91 results about "Guide star" patented technology

Various embodiments of the present invention provide methods, systems, apparatus, and computer program products for providing integrated attitude determination and attitude control for slewing of a satellite. In one embodiment a method is provided. The method comprises after receiving a repointing request, selecting a guide star sample comprising one or more guide stars from a guide star catalog; determining current attitude information; selecting and retrieving at least one point spread function (PSF) image from a PSF library; estimating an expected position for at least one guide star, the at least one guide star being one of the guide stars of the guide star sample; acquiring at least one star tracker image; calculating a cross-correlation function (CCF) to determine shifts in position of the at least one guide star compared to the expected position; and determining updated current attitude information based at least in part on the determined shifts in position.

Interferometric focusing (IF), rather than conventional geometric focusing, of excitation light onto a guide-star that is embedded deeply in tissue, increases its fluorescence intensity. The method can extend the depth of wavefront measurement and improve correction inside of tissues because of its ability to suppress both scattering of diffuse light and aberration of ballistic light. The results showed more than two times improvement in SNR and RMS error of the wavefront measurement. Although only ballistic light in the excitation path is corrected, the intensity after wavefront correction increased by 1.5 times. When applying IF to a two-photon microscope with a near infra-red laser, this method would further extend the measurement depth and achieve high SNR for the wavefront sensor.

The invention provides a method for making a guide star database based on output accuracy of star sensors. The method comprises the following steps: S1, subjecting a basic star database to screening of fixed stars; S2, generating the direction of an optical axis of a test sky area covering the whole celestial sphere; S3, converting the celestial system of coordinates of all the fixed stars in a field of view under the direction of the optical axis into a planar system of image plane projection; S4, dividing an image plane into n regions and arraying fixed stars in each region according to m combination modes; S5, carrying out attitude solution on each combination mode of the fixed stars and removing combination modes with great errors in an accuracy index; S6, searching for fixed stars in the whole view field of the image plane and combination modes of the fixed stars forming polygons with great errors in a mismatching accuracy index; and S7, carrying out steps S2 to S6 on each optical axis direction and combining overlapped fixed star points in each sky area so as to obtain the guide star database. According to the invention, the selection process of guide stars in each field range is optimized, so a fixed star combination eventually chosen is guaranteed to meet requirements of average distribution, and attitude calculation precision is guaranteed to be optimal.

The invention relates to a coarse and fine layered, fast and slow combined and active and passive integrated multi-level composite control method for a spacecraft. A layered control idea in a star-load-fast reflection mirror three-level system includes the following steps: 1) fast reflection mirror third-level control: adopting a guiding star sensor as a measuring component, adopting a fast reflection mirror actuator as an executing mechanism, and adopting a PID controller to realize the ultra-high-precision pointing control of a rolling-pitching axis of a fast reflection mirror; 2) load secondary control: adopting a load star sensor, a micrometer gyroscope and an FSM eddy current as the measuring components, adopting an active pointing ultra-static platform (VIPPS) actuator as the executing mechanism, and adopting the PID controller to realize the high-precision pointing control of the load; and 3) star first-level control: adopting a gyroscope, the load star sensor and a VIPPS eddy current as the measuring components, adopting a momentum wheel as the executing mechanism, and adopting the PID controller to realize the coarse pointing control of the star.

Pulsed, coherent light is generated by optical mixing which takes place inside the resonator of a pulsed laser oscillator. One of the beams to be mixed is generated by the pulsed laser, and the other by a distinct, external laser oscillator. If the light from the external oscillator is modulated, that modulation will be transferred onto the light generated by the optical mixing. This enables modulated light at an expanded range of wavelengths. Using sum frequency generation, light for sodium excitation, such as for a guide star, can be generated with the optimal modulation of spectral and temporal properties. If the type of optical mixing is difference frequency generation, optical parametric amplifiers with improved efficiency and beam quality are enabled.

