123 I intercomparison exercises: Assessment of measurement capabilities in UK hospitals

2018 ◽  
Vol 134 ◽  
pp. 108-111 ◽  
Author(s):  
Kelley M. Ferreira ◽  
Andrew J. Fenwick
Keyword(s):  
Intercomparison Exercises ◽  
Measurement Capabilities

Laser Timing Probe with Frequency Mapping for Locating Signal Maxima

2009 ◽  
Author(s):  
L.S. Koh ◽  
H. Marks ◽  
L.K. Ross ◽  
C.M. Chua ◽  
J.C.H. Phang
Keyword(s):  
Response Time ◽  
Continuous Wave ◽  
Single Point ◽  
Point Measurement ◽  
Cw Laser ◽  
Measurement Capabilities

Abstract A Laser Timing Probe (LTP) system which uses a noninvasive 1.3 µm continuous wave (CW) laser with frequency mapping and single point measurement capabilities is described. The frequency mapping modes facilitate the localization of signal maxima for subsequent single point measurements. Measurements of waveforms with long delays and 50 ps response time from NMOS and PMOS transistors are also shown.

EXPRESS: Design Considerations for Discrete Frequency Infrared Microscopy Systems

2021 ◽  
pp. 000370282110133
Author(s):  
Rohit Bhargava ◽  
Yamuna Dilip Phal ◽  
Kevin Yeh
Keyword(s):  
Imaging System ◽  
Chemical Imaging ◽  
Optical Component ◽  
Imaging Systems ◽  
Imaging Data ◽  
Discrete Frequency ◽  
Figures Of Merit ◽  
Design Considerations ◽  
Hardware Implementations ◽  
Measurement Capabilities

Discrete frequency infrared (DFIR) chemical imaging is transforming the practice of microspectroscopy by enabling a diversity of instrumentation and new measurement capabilities. While a variety of hardware implementations have been realized, considerations in the design of all-IR microscopes have not yet been compiled. Here we describe the evolution of IR microscopes, provide rationales for design choices, and the major considerations for each optical component that together comprise an imaging system. We analyze design choices in illustrative examples that use these components to optimize performance, under their particular constraints. We then summarize a framework to assess the factors that determine an instrument’s performance mathematically. Finally, we summarize the design and analysis approach by enumerating performance figures of merit for spectroscopic imaging data that can be used to evaluate the capabilities of imaging systems or suitability for specific intended applications. Together, the presented concepts and examples should aid in understanding available instrument configurations, while guiding innovations in design of the next generation of IR chemical imaging spectrometers.

scholarly journals Development of a Compound Speckle Interferometer for Precision Three-Degree-of-Freedom Displacement Measurement

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1828
Author(s):  
Hung-Lin Hsieh ◽  
Bo-Yen Sun
Keyword(s):  
Speckle Interferometry ◽  
Degree Of Freedom ◽  
Heterodyne Interferometry ◽  
Beam Splitting ◽  
Speckle Interferometer ◽  
Real World Applications ◽  
Three Degree Of Freedom ◽  
Contact Displacement ◽  
Displacement Measurements ◽  
Measurement Capabilities

In this study, a compound speckle interferometer for measuring three-degree-of-freedom (3-DOF) displacement is proposed. The system, which combines heterodyne interferometry, speckle interferometry and beam splitting techniques, can perform precision 3-DOF displacement measurements, while still having the advantages of high resolution and a relatively simple configuration. The incorporation of speckle interferometry allows for non-contact displacement measurements by detecting the phase of the speckle interference pattern formed from the convergence of laser beams on the measured rough surface. Experiments were conducted to verify the measurement capabilities of the system, and the results show that the proposed system has excellent measurement capabilities suitable for future real-world applications.

OPTICAL CLOCKS AND FREQUENCY METROLOGY FOR SPACE

2007 ◽  
Vol 16 (12b) ◽  
pp. 2537-2540
Author(s):  
HUGH KLEIN
Keyword(s):  
European Space Agency ◽  
Frequency Standard ◽  
Optical Frequency ◽  
Fundamental Physics ◽  
Frequency Standards ◽  
Space Agency ◽  
Primary Frequency ◽  
Measurement Capabilities ◽  
Science Activities ◽  
Frequency Metrology

Optical frequency standards and femtosecond comb measurement capabilities now rival and in some cases exceed those of microwave devices, with further improvements anticipated. Opportunities are emerging for the application of highly stable and accurate optical frequency devices to fundamental physics space science activities, and the European Space Agency (ESA) has recently commissioned studies on different aspects of optical clocks in space. This paper highlights some examples, including the difficulty of comparing very accurate terrestrial clocks at different locations due to fluctuations of the geoid; by locating a primary frequency standard in space, one could avoid geoid-related gravitational redshifts.

scholarly journals Estimating cloud optical thickness and associated surface UV irradiance from SEVIRI by implementing a semi-analytical cloud retrieval algorithm

2012 ◽  
Vol 12 (17) ◽  
pp. 7961-7975 ◽  
Author(s):  
P. Pandey ◽  
K. De Ridder ◽  
D. Gillotay ◽  
N. P. M. van Lipzig
Keyword(s):  
Optical Thickness ◽  
Correlation Coefficients ◽  
Retrieval Algorithm ◽  
Satellite Mission ◽  
Spectral Bands ◽  
Uv Irradiance ◽  
Intercomparison Exercises ◽  
Cloud Optical Thickness ◽  
Mean Square Difference ◽  
Good Agreement

Abstract. In this paper, we describe the implementation of the Semi-Analytical Cloud Retrieval Algorithm (SACURA), to obtain scaled cloud optical thickness (SCOT) from satellite imagery acquired with the SEVIRI instrument and surface UV irradiance levels. In estimation of SCOT particular care is given to the proper specification of the background (i.e. cloud-free) spectral albedo and the retrieval of the cloud water phase from reflectance ratios in SEVIRI's 0.6 μm and 1.6 μm spectral bands. The SACURA scheme is then applied to daytime SEVIRI imagery over Europe, for the month of June 2006, at 15-min time increments. The resulting SCOT fields are compared with values obtained by the CloudSat experimental satellite mission, yielding a negligible bias, correlation coefficients ranging from 0.51 to 0.78, and a root mean square difference of 1 to 2 SCOT increments. These findings compare favourably to results from similar intercomparison exercises reported in the literature. Based on the retrieved SCOT from SEVIRI and radiative transfer modelling approach, simple parameterisations are proposed to estimate the surface UV-A and UV-B irradiance. The validation of the modelled UV-A and UV-B irradiance against the measurements over two Belgian stations, Redu and Ostend, indicate good agreement with the high correlation, index of agreement and low bias. The SCOT fields estimated by implementing SACURA on imagery from geostationary satellite are reliable and its impact on surface UV irradiance levels is well produced.

Sign in / Sign up

Export Citation Format

Share Document