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34results about How to "Improve short-term stability" patented technology

Pattern forming apparatus and pattern forming method, movable member drive system and movable member drive method, exposure apparatus and exposure method, and device manufacturing method

A partial section of an aerial image measuring unit is arranged at a wafer stage and part of the remaining section is arranged at a measurement stage, and the aerial image measuring unit measures an aerial image of a mark formed by a projection optical system. Therefore, for example, when the aerial image measuring unit measures a best focus position of the projection optical system, the measurement can be performed using the position of the wafer stage, at which a partial section of the aerial image measuring unit is arranged, in a direction parallel to an optical axis of the projection optical system as a datum for the best focus position. Accordingly, when exposing an object with illumination light, the position of the wafer stage in the direction parallel to the optical axis is adjusted with high accuracy based on the measurement result of the best focus position.
Owner:NIKON CORP

Porous implant with non-porous threads

A dental implant can comprise a shaft defining a longitudinal axis and having an apical end, a coronal end, and an exterior surface. A portion of the exterior surface can include a porous material. The dental implant can comprise at least one thread, including a non-porous material, having an interior surface and a bone-engaging surface. The interior surface can engage and wind around the exterior surface of the shaft and the bone-engaging surface can extend outwardly from the exterior surface of the shaft. The shaft can include one or more channels configured to communicate a flowable material, stored within the shaft, to the exterior surface. Each channel can include an opening at the exterior surface to release the flowable material. At least one channel can extend between a cavity of the shaft and the exterior surface and can optionally be angled toward the apical end.
Owner:ZIMMER DENTAL INC

Electron Spectroscope With Emission Induced By A Monochromatic Electron Beam

An electroscope system excites a certain area of a surface of a sample to emit electrons with a characteristic distribution of kinetic energies. The analyzed area of the sample is excited by an electron beam produced by a field emission source. A monochromator energy filter for the electron beam is down-stream of the field emission source. The field emission electron source is preferably a Schottky source, and a monochromator energy filter reduces energy dispersion of the electrons of the electron beam to less than 0.2 eV. Microareas of linear dimensions on the order of ten nanometers may be analyzed while observing them. Information on the chemical state of the detected elements present at the surface of the examined microarea of the sample is gathered.
Owner:STMICROELECTRONICS SRL

Method and device for optimizing short-term stability parameters of atomic frequency standard

The invention discloses a method and a device for optimizing short-term stability parameters of an atomic frequency standard, which belong to the field of the atomic frequency standards. The method comprises the steps that a plurality of working parameter points are set; each working parameter point includes a plurality of experiment points which correspond to different parameters to be optimized, each parameter to be optimized corresponds to the plurality of experiment points, and the quantities of the corresponding experiment points are the same, the experiment points corresponding to the same parameter to be optimized are evenly distributed in a value area including two end points of the parameter to be optimized, at most one same experiment point exists in every two working parameter points, and the frequency of each experiment point in all the working parameter points is the same; each parameter to be optimized includes modulation depth, modulation frequency and microwave power; according to each working parameter point, the modulation depth, the modulation frequency and the microwave power are respectively regulated; and frequency discrimination gradient of the atomic frequency standard corresponding to each working parameter point is calculated, and the optimal working parameter point is selected. The method and the device improve the short-term stability of the atomic frequency standard.
Owner:JIANGHAN UNIVERSITY

Andrographolide nano suspension and preparation method thereof

InactiveCN106377500ASmall RDINo significant difference in particle sizeOrganic active ingredientsPowder deliverySolubilityFreeze-drying
The invention belongs to the field of pharmaceutical preparations, and provides an andrographolide nano suspension and a preparation method thereof. The andrographolide has low solubility in water, can be easily excreted by P-gp, has high metabolism rate, and thus, has lower dissolution rate and lower in-vivo bioavailability. In order to enhance the dissolution rate and bioavailability of the drug, a P-gp inhibitor TPGS and an ionic stabilizer SDS are selected to prepare the andrographolide nano suspension by using a medium grinding technique; by using the particle size and distribution as evaluating indicators, a Box-Behnken center combined degisn test optimized preparation technique is utilized to prepare the andrographolide nano suspension; and freeze-drying is used for solidifying. After carrying out the characterization, the research in short-term stability, Caco-2 permeability and in-vitro dissolution, and the in-vivo pharmacokinetic and pharmacodynamic research, the results indicate that the andrographolide nano suspension can increase the dissolution rate of andrographolide and enhance the oral-administration bioavailability and anti-inflammatory action.
Owner:NANJING UNIVERSITY OF TRADITIONAL CHINESE MEDICINE

