Nano-Displacement Measurement with Grating Interference

2011 ◽  
Vol 103 ◽  
pp. 35-40 ◽  
Author(s):  
Min Lan Jiang ◽  
Fu Peng Li ◽  
Xiao Dong Wang
Keyword(s):  
Measurement Accuracy ◽  
Laser Interferometer ◽  
Measuring System ◽  
Experimental Result ◽  
High Signal ◽  
Measurement Technology ◽  
Compact Structure ◽  
Signal Contrast ◽  
Grating Interferometer ◽  
Laser Light Source

Nano-Grating measurement technology has been made great development in our country, for its unique advantage which isn’t available in laser interferometer. This paper presents a Nano-grating interferometer displacement measuring system based on double diffraction grating and Semiconductor laser light source, analyzes the error origin of the system in detail and uses error correction and compensation method to improve the measurement accuracy. The experimental result indicated that the system does have stable interferometer, high signal contrast, and easy adjusted optical path, further more the system with a strong environmental adaptability and compact structure. Under 20mm range and 50mm/sec measurement speed, the system’s measuring repeatability is below 30nm.

scholarly journals In-Line Analysis of Diffusion Processes in Micro Channels by Long Distance Raman Photometric Measurement Technology—A Proof of Concept Study

Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 116
Author(s):  
Julian Deuerling ◽  
Shaun Keck ◽  
Inasya Moelyadi ◽  
Jens-Uwe Repke ◽  
Matthias Rädle
Keyword(s):  
Numerical Aperture ◽  
Spot Size ◽  
Measuring System ◽  
Optical Systems ◽  
Measurement Technology ◽  
Long Distance ◽  
Measuring Point ◽  
Acetone Concentration ◽  
Micro Channels ◽  
Set Up

This work presents a novel method for the non-invasive, in-line monitoring of mixing processes in microchannels using the Raman photometric technique. The measuring set-up distinguishes itself from other works in this field by utilizing recent state-of-the-art customized photon multiplier (CPM) detectors, bypassing the use of a spectrometer. This addresses the limiting factor of integration times by achieving measuring rates of 10 ms. The method was validated using the ternary system of toluene–water–acetone. The optical measuring system consists of two functional units: the coaxial Raman probe optimized for excitation at a laser wavelength of 532 nm and the photometric detector centered around the CPMs. The spot size of the focused laser is a defining factor of the spatial resolution of the set-up. The depth of focus is measured at approx. 85 µm with a spot size of approx. 45 µm, while still maintaining a relatively high numerical aperture of 0.42, the latter of which is also critical for coaxial detection of inelastically scattered photons. The working distance in this set-up is 20 mm. The microchannel is a T-junction mixer with a square cross section of 500 by 500 µm, a hydraulic diameter of 500 µm and 70 mm channel length. The extraction of acetone from toluene into water is tracked at an initial concentration of 25% as a function of flow rate and accordingly residence time. The investigated flow rates ranged from 0.1 mL/min to 0.006 mL/min. The residence times from the T-junction to the measuring point varies from 1.5 to 25 s. At 0.006 mL/min a constant acetone concentration of approx. 12.6% was measured, indicating that the mixing process reached the equilibrium of the system at approx. 12.5%. For prototype benchmarking, comparative measurements were carried out with a commercially available Raman spectrometer (RXN1, Kaiser Optical Systems, Ann Arbor, MI, USA). Count rates of the spectrophotometer surpassed those of the spectrometer by at least one order of magnitude at identical target concentrations and optical power output. The experimental data demonstrate the suitability and potential of the new measuring system to detect locally and time-resolved concentration profiles in moving fluids while avoiding external influence.

TDC Implementation Based on Internal Delay Module of FPGA

2013 ◽  
Vol 816-817 ◽  
pp. 1063-1068
Author(s):  
Rou Gang Zhou ◽  
Yun Fei Zhou ◽  
Guang Dou Liu ◽  
Xiao Tu
Keyword(s):  
Nuclear Physics ◽  
Measurement Accuracy ◽  
Laser Interferometer ◽  
Interpolation Method ◽  
Time Measurement ◽  
Clock Signal ◽  
Signal Delay ◽  
Digital Conversion ◽  
Sampling Points ◽  
Stable Performance

Currently the time to digital converter (TDC) integrated in FPGA performs time-to-digital conversion in the carry chain mode and inter-slot offset is caused to be severe by internal wiring in the FPGA. Based on the carry chain interpolation method, this paper proposes the method for using a delay module in FPGA to achieve accurate signal delay. By calculating the phase difference of multi-clock signal between two latch sampling points, the interval between two sampling points was obtained. Experimental results indicate a measurement accuracy of 78ps or 52ps can be reached by precisely collecting time through the delay module in FPGA. Compared to the carry chain interpolation method, this method is significantly advantageous in small inter-slot offset, stable performance and convenient design and can meet the requirement for time measurement or requirement by laser interferometer with a nm-level accuracy in nuclear physics.

