This paper presents a novel method for controlling the laser-drilling process for a hole by monitoring induced plasma emission. The variation of light brightness from laser-induced plasma is used as an indicator to control laser percussion drilling. Through on-line plasma emission acquisition and analysis, we obtain the positive association between the increased depth and the optical signal output. A coaxial photodiode is used to estimate the brightness levels of laser-induced plasma. The above constitute an inexpensive and practical on-line feedback system that can be easily implemented in the laser systems. All of the processing work is performed in air under standard atmospheric conditions without gas assist. The acquired signal for drilling could also be used as an input to a focus point process control scheme. Moreover, the technology demonstrates the feasibility to develop an automated laser micromachining system. Experimental results show that drilling efficiency was increased 47% by applying the proposed defocusing laser percussion drilling.

A specialized high accurate gear artifact measuring instrument based on laser interferometry is developed in National Institute of Metrology (NIM, China), to fulfill the increasing demand for high accurate calibration of gear artifacts. This measuring instrument mainly consists of three linear guide rails, a rotary table, a 3D scanning probe and a laser measuring system. In the laser measuring system, laser beam from laser head is splited along two paths, one is arranged tangent to the base circle of gear for the measurement of profile deviation, another is arranged parallel to the gear axis for the measurement of helix deviation, both laser measurement performed with a resolution of 0.3nm. To minimize the influence of Abbe error, two cube-corner reflectors are placed close to the tip of probe. This measuring instrument operated automatically, during the measurement of gear artifact, all the signals from guide rails, rotary table, probe and laser measuring system are obtained synchronously. A software collects all the data for further calculation and evaluation. Development of this instrument makes it possible to guarantee the measurement of profile and helix direct traceable to the standard laser wavelength.

The use of optical systems for the dimensional inspection in industrial production (e.g. automotive, aeronautic) is steadily increasing. However, a thorough performance verification of such systems must still become more popular; now international standards have been published and the habit of verification may improve. The presentation will introduce to the key elements of prevailing standards. The basic rules for performance verification of Video CMMs and CMMs with fringe projection sensors and laser scanners, stand alone fringe projection and scanner systems will be discussed. In order to facilitate the verification according to prevailing standards, the author has developed a series of reference objects. These will be presented. A thematic excursion to some reference objects developed for the verification of photogrammetric and tomography systems will be made. For each measurement system the inherent problems and the developed solutions for the corresponding test artefacts will be analyzed.

Flick standard is a cylindrical artifact with a flat part for calibrating the magnification of a probe of roundness measuring-instruments. A probe magnification of roundness measuring-instruments is evaluated by measuring a calibrated flick value of a flick standard. The flick value is a distance between a cross-section circle and a cross-section line. In factory field, it is required that the flick value is calibrated within 0.1 µm with respect to several micrometer to several hundred micrometer. The flick value is generally calibrated by an accurate roundness measuring-instrument. It has a linear error of a probe with about 0.1% or more gain error. When the flick value is 100 µm, the measurement uncertainty is 0.1 µm or more. We calibrated a flick standard using an ultra-high accurate coordinate measuring instrument (CMM) with a laser interferometer to ensure the measurement uncertainty within 0.1 µm. The length measurement system by the laser interferometer is according to the abbe principle. In this paper, we describe the calibration method of a flick standard using the CMM. We calibrated the flick standard using a multiple-measurement technique to eliminate the systematic error of the CMM and estimated its uncertainty based on the analysis of variance. Finally, the proposed calibration method is validated through experiments.

X-ray reflectometry (XRR) is a powerful tool for the structural characterization of thin films. However the standardized protocols of the measurements and their analyses need to be established for the reliable and reproducible characterization. The collaborative work between National Institute of Standards and Technology (NIST, USA) and National Metrology Institute of Japan (NMIJ, Japan) for thickness evaluation by XRR has been carried out in order to support the activities for the standardization of the thickness evaluation. In order to evaluate the accurate thickness of thin film structures by XRR experiments, the appropriate model construction of the structures should be required for the XRR data analysis. However there have been numerous discussions about the structures especially around the film/substrate interface. We tried to clarify a depth density distribution of a thermal oxide thin film on a Si substrate by comparing the XRR results obtained from several films which were oxidized by different processes.