A curve fitting signal processing scheme for a white-light interferometric system with a synthetic source

Remote Internal Diameter Measurement of Ring Gauge Based on a Low-Coherence Tandem Scheme

“…As far as the remote distant measurement based on two connected Michelson interferometers (namely, tandem interrferometric scheme) is concerned, Flournoy [5] et al seem to have been the first, in the 1970s, to measure variations in moving transparent films. After that, various experiments were proposed using a white-light tandem scheme between two separated points -a transducer point and a receiver point -for measurement of the displacement [6][7][8], high-sensitivity detection of low surface-reflectivity [9], precision group refractive-index metrology [10][11][12] and remote calibration of length standards [1][2][3]. More recently, Volkov et al applied a tandem interferometry for monitoring of metalorganic vapour-phase epitaxy processes [13], Kao et al presented a scanning white-light tandem interrferometric method for determining the cell gap of liquid crystal displays [14] and Wei et al proposed and experimentally demonstrated a more general tandem technique, called a femtosecond optical frequency comb-based tandem interferometer, which takes advantages of both the temporal coherence characteristics of a femtosecond optical frequency comb light source and the transmission characteristics of acquired length information based on a tandem interferometer [15].…”

“…However, in all of these previous works [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15], the measurement is restricted to only outside size, and few technologies of determining the internal size were given.…”