scholarly journals Radiant measurement accuracy of micrometeors detected by the Arecibo 430 MHz Dual-Beam Radar

2004 ◽  
Vol 4 (3) ◽  
pp. 621-626 ◽  
Author(s):  
D. Janches ◽  
M. C. Nolan ◽  
M. Sulzer
Keyword(s):  
Measurement Accuracy ◽  
Signal To Noise Ratio ◽  
Side Lobe ◽  
Beam Axis ◽  
Main Beam ◽  
High Signal ◽  
Precise Knowledge ◽  
Dual Beam ◽  
Arecibo Observatory ◽  
Meteoric Material

Abstract. Precise knowledge of the angle between the meteor vector velocity and the radar beam axis is one of the largest source of errors in the Arecibo Observatory (AO) micrometeor observations. In this paper we study ~250 high signal-to-noise ratio (SNR) meteor head-echoes obtained using the dual-beam 430 MHz AO Radar in Puerto Rico, in order to reveal the distribution of this angle. All of these meteors have been detected first by the radar first side lobe, then by the main beam and finally seen in the side lobe again. Using geometrical arguments to calculate the meteor velocity in the plane perpendicular to the beam axis, we find that most of the meteors are travelling within ~15° with respect to the beam axis, in excellent agreement with previous estimates. These results suggest that meteoroids entering the atmosphere at greater angles may deposit their meteoric material at higher altitudes explaining at some level the missing mass inconsistency raised by the comparisson of meteor fluxes derived from satellite and traditional meteor radar observations. They also may be the source of the observed high altitude ions and metalic layers observed by radars and lidars respectively.

Key technologies analysis and design of ultra-clean & ultra-stable spacecraft for gravitational wave detection

2021 ◽  
pp. 2140021
Author(s):  
Kun Chen ◽  
Xiaofeng Zhang ◽  
Tong Guo ◽  
Zhi-Ming Cai ◽  
Keyword(s):  
Gravitational Wave ◽  
Measurement Accuracy ◽  
Laser Interferometer ◽  
Gravitational Interaction ◽  
Thermal Control ◽  
Theory Of Relativity ◽  
Gravitational Wave Detection ◽  
Analysis And Design ◽  
Wave Detection ◽  
Key Technologies

The observation of gravitational wave enables human to explore the origin, formation and evolution of universe governed by the gravitational interaction and the nature of gravity beyond general theory of relativity. The groundbreaking discovery of Gravitational Wave by Laser Interferometer Gravitational-Wave Observatory provides a brand-new observation way. While detecting gravitational wave on ground is limited by noises and test scale, space detection is an optimized alternative to learn rich sources in range of 0.1 mHz–1 Hz. Considering the great significance of space gravitational wave detection, ESA proposed LISA project, CAS also proposed Taiji project. Due to the extremely weak gravitational wave signal and high measurement accuracy requirement, the spaceborne GW observation antenna is accomplished by three spacecrafts constitute isosceles triangle formation intersatellite interferometer. The arm length of the interferometer reaches millions of kilometers between them, and the measurement accuracy reaches pico-meter magnitude. There are many key technologies including pm magnitude space laser interferometer metrology, drag-free control using TM of Gravity Reference Sensor, [Formula: see text]N micro thruster, ultra-clean & ultra-stable spacecraft, etc. This paper focuses on key technologies of the ultra-clean & ultra-stable spacecraft, analyzing the design of mechanical, thermal control and magnetic clean. Moreover, it reports the preliminary results of the technological breakthrough.

The Analysis and Design of a Large Stroke with High-Precision Polarized Laser Interferometer System

2016 ◽  
Vol 679 ◽  
pp. 129-134
Author(s):  
Wan Duo Wu ◽  
Qiang Xian Huang ◽  
Chao Qun Wang ◽  
Ting Ting Wu ◽  
Hong Xie
Keyword(s):  
High Precision ◽  
Measurement Accuracy ◽  
Laser Interferometer ◽  
Laser Interferometry ◽  
Phase Shifting ◽  
Single Frequency ◽  
Rejection Method ◽  
The Common ◽  
Frequency Laser ◽  
Polarization Phase

The technique utilizing single-frequency laser interferometry has very high measurement accuracy, but it has rigorous requirements for optical design which is affected by many factors. In order to achieve single-frequency laser interferometry with large stroke and high precision, the integral layout, the polarization phase shifting technique and the common mode rejection method are adopted to design the length interferometry system. This paper analyzes factors and design requirements which affect measurement accuracy with large stroke. Based on polarization phase shifting technique, the system employs the four-beam-signal detection technique and the common mode rejection method, to make a differential processing of four mutually orthogonal signals. Thus, the influences of zero-drift of intensity and environmental change on system are reduced. Combined with a 200 phase subdivision, the system achieves the resolution with 0.8 nm. Under the VC++ environment, the displacement measurement results are compensated and corrected according to the environmental parameters. Compared with the Renishaw XL-80 laser interferometer, the system has better stability in short term. In the measuring range of 60 mm, the effectiveness of the system is verified.

