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Cs fountain clock 1

Error analysis 1

FS optical comb 1

Optical metrology 1

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Stereo deflectometry 1

Three-dimensional shape measurement 1

frequency standard 1

lateral shearing interferometry 1

metrology 1

metrology，certification and accreditation，inspection and testing 1

multi-probe error separation 1

national quality infrastructure (NQI)，standards 1

self-referenced measurement 1

stabilized laser 1

surface metrology 1

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Development Strategy of National Quality Infrastructure in China

Gong Kenan, Yu Lianchao, Xu Xuelin

Strategic Study of CAE 2021, Volume 23, Issue 3, Pages 46-52 doi: 10.15302/J-SSCAE-2021.03.015

Abstract:

National quality infrastructure (NQI) is the technical foundation of a country’s high-quality development and an important component of the national innovation system. Improving the technical capacity and management level of the NQI is a key means to promote China’s strength in science and technology and product quality. Conducting strategic research on NQI is critical for transforming China from a country of quantity to a country of quality. This study analyzes the status quo and existing problems in the development of quality infrastructure in China and abroad and proposes the overall idea, objectives, and future direction of the NQI development strategy for China. Furthermore, we propose several policies to provide support and reference for the scientific development of China’s NQI, including clarifying the strategic positioning of NQI, optimizing the construction of NQI, consolidating NQI technical foundations and systemic services, strengthening diversified resource investment, and participating in the international exchanges of NQI.

Keywords： national quality infrastructure (NQI)，standards metrology，certification and accreditation，inspection

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Review of self-referenced measurement algorithms: Bridging lateral shearing interferometry and multi-probe error separation

Dede ZHAI, Shanyong CHEN, Ziqiang YIN, Shengyi LI

Frontiers of Mechanical Engineering 2017, Volume 12, Issue 2, Pages 143-157 doi: 10.1007/s11465-017-0432-3

Abstract:

With the development of new materials and ultra-precision processing technology, the sizes of measured objects increase, and the requirements for machining accuracy and surface quality become more exacting. The traditional measurement method based on reference datum is inadequate for measuring a high-precision object when the quality of the reference datum is approximately within the same order as that of the object. Self-referenced measurement techniques provide an effective means when the direct reference-based method cannot satisfy the required measurement or calibration accuracy. This paper discusses the reconstruction algorithms for self-referenced measurement and connects lateral shearing interferometry and multi-probe error separation. In lateral shearing interferometry, the reconstruction algorithms are generally categorized into modal or zonal methods. The multi-probe error separation techniques for straightness measurement are broadly divided into two-point and three-point methods. The common features of the lateral shearing interferometry method and the multi-probe error separation method are identified. We conclude that the reconstruction principle in lateral shearing interferometry is similar to the two-point method in error separation on the condition that no yaw error exists. This similarity may provide a basis or inspiration for the development of both classes of methods.

Keywords： self-referenced measurement lateral shearing interferometry multi-probe error separation surface metrology

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Microwave－Optical Frequency Standards at NIM：Realizing of Definition of Metre and Second

Li Tianchun

Strategic Study of CAE 2007, Volume 9, Issue 6, Pages 27-31

Abstract:

The paper presents the realization, at NIM, of SI time unit second using the NIM4 cesium fountain clock, SI length unit meter using a femto-second (FS) optical frequency comb and calibration of wavelengths of stabilized lasers by this FS comb. The uncertainty of NIM4 fountain clock was evaluated as 5 × 10 ^{- 15}. The frequency uncertainty of the FS optical comb locked to a H-maser, which is steered by NIM4 clock, was estimated as 2. 2 × 10^{- 14}. The function, significance of Cs fountain clock, stabilized lasers, optical comb and relationship among them are discussed. Finally the progress of NIM5 fountain clock and the construction of a Sr atom optical clock started in 2006 at NIM are reported.

Keywords： metrology frequency standard stabilized laser Cs fountain clock FS optical comb

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Performance Analysis and Evaluation of Geometric Parameters in Stereo Deflectometry Article

Yongjia Xu, Feng Gao, Xiangqian Jiang

Engineering 2018, Volume 4, Issue 6, Pages 806-815 doi: 10.1016/j.eng.2018.10.007

Abstract:

This paper presents a novel geometric parameters analysis to improve the measurement accuracy of stereo deflectometry. Stereo deflectometry can be used to obtain form information for freeform specular surfaces. A measurement system based on stereo deflectometry typically consists of a fringe-displaying screen, a main camera, and a reference camera. The arrangement of the components of a stereo deflectometry system is important for achieving high-accuracy measurements. In this paper, four geometric parameters of a stereo deflectometry system are analyzed and evaluated: the distance between the main camera and the measured object surface, the angle between the main camera ray and the surface normal, the distance between the fringe-displaying screen and the object, and the angle between the main camera and the reference camera. The influence of the geometric parameters on the measurement accuracy is evaluated. Experiments are performed using simulated and experimental data. The experimental results confirm the impact of these parameters on the measurement accuracy. A measurement system based on the proposed analysis has been set up to measure a stock concave mirror. Through a comparison of the given surface parameters of the concave mirror, a global measurement accuracy of 154.2 nm was achieved.

Keywords： Optical metrology Error analysis Stereo deflectometry Three-dimensional shape measurement Performance