Moon observation system

The invention discloses a moon observation system which is composed of an astronomical telescope, a ground-based microwave radiometer, a two-dimensional scanning mechanism and a controller. The systemis simple in structure and easy to implement. The ground-based microwave radiometer is installed on a two-dimensional turntable, the pitch angle of the initial position of the moon is obtained by theastronomical telescope, the initial position is calibrated by the controller, and the two-dimensional turntable is controlled to automatically track and scan the track of the moon; the moon brightness temperature signal is reflected by the antenna to enter an antenna feed system and enters a radiation receiver after polarization separation, and a voltage acquisition signal and a variance curve can be obtained in real time after detection and the moon brightness temperature value can also be calculated and thus the test efficiency can be effectively improved. The moon observation system has certain universality and can be applied to moon brightness temperature measurement based on ground-based microwave radiometers of different frequency bands to explore the stability and time distributioncharacteristics of microwave radiation characteristics.
Owner:SHANGHAI SPACEFLIGHT INST OF TT&C & TELECOMM

Method and device for taming rubidium clock by combining common-view and one-way time service of Beidou satellite

InactiveCN113311694ASolve the problem that it cannot be traced back to UTC time and the timing deviation is largeSimple working principleRadio-controlled time-piecesCommunication linkTime signal
The invention discloses a method and device for taming a rubidium clock by combining common view and one-way time service of a Beidou satellite. The device comprises a host provided with a display screen. A main control board is installed in the host, and is provided with a Beidou and time signal measurement module, a data collection processing and display control module, a power module, and a phase locking and rubidium clock module. According to the method, the working principle is simple, the problem that a traditional Beidou cannot trace the UTC time during rubidium clock taming and the time service deviation is large is solved, and meanwhile the problems that the taming period of taming a rubidium clock through a Beidou common-view method is too long, common-view equipment breaks down or a communication link is abnormal, and time difference cannot be obtained for taming are solved.
Owner:北京卓越航导科技有限责任公司

Three-dimensional positioning method based on ultra wide band and air pressure sensor fusion

The invention discloses a three-dimensional positioning method based on fusion of an ultra wide band and an air pressure sensor. The method comprises the following specific steps: performing three-dimensional calculation based on ultra wide band data, obtaining high-precision two-dimensional position information and a height estimation value, and then fusing the height estimation value obtained bycalculation with barometric sensor data to obtain a height value with higher stability. The stability of fused height data is further improved, abnormal values of height estimation in pure ultra-wideband three-dimensional positioning can be suppressed, and the effect is remarkable for the abnormal values of both isolated outliers and continuous outliers. In addition, the requirement for frequentcalibration of two differential air pressure stations in traditional differential height measurement is avoided, and the practicability is further improved.
Owner:ZHENGZHOU LOCARIS ELECTRONICS TECH CO LTD

Device for actively calibrating optical fiber transmission of microwave signals by means of photoelectric oscillator

A device for actively calibrating optical fiber transmission of microwave signals by means of a photoelectric oscillator comprises a central station and a base station, wherein the central station is connected with the base station through a single-mode optical fiber. The device can overcome defects of a traditional electronic method at aspects of bandwidth, weight, size, electromagnetic interference, etc. Furthermore the device overcomes a bottleneck of realizing stable-phase transmission of high-frequency microwave signals through electronic technology.
Owner:INST OF SEMICONDUCTORS - CHINESE ACAD OF SCI

Perpendicular coupling nanometer optical waveguide dual-optical-path chip atomic clock

The invention discloses a perpendicular coupling nanometer optical waveguide dual-optical-path chip atomic clock which comprises a laser, light beams emitted by the laser enter a Y waveguide beam splitter through coupling of a perpendicular coupling optical grating I, one beam of light is output after passing by a phase modulation unit, another beam of light is output after regulation compensation, the two beams of light are output after passing by the perpendicular coupling optical grating I and a perpendicular coupling optical grating II respectively, enter a rubidium atom air chamber after passing by a polarizing film, an attenuation plate and a wave plate and after collimation and focussing and are input into an integrated circuit chip by a subtracter after emitted and converted into electrical signals by a detection unit, and the integrated circuit chip controls the laser and the phase modulation unit. According to the scheme, luminous power fluctuation and frequency fluctuation noise influences can be reduced greatly through dual-optical-path common-mode rejection, the signal-to-noise ratio of a CPT atomic clock is effectively improved, and accordingly, the short period stability of a chip level atomic clock can be improved greatly.
Owner:ZHONGBEI UNIV

