The measurement error induced by intensity scintillation for single-pass and double-pass imaging polarimetry

Optik ◽  
2018 ◽  
Vol 170 ◽  
pp. 95-100 ◽  
Author(s):  
Benxi Yao ◽  
Naiting Gu ◽  
Changhui Rao
Keyword(s):  
Measurement Error ◽  
Double Pass ◽  
Single Pass ◽  
Imaging Polarimetry

Flattop Broadband Wavelength Conversion Based on Cascaded Second-Harmonic Generation and Difference Frequency Generation in Step-Segmented Quasi-Phase Matched Gratings

2014 ◽  
Vol 989-994 ◽  
pp. 3790-3793
Author(s):  
Hai Dong Wu ◽  
Jin Song Guo ◽  
Yun Wen Wu ◽  
Zhao Xia Wang
Keyword(s):  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
Wavelength Conversion ◽  
Second Harmonic ◽  
Difference Frequency Generation ◽  
Difference Frequency ◽  
Double Pass ◽  
Single Pass ◽  
Frequency Generation ◽  
Matching Response

Bandwidth enhancement and response flattening of wavelength conversion based on single-pass and double-pass cascaded second harmonic generation and difference frequency generation in step-segmented quasi-phase matched (QPM) gratings are investigated. For the same waveguide length, high conversion efficiency, flat response and broad signal bandwidth can be obtained simultaneously by optimizing the poling period of the step-segmented QPM structure. The conversion bandwidths in a 3-cm-long five-step-segmented waveguide are 134 nm for single-pass scheme and 132 nm for the double-pass one, respectively, which are both over the whole conventional band and long-wavelength band. The ripple on the matching response can keeps less than 0.2 dB as well.

Evaluating the Performance of a Modified Solar Air Heater With Pierced Cover and Packed Mesh Layers

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Raheleh Nowzari ◽  
Hasan Saygin ◽  
L.B.Y. Aldabbagh
Keyword(s):  
Airflow Rate ◽  
Solar Air Heater ◽  
Centrifugal Fan ◽  
Construction Costs ◽  
Double Pass ◽  
Counter Flow ◽  
Single Pass ◽  
Air Heater ◽  
Current Design ◽  
Thermohydraulic Efficiency

Abstract An experimental study was conducted to evaluate the thermal efficiency of a modified solar air heater. In the current design, air enters the collector through holes in front glass, passes through mesh layers, and exits at the backside of the air heater. A centrifugal fan was used to circulate air through the system. The design offers low construction costs and less solar radiation reflected from the collector. The modified collector was examined with various bed heights (30, 50, and 70 mm) and different mass flowrates of air varying from 0.011 kg/(s m2) to 0.043 kg/(s m2). The results showed that a counter flow collector with pierced cover had 5.6–9.7% higher efficiency than the single-pass one. The average efficiencies of the current design collector were found to be 55.2%, 44.6%, and 39.7% for the single-pass and 60.8%, 50.9% and 45.4% for the double-pass collector at 30, 50, and 70 mm bed heights and airflow rate of 0.043 kg/(s m2), respectively. The thermohydraulic efficiency, temperature difference, and perforated cover surface temperature were analyzed at each test and their effects on the system performance were evaluated. The highest amount of pressure drop through the collector was measured in the collector with a 70-mm bed height and a maximum air flowrate.

scholarly journals OPTIMIZATION OF THE 1050nm PUMP POWER AND FIBER LENGTH IN SINGLE-PASS AND DOUBLE-PASS THULIUM DOPED FIBER AMPLIFIERS

2009 ◽  
Vol 14 ◽  
pp. 431-448 ◽  
Author(s):  
Siamak Dawazdah Emami ◽  
Sulaiman Wadi Harun ◽  
Faidz Abd-Rahman ◽  
Hairul Azhar Abdul-Rashid ◽  
Siti Aida Daud ◽  
...  
Keyword(s):  
Pump Power ◽  
Fiber Length ◽  
Fiber Amplifiers ◽  
Double Pass ◽  
Single Pass

scholarly journals Measuring Height Characteristics of Sagebrush (Artemisia sp.) Using Imagery Derived from Small Unmanned Aerial Systems (sUAS)

