A new optical method for high-accuracy determination of aperture area

Ikonen, Erkki; Toivanen, P.; Lassila, Antti

doi:10.1088/0026-1394/35/4/25

Cited by 34 publications

(38 citation statements)

References 3 publications

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“…The laser scanning method is described in detail in [18][19][20]. Therefore, only a brief introduction is given here.…”

Section: Laser Scanning Methods For the Aperture Area Determinationmentioning

confidence: 99%

“…(6) is presented in [19] for a relaxed requirement of the beam grid dimensions and general beam shape, not limited to a perfect Gaussian. For an aperture considerably smaller than the laser beam lattice, the aperture area can now be obtained by combining Eqs.…”

Section: Laser Scanning Methods For the Aperture Area Determinationmentioning

confidence: 99%

“…Several methods for determining the area of an aperture have been developed, which utilize either mechanical contact [16,17] or optical techniques [18][19][20][21][22][23][24][25]. In addition, a spatially uniform irradiance source can be used to compare the area of two apertures [16,26,27].…”

Section: Introductionmentioning

confidence: 99%

“…While most methods measure the diameter of a round aperture, some measure the area directly and can be used to measure irregular apertures. Lassila et al developed such an optical method for direct determination of aperture area [18][19][20], in which a two-dimensional superposition of equally spaced Gaussian laser beams is used to form a uniform irradiance distribution. In practice, this is accomplished by having an intensity-stabilized laser beam and scanning the aperture in front of the laser beam.…”

Section: Introductionmentioning

confidence: 99%

“…The method has been validated by comparing the measured area of apertures of different sizes to the area determined using mechanical contact methods [18][19][20].…”

Section: Introductionmentioning

confidence: 99%

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Optical aperture area determination for accurate illuminance and luminous efficacy measurements of LED lamps

Dönsberg

Mäntynen

Ikonen

2016

Opt Rev

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The measurement uncertainty of illuminance and, consequently, luminous flux and luminous efficacy of LED lamps can be reduced with a recently introduced method based on the predictable quantum efficient detector (PQED). One of the most critical factors affecting the measurement uncertainty with the PQED method is the determination of the aperture area. This paper describes an upgrade to an optical method for direct determination of aperture area where superposition of equally spaced Gaussian laser beams is used to form a uniform irradiance distribution. In practice, this is accomplished by scanning the aperture in front of an intensity-stabilized laser beam. In the upgraded method, the aperture is attached to the PQED and the whole package is transversely scanned relative to the laser beam. This has the benefit of having identical geometry in the laser scanning of the aperture area and in the actual photometric measurement. Further, the aperture and detector assembly does not have to be dismantled for the aperture calibration. However, due to small acceptance angle of the PQED, differences between the diffraction effects of an overfilling plane wave and of a combination of Gaussian laser beams at the circular aperture need to be taken into account. A numerical calculation method for studying these effects is discussed in this paper. The calculation utilizes the Rayleigh-Sommerfeld diffraction integral, which is applied to the geometry of the PQED and the aperture. Calculation results for various aperture diameters and two different aperture-to-detector distances are presented.

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“…The laser scanning method is described in detail in [18][19][20]. Therefore, only a brief introduction is given here.…”

Section: Laser Scanning Methods For the Aperture Area Determinationmentioning

confidence: 99%

Section: Laser Scanning Methods For the Aperture Area Determinationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…The method has been validated by comparing the measured area of apertures of different sizes to the area determined using mechanical contact methods [18][19][20].…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Optical aperture area determination for accurate illuminance and luminous efficacy measurements of LED lamps

Dönsberg

Mäntynen

Ikonen

2016

Opt Rev

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Absolute Primary Radiometric Thermometry

Sapritsky

Prokhorov²

2020

Blackbody Radiometry

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International Comparison

Khel¹

2014

Encyclopedia of Quality of Life and Well-Being Research

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Abstract. An international comparison has been conducted to compare the illuminance responsivity scales (A/lx) and the units of luminous ux (lm) maintained at the National Institute of Standards and Technology (NIST, USA) and the Helsinki University of Technology (HUT, Finland). Both laboratories realize the illuminance unit by absolutely calibrated photometers and the luminous ux unit by the absolute integrating-sphere method. Standard photometers were used as transfer standards for the illuminance responsivity comparison, and standard lamps in the luminous ux comparison. The ratio of the measured illuminance responsivity values (HUT/NIST) was 0.9992 with an expanded uncertainty of 0.0013, and the ratio of the measured luminous ux values was 1.0006 with an expanded uncertainty of 0.0018. The relative expanded uncertainties of the agreement of the units, including the uncertainties of the realizations of the units as well as the uncertainty of the comparison, were 0.0047 and 0.0101, respectively.

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A new optical method for high-accuracy determination of aperture area

Cited by 34 publications

References 3 publications

Optical aperture area determination for accurate illuminance and luminous efficacy measurements of LED lamps

Optical aperture area determination for accurate illuminance and luminous efficacy measurements of LED lamps

Absolute Primary Radiometric Thermometry

International Comparison

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