High-stability combined region time service frequency generation equipment

The invention discloses high-stability combined region time service frequency generation equipment and aims to provide time service frequency generation equipment with high reliability, high length stability and a wide application range. The invention adopts the technical scheme that a receiving switching unit inputs two paths of selected satellite second signals from different sources into a locking unit to carry out frequency locking, two paths of phase-locked standard frequency signals generated by the locking unit and are respectively output to a signal processing unit A and a signal processing unit B; one path of satellite second signal is also used for carrying out frequency correction on a rubidium clock connected in parallel between a three-selection two-open device and a first analog phase-locked loop PLL_A, and one path of standard frequency signal is generated and transmitted to a signal processing unit C; and the signal processing units carry out signal shaping, amplification, shunting and coding on three paths of standard frequency signals from different sources, the obtained signals are subjected to frequency division, output to a far-end time service unit and are converted into optical signals by an optical-electrical converter, and the optical signals are transmitted to an equipment machine room by one or multiple paths of optical fibers and then are converted into electric signals, and the electric signals are transmitted by an antenna so as to complete a clock time service of a receiving end.
Owner:10TH RES INST OF CETC

Coherent population trapping atomic frequency standard and method for improving short-term stability thereof

The invention discloses a coherent population trapping atomic frequency standard and a method for improving the short-term stability thereof and belongs to the field of atomic frequency standards. The atomic frequency standard comprises a voltage controlled crystal, a polarized excitation unit, a physical unit, a servo loop, a control unit and a system relaxation time detection unit. The polarized excitation unit is used for producing microwave searching signals according to the output frequency of the atomic frequency standards; the physical unit is used for producing optical detecting signals under the effect of the microwave searching signals; the servo loop is used for producing synchronous phase demodulation signals performing synchronous phase demodulation on the optical detecting signals; the control unit is used for producing rectifying voltage affecting the voltage controlled crystal according to the synchronous phase demodulation signals; the system relaxation time detection unit is used for detecting the system relaxation time delta t of the atomic frequency standard; the control unit is further used for performing timing control on an optical switch and the servo loop of the physical unit according to the system relaxation time delta t and controlling the servo loop to perform synchronous phase demodulation on the optical detecting signals produced by the physical signals after controlling the optical switch of the physical unit to switch on for N delta t.
Owner:JIANGHAN UNIVERSITY

End-coupling nano optical waveguide type dual-optical-path chip-scale atomic clock

The invention discloses an end-coupling nano optical waveguide type dual-optical-path chip-scale atomic clock comprising a laser device. An emergent light beam of the laser device enters a Y-waveguide beam splitter through coupling of the end-coupling input end, wherein one light beam is outputted after passing through a phase modulation unit while the other light beam is outputted after adjust compensation, and the two light beams are outputted after passing through a vertical coupling grating II and a vertical coupling grating III respectively and sequentially pass through a polaroid, attenuation slices, a wave plate, collimation and focusing prior to entering an air chamber. After being emergent, the two light beams are converted into electrical signals through a detection unit, the electrical signals are inputted into an integrated circuit chip through a subtracter, and the integrated circuit chip is used for regulating and controlling the laser device and the phase modulation unit. The end-coupling nano optical waveguide type dual-optical-path chip-scale atomic clock has the advantages that the effect of optical power fluctuation and frequency fluctuation noise can be greatly weakened and the signal-to-noise ratio of the CPT atomic clock can be effectively improved through dual-optical-path common-mode rejection, so that short-term stability of the chip-scale atomic clock can be greatly enhanced.
Owner:ZHONGBEI UNIV

Time keeping method for controlling voltage-controlled crystal oscillator based on temperature variation difference

