Alliance Fiber Optic Products, Inc.

Raintree Scientific Instruments (shanghai) Corporation

Tongxin Lu

Zhupei Shi

Xiaohan Wang

Zheng Yan

Minh Quang Tran

Jerry Lee

The present invention discloses an optical measurement and/or inspection device that, in one application, may be used for inspection of semiconductor devices. A method is disclosed for extracting information of a device-under-test for an ellipsometer, comprising the steps: providing a plurality of incoming polarized beams using a plurality of polarizers, where each of the beams being polarized at a designated polarizing angle; using a parabolic reflector to focus said plurality of incoming polarized beams on a spot on a DUT; using a parabolic reflector to collect a plurality of beams reflected from said DUT; and analyzing said collected beams using a plurality of analyzers, wherein each of the analyzers having a designated polarizing angle with respect to its respective polarizer.

Spectroscopic ellipsometers

A controllable attenuator includes a pair of collimators respectively connected to input and output fibers. A pair of reflection devices are respectively positioned behind the pair of collimators opposite to the corresponding input and output fibers. A U-like light path is defined among the pair of collimators and the pair of reflection devices. A neutral density filter is moveably positioned between the pair of reflection devices wherein a moving direction of the filter is preferably parallel to a longitudinal direction of the pair of collimators. An ND filter position indicator such as a potentiometer, is used to dynamically monitor attenuation setting.

Controllably variable optical attenuator

Method and apparatus for wavelength control and measurement are disclosed. An optical signal to be measured is tapped off a portion thereof referring to as a source signal. Together with a reference signal, the source signal is coupled to a tunable filter. The frequency response or passing band of the tunable filter is so controlled that one wavelength &lgr; from the source signal and one wavelength &lgr; from the reference signal transmit through. Relying on a band separation filter, the wavelength &lgr; is separated from the reference signal and coupled to a gas cell of a known spectrum, a filtered signal of the wavelength &lgr; is then coupled to a photo-detector for subsequent electrical measurement. In accordance with the known spectrum, the wavelength &lgr; can be precisely derived.

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San Jose, CA, United States of America

Tongxin Lu