The doctoral dissertations of the former Helsinki University of Technology (TKK) and Aalto University Schools of Technology (CHEM, ELEC, ENG, SCI) published in electronic format are available in the electronic publications archive of Aalto University - Aaltodoc.
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Optical Power Measurements: Applications in Fiber Optics and Ultraviolet Radiometry

Jouni Envall

Dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the Department of Electrical and Communications Engineering for public examination and debate in Auditorium S5 at Helsinki University of Technology (Espoo, Finland) on the 30th of June, 2006, at 12 noon.

Overview in PDF format (ISBN 951-22-8265-8)   [832 KB]
Dissertation is also available in print (ISBN 951-22-8264-X)

Abstract

The work described in this thesis has concentrated on development and characterization of detectors, measurement setups and measurement methods for the needs of optical metrology in the fields of fiber optics and ultraviolet (UV) radiometry.

A straightforward detector design for fiber optic power measurements, consisting of a single InGaAs photodiode, has been introduced. The simple and cost effective detectors were found applicable in high-precision measurements at <1-mW level with a combined measurement uncertainty of 0.9% (k=2).

Another detector type for fiber optic power measurements, consisting of an integrating sphere and an InGaAs photodiode, has been characterized for measurements at power levels up to 200 mW. Further characterizations have extended the power range up to 650 mW. The measurement uncertainty of the detector is 0.8% at 1-mW level and 1.3% at 100-mW level (k=2). The capability for accurate measurements of fiber optic power at 100-mW level has been found useful in studying the non-linear properties of optical fibers.

A high-intensity spectral comparator facility for measurements of spectral irradiance responsivity s(λ) at UV is presented. The setup consists of a single grating monochromator and intense xenon source. The high power levels are needed to obtain sufficient levels in narrow-band (1 nm) spectral measurements with broadband UV detectors. The power levels obtained were high enough even for measurements at UVB region (280-315 nm).

A sophisticated method for calibration of broadband detectors was tested. The method is based on the measured s(λ) of the detector. This method enables the irradiance responsivity of the detector to be calculated for any source whose spectral shape is known. The consistency between this method and the widely used spectroradiometric method was show.

A novel method for inter-comparisons of calibration facilities of broadband UV detectors is introduced. The method is based on the known s(λ) and angular response of the detector. The applicability of the method was verified with a successful inter-comparison between five laboratories.

This thesis consists of an overview and of the following 4 publications:

  1. Envall, J., Kärhä, P., Ikonen, E. 2004. Measurements of fibre optic power using photodiodes with and without an integrating sphere. Metrologia, vol. 41, pp. 353-358.
  2. Envall, J., Andersson, A., Petersen, J.C., Kärhä, P. 2005. Realization of the scale of high fiber optic power at three national standards laboratories. Applied Optics, vol. 44, pp. 5013-5017.
  3. Envall, J., Kärhä, P., Ikonen, E. Calibration of broadband ultraviolet detectors by measurement of spectral irradiance responsivity. Review of Scientific Instruments. (in press)
  4. Envall, J., Ylianttila, L., Moseley, H., Coleman, A., Durak, M., Kärhä, P., Ikonen, E. 2006. Investigation of comparison methods for UVA irradiance responsivity calibration facilities. Metrologia, vol. 43, S27-S30.

Keywords: optical power, measurement standard, calibration, fiber optics, ultraviolet, spectral irradiance responsivity

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© 2006 Helsinki University of Technology

Last update 2011-05-26