of a laser direct-writing micro-fluidic chip with a high vertical depth ratio can be achieved, the laser processing efficiency is improved, and the system is simple in structure, convenient to operate and capable of being used for high-efficiency and high-quality processing of micro-fluidic chips in various schemes.

The invention relates to a pin-like light beam generation device and a deep hole laser machining device and method, and belongs to the technical field of laser machining. The problems that in the prior art, the Rayleigh length of a light beam generated by focusing a laser through a lens is small, and the precision and efficiency of deep hole laser machining are low are solved. The pin-like light beam generation device comprises a collimation assembly used for collimating a Gaussian light beam generated by a laser device, and a phase mask plate used for carrying out cubic phase front regulation and control on the collimated Gaussian light beam to obtain a pin-like light beam. According to the device, the pin-like light beam with a large Rayleigh length can be obtained, and the precision and efficiency of deep hole laser machining are improved to a great extent.

A mode-locking solid-state laser apparatus is a soliton-type mode-locking solid-state laser apparatus, having a solid-state laser medium, a saturable absorption mirror and a negative group velocity dispersion element in a resonator, wherein the solid-state laser medium and he absorption mirror are disposed at a distance not greater than twice a Rayleigh length. Then, the absorption modulation depth Delta R of the saturable absorption mirror is set to a value not less than 0.4%, and the absolute value lDl of a total intracavity dispersion amount when light having a predetermined wavelength makes one round trip in the resonator, which is represented by the following mathematic expression (1), is set within a pulse bandwidth in which operation modes other than a fundamental period soliton pulse can be suppressed by the saturable absorption mirror.

The invention provides a laser processing device and system, and relates to the technical field of underwater laser processing. The laser processing device comprises a circular polarizer, a collimation assembly, a phase modulation element and a focusing lens. The circular polarizer, the collimation assembly, the phase modulation element and the focusing lens are sequentially arranged in the transmission direction of the laser beam; the circular polarizer is used for converting a to-be-processed light beam into circularly polarized light; the collimation assembly is used for collimating the circularly polarized light to obtain a collimated light beam; the phase modulation element is used for performing phase modulation on the collimated light beam to obtain a modulated light beam; the focusing lens is used for focusing the modulated light beam to obtain a target light beam, and the target light beam is used for machining an underwater to-be-machined object. In the design, the Rayleigh length of the target light beam is longer, and the target light beam has good water turbulence resistance, so that phase disturbance caused by water turbulence can be effectively reduced, the underwater laser processing quality is ensured, and the underwater laser processing efficiency is improved.

A system for correcting the wavefront of a laser beam includes a beamsplitter for splitting off a fraction of the laser beam to be used as a diagnostic beam, a focusing element for bringing the diagnostic beam to a focus, a measurement subsystem for measuring sizes of the diagnostic beam at upstream and / or downstream locations with respect to a nominal location of the focus, and at least one adaptive optic, located upstream from the beamsplitter, for correcting the wavefront of the laser beam at least partly based on the measured sizes of the diagnostic beam at the upstream and / or downstream locations. The upstream and downstream locations correspond to mid-field locations in the laser beam as imaged by the focusing element. The system takes advantage of the sensitivity of the laser beam size to a waist location shift being greatest at one Rayleigh length from the nominal waist location.

The invention relates to the technical field of silicon nitride ceramic trepanning, in particular to a femtosecond laser trepanning method and device for silicon nitride ceramic. The invention discloses a femtosecond laser trepanning method for silicon nitride ceramics. The method comprises the following steps: pre-preparation work; the fixed silicon nitride ceramic substrate is holed based on a three-stage scanning strategy, and the effective depth of field is constrained by the Rayleigh length; the three-stage scanning strategy is as follows: S1, low-energy grooving; s2, high-energy multiple cutting; s3, performing low-energy stroke trimming; annular feeding is executed according to a preset two-dimensional hole site vector path during scanning in each stage of the three-stage machining process. According to the method, high-quality and high-controllability micropore array processing can be realized on the silicon nitride ceramic substrate, and the method has wide engineering application value.

A mode-locking solid-state laser apparatus is a soliton-type mode-locking solid-state laser apparatus, having a solid-state laser medium, a saturable absorption mirror and a negative group velocity dispersion element in a resonator, wherein the solid-state laser medium and he absorption mirror are disposed at a distance not greater than twice a Rayleigh length. Then, the absorption modulation depth Delta R of the saturable absorption mirror is set to a value not less than 0.4%, and the absolute value lDl of a total intracavity dispersion amount when light having a predetermined wavelength makes one round trip in the resonator, which is represented by the following mathematic expression (1), is set within a pulse bandwidth in which operation modes other than a fundamental period soliton pulse can be suppressed by the saturable absorption mirror.

The invention relates to a mode-locked solid-state laser apparatus having a resonator which includes a solid-state laser medium, a saturable absorption mirror, and a negative group dispersion element therein, in which the solid-state laser medium and the saturable absorption mirror are disposed at a distance not greater than twice a Rayleigh length which is determined by the beam radius of oscillation light formed at the saturable absorption mirror. The apparatus further includes a dichroic mirror in the resonator that reflects excitation light inputted from a direction crossing the optical axis of the resonator toward the solid-state laser medium and transmits oscillation light.

The invention relates to a thick plate myriawatt-level fiber laser perforation method, which comprises a conventional cutting machine mounted on a cutting platform, and comprises the following steps: S1, an optical control module is added on the conventional cutting, and the optical control module comprises a perforation focus lens module and a cutting focus lens module; s2, a workpiece to be cut is placed on a cutting platform, and a punching focus lens module is selected; s3, setting hole parameters of the punching focus lens module, such as laser power, pulse form and light emitting time; s4, a punching focus lens module is opened, and punching is carried out; and S5, a control system of a conventional cutting machine is used, a punching focus lens module is switched, and cutting is carried out. The device has the advantages that the optical module is added, the focusing diameter and the Rayleigh length of a laser beam are controlled, and the high-power laser drilling quality and efficiency are improved.

