A high-resolution Raman gain spectrometer for spectral lineshape studies

1991 ◽  
Vol 69 (5) ◽  
pp. 558-563 ◽  
Author(s):  
J. W. Forsman ◽  
P. M. Sinclair ◽  
P. Duggan ◽  
J. R. Drummond ◽  
A. D. May
Keyword(s):  
High Resolution ◽  
Continuous Wave ◽  
Signal To Noise Ratio ◽  
Integration Time ◽  
Raman Gain ◽  
Spectral Lineshape ◽  
Spectral Profiles ◽  
And Performance

The details and performance of a shot-noise-limited high-resolution (≤ 2 MHz) Raman gain spectrometer are discussed and compared to a "standard" continuous wave (cw) spectrometer. For a single pass cell and 1 s integration time, a signal-to-noise ratio greater than 1000 is obtained for the Q(2) line of D2 at pressures above a few atmospheres. The quality of the spectrometer for the determination of spectral profiles is demonstrated by examining the Dicke narrowing of the line.

scholarly journals High-speed high-resolution laser diode-based photoacoustic microscopy for in vivo microvasculature imaging

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Xiufeng Li ◽  
Victor T C Tsang ◽  
Lei Kang ◽  
Yan Zhang ◽  
Terence T W Wong
Keyword(s):  
High Resolution ◽  
High Speed ◽  
High Performance ◽  
Continuous Wave ◽  
Signal To Noise Ratio ◽  
Cost Effective ◽  
High Signal ◽  
Photoacoustic Microscopy ◽  
Mouse Ear

AbstractLaser diodes (LDs) have been considered as cost-effective and compact excitation sources to overcome the requirement of costly and bulky pulsed laser sources that are commonly used in photoacoustic microscopy (PAM). However, the spatial resolution and/or imaging speed of previously reported LD-based PAM systems have not been optimized simultaneously. In this paper, we developed a high-speed and high-resolution LD-based PAM system using a continuous wave LD, operating at a pulsed mode, with a repetition rate of 30 kHz, as an excitation source. A hybrid scanning mechanism that synchronizes a one-dimensional galvanometer mirror and a two-dimensional motorized stage is applied to achieve a fast imaging capability without signal averaging due to the high signal-to-noise ratio. By optimizing the optical system, a high lateral resolution of 4.8 μm has been achieved. In vivo microvasculature imaging of a mouse ear has been demonstrated to show the high performance of our LD-based PAM system.

scholarly journals PENENTUAN PRIORITAS PENINGKATAN KUALITAS JASA DENGAN MENGGUNAKAN METODE IMPORTANCE-PERFORMANCE ANALYSIS (IPA) DAN INDEKS POTENTIAL GAIN CUSTOMER VALUE (PGCV)

2021 ◽  
Vol 23 (2) ◽  
pp. 352
Author(s):  
Nur Hakim Arifianto ◽  
Sauptika Kancana ◽  
Adi Soeprapto
Keyword(s):  
Customer Value ◽  
Sampling Methods ◽  
Spare Parts ◽  
Quality Of Services ◽  
Repair Shop ◽  
Potential Gain ◽  
Margin Of Error ◽  
And Performance

The purpose of the research is (1) analyzing the level of conformity betweenexpectations (importance) customer and performance (performance) of the company against the quality of services provided by Yamaha Motorcycle repair shop (2) Determine the priority Quality improvement based on the level of conformity and index of Potential Gain Customer Value (PGCV) to improve the quality of services provided by Yamaha Motorcycle repair shop. The population in this research is a customer Yamaha Motorcycle repair shop Demangan Yogyakarta for approximately arround 2 months April 2019 till June 2019.Determination of the number of samples will be determined by the level of Confidance 95% and margin of error is 10% then obtained the number of samples as many as 98 people. The sampling techniques used in this study were based on Non Probabiliy Sampling methods using the Accidental Sampling approach.The results showed that (1) the level of conformity between expectations (importance) of the customer and performance (performance) of the company against the quality of services provided by the Yamaha Motorcycle repair shop Demangan Yogyakarta has an average level of conformity Below 100% of which is 88.30%. 88.30% means the company lacks or does not fulfill what is considered important by the customer and the service has not beensatisfactory; (2) Priority of improvement of service quality (top priority in the Quadrant A IPA diagram with index PGCV) namely: 1) Workshop Yamaha new source Motor Demangan has a complete spare parts, 2) equipment used Yamaha Workshop new source Demangan complete, 3) Employees Yamaha Motorcycle repairshop Demangan tell the customers when the service is certainly motorbike will be delivered, 4) Employees Yamaha Motorcycle repair shop Demangan always ready in responding to customer demand, 5) Mechanics workshop Yamaha Motorcycle repair shop Demangan fast In servicing motorcycles, 6) Employees Yamaha Motorcycle repair shop Demangan always able to answer questions related to Yamaha motorcycles, 7) Employees Yamaha Motorcycle repair shop Demangan always prioritize the expectations of customers.