The invention provides a time keeping method for controlling a voltage-controlled crystal oscillator based on a temperature change difference, and the method comprises the steps: collecting the ambient temperature around the crystal oscillator when the crystal oscillator normally operates to track a reference source, and averaging the ambient temperature through accumulation to generate a temperature reference; subtracting the reference temperature from the ambient temperature around the crystal oscillator after the reference source is disconnected, and calculating the temperature deviation around the crystal oscillator; and converting the temperature deviation into the voltage-controlled voltage of the crystal oscillator, and eliminating the frequency deviation of the crystal oscillator at the holding moment. According to the invention, the crystal oscillator is controlled according to the relationship between the temperature deviation and the control quantity of the voltage-controlled crystal oscillator, so that the short-term stability of the crystal oscillator is not obviously reduced, and the retention capability of the output time signal of the crystal oscillator is improved.
Owner:NAT TIME SERVICE CENT CHINESE ACAD OF SCI

System or method for calibrating a radiation detection medium

Methods and devices for calibrating a radiotherapy system are disclosed. The method includes providing a detection medium that responds to exposure to ionizing radiation, and preparing a calibration dose response pattern by exposing predefined regions of the detection medium to different ionizing radiation dose levels. The method also includes measuring responses of the detection medium in the predefined regions to generate a calibration that relates subsequent responses to ionizing radiation dose. Different dose levels are obtained by differentially-shielding portions of the detection medium from the ionizing radiation using, for example, a multi-leaf collimator, a secondary collimator, or an attenuation block. Different dose levels can also be obtained by moving the detection medium between exposures. The disclosed device includes a software routine fixed on a computer-readable medium that is configured to generate a calibration that relates a response of a detection medium to ionizing radiation dose.
Owner:RADIOLOGICAL IMAGING TECH

Method for integrating modulator in feedback laser module

Thisa invention relates to a method for integrating modulator in a feedback laser module characterizing in applying a secondary cooling technology and a photoelectric separation technology to increase the short and long term stability of output optical power, then applyihng a refrigerator to control the temperature and monitor its temperature with a thermistor to adjust and stabilize laser diode source in the applification of WDM, finally introducing passive optical applicances and laser module with the wavelength monitor and control ability to integrate and package a micro-optical demodulator module in a 14-feet butterfly high power feed back laser.
Owner:浙江富春江通信集团有限公司 +1

Broadband wide-range locking method and system for repetition frequency of optical frequency comb

The invention discloses a broadband large-range locking method and system for the repetition frequency of an optical frequency comb, and the method employs a switch phase discrimination scheme, enlarges the dynamic range of error signal recognition, and enables the repetition frequency locking system of the optical frequency comb not to be liable to lose lock. A fast PI controller is used for controlling an EOM in an optical system to achieve high-speed control over the range of dozens of Hz and the MHz bandwidth, and the short-term stability of repetition frequency locking is improved. The slow PI controller is used for controlling the PZT in the optical system to realize medium-speed control of the bandwidth of dozens of kHz in a range of several kHz, and the medium and long-term stability of repetition frequency locking is improved; and the ultra-slow PI controller is used for controlling the temperature of the cavity of the optical system, low-speed control of the bandwidth lower than 1Hz in the range of dozens of kHz is achieved, and the long-term stability of repetition frequency locking is improved.
Owner:西安纳飞光电科技有限公司

Method and device for optimizing short-term stability parameters of atomic frequency standard

The invention discloses a method and device for optimizing short-term stability parameters of an atomic frequency standard, belonging to the field of atomic frequency standards. Method: set multiple working parameter points; each working parameter point includes multiple experimental points and each experimental point corresponds to a different parameter to be optimized, and each parameter to be optimized corresponds to multiple experimental points and the number of corresponding experimental points is the same. The experimental points corresponding to the same parameter to be optimized are evenly distributed in the value range of the parameter to be optimized and include the two ends of the value range. There is at most one experimental point in every two working parameter points that is the same, and each experimental point is in all The number of occurrences in the working parameter points is equal; the parameters to be optimized include modulation depth, modulation frequency and microwave power; adjust the modulation depth, modulation frequency and microwave power according to each working parameter point; calculate the frequency discrimination of the atomic frequency standard corresponding to each working parameter point Slope, select the best working parameter point. The invention improves the short-term stability of the atomic frequency standard.
Owner:JIANGHAN UNIVERSITY