An Experimental Study on Saturated Liquid Nitrogen’s Boiling Under Transient Pulsed Laser Irradiation

2004 ◽  
Author(s):  
Zhaoyi Dong ◽  
Xiulan Huai ◽  
G.-X. Wang
Keyword(s):  
Temperature Variation ◽  
High Speed ◽  
Short Pulse ◽  
Heating Surface ◽  
High Heat ◽  
Measuring System ◽  
Experimental Result ◽  
High Speed Photography ◽  
High Heat Flux ◽  
Explosive Boiling

Liquid nitrogen (LN2) was widely applied in many areas, but researches on the boiling behavior under the transient high heat flux have not been reported. In this paper, the high power short pulse duration laser was used to heat the saturated LN2 rapidly, and the high-speed photography aided by the spark light system was employed to take series of photos which displayed the process of LN2’s boiling behavior under such conditions. At the same time, a special temperature measuring system was applied to record the temperature variation of the heating surface. The experimental result disclosed that at the earlier stage of laser heating, an explosive boiling would happen within LN2. After the newly-defined changeover time, the conventional boiling behavior would follow. Therefore the changeover time became an important index to distinguish these two kinds of boiling behaviors. By analyzing the temperature variation of the heating surface, it is found that the latent heat released by the crack of bubbles in explosive boiling is an important factor that greatly influences the boiling heat transfer mechanism.

A false aneurysm

2012 ◽  
Vol 126 (S2) ◽  
pp. S14-S15
Author(s):  
D Mitchell ◽  
C Repanos ◽  
W B Coman
Keyword(s):  
Computed Tomography ◽  
Head And Neck ◽  
False Aneurysm ◽  
High Signal ◽  
Thyroid Remnant ◽  
Recurrent Tumour ◽  
Carcinoma Of The Larynx ◽  
Recurrent Squamous Cell Carcinoma ◽  
Signal Contrast ◽  
Salvage Laryngectomy

AbstractObjective:We report a case of a remaining hemi-thyroid following laryngectomy, which was misinterpreted as a pseudoaneurysm.Methods:Case report and comment on this understandable error which is easily avoidable.Results:A 59-year-old man had undergone salvage laryngectomy for recurrent squamous cell carcinoma of the larynx, which had previously been treated with radiotherapy. Three months after his laryngectomy, he presented with a sore neck and subcutaneous collections. Computed tomography revealed a unilateral mass with high signal contrast uptake anterior to the left common carotid artery, which was thought initially to be a carotid pseudoaneurysm. Further investigation, including ultrasonography and a review by the senior head and neck radiologist, demonstrated that this mass was actually the remnant hemi-thyroid preserved at laryngectomy (which is often misshapen compared with a normal hemi-thyroid). The collections were found to be recurrent tumour, and unnecessary further interventions were avoided.Conclusion:Ultrasonography easily distinguishes between a thyroid remnant and a pseudoaneurysm. Furthermore, the opinion of an experienced head and neck radiologist may be vital when interpreting complex post-surgical head and neck radiology.

Effect of Focusing Status on Dimension Measurement Accuracy in Micro Measurement System Based on CCD

2008 ◽  
Vol 392-394 ◽  
pp. 435-438
Author(s):  
Hua Guo ◽  
L. Bai ◽  
J. Liu ◽  
Y. Shi
Keyword(s):  
Measurement System ◽  
Measurement Accuracy ◽  
Experimental Result ◽  
Evaluation Function ◽  
Dimension Measurement ◽  
Special Software ◽  
Institute Of Technology ◽  
Relationship Of ◽  
The Relationship ◽  
Automatic Focusing

This paper adopted the photoelectric micro measurement system based on CCD which was independently developed by Laboratory of Process Automatic and Detection Harbin Institute of Technology to detect dimension of the small precise parts. Under the various focusing status, it was discovered that articulation of focusing has huge effect on the measurement of measurand. According to the characteristics of measurand, we adopted the entropy function as the evaluation function of automatic focusing, developed a special software to process entropy value of the picked images, and obtained the relationship of focusing evaluation function and measurement error through a large number of experiments. The experimental result effectively verified the effect of articulation of focusing on dimension measurement.

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