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Sources of Error in UV Radiation Measurements

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ABSTRACT

Increasing commercial, scientific, and technical applications involving ultraviolet (UV) radiation have led to the demand for improved understanding of the performance of instrumentation used to measure this radiation. There has been an effort by manufacturers of UV measuring devices (meters) to produce simple, optically filtered sensor systems to accomplish the varied measurement needs. We address common sources of measurement errors using these meters. The uncertainty in the calibration of the instrument depends on the response of the UV meter to the spectrum of the sources used and its similarity to the spectrum of the quantity to be measured. In addition, large errors can occur due to out-of-band, non-linear, and non-ideal geometric or spatial response of the UV meters. Finally, in many applications, how well the response of the UV meter approximates the presumed action spectrum needs to be understood for optimal use of the meters.

No MeSH data available.


Angular response of two UV meters.
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f6-j64lar: Angular response of two UV meters.

Mentions: Each meter was tested by precisely rotating the meter about an axis at the aperture while irradiating the meter with a narrow light beam. The results of these measurements are shown in Fig. 6 [4]. From the figure, we see for Meter A responsivity to light at 30° from normal was 3.5 % less than ideal, and Meter B was low by 45 %. An angle of 30° is at the edge of a solid angle corresponding to a numerical aperture (NA) of 0.5. Commercial photolithography instruments often use such a large solid angle. Since an accurate determination of the spatial characteristics of the incoming light in a stepper is not feasible, the use of a meter with a large nearly ideal angular response is strongly recommended. Otherwise, error is introduced when a different incident irradiation geometry from the source being measured is used in the calibration of a meter.


Sources of Error in UV Radiation Measurements
Angular response of two UV meters.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4862826&req=5

f6-j64lar: Angular response of two UV meters.
Mentions: Each meter was tested by precisely rotating the meter about an axis at the aperture while irradiating the meter with a narrow light beam. The results of these measurements are shown in Fig. 6 [4]. From the figure, we see for Meter A responsivity to light at 30° from normal was 3.5 % less than ideal, and Meter B was low by 45 %. An angle of 30° is at the edge of a solid angle corresponding to a numerical aperture (NA) of 0.5. Commercial photolithography instruments often use such a large solid angle. Since an accurate determination of the spatial characteristics of the incoming light in a stepper is not feasible, the use of a meter with a large nearly ideal angular response is strongly recommended. Otherwise, error is introduced when a different incident irradiation geometry from the source being measured is used in the calibration of a meter.

View Article: PubMed Central - PubMed

ABSTRACT

Increasing commercial, scientific, and technical applications involving ultraviolet (UV) radiation have led to the demand for improved understanding of the performance of instrumentation used to measure this radiation. There has been an effort by manufacturers of UV measuring devices (meters) to produce simple, optically filtered sensor systems to accomplish the varied measurement needs. We address common sources of measurement errors using these meters. The uncertainty in the calibration of the instrument depends on the response of the UV meter to the spectrum of the sources used and its similarity to the spectrum of the quantity to be measured. In addition, large errors can occur due to out-of-band, non-linear, and non-ideal geometric or spatial response of the UV meters. Finally, in many applications, how well the response of the UV meter approximates the presumed action spectrum needs to be understood for optimal use of the meters.

No MeSH data available.