Abstract: A matrix with a biologically active substance is exposed to UV radiation. The biologically active substance is selected to initiate photoconversions originating vitamin D synthesis. An optical parameter of the biologically active substance is being changed under UV irradiation. Change of the optical parameter is measured, thus measuring the amount of UV radiation that has caused the vitamin D synthesis occurred through photoconversion. Measuring occurs by way of a dosimeter.

Abstract: A method for estimating a chemical composition of a material in a borehole penetrating the earth, the method includes: placing an analysis unit into the borehole; placing a sample of the material onto an enhanced surface of the analysis unit, the enhanced surface having a feature configured to increase an electric susceptibility of the sample at an interface between the sample and the enhanced surface; illuminating the sample at the interface with a first light beam and a second light beam; measuring sum frequency light generated from the illuminating; and analyzing the sum frequency light to estimate the chemical composition of the material.

Abstract: A PET scanner (8) includes a ring of detector modules (10) encircling an imaging region (12). Each of the detector modules includes at least one detector pixel (24,34). Each detector pixel includes a scintillator (20, 30) optically coupled to one or more sensor APDs (54) that are biased in a breakdown region in a Geiger mode. The sensor APDs output a pulse in response to the light from the scintillator corresponding to a single incident radiation photon. A reference APD (26, 36) also biased in a break-down down region in a Geiger mode is optically shielded from light and outputs a temperature dependent signal. At least one temperature compensation circuit (40) adjusts a bias voltage applied to the sensor APDs based on the temperature dependent signal.

Abstract: A compact image sensor for imaging radiation emitted by fluorescing objects exposed to excitation light is disclosed. The compact image sensor includes a light guide defining a longitudinal axis for channeling radiation emitted by the fluorescing object; a reflective surface defined on the light guide that is oriented at an angle with respect to the longitudinal axis of the light guide to reflect the excitation light away from a detector of the image sensor; and the detector positioned at an end of the light guide for imaging radiation emitted by the fluorescing object. Also disclosed is a fluorescence imaging system for imaging radiation emitted by a fluorescing object to be imaged by compact image sensor and a method of fluorescence imaging.