Abstract: An interferometric measuring device for recording the shape, the roughness or the clearance distance of the surface of a measured object is provided, the measuring device having a modulating interferometer, to which is supplied short-coherent radiation by a radiation source, and which has a first beam splitter for splitting the radiation supplied into a first beam component guided via a first arm, and into a second beam component guided via a second arm. One beam is shifted with respect to the other beam, with the aid of a modulating device, in terms of the beam's light phase or light frequency, and passes through a delay line. The two beams are subsequently combined at an additional beam splitter of the modulating interferometer.

Abstract: A coherent differential absorption lidar (DIAL) device 2 comprises a transmit portion 4 for directing a combined light beam to a remote target and a receive portion 5 for receiving light returned from the remote target and for coherently mixing the received light with its associated local oscillator beam. The combined beam comprises at least two component light beams of discrete wavelengths. The device further comprises a signal correction means. The signal correction means comprising a means for extracting a portion of each component light beam from the transmit portion, a means for introducing a frequency difference 62 between each extracted component light beam and its associated local oscillator beam and a means for directing the extracted beam into the receive portion. This provides an additional correction signal thereby improving device performance.

Abstract: Defects are prevented from occurring during an exposure process by detecting vibration of and measuring the relative position of components of the exposure apparatus. The exposure apparatus includes an external frame on which a reference mirror is disposed, a projection lens, a first mirror fixed relative to the projection lens, a wafer stage, a second mirror fixed relative to the wafer stage, and an interferometer system that detects vibration of the projection lens using the reference mirror and the first mirror and detects the position of the wafer stage relative to the projection lens using the first and second mirrors. A second interferometer system may be provided to detect vibration of the first interferometer system.

Abstract: A phase shift interferometer (100) has an illuminating optical system (200) that emits a P-wave and an S-wave, a collimator lens (110), a reference half mirror (120), a pinhole plate (130) having a pinhole (131), and a phase shift interference fringe acquiring section (300) that allows an object light and a reference light contained in the light beam passed through the pinhole (131) interfere with each other in four different phases to acquire interference fringes with different phases. In the S-wave, only the reference light (SR) reflected by the reference half mirror (120) is passed through the pinhole (131), and the object light (SM) reflected by a surface-to-be-measured is blocked by the pinhole plate (130). In the P-wave, only the object light (PM) reflected by the surface-to-be-measured is passed through the pinhole (131), and the reference light (PR) reflected by the reference half mirror (120) is blocked by the pinhole plate (130).

Abstract: An interferometer is provided, comprising a source, a unit under test (UUT) with at least a first surface and second surface, a reflective optic, a detector and light from the source. The light is transmitted through the unit under test and reflects off of the reflective optic, which directs the light back to the unit under test. A first portion of light is reflected off the first surface of the UUT. A second portion of light is reflected off the second surface of the UUT. The first and second portions of light are then reflected by the reflective optic and are then transmitted through the UUT. The two portions of light are incident on the detector, where the first and second portions of light coherently add and the interference pattern is detected by the detector. A method for measuring the transmitted wavefront of the UUT is also provided.

Abstract: Disclosed herein are methods and apparatus for testing interferometric modulators. The interferometric modulators may be tested by applying a time-varying voltage stimulus and measuring the resulting reflectivity from the modulators.