Design and characterization of a large area uniform radiance source for calibration of a remote sensing imaging system

McKee, Greg; Pal, Samir Kumar; Seth, Harish; Bhardwaj, Ashutosh; Sahoo, Hari Sankar

doi:10.1117/12.732122

Cited by 11 publications

(6 citation statements)

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“…The diameter tolerance of any optomechanical system corresponds, as maximum, to commercial tolerances (AE0.050 mm); therefore, the uncertainty due to sphere diameter, port fraction, etc., is less than 0.2%. According to the literature, 28,29 the rest of the uncertainties (flux emitted by standard lamp, standard reflectance, lamp current setting, lamp current drift, etc.) would give a total uncertainty of less than 2% in the synthetic pattern.…”

Section: Measurements and Resultsmentioning

confidence: 99%

A new method of measuring and monitoring light pollution in the night sky

Rabaza

Aznar-Dols

Mercado-Vargas

et al. 2014

Lighting Research & Technology

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This paper describes a method of measuring and monitoring light pollution in the night sky. This method is capable of instantly quantifying the levels of artificial radiance and monochromatic luminance of the sky glow by means of a system that includes an all-sky camera as well as several interference filters. The calibration is done with an integrating sphere where the measurement pattern used is obtained from the light reflected from the inner wall of the sphere which comes from radiation emitted by a calibration lamp with a known luminous flux. The inner wall of this sphere is a Lambertian surface, which ensures that the light reflected or falling on it is uniformly dispersed in all directions (i.e. the surface luminance is isotropic).

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Section: Measurements and Resultsmentioning

confidence: 99%

A new method of measuring and monitoring light pollution in the night sky

Rabaza

Aznar-Dols

Mercado-Vargas

et al. 2014

Lighting Research & Technology

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“…It is illuminated by numerous uniform lambert sources -apertures of primary ISs. It guarantees the high uniformity in comparison with a classical IS or with an IS pumped by one other IS 13,14 .…”

Section: Fig 1 Principal Scheme Of An Integrating Multi Spherementioning

confidence: 99%

Precise prelaunch radiometric calibration of VIIRs

Mikheenko

Borovytsky

Hudz

2015

Earth Observing Systems XX

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The paper presents the new approach that includes technique, scheme and instruments for precise calibration of space-borne and airborne visible infrared imaging radiometers (VIIRs). The key component of this technique is the precise uniform light source based on optically-interconnected integrating spheres. The light source contains several (5…11) primary integrating spheres of small diameters which are installed on a secondary integrating sphere of bigger diameter. The initial light sources -halogen lamps or light emitted diodes are installed inside the primary integrating spheres. These spheres are mounted on the secondary integrating sphere. The radiation comes from the primary integrating spheres to the secondary one through diaphragms which diameters can be varied. The secondary integrating sphere has an output aperture where uniform radiance emits. As a result the output radiance can be varied in extremely wide range -up to 800 W/(st·m 2 ) with dynamic range 1 000 000 -without any change of spectral characteristics. Non-uniformity of the radiance distribution throughout the output aperture can be smaller 0.5 % because the secondary integrating sphere is illuminated uniformly and it does not contain lamps inside. The paper discusses the requirements to calibration system, the application of this light source in calibration procedures, metrological aspects of radiometric calibration.

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“…1 The 2 m diameter source had a 1.2 m diameter exit port that was required to produce known levels of spectral radiance at several wavelengths through the visible to near-infrared (VIS) and short-wave infrared (SWIR) spectral regions. Table 1 gives the specified maximum and minimum spectral radiance levels that were required for the system.…”

Section: System Descriptionmentioning

confidence: 99%

Linearity improvement in a high dark-current short-wave infrared array spectrometer

D'Amato¹,

Griffiths²,

Leland³

2007

Earth Observing Systems XII

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Spectrometers that include extended-range linear InGaAs arrays make it possible to measure optical signals to 2500 nm. Available arrays, however, have more than 100 times the dark current as that of conventional arrays, which are limited to 1700 nm. This behavior leads to non-linearity in a short-wave infrared spectroradiometer used to monitor spectral radiance of an integrating sphere uniform source. A method of improving linearity in an extended-range InGaAs array is presented. The non-linearity is corrected using a multi-point calibration at a number of lamp power levels whereby the calibration factor for each wavelength point depends on the lamp power in the integrating sphere. An algorithm in the spectroradiometer software chooses the correct calibration factors and reports the system spectral radiance values accordingly. This method reduced error by more than a factor of two.

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Design and characterization of a large area uniform radiance source for calibration of a remote sensing imaging system

Cited by 11 publications

References 0 publications

A new method of measuring and monitoring light pollution in the night sky

A new method of measuring and monitoring light pollution in the night sky

Precise prelaunch radiometric calibration of VIIRs

Linearity improvement in a high dark-current short-wave infrared array spectrometer

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