Abstract: The present invention is directed to a system and method for tuning an optical fiber Bragg grating by using a circular mechanism which uniformly stretches the fiber along its length while at the same time preserving the minimal size for stretching.

Abstract: The present invention is directed to a system and method for tuning an optical fiber Bagg grating by using a cicular mechanism which uniformly stretches the fiber along its length while at the same time preserving the minimal size for stretching.

Abstract: Temperature compensated fiber stretching is accomplished by amplifying with a unique flexure the relative displacement between a rigid frame and a longitudinal spacing element. For passive compensation, relative displacement results from differential thermal expansion between the frame and the longitudinal spacer. For active thermal compensation and/or for wavelength tuning of an embedded fiber Bragg grating, relative displacement results from combining differential thermal expansion with active feedback length control of the longitudinal spacer. The feedback control can stabilize using length feedback from a displacement sensor or actively control length using temperature feedback, including logic elements, for example algorithms or look up tables. In an optical system, combined passive compensation and active control with flexure amplification provide superior thermal wavelength stability and tuning range.

Abstract: The present invention resides in a Fourier filter to detect defects on semiconductor wafers. The present invention relates to a Fourier filter to detect defects on semiconductor wafers which is less susceptible to having the filter output affected by vibrations and which avoids the physical contact from conventional damping.