High Stability Combination Area Timing Frequency Generation Equipment

The invention discloses high-stability combined region time service frequency generation equipment and aims to provide time service frequency generation equipment with high reliability, high length stability and a wide application range. The invention adopts the technical scheme that a receiving switching unit inputs two paths of selected satellite second signals from different sources into a locking unit to carry out frequency locking, two paths of phase-locked standard frequency signals generated by the locking unit and are respectively output to a signal processing unit A and a signal processing unit B; one path of satellite second signal is also used for carrying out frequency correction on a rubidium clock connected in parallel between a three-selection two-open device and a first analog phase-locked loop PLL_A, and one path of standard frequency signal is generated and transmitted to a signal processing unit C; and the signal processing units carry out signal shaping, amplification, shunting and coding on three paths of standard frequency signals from different sources, the obtained signals are subjected to frequency division, output to a far-end time service unit and are converted into optical signals by an optical-electrical converter, and the optical signals are transmitted to an equipment machine room by one or multiple paths of optical fibers and then are converted into electric signals, and the electric signals are transmitted by an antenna so as to complete a clock time service of a receiving end.
Owner:10TH RES INST OF CETC

Distributed online monitoring system for underwater sound production of marine mammals

The invention relates to a distributed online monitoring system for underwater sound production of marine mammals, which belongs to the field of sound signal acquisition and processing and comprises acoustic monitoring nodes and ashore terminals which are distributed. The acoustic monitoring node is composed of a hydrophone, an acoustic signal acquisition module, a real-time processing and identification module, a synchronous positioning module and a real-time communication module; the acoustic monitoring nodes are distributed in water and convert acoustic signals into data signals; the real-time processing recognition module recognizes which kind of animal sends out the sound signal in real time, and records the time when the signal is detected; the synchronous positioning module is used for resolving the position of the acoustic monitoring node and realizing clock synchronization of the synchronous positioning module, and the real-time communication module is used for sending working information to a shore terminal; the ashore terminal receives the information of each acoustic monitoring node and realizes the positioning of a sounding mammal; and the system provided by the invention can realize real-time on-line monitoring of underwater sound production of animals in an on-line and long-distance manner.
Owner:THE FIRST INST OF OCEANOGRAPHY SOA +1

Coherent Population Trapped Atomic Frequency Standard and the Method of Improving Its Short-term Stability

The invention discloses a coherent population trapping an atomic frequency standard and a method for improving its short-term stability, belonging to the field of atomic frequency standards. The atomic frequency standard includes: a voltage-controlled crystal oscillator; a linear polarization excitation unit, which is used to generate a microwave search signal according to the output frequency of the voltage-controlled crystal oscillator; a physical unit, which is used to generate an optical detection signal under the action of the microwave search signal; a servo loop, It is used to perform synchronous phase detection on the optical detection signal to generate a synchronous phase detection signal; the control unit is used to generate a correction voltage based on the synchronous phase detection signal to act on the voltage-controlled crystal oscillator; the system relaxation time detection unit is used to detect the atomic frequency standard system Relaxation time Δt; the control unit is also used for timing control of the optical switch and servo loop in the physical unit according to the system relaxation time Δt, after controlling the optical switch in the physical unit to be turned on for N Δt time lengths, control The servo loop performs synchronous phase detection on the optical detection signal generated by the physical unit.
Owner:JIANGHAN UNIVERSITY

A laser frequency stabilization system

The invention discloses a laser frequency stabilization system, belonging to the field of lasers. The system includes: a reference laser, a first electro-optic modulator, a first polarization beam splitter, a first half-wave plate, a Fabry-Perot interferometer, a second half-wave plate, a second polarization beam splitter, a second electro-optic Modulator and laser to be stabilized; Piezoelectric ceramics, the first driving source that outputs the first reference signal to the first electro-optic modulator, the first photoelectric unit that is arranged on the reflected optical path of the first polarization beam splitter prism, and the first oscillation signal A first mixer for mixing with the frequency signal output by the first photoelectric unit, a driving source for generating a voltage signal according to the signal output by the first mixer; a second driving source for outputting a second reference signal to the second electro-optical modulator The source is a second photoelectric unit arranged on the reflected optical path of the second polarization beam splitter, and a second mixer for mixing the second oscillation signal and the frequency signal output by the second photoelectric unit.
Owner:JIANGHAN UNIVERSITY
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