Xiangqian Jiang

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We introduce a new optical interferometry system for fast areal surface measurement of microscale and nanoscale surfaces that are immune to environmental noise. Wavelength scanning interferometry together with an acousto-optic tunable filtering technique is used to measure surfaces with large step heights. An active servo control system serves as a(More)
A wavelength scanning interferometer for measuring the surface and thickness of a transparent film has been studied. A halogen light source combined with an acousto-optic tuneable filter is used to generate a sequence of filtered light in a Linnik interferometer, which leads to a sequence of interferograms captured by a CCD camera. When a transparent thin(More)
Geometrical product specification and verification (GPS) matrix system is a universal tool for expressing geometrical requirements on product design drawings. It benefits product designers through providing detailed description of functional requirements for geometrical products, and through referring to corresponding manufacturing and verification(More)
Freeform surfaces are widely used in advanced optical and mechanical devices. In order to assess the form quality of a freeform surface, it is required to match the measurement surface with the design template. To improve the matching efficiency and accuracy, the whole procedure is divided into two stages, rough matching and final fitting. A new rough(More)
We propose a self-reference multiplexed fiber interferometer (MFI) by using a tunable laser and fiber Bragg grating (FBG). The optical measurement system multiplexes two Michelson fiber interferometers with shared optical path in the main part of optical system. One fiber optic interferometer is used as a reference interferometer to monitor and control the(More)
Improved online techniques for surface profile measurement can be beneficial in high/ultra-precision manufacturing, in terms of enabling manufacture and reducing costs. This paper introduces a spatially dispersed short-coherence interferometer sourced by a super luminescent diode. This technique uses a broadband light source, which is spatially dispersed(More)
We introduce a new surface measurement method for potential online application. Compared with our previous research, the new design is a significant improvement. It also features high stability because it uses a near common-path configuration. The method should be of great benefit to advanced manufacturing, especially for quality and process control in(More)
Wavelength scanning interferometry (WSI) can be used for surface measurement with discontinuous surface profiles by producing phase shifts without any mechanical scanning process. The choice of algorithms for the WSI to analyze the fringe pattern depends on the desired accuracy and computing speed. This paper provides comparison of four different algorithms(More)
Light beam scanning using a dispersive element and wavelength tuning is coupled with fiber-optic interferometry to realize a new surface measurement instrument. The instrument is capable of measuring nanoscale surface structures and form deviations. It features active vibration compensation and a small optical probe size that may be placed remotely from the(More)
The most common approach for fingerprint analysis is using minutiae that identifies corresponding features and evaluates the resemblance between two fingerprint impressions. Although many minutiae point pattern matching algorithms have been proposed, reliable automatic fingerprint verification remains as a challenging problem. Finger print recognition can(More)