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The Stokes parameters (S0, S1, S2, and S3) of monochromatic light can be measured using the adjustable azimuth settings of a quarter-wave plate and a polarizer. When measuring the Stokes parameters of light of an arbitrary wavelength, the measurement of S3 is affected by the phase difference error Δq(λi), due to the mismatch with respect to wavelength with the quarter-wave plate. In this method, Δq(λi), due to such a mismatch of incident light of arbitrary wavelength, can be overcome by a judicious choice of azimuth settings of the quarter-wave plate and the use of a polarizer; however, the use of a precision quarter-wave plate is necessary. The present paper proposes a measurement method of Stokes parameters of incident light of arbitrary wavelength using a quarter-wave plate with phase difference errors.

A phase unwrapping method that employs scattered-light photoelasticity with unpolarized light was proposed for automated three-dimensional stress analysis [Appl. Opt. 45, 8848 (2006)]. I now demonstrate the validity of this method by performing nondestructive measurements at three different wavelengths of the secondary principal stress direction psi(j) and the total relative phase retardation rho(jtot) in the plane that contains the rotated principal stress directions in a spherical frozen stress model and compare the results obtained with mechanically sliced models. The parameters psi(j) and rho(jtot) were measured nondestructively over the entire field of view for the first time, to the best of my knowledge.

In scattered-light photoelasticity with unpolarized light, the secondary principal stress direction psi and the relative phase retardation rho in a three-dimensional stressed model with rotation of the principal stress axes can be obtained by use of Stokes parameters. For completely automated stress analysis, measurements of the total relative phase retardation and the secondary principal stress direction over the entire field are required, and it is necessary to unwrap psi and rho. A phase unwrapping method is thus proposed for the determination of these values based on scattered-light photoelasticity. The values are easily obtained via an arctangent function, overcoming the error associated with the quarter-wave plate by employing an incident light of different wavelengths. The proposed technique provides automated and nondestructive determination of the total relative phase retardation and the secondary principal stress direction in a model exhibiting rotation of the principal stress axes.

We propose a focusing waveguide mirror with a shallow tapered edge in a slab waveguide and demonstrate it by planar processes and wet etching. A light beam 2 mm wide is focused to 6.5 µm full width at half-maximum at a wavelength of 0.6328 µm. A reflectivity of higher than 90% at the tapered edge is obtained. The inclination ratio of the tapered mirror edge is 1:90. Fairly good correspondence between measured and calculated focused spot sizes is obtained.

We have developed an innovation of the polarized reflectances measurement technique for thickness and index (PRETTI) method, PRETTI-S, which is a simple and accurate technique to obtain the refractive index n and thickness d of a thin film by using S-polarized and P-polarized reflectances measured at oblique angles of incidence. In the PRETTI-S method, the n and d are determined by using only S-polarized reflectances. Therefore, the measurement and numerical procedure to extract the n and d are simpler than the conventional PRETTI method. As an example, measurement of a single-layer film (SiO(2)/Si) is carried out and excellent confirmation is obtained.

A new technique to obtain the refractive index and thickness of a thin film simultaneously is presented. The reflectances of p-polarized light and s-polarized light are measured at various angles of incidence, and by a numerical procedure the film index and thickness are extracted from the measured reflectances. The measurements and numerical procedure are simple, and the values obtained are accurate. As an example, we made measurements on a single layer film (SiO(2)/Si) and a double layer film (SiON/SiO(2)/Si) and confirmed that the values obtained were consistent.

The stress distribution in a model of the human ankle joint was measured nondestructively by using scattered-light polarizer photoelasticity [Kihara et al., Appl. Opt. 24, 3363 (1985)]. The present paper describes experimental results for 3-D stress distributions for front and side views of three solid models of the human ankle joint under static loading, which have different dorsiflexions; they are measured nondestructively using this method. The three ankle joint models correspond to the 10 degrees dorsiflexion, the neutral, and the 10 degrees plantar flexion positions, respectively.