scholarly journals Implementation of a speckle-correlation-based optical lever with extended dynamic range

2019 ◽  
Vol 58 (22) ◽  
pp. 5982 ◽  
Author(s):  
A. Vijayakumar ◽  
D. Jayavel ◽  
M. Muthaiah ◽  
Shanti Bhattacharya ◽  
Joseph Rosen
Keyword(s):  
Dynamic Range ◽  
Speckle Correlation ◽  
Optical Lever ◽  
Extended Dynamic

scholarly journals Spatial Multiplexing Technique for Improving Dynamic Range of Speckle Correlation based Optical Lever

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Vijayakumar Anand ◽  
Shanti Bhattacharya ◽  
Joseph Rosen
Keyword(s):  
Dynamic Range ◽  
Speckle Pattern ◽  
Image Sensor ◽  
Initial Position ◽  
Spatial Multiplexing ◽  
Angular Orientation ◽  
Correlation Peak ◽  
Intensity Pattern ◽  
Speckle Correlation ◽  
Optical Lever

Abstract Speckle correlation based optical levers (SC-OptLev) possess attractive characteristics suitable for sensing small changes in the angular orientations of surfaces. In this study, we propose and demonstrate a spatial multiplexing technique for improving the dynamic range of SC-OptLev. When the surface is in its initial position, a synthetic speckle intensity pattern, larger than the area of the image sensor is created by transversely shifting the image sensor and recording different sections of a larger speckle pattern. Then, the acquired images are stitched together by a computer program into one relatively large synthetic speckle pattern. Following the calibration stage, the synthetic speckle intensity pattern is used to sense changes in the surface’s angular orientation. The surface is monitored in real-time by recording part of the speckle pattern which lies within the sensor area. Next, the recorded speckle pattern is cross-correlated with the synthetic speckle pattern in the computer. The resulting shift of the correlation peak indicates the angular orientations of the reflective surface under test. This spatial-multiplexing technique enables sensing changes in the angular orientation of the surface beyond the limit imposed by the physical size of the image sensor.

AN OCEAN BOTTOM, D COMPONENT MAGNETOMETER

Geophysics ◽  
1967 ◽  
Vol 32 (6) ◽  
pp. 978-987 ◽  
Author(s):  
J. H. Filloux
Keyword(s):  
Electric Field ◽  
Dynamic Range ◽  
North Pacific Ocean ◽  
Mooring Line ◽  
Ocean Bottom ◽  
Magnetic Fluctuations ◽  
Sea Floor ◽  
The North ◽  
Low Profile ◽  
Optical Lever

The distribution of electric conductivity in the crustal and upper mantle materials beneath the ocean may be estimated from measurements of the relationship between the magnetic fluctuations and the induced electric field at the ocean bottom. Techniques for the measurement of the electric field have been available for a few years. The horizontal magnetic fluctuations to the magnetic east, usually called D, can be recorded with a simple instrument placed on the sea floor at any depth. This instrument uses a magnet pair which orients itself among the main horizontal field H. The coupling of the magnets to the mirror of a sensitive optical lever is delayed until the instrument has reached the bottom. There is no need to perform any orientation in situ. The instrument resolves 1 γ or less and has a dynamic range of at least 2500 γ. It is capable of recording for approximately 40 days at the rate of 30 readings per hour on self‐contained dry cells. It is lowered to the sea floor and recovered by means of a mooring line connected to a surface float. The low‐profile supporting tripod is effectively decoupled from the mooring tackle as evidenced by the lack of motion of the magnetometer during 26 days of recording. A sample of the observed fluctuations on the floor of the North Pacific Ocean, 600 km offshore, is given.

scholarly journals Photodetector resistant to background light noise with extended dynamic range of input signals