Drones ◽  
2020 ◽  
Vol 4 (1) ◽  
pp. 6 ◽  
Author(s):  
Ryan G. Howell ◽  
Ryan R. Jensen ◽  
Steven L. Petersen ◽  
Randy T. Larsen
Keyword(s):  
Data Storage ◽  
Accuracy Assessment ◽  
Point Clouds ◽  
Unmanned Aerial Systems ◽  
Surface Model ◽  
Sage Grouse ◽  
Double Pass ◽  
Single Pass ◽  
3D Point Clouds ◽  
Aerial Systems

In situ measurements of sagebrush have traditionally been expensive and time consuming. Currently, improvements in small Unmanned Aerial Systems (sUAS) technology can be used to quantify sagebrush morphology and community structure with high resolution imagery on western rangelands, especially in sensitive habitat of the Greater sage-grouse (Centrocercus urophasianus). The emergence of photogrammetry algorithms to generate 3D point clouds from true color imagery can potentially increase the efficiency and accuracy of measuring shrub height in sage-grouse habitat. Our objective was to determine optimal parameters for measuring sagebrush height including flight altitude, single- vs. double- pass, and continuous vs. pause features. We acquired imagery using a DJI Mavic Pro 2 multi-rotor Unmanned Aerial Vehicle (UAV) equipped with an RGB camera, flown at 30.5, 45, 75, and 120 m and implementing single-pass and double-pass methods, using continuous flight and paused flight for each photo method. We generated a Digital Surface Model (DSM) from which we derived plant height, and then performed an accuracy assessment using on the ground measurements taken at the time of flight. We found high correlation between field measured heights and estimated heights, with a mean difference of approximately 10 cm (SE = 0.4 cm) and little variability in accuracy between flights with different heights and other parameters after statistical correction using linear regression. We conclude that higher altitude flights using a single-pass method are optimal to measure sagebrush height due to lower requirements in data storage and processing time.

Double Pass 595 nm pulsed dye laser at a 6 minute interval for the treatment of port-wine stains is not more effective than single pass

2012 ◽  
Vol 44 (3) ◽  
pp. 199-204 ◽  
Author(s):  
M.A.D. Peters ◽  
A.M. van Drooge ◽  
A. Wolkerstorfer ◽  
M.J.C. van Gemert ◽  
J.P.W. van der Veen ◽  
...  
Keyword(s):  
Dye Laser ◽  
Pulsed Dye Laser ◽  
Port Wine ◽  
Double Pass ◽  
Port Wine Stains ◽  
Single Pass ◽  
Minute Interval

A single-double pass Sisam spectrometer for the near infrared

1977 ◽  
Vol 353 (1674) ◽  
pp. 421-430 ◽  
Keyword(s):  
High Resolution ◽  
Near Infrared ◽  
Line Emission ◽  
Signal Strength ◽  
Emission Sources ◽  
Double Pass ◽  
Single Pass ◽  
Modulation Technique ◽  
Infra Red ◽  
Coherent Modulation

A double-pass Sisam spectrometer of high resolution and sensitivity, previously described, has been modified for single-pass operation. For discrete line emission sources, this modification provides a gain of a factor of 6 in sensitivity at the expense of a loss of a factor of 2 in resolution in the near infra red region. As is demonstrated, the modified instrument is particularly suitable for the study of weak spectral sources. A coherent modulation system has also been incorporated which eliminates the periodic variations in signal strength arising from the non-coherent modulation technique previously employed.

DOUBLE PASS S-BAND EDFA

2006 ◽  
Vol 15 (03) ◽  
pp. 303-307
Author(s):  
HARITH AHMAD ◽  
SULAIMAN WADI HARUN
Keyword(s):  
Pump Power ◽  
Short Wavelength ◽  
Fiber Amplifier ◽  
Small Signal Gain ◽  
Small Signal ◽  
Double Pass ◽  
Erbium Doped Fiber Amplifier ◽  
Single Pass ◽  
Gain Enhancement ◽  
Erbium Doped

A double-pass erbium-doped fiber amplifier (EDFA) based on a depressed cladding erbium-doped fiber, which operates in the short wavelength (S-band) region is proposed and demonstrated. This amplifier provides a small signal gain as high as 30 dB at 1500 nm, using only 15 m depressed cladding erbium-doped fiber (EDF) and 130 mW of 980 nm pump power. Compared to the single-pass configuration, this amplifier shows a gain enhancement of about 14 dB for pump powers above 120 mW. However, noise figures penalties of less than 0.9 dB are obtained for these pump powers. The proposed double-pass amplifier will play an important role in the development of a practical S-band EDFA from the perspective of economical usage of EDF and pump power.

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