The invention relates to a single-frequency solid-state raman laser, and belongs to the technical field of lasers. The single-frequency solid-state raman laser comprises a pumping source, a coupling lens group, a laser gain medium, a raman crystal, an endoscope M1, an endoscope M3, an endoscope M4, a beam splitter M5 and a temperature control system, wherein the pumping source outputs a pump light; the coupling lens group, the endoscope M1, the laser gain medium, the raman crystal, the endoscope M3, a first FP etalon, a second FP etalon, the endoscope M4 and the beam splitter M5 are arranged along the propagation direction of the pump light; the temperature control system is arranged out of the laser gain medium and the raman crystal, so that stable single-frequency raman laser output with a high-peak power can be achieved; the single-frequency solid-state raman laser can be applied to the fields of a sodium guide star, nonlinear conversion, terahertz generation, laser medical treatment and the like, and has the characteristics of being wide in applicability, compact in structure, good in stability, simple to operate, low in cost, beneficial to industrial production and the like.

A dual-mode sensor uses the active guidance radiation as a “guide star” to generate a wavefront error estimate for the primary optical element in-situ without interfering with the generation of either the active guidance or passive imaging guidance signals. An array of optical focusing elements performs the normal function of spatially encoding an angle of incidence of the active guidance radiation at an entrance pupil onto an active imaging detector. The array also performs an additional function of spatially encoding wavefront tilt deviations emanating from sub-pupils of an exit pupil onto the active imaging detector. A processor processes the electrical signals from the imaging detector in accordance with the respective spatial encodings to generate an active guidance signal and the wavefront error estimate for the primary optical element.

Provided is a 589 nm laser based on raman frequency conversion and laser sum frequency. The 589 nm laser based on the raman frequency conversion and the laser sum frequency is composed of a 1064 nm laser source, a faraday isolator, a half slide, a beam split element, a front cavity mirror of a first raman resonant cavity, a tungstic acid gadolinium potassium crystal, a rear cavity mirror of the first raman resonant cavity, a first filtering lens, a first reflecting mirror, a front cavity mirror of a second raman resonant cavity, a barium nitrate crystal, a rear cavity mirror of the second raman resonant cavity, a second filtering lens, a second reflecting mirror, a nonlinear crystal and a third filtering lens. According to the 589 nm laser based on the raman frequency conversion and the laser sum frequency, the structure is simple, synchronization is easy to realize, the obtained 589 nm can be used for generating sodium guide stars, and the 589 nm laser based on the raman frequency and the laser sum frequency has an important significance in fields of astronomy, national defense and the like.

The invention relates to a space astronomical telescope guiding image stabilization precision testing method and apparatus, belonging to the technical field of photoelectric test. The space astronomical telescope guiding image stabilization precision testing method and apparatus can simulate the input target for testing the space astronomical telescope guiding image stabilization precision. Under the condition of maintaining the space astronomical telescope and the guiding unmovable, the input target is changed, after the image stabilization mechanism completes the normal image stabilization, the position pixel change of the star point dynamic target is calculated according to the star point dynamic target image output by the space astronomical telescope, and the precision of the space astronomical telescope guiding image stabilization can be determined according to the position pixel change, and after the multitime image stabilization of the image stabilization mechanism, the position pixel changes of the star point dynamic target for multiple times can be compared, so that the accuracy of the guiding image stabilization precision testing result can be improved. A reference method and device is provided for the detection of a large-view-field space astronomical telescope system.

The invention discloses a large-visual-field-angle multilayer conjugate self-adaptive optical focusing and microscopic system and method. The light emitted from a laser is incident on three spatial light modulators; the light beam modulated by the spatial light modulators is focused on a scattering medium and then imaged by an imaging lens; the scattering medium is divided into two layers including two conjugate spatial light modulators and a pupil-type spatial light modulator; the two conjugate spatial light modulators are respectively conjugated to the two layers of the scattering medium; and the pupil-type spatial light modulator is arranged among the two conjugate spatial light modulators and the scattering medium. The system and method of the invention use a plurality of guide stars and a plurality of wave-front correctors to correct the aberrations generated at different thicknesses of biological samples at the same time, overcome the disadvantages that the traditional adaptive optical imaging technology has a small viewing angle, a poor non-target point correction effect and a low correction speed, and can realize large-view-field, multi-zone, high-quality focus and high-resolution microscopic imaging.