2021 ◽  
pp. 3-8
Author(s):  
V. M. Lipka ◽  
V. V. Ryukhtin ◽  
Yu. G. Dobrovolsky
Keyword(s):  
Dynamic Range ◽  
Automatic Gain Control ◽  
Modulation Frequency ◽  
Low Frequency ◽  
Gain Control ◽  
Ambient Air ◽  
Frequency Range ◽  
Background Light ◽  
Useful Signal ◽  
Extended Dynamic

Measurement of periodic optical information signals in the background light noise with a photodetector with extended dynamic range is an urgent task of modern electronics and thus has become the aim of this study. To increase the dynamic range of the photodetector, a new version of the automatic gain control (AGC) circuit has been developed, which consists of an AGC controller, an output photodetector amplifier and an AGC detector. The authors measured the dynamic range of the photodetector when receiving optical radiation with a wavelength of 1064 nm in the power range from 2.10–8 to 2.10–5 W at a modulation frequency of 20 kHz with the AGC on. Under these conditions, the dynamic range of the photodetector was found to be up to 67 dB. If the AGC was off, the dynamic range did not exceed 30 dB. Thus, the study made it possible to create a photodetector with an extended dynamic range up to 67 dB based on a new version of the AGC circuit. The design of the photodetector allowed choosing a useful signal of a particular modulation frequency in the frequency range from 3 to 45 kHz and effectively suppresses the frequencies caused by optical interference in the low frequency range from the frequency of the input signal of constant amplitude up to 3 kHz inclusive. This compensates the current up to 15 mA, which is equivalent to the power of light interference of about 15 mW. Further research should address the issues of reliability of the proposed photodetector design and optimization of its optical system. The photodetector can be used in geodesy and ambient air quality monitoring.

scholarly journals Optical spectroanalyzer with extended dynamic range for pharmacokinetic investigations of photosensitizers in biotissue

2019 ◽  
Vol 8 (1) ◽  
pp. 46-51 ◽  
Author(s):  
G. A. Meerovich ◽  
E. V. Akhlyustina ◽  
T. A. Savelieva ◽  
K. G. Linkov ◽  
V. B. Loschenov
Keyword(s):  
Dynamic Range ◽  
Spectrum Analyzer ◽  
Pharmacokinetic Studies ◽  
Fluorescent Properties ◽  
Accumulation Time ◽  
Fluorescent Method ◽  
Calibration Samples ◽  
Hardware Circuit ◽  
Improved Accuracy ◽  
Extended Dynamic

Currently, the most promising method for the study of pharmacokinetics of drugs with fluorescent properties is the spectral-fluorescent method. In this article, we propose an algorithm for expanding the dynamic range of the spectrum analyzer by automatically monitoring the maximum spectral density in the recorded fluorescence spectrum and automatically controlled changes in the accumulation time depending on this value, followed by compensation of the output signal with regard to this change, as well as hardware circuit solutions that allow this algorithm.Testing of LESA-01-"Biospeс" spectrum analyzer, upgraded using the proposed approach, was carried out on photosensitizer dispersions based on tetra-3-phenylthiophthalocyanine hydroxyaluminium of various concentrations (from 0.01 mg/l to 50 mg/l), approximately corresponding to the concentrations realized in the process of studying pharmacokinetics in calibration samples and tissues of experimental animals.The proposed solutions that implement the algorithm for recording fluorescence spectra with automatic change of accumulation time depending on the signal level, ensured a significant expansion of the dynamic range of the spectrum analyzer (up to 3.5 orders of magnitude) and improved accuracy in pharmacokinetic studies.

FBG-Embedded Oblong Diaphragms with Extended Dynamic Range

2018 ◽  
Vol 2 (2) ◽  
pp. 1-4 ◽  
Author(s):  
Arnaldo G. Leal-Junior ◽  
Anselmo Frizera ◽  
Camilo R. Diaz ◽  
Moises R. N. Ribeiro ◽  
Maria Jose Pontes
Keyword(s):  
Dynamic Range ◽  
Extended Dynamic
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