scholarly journals Deformation in Nisyros volcano (Greece) using differential radar interferometry

2001 ◽  
Vol 34 (4) ◽  
pp. 1587 ◽  
Author(s):  
I. S. PARCHARIDIS ◽  
E. LAGIOS
Keyword(s):  
High Resolution ◽  
Aegean Sea ◽  
Radar Interferometry ◽  
Differential Gps ◽  
Interferometric Phase ◽  
Differential Radar Interferometry ◽  
Differential Interferogram ◽  
Gps Observations

Nisyros Volcano located at the southeastern Aegean Sea (Greece) has recently shown (1996-97) a high seismic activity, associated with a significant deformation has determined by DGPS measurements. The determination of the overall deformation of the island was also attempted by Differential Radar Interferometry (DInSAR). The DInSAR analysis has been applied using the ERS-2 satellite data, covering the period 1996-1999. The removal of the interferometric phase related to the topography has been done using an external high resolution DEM. Two areas of the island show a good coherence, the southwestern and the eastern part. Almost two interferometric fringes were respectively recognized and evaluated. These two zones coincide with the main tectonic fractures of the island. The time separation and resolution, which consist important factors, for the extraction of the effective information and the quality of the finally produced differential interferogram, seem however that influence very slight its accuracy. The deformation outlined by the interferogram is compatible with the existing differential GPS observations.

Determining the Quality of Compression in High Resolution Satellite Images Using Different Compression Methods

2015 ◽  
Vol 20 ◽  
pp. 202-217
Author(s):  
S. Sanjith ◽  
R. Ganesan
Keyword(s):  
High Resolution ◽  
Image Quality ◽  
Satellite Images ◽  
Signal To Noise Ratio ◽  
Joint Photographic Expert Group ◽  
Expert Group ◽  
Signal To Noise ◽  
High Resolution Satellite Images ◽  
Noise Ratio

Measuring the quality of image is very complex and hard process since the opinion of the humans are affected by physical and psychological parameters. So many techniques are invented and proposed for image quality analysis but none of the methods suits best for it. Assessment of image quality plays an important role in image processing. In this paper we present the experimental results by comparing the quality of different satellite images (ALOS, RapidEye, SPOT4, SPOT5, SPOT6, SPOTMap) after compression using four different compression methods namely Joint Photographic Expert Group (JPEG), Embedded Zero tree Wavelet (EZW), Set Partitioning in Hierarchical Tree (SPIHT), Joint Photographic Expert Group – 2000 (JPEG 2000). The Mean Square Error (MSE), Signal to Noise Ratio (SNR) and Peak Signal to Noise Ratio (PSNR) values are calculated to determine the quality of the high resolution satellite images after compression.

scholarly journals The GRAVITY fringe tracker

2019 ◽  
Vol 624 ◽  
pp. A99 ◽  
Author(s):  
S. Lacour ◽  
R. Dembet ◽  
R. Abuter ◽  
P. Fédou ◽  
G. Perrin ◽  
...  
Keyword(s):  
Group Delay ◽  
Signal To Noise Ratio ◽  
Phase Delay ◽  
Integration Time ◽  
Reference Source ◽  
Path Delay ◽  
Control Loop ◽  
Auto Regressive ◽  
Fringe Tracking

Context. The GRAVITY instrument was commissioned on the VLTI in 2016 and is now available to the astronomical community. It is the first optical interferometer capable of observing sources as faint as magnitude 19 in K band. This is possible through the fringe tracker, which compensates the differential piston based on measurements of a brighter off-axis astronomical reference source. Aims. The goal of this paper is to describe the main developments made in the context of the GRAVITY fringe tracker. This could serve as basis for future fringe-tracking systems. Methods. The paper therefore covers all aspects of the fringe tracker, from hardware to control software and on-sky observations. Special emphasis is placed on the interaction between the group-delay controller and the phase-delay controller. The group-delay control loop is a simple but robust integrator. The phase-delay controller is a state-space control loop based on an auto-regressive representation of the atmospheric and vibrational perturbations. A Kalman filter provides the best possible determination of the state of the system. Results. The fringe tracker shows good tracking performance on sources with coherent K magnitudes of 11 on the Unit Telescopes (UTs) and 9.5 on the Auxiliary Telescopes (ATs). It can track fringes with a signal-to-noise ratio of 1.5 per detector integration time, limited by photon and background noises. During good seeing conditions, the optical path delay residuals on the ATs can be as low as 75 nm root mean square. The performance is limited to around 250 nm on the UTs because of structural vibrations.

scholarly journals Homodyne Spectroscopy with Broadband Terahertz Power Detector Based on 90-nm Silicon CMOS Transistor

