The inverse square law in metrology considering a finite photosensitive area

Sakamoto, Takayuki; Kitaguchi, K; Iwanaga, Toshihide

doi:10.1177/1477153519871324

Cited by 2 publications

(2 citation statements)

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“…Even with such a dedicated meter, parallax errors cannot be avoided, as shown throughout Section 3, let alone with irregular objects. Another source of error is the finite photosensitive area of the illuminance meter, 25 which in this study is assumed to be infinitely small. In other words, only the centre of the photosensitive area is considered in the calculation.…”

Section: Discussionmentioning

confidence: 99%

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Parallax errors in cubic illuminance measurement

Mangkuto

Revantino

2020

Lighting Research & Technology

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The cubic illuminance concept has long been proposed to indicate light modelling in three-dimensional space. An issue relatively less discussed with regard to its measurement is the potential error due to the finite size of the cube centred at the reference point, yielding a parallax effect. In short, the measured cubic illuminance around a finite-sized object will differ from the designed values that are based on the assumption that the object is a point in space. This paper therefore aims to determine the frequency distribution of errors in estimating scalar ( Esr) and cylindrical ( Ecl) illuminances, vector to scalar illuminance ratio, and cylindrical to horizontal illuminance ratio, due to finite cube size. General uncertainty principle in measurement is employed by introducing random values of cube length and its spatial position. A linear trend is observed between cubic illuminance on the finite cube and the corresponding true values. The Esr and Ecl are approximated more accurately in the case of a point source with a small beam angle. The cube length also influences the accuracy of the results; larger cube length tends to yield less accurate estimations. To achieve maximum error of 20% in estimating Esr and Ecl for a given source–reference point distance, the cube length should not exceed 15% of such a distance.

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Section: Discussionmentioning

confidence: 99%

“…For simplicity, the photosensitive area of the receiver is assumed to be infinitely small. Shibuya et al 25 have elaborated the potential errors due to finite photosensitive area illuminated by a point light source. When the measurement distance is five times the radius of the photosensitive area, the resulting error is approximately 3%.…”

Section: Observed Scenementioning

confidence: 99%

Parallax errors in cubic illuminance measurement

Mangkuto

Revantino

2020

Lighting Research & Technology

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The effect of glass neutral density filter on illuminance measurement error

Nelfyenny

Achmadi

Prihhapso

et al. 2021

J. Phys.: Conf. Ser.

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We present an analysis of the illuminance measurement results when a glass neutral density filter (ND Filter) inserted between light source and photometer. ND filters are widely used as an alternative solution in illuminance calibration systems to perform lower illuminance level which caused by inadequate length of the photometric bench. However, there are some variables that must be considered when inserting ND filters in illuminance measurement, one of which is the perceived color temperature of the light source which is influenced by the non-flatness profile of the filter’s spectral. This research was conducted by calculating correction factor for each ND filters, which contribute to illuminance error. Six different ND filters in the range of 1% to 49% are used in this experiment. Scanning the spectral distribution of filter are done to analyzing the change of color temperature of the light source as it passes through an ND filter, due to the lamp must correspond to Illuminant A. This research shows the illuminance measurement error can be up to 20% proportionality to the transmittance as the effect of using ND filters. The results of this study are expected to provide recommendations for the calibration laboratory, especially in illuminance meter calibration.

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The inverse square law in metrology considering a finite photosensitive area

Cited by 2 publications

References 1 publication

Parallax errors in cubic illuminance measurement

Parallax errors in cubic illuminance measurement

The effect of glass neutral density filter on illuminance measurement error

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