Effects of multiple reflections on nonlinear absorption measurements.

Accurate measurement of nonlinear absorption coefficients by transmission-based techniques, such as Z-scan and its modifications, remains challenging due to high measurement errors. In this Letter, we claim that one of the reasons for that could lie in ignoring multiple reflections of light in plane-parallel samples in the presence of multi-photon excitation. Closed-form formulations for transmittance and reflectance coefficients, considering both linear and multiphoton absorption, are obtained in the geometrical optics approximation.

Technical Note: ID-card-size dosimeter based on radiochromic films for continuous personnel monitoring.

Purpose: This paper is aimed at investigating the feasibility of developing a personal dosimeter of cumulative radiation dose which would incorporate the following features: 1) a small size compared to that of a proximity ID card; 2) instant dose readout; 3) no power source; 4) moderate cost. The dosimeter is proposed as a potential replacement for TLD and OSL dosimeters used by nuclear industry workers and some medical staff groups.

Methods: An original detector design is developed containing a two-color LED, two photodetectors located in one plane covered with a mirror coating.