Requirements of surface quality of silicon wafer are increasingly restrict. Many investigations have been done to inspect defects on silicon wafer. However, rare studies have been reported on defect components inspection which is also critical to trace to the source of defects and monitor the manufacture processes in time. In order to inspect the components of contaminated particles on silicon wafer, especially with a high speed and in line mode, dual nanosecond pulse laser system both wavelengths at 532nm is designed in which one laser pumps the particles away from wafer surface almost without damage, the other laser breakdowns the particles in air above the wafer surface to obtain the emission lines of the contaminated particles by a spectroscopy with CCD. The sensitivity of the dual pulse laser system is evaluated.
We have investigated the use of atomic force microscope (AFM) cantilevers as encoder for real-time high-resolution
displacement measurements. Mathematical derivations show that two AFM cantilevers signals are needed for real-time
forward and backward displacement measurements in any planar direction and in x- or y-axis direction respectively when
two are paired with a 1D sinusoidal grating. Tuning-fork (TF) cantilevers are the best choice among AFM cantilevers for
the setup of a multi-cantilever encoder head. During the study an AFM head with up to three TF cantilevers as the
encoder has been designed and built. The system was experimentally tested for its performance and feasibility of realtime
displacement measurements in x- or y- axis by using two cantilevers. To achieve a correct reading the distance
between two cantilever tips is preset in such a way that the two 1D sinusoidal grating position-encoded signals have a
quadrature phase shift form. The decoding algorithm is based on directly unwrapping of the phase from the signals in
real-time. Cross-correlation filtering and differentiation process of two encoded signals could be applied to suppress the
noise and to reduce the offset and tilt of the encoded signals and by this allows a successful implementation of real-time
Bragg grating-based sensor devices are popular as they are relatively simple to fabricate and use, but the need for compensation for temperature effects is of particular importance for accurate and reliable measurement of other parameters. Equally, the use of rare-earth-doped fiber has revolutionized many aspects of both communications and sensor systems and recent research has produced fluorescence decay-time and intensity ratio transducer devices which yield reproducible and accurate temperature measurement. This work reports on research carried out on sensor devices using co-located Bragg gratings and fluorescence decay-time sensors, using both separate optical fibers (plain and rare-earth-doped silica respectively) or with the Bragg grating actually written into the fluorescent fiber. The sensor system thus created is simple and effective with a single optical source used to excite both the fluorescence emission (which provides decay time information) and to enable the measure-induced Bragg grating wavelength shift to be determined. With such systems under test, satisfactory strain and temperature resolutions have been achieved. Applications include temperature compensated structural monitoring and monitoring of temperature in structures where the sensors are exposed to strain.