Abstract

We present a technique we developed to measure specular reflectances of mirrors immersed in liquids and in air. The method works with a broad range of angles of incidence (Ө = 15–75°). The wavelength range used in this research was from 250 to 800 nm, and the state of polarization of the incident rays could be continuously varied with respect to the phase of incidence. The technique used in this study is based on a low-cost variable-angle reflectometer and a commercial spectrophotometer. Here we discuss the protocol we devised to extract reflectances with this instrument. This procedure was tested with samples that were measured through the use of ellipsometric techniques. The main advantages of the method discussed here are versatility, speed, and the availability of the equipment used; these are particularly useful for controlling the quality of a large number of samples. We present the results of reflectance measurements in water for dielectric coated aluminum intended for use in light concentrators for the Sudbury Neutrino Observatory. The error in our estimate of the overall reflectance, weighted over operational distributions of wavelength and incident angle, is ±3% for one sample and ±5% for the 2000 m² of coated material involved in this observatory.

© 1995 Optical Society of America

Optical properties of UV transmitting acrylics for use in a heavy water Cerenkov detector

Joanne C. Zwinkels, W. F. Davidson, and C. X. Dodd
Appl. Opt. 29(22) 3240-3248 (1990)

NBS specular reflectometer–spectrophotometer

Victor R. Weidner and Jack J. Hsia
Appl. Opt. 19(8) 1268-1273 (1980)

Sensitivity of the reflection technique: optimum angles of incidence to determine the optical properties of materials

B. J. Stagg and T. T. Charalampopoulos
Appl. Opt. 31(22) 4420-4427 (1992)

Use of a laser beam with an oblique angle of incidence to measure the reduced scattering coefficient of a turbid medium

Lihong Wang and Steven L. Jacques
Appl. Opt. 34(13) 2362-2366 (1995)

Procedures and standards for accurate spectrophotometric measurements of specular reflectance

Joanne C. Zwinkels, M. Noël, and C. X. Dodd
Appl. Opt. 33(34) 7933-7944 (1994)