The invention discloses an astronomical site-selecting instrument guide star device and a working method thereof. The astronomical site-selecting instrument guide star device consists of a lens, a camera and guide star software, wherein an output signal is connected with an equatorial telescope. The astronomical site-selecting instrument guide star device is characterized in that an automatic guide adapter is arranged between the guide star software and the equatorial telescope. The automatic guide adapter is composed of a micro controller and a four-path switch switcher; the camera is used for continuously taking a candid photograph of the target area, and providing the candid photograph to the guide star software through a computer; the guide star software is used for processing the target area image, identifying a target celestial body, and sending the target celestial body position correction amount to the automatic guide adapter which controls the movement of the equatorial telescope. According to the astronomical site-selecting instrument guide star device disclosed by the invention, a star searching function and a star guide function share the same hardware, the device is simple; the target celestial body is automatically identified through an algorithm, and the astronomical site-selecting instrument is assisted to automatically search and point the target celestial body; the correction amount of target celestial body position is calculated in real time through the algorithm, and fed back to the equatorial telescope through the automatic guide adapter, so that the target celestial body is automatically tracked; when a telescope is caused to shake by wind load, the target celestial body also can be tracked.

The invention discloses a splicing method of a space astronomical camera guide star CCD and detection CCD, and aims to solve the technical problem that a back-illuminated guide star CCD and a detection CCD cannot be spliced by using a traditional high-magnification tool microscope imaging method in the prior art. The method sequentially comprises the steps of screening, thermal deformation verification, splicing, initial adjustment, measurement, trimming, fixing and splicing verification. The splicing method can enable the splicing height and collinear error of the guide star CCD and the detection CCD to meet the focal depth requirement of the space astronomical camera, and has the characteristics of simple operation and high splicing precision.

The invention provides a star sensor based star tracking method. The method comprises steps as follows: firstly, angular velocity is estimated and filtered; then, star vectors are predicted and transformed into star points; finally, the star points are extracted from a wave gate with a prediction star point as the center. The method does not depend on attitude information, only the star vector of the star point of each frame is required to be modeled as a whole, and a star point predicted value is obtained on the basis of the star vector and a parameter of a star sensor. The method adopts a simple model and is small in computational amount and easy to implement; different from an existing star tracking method used for calculating angular velocity and recursion based on quaternion differential and adopting a guide star catalogue, the method has the advantages that the angular velocity can be directly computed on the basis of star vector differential for star vector recursion, the star tracking is further realized, and the method can be used as an effective complement to existing star tracking methods.

A compact adaptive optics system for long-range horizontal paths imaging that improves degraded images. The system uses a filter that corresponds to the three colors in a typical color detector element, one or more optic elements, a deformable mirror, and a detector. Focus errors, due to turbulence, in the image recorded by the detector element show up as image shifts in the three distinct color images. The shifts and statistics of these shifts between these simultaneous images are used to create control signals for the deformable mirror resulting in a compact adaptive optic system for horizontal paths without need for a point source located at the distance scene being imaged. Analysis of the relative pixel shifts in various regions of the image provides third order statistics revealing tip/tilt and additional Zernikes modes that are used to control a deformable mirror without the need for a guide star/point-source.

The invention relates to a device and a method for outputting solid-state sum-frequency spectrum-continuous laser light for sodium guide stars, and belongs to the technical field of laser light and astronomy adaptive optics. The device comprises a solid-state 1064nm fundamental-frequency laser device, a solid-state 1319nm fundamental-frequency laser device, a plane high-reflectivity mirror, a beamcombiner, a converging ball lens, a sum-frequency crystal, a collimating ball lens and a beam splitter. The device and the method have the advantages that 589nm sum-frequency laser light can be generated by nonlinear sum frequencies of the solid-state 1064nm fundamental-frequency laser device and the solid-state 1319nm fundamental-frequency laser device, acousto-optic frequency-shifted feedback spectrum-continuous laser light can be simultaneously outputted by at least one of the solid-state 1064nm fundamental-frequency laser device and the solid-state 1319nm fundamental-frequency laser device, accordingly, the 589nm sum-frequency laser light can be driven to become spectrum-continuous sum-frequency laser light, atmosphere sodium atoms at all rates can be sufficiently excited and utilized, high-brightness and efficient sodium guide star return light can be implemented, and requirements of astronomy adaptive optics and application such as white light atom cooling and gas detection canbe met; the integral device is simple, compact and small and is convenient to maintain.