Disclosed is a waveguide polarizing optical device, including a first waveguide polarizer (6), a section of a second optical waveguide (31) and a second thin-plate polarizer (52) having a physical thickness T and a refractive index n, the second thin-plate polarizer (52) being disposed on the optical path between a waveguide end (8) of the first polarizer (6) and one end (32) of the second optical waveguide (31), the physical distance d between the waveguide end (8) of the first polarizer (6) and the end (32) of the second optical waveguide (31) being less than or equal to twice the Rayleigh length and the physical thickness T of the second polarizer (52) being less than or equal to the physical distance d.

The invention relates to the technical field of laser cutting, in particular to a parameter self-adaption method and system for laser cutting, and the method comprises the steps: constructing a solution space containing laser power and cutting speed, and initializing a plurality of nectar sources of an artificial bee colony algorithm; the follow-up error in the laser cutting process is collected in real time, the risk index of the current working condition is calculated according to the Rayleigh length, the size of the follow-up error and the change rate, and then the search step length and the fitness weight are determined; generating a new solution in the neighborhood of the nectar source by using the search step size, and calculating a fitness function value of the new solution according to the fitness weight; and the nectar sources are updated according to a greedy selection strategy, the nectar source with the highest fitness function value is selected as the optimal control parameter after iteration is completed, and the laser power and the cutting speed are adjusted according to the optimal control parameter. According to the technical scheme, the stability of a cutting energy field can be maintained, and the quality defects of slag adhering, incomplete cutting and the like are effectively overcome.

There are many de-convolution algorithms (using Fourier transforms for example) that allow calculation of ki and Ri given the image values of I (xi, yi). The problem arises when the PSF's are closer together than a Rayleigh length: the number of artifact images (false images) available from a typical de-convolution algorithm may then be very large. Thus the overall probability of a false de-convolved image also is very large. This is the ambiguous image problem first identified by Toraldo di Francia (Reference 1). We solve this problem by finding the maximum in the Laplacian (i.e., take largest second derivative) along the isophote ridges on which the first derivative=0 (on a circle around the maximum). To correctly use this algorithm we must apply it to an off axis telescope.

A lidar system adapted to perform a wind measurement related to a focal zone (ZF) of a laser beam (F) emitted by the system. The system comprises time control means (40) for the laser beam adapted to place this laser beam in the form of successive laser pulses such that each laser pulse has a single length greater than or equal to twice the Rayleigh length (lR) divided by the propagation velocity of the laser pulse in the atmosphere and less than 20 [mu] s. Advantageously, the individual length of each laser pulse is between 0.2 and 5 times the coherence time of the effective atmosphere in the focal region. The lidar system provides a better spectral CNR ratio at an equivalent spatial resolution than the spectral CNR ratio of a system at a current technology development level.

The invention provides a light beam shaping device and an optical system, the light beam shaping device comprises a first optical module, and the first optical module comprises a light splitting unit, a delay unit and an imaging unit; the light splitting unit is used for splitting the first light beam into N first split light beams in a first plane and emitting the first split light beams in parallel; the delay unit is arranged on the light emitting side of the light splitting unit and used for enabling the first split light beams to be emitted through different propagation lengths, and the minimum delay value between the emitted first split light beams is larger than or equal to the coherence length of the first light beams; the imaging unit is arranged on the light emitting side of the delay unit and used for imaging the first split light beams emitted through the different propagation lengths, the difference of the longitudinal positions of real images of the first split light beams is smaller than one time of the Rayleigh length, and the transverse positions of the real images of the first split light beams are overlapped. Through the light beam shaping device and the optical system provided by the invention, the problem that the existing Gaussian laser beam is not suitable for thin film processing is particularly solved.

The application relates to a picosecond laser with high beam quality, comprising: a pump source for providing pump energy to an amplification crystal; a laser oscillator for providing high-beam-quality signal light to the amplification crystal; the amplification crystal for realizing amplification of signal light power; a pump light shaping system, which comprises a first lens group formed by a first plano-convex lens and a second plano-convex lens and a third plano-convex lens arranged at intervals with the first lens group, the pump light is subjected to quasi-collimation processing through the first lens group, and then is focused through the third plano-convex lens arranged at intervals, so that the Rayleigh length of the focused pump light completely falls in the amplification crystal; and a signal light shaping system, which comprises a fourth plano-convex lens arranged on the upstream of the light path of the amplification crystal and a second lens group formed by a fifth plano-convex lens and a first plano-concave lens, the signal light is focused through the fourth plano-convex lens, and then is subjected to expansion collimation through the second lens group, so that the Rayleigh length of the signal light completely falls in the amplification crystal, the pump light and the signal light are in a uniformly distributed state in the amplification crystal, the amplification crystal generates uniform heat distribution, the thermal lens effect is eliminated, the occurrence probability of the thermal birefringence effect and the thermal distortion effect is reduced, and the amplification efficiency of the light beam and the quality of the output light beam are greatly improved.

A frequency converter for converting a single-mode input beam at a fundamental frequency to an output beam at a converted frequency is configured with a plurality of phase-separated optical components defining a resonant cavity. The optical assembly shapes the input beam to have at least one beam waist within the cavity. The frequency converter also includes a nonlinear crystal located within the resonator in a diverging beam having a Rayleigh length less than the round-trip length of the resonator such that the center of the crystal is aligned with the beam waist along the beam path. separate, or the nonlinear crystal is located in a collimated beam whose Rayleigh length is greater than the resonator round-trip length.