Investigation of a Three-Dimensional Micro-Scale Sensing System Based on a Tapered Self-Assembly Four-Cores Fiber Bragg Grating Probe

Abstract

Three-dimensional micro-scale sensors are in high demand in the fields of metrology, precision manufacturing and industry inspection. To extend the minimum measurable dimension and enhance the accuracy, a tapered four-cores fiber Bragg grating (FBG) probe is proposed. The sensing model is built to investigate the micro-scale sensing characteristics of this method and the design of the tapered stylus is found to influence the accuracy. Therefore, a π/2 phase-shift point is introduced into the FBGs comprised in the probe to suppress spectrum distortion and improve accuracy. Then, the manufacturing method based on capillary self-assembly is proposed to form the probe and the critical length to form a square array for four cylindrical fibers is verified to be effective for the tapered fibers. Experimental results indicate that the design of the tapered stylus can extend the minimum measurable dimension by twofold and has nearly no influence on its sensitivity. The three-dimensional measurement repeatability is better than 31.1 nm and the stability is better than 200 nm within once measuring process. Furthermore, the measurement precision of the three-dimensional micro-scale measurement results is less than 150 nm. It would be widely used in measuring micro-scale features for industry inspection or metrology.

Development of a High-Function Fiber Stylus for Microstructure Measurement with Water-Repellent and Antistatic Coatings

“…However, it is extremely difficult to accurately measure microstructures such as micrometer-order small holes and grooves with a high aspect ratio. Various microstructure measurement system based on different principles have been proposed [4][5][6][7][8][9][10][11][12][13][14][15].…”

Microscopic Three-Dimensional Measurement Based on Telecentric Stereo and Speckle Projection Methods

“…Among them, non-contact optical methods have been widely used because of their non-destructiveness, flexibility, and high efficiency. Some measurement methods such as digital holography [ 3 ], confocal microscopy [ 4 ], white-light interferometry [ 5 ] and optical fiber probe method [ 6 , 7 , 8 ], etc., can achieve submicron or even nano-scale measurement accuracy, whereas their measurement ranges are in sub-millimeter, micron, or sub-micron scale.…”