The invention relates to the field of optimal position planning of movable guide stars, and provides a real-time planning method for an optimal position of a movable guide star of an adaptive opticalsystem. The method comprises the steps that: on the basis of sufficient actual measurement atmospheric turbulence profile data accumulation, profile statistical distribution characteristics are obtained through clustering analysis; on the basis of analyzing statistical distribution characteristics, the positions of the guide stars corresponding to different types of profiles are obtained by utilizing a Monte Carlo simulation and optimization algorithm, and the mapping relationship between different turbulence profiles and the optimized positions of the movable guide stars is further obtained through adoption of a machine learning method. The optimal position of the corresponding movable guide star can be quickly calculated according to the actually measured turbulence data in practical application.

A system for assisting in observing a celestial object and providing synthetic guide star generation. A lasing system provides radiation at a frequency at or near 938 nm and radiation at a frequency at or near 1583 nm. The lasing system includes a fiber laser operating between 880 nm and 960 nm and a fiber laser operating between 1524 nm and 1650 nm. A frequency-conversion system mixes the radiation and generates light at a frequency at or near 589 nm. A system directs the light at a frequency at or near 589 nm toward the celestial object and provides synthetic guide star generation.

The invention relates to the technical field of a self-adaptive optical system, and in particular to a sodium guide star laser atmospheric link compensation system. The system comprises a first laserbeam expanding system, a second laser beam expanding system, a dichroic mirror, a deformation mirror, a beam combining and expanding system, a wavefront detection and control system, a reflecting mirror and a calibration light source. According to the system, another laser different from the sodium laser wave length and the sodium laser combining beam are emitted in common-caliber and are converged on an atmospheric layer of a sodium laser transmission path to generate atmospheric back scattering; the atmospheric turbulence distortion is measured and compensated by using a back-scattering image; when the sodium laser emits, the phase distortion opposite to the atmospheric turbulence is carried and counteracted when the laser passes through the atmospheric turbulence so that the sodium laser has flat wavefront distributions, smaller light spot diameter and higher energy density when reaching the sodium layer for convergence, thereby being beneficial to reducing the measurement error ofthe self-adaptive optical system of the ground-based optical telescope and improving the imaging correction effect.

The present invention relates to a solid laser source applicable to the generation of a polychromatic sodium guide star. The device comprises a semiconductor pump light source, a laser oscillator, a second harmonic generation module and a fourth harmonic generation module; the semiconductor pump light source is used for emitting pump light; the pump light is pulsed light; the repetition frequency of the pulsed light ranges from 200 Hz to 1 KHz; the pulse width of the pulsed light ranges from 80 microseconds to 300 microseconds; the laser oscillator is used for oscillating the pump light emitted from the semiconductor pump light source to generate laser of a first wavelength; the second harmonic generation module is used for converting the laser of the first wavelength into laser of a second wavelength, wherein the second wavelength is smaller than the first wavelength and is larger than 330 nm; and the fourth harmonic generation module is used for converting the laser of the second wavelength into 330-nm laser. Since the front part of a single output pulse has high peak power, a nonlinear attenuation effect appears in atmospheric transmission, and as a result, attenuation of the 330-nm laser caused by atmosphere is weakened; and the rear part of the single output pulse has proper average power which is matched with sodium atom density in the sodium layer of the atmosphere, and a large number of photon echoes can be generated.

The invention relates to a triangle recognizing method based on a maximum interior angle hash function. The triangle recognizing method comprises the following steps: 1, constructing a guide star catalog by adopting a star magnitude threshold value method according to a basic star catalog; constructing a triangle by using any three stars, constructing a triangle feature library by taking the maximum interior angle as a basic feature value, carrying out blocking storage according to the magnitude of interior angles, and constructing a hash function based on the maximum interior angle; 2, reading the guide star catalog and a guide feature library; preferentially recognizing brighter fixed stars during recognition, carrying out descending sorting on a star extraction result according to the magnitude of a gray value, constructing observation triangles, computing a related star angular distance, determining the maximum interior angles of the observation triangles, locating a subblock of the feature library by adopting a mode of the hash function, and carrying out the recognition on each observation triangle in the subblock, thus increasing the recognition speed. According to the triangle recognizing method disclosed by the invention, the number of feature triangles is greatly reduced; compared with a traditional triangle recognizing algorithm based on the star angular distance, the comparison times of the star angular distance are reduced, and the recognition speed is increased.