2021 ◽  
Vol 11 (1) ◽  
pp. 412
Author(s):  
Kęstutis Ikamas ◽  
Dmytro B. But ◽  
Alvydas Lisauskas
Keyword(s):  
Continuous Wave ◽  
Detection System ◽  
Signal To Noise Ratio ◽  
High Sensitivity ◽  
Complementary Metal Oxide Semiconductor ◽  
Oxide Semiconductor ◽  
Integration Time ◽  
Thz Spectroscopy ◽  
Homodyne Detection ◽  
Cmos Transistor

Over the last two decades, photomixer-based continuous wave systems developed into versatile and practical tools for terahertz (THz) spectroscopy. The high responsivity to the THz field amplitude of photomixer-based systems is predetermined by the homodyne detection principle that allows the system to have high sensitivity. Here, we show that the advantages of homodyne detection can be exploited with broadband power detectors combined with two photomixer sources. For this, we employ a THz detector based on a complementary metal-oxide-semiconductor field-effect transistor and a broadband bow-tie antenna (TeraFET). At 500 GHz and an effective noise bandwidth of 1 Hz, the response from one photomixer-based THz source resulted in an about 43 dB signal-to-noise ratio (SNR). We demonstrate that by employing a homodyne detection system by overlaying the radiation from two photomixers, the SNR can reach up to 70 dB at the same frequency with an integration time 100 ms. The improvement in SNR and the spectroscopic evidence for water vapor lines demonstrated up to 2.2 THz allow us to conclude that these detectors can be successfully used in practical continuous wave THz spectrometry systems.

scholarly journals DAB Signal Preprocessing for Passive Coherent Location

Sensors ◽  
2022 ◽  
Vol 22 (1) ◽  
pp. 378
Author(s):  
Gustaw Mazurek
Keyword(s):  
Complexity Analysis ◽  
Signal To Noise Ratio ◽  
Integration Time ◽  
Moving Target ◽  
Digital Audio ◽  
Minimal Cost ◽  
Signal To Noise ◽  
Signal Preprocessing ◽  
Correlation Properties

Digital Audio Broadcast (DAB) transmitters can be successfully used as illumination sources in Passive Coherent Location (PCL). However, extending the integration time in such a configuration leads to the occurrence of periodical artifacts in the bistatic range/Doppler plots, resulting from the time structure of the DAB signal. In this paper, we propose some methods of signal preprocessing (based on symbol removal, substitution by noise, and duplication) that operate on the DAB transmission frame level and improve the received signal’s correlation properties. We also demonstrate that two of these methods allow us to avoid the mentioned artifacts and thus to improve the quality of the range/Doppler plots with detection results. We evaluate the performance of the proposed methods using real DAB signals acquired in an experimental PCL platform. We also provide the analysis of the Signal to Noise Ratio (SNR) during the detection of a moving target which shows that the proposed solution, based on symbol duplication, can offer around 3 dB of gain in SNR. Finally, we carry out the computational complexity analysis showing that the proposed method can be implemented with a minimal cost after some optimizations.

scholarly journals mGEODAR—A Mobile Radar System for Detection and Monitoring of Gravitational Mass-Movements

Sensors ◽  
2020 ◽  
Vol 20 (21) ◽  
pp. 6373
Author(s):  
Anselm Köhler ◽  
Lai Bun Lok ◽  
Simon Felbermayr ◽  
Nial Peters ◽  
Paul V. Brennan ◽  
...  
Keyword(s):  
High Resolution ◽  
Real Time ◽  
Continuous Wave ◽  
Signal To Noise Ratio ◽  
Mass Movement ◽  
Radar System ◽  
Gravitational Mass ◽  
Mass Movements ◽  
Low Resolution ◽  
Wave Radar

Radar measurements of gravitational mass-movements like snow avalanches have become increasingly important for scientific flow observations, real-time detection and monitoring. Independence of visibility is a main advantage for rapid and reliable detection of those events, and achievable high-resolution imaging proves invaluable for scientific measurements of the complete flow evolution. Existing radar systems are made for either detection with low-resolution or they are large devices and permanently installed at test-sites. We present mGEODAR, a mobile FMCW (frequency modulated continuous wave) radar system for high-resolution measurements and low-resolution gravitational mass-movement detection and monitoring purposes due to a versatile frequency generation scheme. We optimize the performance of different frequency settings with loop cable measurements and show the freespace range sensitivity with data of a car as moving point source. About 15 dB signal-to-noise ratio is achieved for the cable test and about 5 dB or 10 dB for the car in detection and research mode, respectively. By combining continuous recording in the low resolution detection mode with real-time triggering of the high resolution research mode, we expect that mGEODAR enables autonomous measurement campaigns for infrastructure safety and mass-movement research purposes in rapid response to changing weather and snow conditions.

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