Profile: Litel Instruments, Inc. is a provider of measuring instruments. Our products offer complete characterization of the optical capabilities of lithography systems in order to identify, diagnose and reduce fabrication variations and errors. Our Z-height mapper(ZMAP) consists of both hardware and software which includes four different modes of focus measurements that allows the user to measure the focus components of a lithography exposure tool. Our in-situ interferometer(ISI) is an wavefront interferometer providing measurement of lithography tool lens aberrations and it eliminates the need for monitor wafers & it also measures multiple locations in the lens field for flexible full projection lens characterization.