Abstract: A method and apparatus for measuring the change in refractive index of a material with respect to temperature. The invention contemplates measuring the change in length of the material with respect to temperature over a predetermined temperature range with a Fizeau Interferometer by measuring the change in length through a vacuum at a point adjacent the length to produce a first set of data. Also measured is the change in the same length of the same material with respect to temperature over the same predetermined temperature range with the Interferometer by measuring the change in the length through the material to produce a second set of data. Determining the difference between the first and second sets of data produces resulting data which is the change in refractive index of the material with respect to temperature.

Abstract: A method and apparatus for optically measuring coefficient of thermal expansion includes an optical dilatometer system. The system provides a housing having a chamber defined therein and a transparent end adapted for receiving a focused laser beam into the chamber. The housing is adapted for maintaining a vacuum in the chamber. The optical dilatometer system further provides an interferometer comprising first and second interference surfaces, the interferometer being positioned within the chamber. The system further provides a test sample positioned between the first and second interference surfaces. The method includes the step of transmitting a focused laser beam through the transparent end and to the interferometer, thereby generating an interference pattern defined by Newton rings. The Newton ring interference pattern is utilized to determine the coefficient of thermal expansion of the test sample.

Abstract: A method and apparatus for optically measuring coefficient of thermal expansion includes an optical dilatometer system. The system provides a housing having a chamber defined therein and a transparent end adapted for receiving a focused laser beam into the chamber. The housing is adapted for maintaining a vacuum in the chamber. The optical dilatometer system further provides an interferometer comprising first and second interference surfaces, the interferometer being positioned within the chamber. The system further provides a test sample positioned between the first and second interference surfaces. The method includes the step of transmitting a focused laser beam through the transparent end and to the interferometer, thereby generating an interference pattern defined by Newton rings. The Newton ring interference pattern is utilized to determine the coefficient of thermal expansion of the test sample.

Abstract: A laser block for a ring laser angular rate sensor is provided with an expandable ring inserted into a cavity through the block. The ring is rigidly expanded against the walls of the cavity with substantially zero axial deflection to increase the stiffness of the ring laser block with respect to forces perpendicular to its lasing plane.