Verification of Angular Response of Sky Quality Meter with Quasi-Punctual Light Sources

Sky Quality Meter (SQM) is a commercial instrument based on photometers widely used by amateur astronomers for skyglow measurement from the ground. In the framework of the MINLU project, two SQM-LE units were integrated in an autonomous sensor suite realized and tested at University of Padova for mo...

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Autores principales:	Mirco Bartolomei, Lorenzo Olivieri, Carlo Bettanini, Stefano Cavazzani, Pietro Fiorentin
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	sky quality meter light pollution sky brightness Chemical technology TP1-1185
Acceso en línea:	https://doaj.org/article/b70becc9e5bd4b0aad6e9ef657e440f0
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spelling	oai:doaj.org-article:b70becc9e5bd4b0aad6e9ef657e440f02021-11-25T18:57:19ZVerification of Angular Response of Sky Quality Meter with Quasi-Punctual Light Sources10.3390/s212275441424-8220https://doaj.org/article/b70becc9e5bd4b0aad6e9ef657e440f02021-11-01T00:00:00Zhttps://www.mdpi.com/1424-8220/21/22/7544https://doaj.org/toc/1424-8220Sky Quality Meter (SQM) is a commercial instrument based on photometers widely used by amateur astronomers for skyglow measurement from the ground. In the framework of the MINLU project, two SQM-LE units were integrated in an autonomous sensor suite realized and tested at University of Padova for monitoring light pollution from drones or sounding balloons. During the ground tests campaign before airborne measurement, the performance of both SQM units was verified in laboratory using controlled light sources as a reference input; the results showed that both units presented an angular response deviating consistently from the expected performance and that the sensors’ field of view was larger than the one declared in the manufacturer’s datasheet. This aspect in particular would affect direct skyglow measurements during flight as light sources close to the boundaries of the field of view would not be attenuated but instead detected by the sensors. As a direct consequence, the measurement of low-intensity skyglows at stratospheric altitudes could be affected by high-intensity punctual sources acting as lateral disturbances. A dedicated test campaign was therefore conceived and realized to investigate SQM unit response to light sources in the field of view and identify the true angular response curve; the setup consisted in a controlled rotatory stage moving the unit in front of a fixed diffusive light source. Different test conditions were used to validate the experimental procedure, demonstrating the repeatability of the measurements. This paper presents the experimental campaign and the resulting SQM angular response curve; results indicate for both SQMs a larger than expected field of view and the presence of a double peak in the angular response, which is likely related to a non-perfect alignment of SQMs collimation optics. Furthermore, the wider resulting curves suggest that the contribution of lateral sources is more prominent with respect to the response predicted by the manufacturer. For this reason, the utilization of baffles to restrict SQMs field of view is analyzed to minimize the disturbance of lateral light sources and two different geometries are presented.Mirco BartolomeiLorenzo OlivieriCarlo BettaniniStefano CavazzaniPietro FiorentinMDPI AGarticlesky quality meterlight pollutionsky brightnessChemical technologyTP1-1185ENSensors, Vol 21, Iss 7544, p 7544 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	sky quality meter light pollution sky brightness Chemical technology TP1-1185
spellingShingle	sky quality meter light pollution sky brightness Chemical technology TP1-1185 Mirco Bartolomei Lorenzo Olivieri Carlo Bettanini Stefano Cavazzani Pietro Fiorentin Verification of Angular Response of Sky Quality Meter with Quasi-Punctual Light Sources
description	Sky Quality Meter (SQM) is a commercial instrument based on photometers widely used by amateur astronomers for skyglow measurement from the ground. In the framework of the MINLU project, two SQM-LE units were integrated in an autonomous sensor suite realized and tested at University of Padova for monitoring light pollution from drones or sounding balloons. During the ground tests campaign before airborne measurement, the performance of both SQM units was verified in laboratory using controlled light sources as a reference input; the results showed that both units presented an angular response deviating consistently from the expected performance and that the sensors’ field of view was larger than the one declared in the manufacturer’s datasheet. This aspect in particular would affect direct skyglow measurements during flight as light sources close to the boundaries of the field of view would not be attenuated but instead detected by the sensors. As a direct consequence, the measurement of low-intensity skyglows at stratospheric altitudes could be affected by high-intensity punctual sources acting as lateral disturbances. A dedicated test campaign was therefore conceived and realized to investigate SQM unit response to light sources in the field of view and identify the true angular response curve; the setup consisted in a controlled rotatory stage moving the unit in front of a fixed diffusive light source. Different test conditions were used to validate the experimental procedure, demonstrating the repeatability of the measurements. This paper presents the experimental campaign and the resulting SQM angular response curve; results indicate for both SQMs a larger than expected field of view and the presence of a double peak in the angular response, which is likely related to a non-perfect alignment of SQMs collimation optics. Furthermore, the wider resulting curves suggest that the contribution of lateral sources is more prominent with respect to the response predicted by the manufacturer. For this reason, the utilization of baffles to restrict SQMs field of view is analyzed to minimize the disturbance of lateral light sources and two different geometries are presented.
format	article
author	Mirco Bartolomei Lorenzo Olivieri Carlo Bettanini Stefano Cavazzani Pietro Fiorentin
author_facet	Mirco Bartolomei Lorenzo Olivieri Carlo Bettanini Stefano Cavazzani Pietro Fiorentin
author_sort	Mirco Bartolomei
title	Verification of Angular Response of Sky Quality Meter with Quasi-Punctual Light Sources
title_short	Verification of Angular Response of Sky Quality Meter with Quasi-Punctual Light Sources
title_full	Verification of Angular Response of Sky Quality Meter with Quasi-Punctual Light Sources
title_fullStr	Verification of Angular Response of Sky Quality Meter with Quasi-Punctual Light Sources
title_full_unstemmed	Verification of Angular Response of Sky Quality Meter with Quasi-Punctual Light Sources
title_sort	verification of angular response of sky quality meter with quasi-punctual light sources
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/b70becc9e5bd4b0aad6e9ef657e440f0
work_keys_str_mv	AT mircobartolomei verificationofangularresponseofskyqualitymeterwithquasipunctuallightsources AT lorenzoolivieri verificationofangularresponseofskyqualitymeterwithquasipunctuallightsources AT carlobettanini verificationofangularresponseofskyqualitymeterwithquasipunctuallightsources AT stefanocavazzani verificationofangularresponseofskyqualitymeterwithquasipunctuallightsources AT pietrofiorentin verificationofangularresponseofskyqualitymeterwithquasipunctuallightsources
_version_	1718410485238333440

Verification of Angular Response of Sky Quality Meter with Quasi-Punctual Light Sources

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