Abstract: One system of the present invention includes a modulated light source subsystem to provide a first light signal with a first modulation index, and a second light signal with a second modulation index. The system also includes a region to receive an analyte for evaluation and direct the first light signal thereto, and a detector responsive to the second light signal and a third light signal from the region to provide an output representative of spectroscopic information. The third light signal further includes noise induced by residual amplitude modulation that is reduced at the detector by the second light signal in accordance with a difference between the first modulation index and the second modulation index.

Abstract: Techniques for measuring the temperature at various locations through the thickness of glass products and to control the glass processing operation with the sensed temperature information are disclosed. Fluorescence emission of iron or cerium in glass is excited and imaged onto segmented detectors. Spatially resolved temperature data are obtained through correlation of the detected photoluminescence signal with location within the glass. In one form the detected photoluminescence is compared to detected scattered excitation light to determine temperature. Stress information is obtained from the time history of the temperature profile data and used to evaluate the quality of processed glass. A heating or cooling rate of the glass is also controlled to maintain a predetermined desired temperature profile in the glass.

Abstract: A non-destructive and non-contact method for measuring stress at the mid-plane of tempered glass plates that uses Bragg scattering from a pair of thermal gratings. The gratings are formed by parallel writing beams of laser light retroreflected through the glass. The polarization state of light from a delayed laser beam that scatters from both these thermal gratings is measured, and the change in polarization of the doubly scattered light with separation between the two gratings is correlated to the in-plane stress. Systems and techniques to take these measurements and control a glass manufacturing process are also disclosed.

Abstract: Techniques for measuring the temperature at various locations through the thickness of glass products and to control the glass processing operation with the sensed temperature information are disclosed. Fluorescence emission of iron or cerium in glass is excited and imaged onto segmented detectors. Spatially resolved temperature data are obtained through correlation of the detected photoluminescence signal with location within the glass. In one form the detected photoluminescence is compared to detected scattered excitation light to determine temperature. Stress information is obtained from the time history of the temperature profile data and used to evaluate the quality of processed glass. A heating or cooling rate of the glass is also controlled to maintain a predetermined desired temperature profile in the glass.