Determination of Focal Plane in Digital Holography Based on Integrated Gray-Level Gradient Method

2011 ◽  
Vol 48 (11) ◽  
pp. 110901 ◽  
Author(s):  
李光勇 Li Guangyong ◽  
黄亮 Huang Liang ◽  
唐丽丽 Tang Lili ◽  
杨岩 Yang Yan
Keyword(s):  
Gradient Method ◽  
Focal Plane ◽  
Digital Holography ◽  
Gray Level

Focal plane location using integrated gray-level gradient method in digital particle holography

Optik ◽  
2012 ◽  
Vol 123 (7) ◽  
pp. 609-616 ◽  
Author(s):  
Guangyong Li ◽  
Changhua Lin ◽  
Lili Tang ◽  
Liang Huang ◽  
Yan Yang
Keyword(s):  
Gradient Method ◽  
Focal Plane ◽  
Gray Level

scholarly journals Does Non-ionizing Radiant Energy Affect Determination of the Evaporation Rate by the Gradient Method?

1991 ◽  
Vol 96 (1) ◽  
pp. 35-46 ◽  
Author(s):  
Sveinn Kjartansson ◽  
Karen Hammarlund ◽  
Per Åke Öberg ◽  
Gunnar Sedin
Keyword(s):  
Gradient Method ◽  
Evaporation Rate ◽  
Radiant Energy

Determination of Phase Shift by Digital Holography

2019 ◽  
Vol 888 ◽  
pp. 43-46
Author(s):  
Yoshitaka Takahashi ◽  
Masatoshi Saito ◽  
Toru Nakajima ◽  
Masakazu Shingu
Keyword(s):  
Phase Shift ◽  
Noise Reduction ◽  
Digital Holography ◽  
High Accuracy ◽  
Measured Data ◽  
Phase Shifting ◽  
Surface Shape ◽  
Shape Measurement ◽  
Phase Shifting Interferometry

In phase shifting interferometry phase shift is applied by various ways, but applying it with high accuracy, especially by LD current modulation, is not easy. In order to determine the accurate phase shift a new method has been proposed that the value of LD current corresponding to π/2 phase shift can be determined by phase shifting digital holography. The measured data of standard in surface shape measurement were used for calibration, and the obtained value was confirmed to cause noise reduction and improvement of holographic reconstructed images in digital holography.

scholarly journals The Feasibility of a CCD for an Astrometric Refractor

1995 ◽  
Vol 167 ◽  
pp. 347-348
Author(s):  
A. R. Upgren ◽  
Alice Morales ◽  
Jose Herrero ◽  
J. W. Griese ◽  
J. M. Vincent ◽  
...  
Keyword(s):  
Focal Plane ◽  
Blue Filter ◽  
Trigonometric Parallaxes ◽  
Van Vleck

The 0.5m refracting telescope of the Van Vleck Observatory has been active in the determination of trigonometric parallaxes since its first observations in 1922. Its lenses were ground by C.A.R. Lundin of the Alvan Clark Co. for photographic use. Coma was minimized across the field and vignetting was also kept to a minimum. Partly as a consequence the focal curve is very steep in the blue and green regions of the spectrum, as is shown in Fig. 1. A Wratten No. 12 minus blue filter is used to filter out all wavelengths to the blue of about 5200 å. The region between 5200 å and 6000 å is very flat with the focal plane varying over a range of about one millimeter. Towards the red region it steepens, although not enough to impair images on photographic plates of emulsion types 103a-D and IIIa-F, the two in widespread use in recent years.

Calibration Procedure for Attenuation Coefficient Measurements in Highly Opaque Media Using Infrared Focal Plane Array (IRFPA) Spectroscopy

2018 ◽  
Vol 72 (2) ◽  
pp. 177-187 ◽  
Author(s):  
Sara Kirchner ◽  
Sebastien Narinsamy ◽  
Alain Sommier ◽  
Marta Romano ◽  
Meguya Ryu ◽  
...  
Keyword(s):  
Coming Out ◽  
Focal Plane ◽  
Aqueous Media ◽  
Focal Plane Array ◽  
Calibration Procedure ◽  
Integration Time ◽  
Intensity Level ◽  
Infrared Focal Plane Array ◽  
Ir Spectroscopic

The purpose of this article is to present a new calibration procedure for spectroscopic measurements using an infrared focal plane array (IRFPA) spectrometer on highly opaque middle-wave infrared (MWIR) media. The procedure is based on the properties of the IRFPA camera and especially the integration time (IT), which is the main parameter that can be adjusted to control the sensitivity of the measurements. The goal of the paper is to experimentally validate this dependence with the direct reference intensity light coming out of the IR monochromator in order to predict the spectrum shape and intensity level in a range out of the camera saturation. This method allows determining spectrum used as background for transmittance calculation. It has been applied in the case of measurement of water transmittance, which is a highly opaque medium and whose measurement requires high ITs. The main result is the ability to take an IR spectroscopic imaging measurement through 300 µm of water and the determination of its transmittance with sufficient sensitivity due to the proposed calibration procedure. This procedure allows the possibility of transitory studies in heterogeneous aqueous media.

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