Abstract
An optical method for calibration of the aperture area is described and studied both theoretically and experimentally. A spatially uniform, known irradiance is formed over the aperture by overlapping identical, parallel laser beams centred at constant spacing in an orthogonal lattice. The ratio of the throughput power and irradiance gives the area of the aperture. The method has several advantages compared with previous methods: it measures the area of the aperture directly, the shape of the aperture is not limited to a circle, it is relatively inexpensive to establish, it does not damage the edges of the aperture and the calibration set-up is similar to that for the actual use of the aperture. It is estimated that the relative standard uncertainty is 1.6 × 10-4 in calibration of a circular 3 mm diameter aperture. The results that the present method gave for one aperture have been compared with the result of a mechanical calibration at the National Physical Laboratory (UK). The relative difference between the results was 2.4 × 10-4, with a combined standard uncertainty of 2.5 × 10-4.
| Original language | English |
|---|---|
| Pages (from-to) | 973-977 |
| Number of pages | 5 |
| Journal | Measurement Science and Technology |
| Volume | 8 |
| Issue number | 9 |
| DOIs | |
| Publication status | Published - 1 Jan 1997 |
| MoE publication type | A1 Journal article-refereed |
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An optical method for direct determination of the radiometric aperture area at high accuracy. / Lassila, A.; Toivanen, P.; Ikonen, E.
In: Measurement Science and Technology, Vol. 8, No. 9, 01.01.1997, p. 973-977.Research output: Contribution to journal › Article › Scientific › peer-review
TY - JOUR
T1 - An optical method for direct determination of the radiometric aperture area at high accuracy
AU - Lassila, A.
AU - Toivanen, P.
AU - Ikonen, E.
PY - 1997/1/1
Y1 - 1997/1/1
N2 - An optical method for calibration of the aperture area is described and studied both theoretically and experimentally. A spatially uniform, known irradiance is formed over the aperture by overlapping identical, parallel laser beams centred at constant spacing in an orthogonal lattice. The ratio of the throughput power and irradiance gives the area of the aperture. The method has several advantages compared with previous methods: it measures the area of the aperture directly, the shape of the aperture is not limited to a circle, it is relatively inexpensive to establish, it does not damage the edges of the aperture and the calibration set-up is similar to that for the actual use of the aperture. It is estimated that the relative standard uncertainty is 1.6 × 10-4 in calibration of a circular 3 mm diameter aperture. The results that the present method gave for one aperture have been compared with the result of a mechanical calibration at the National Physical Laboratory (UK). The relative difference between the results was 2.4 × 10-4, with a combined standard uncertainty of 2.5 × 10-4.
AB - An optical method for calibration of the aperture area is described and studied both theoretically and experimentally. A spatially uniform, known irradiance is formed over the aperture by overlapping identical, parallel laser beams centred at constant spacing in an orthogonal lattice. The ratio of the throughput power and irradiance gives the area of the aperture. The method has several advantages compared with previous methods: it measures the area of the aperture directly, the shape of the aperture is not limited to a circle, it is relatively inexpensive to establish, it does not damage the edges of the aperture and the calibration set-up is similar to that for the actual use of the aperture. It is estimated that the relative standard uncertainty is 1.6 × 10-4 in calibration of a circular 3 mm diameter aperture. The results that the present method gave for one aperture have been compared with the result of a mechanical calibration at the National Physical Laboratory (UK). The relative difference between the results was 2.4 × 10-4, with a combined standard uncertainty of 2.5 × 10-4.
UR - http://www.scopus.com/inward/record.url?scp=0031235698&partnerID=8YFLogxK
U2 - 10.1088/0957-0233/8/9/003
DO - 10.1088/0957-0233/8/9/003
M3 - Article
AN - SCOPUS:0031235698
VL - 8
SP - 973
EP - 977
JO - Measurement Science and Technology
JF - Measurement Science and Technology
SN - 0957-0233
IS - 9
ER -