Fractional Fringe Order Method Using Fourier Analysis for Absolute Measurement of Block Gauge Thickness

Tsai, Ming-Hong; Huang, Hongxin; Itoh, Masahide; Yatagai, Toyohiko

doi:10.1007/s10043-999-0449-x

Cited by 15 publications

(9 citation statements)

References 18 publications

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“…Next, the integer m i is decided so as to satisfy the inequality constraint of | L − L i | < α(λ i /2) for all λ i simultaneously with α being a positive constant selected as small as 1/100. This process is implemented in real time by numerical iteration using LabVIEW software (National Instruments) by adopting the conventional algorithm of the excess fraction method 38 , or smart algorithms devised to minimize the computation time in dealing with a large group of m i candidates 39 40 . Convergence to a unique true solution of m i requires that the uncertainty of L i should be less than a quarter of λ i , i.e.…”

Section: Resultsmentioning

confidence: 99%

Comb-referenced laser distance interferometer for industrial nanotechnology

Jang

Wang

Hyun

et al. 2016

Sci Rep

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A prototype laser distance interferometer is demonstrated by incorporating the frequency comb of a femtosecond laser for mass-production of optoelectronic devices such as flat panel displays and solar cell devices. This comb-referenced interferometer uses four different wavelengths simultaneously to enable absolute distance measurement with the capability of comprehensive evaluation of the measurement stability and uncertainty. The measurement result reveals that the stability reaches 3.4 nm for a 3.8 m distance at 1.0 s averaging, which further reduces to 0.57 nm at 100 s averaging with a fractional stability of 1.5 × 10−10. The uncertainty is estimated to be in a 10−8 level when distance is measured in air due to the inevitable ambiguity in estimating the refractive index, but it can be enhanced to a 10−10 level in vacuum.

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Section: Resultsmentioning

confidence: 99%

Comb-referenced laser distance interferometer for industrial nanotechnology

Jang

Wang

Hyun

et al. 2016

Sci Rep

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“…On the other hand, the integer m i has to be identified by solving all the equations of equation (1) simultaneously. This implies that equation (1) represents indeterminate simultaneous equations whose solutions have to be found by iterative search (Tsai et al, 1999). This implies that equation (1) represents indeterminate simultaneous equations whose solutions have to be found by iterative search (Tsai et al, 1999).…”

Section: Measurement Methodsmentioning

confidence: 99%

Real-time absolute distance measurement by comb-based generation of multiple wavelengths

Hyun

Kim

Chun

et al. 2012

IJNM

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We present a novel scheme of exploiting the frequency comb of a femtosecond laser as the wavelength ruler for real-time measurement of absolute distances. Four different wavelengths are simultaneously generated in parallel to perform absolute distance measurements by means of multi-wavelength interferometry at an update rate of 100 Hz. When compared to commercial laser interferometers, the proposed scheme shows a discrepancy of 32 nm on average in measuring a ~2.3 m distance, proving to be a competitive tool for industrial applications.

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“…Such improvement is notable especially in the calibration of long GBs. The length of a GB can be determined from the following equation [14]:…”

Section: Gauge Block Interferometermentioning

confidence: 99%

“…In order to determine N, several wavelengths should be used for the measurement of L. In addition, the GB length must be known within a certain range. The number of wavelengths used depends on how wide this range is, the wavelength difference values, and the fraction measurement uncertainty [14]. For previous knowledge of a GB length within 1 mm (which could be easily mechanically measured), four wavelengths will be sufficient [11].…”

Section: Gauge Block Interferometermentioning

confidence: 99%

Absolute gauge block calibration using ultra-precise optical frequency synthesizer locked to a femtosecond comb

2015

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In this paper, we report a gauge block (GB) calibration that is traceable to the SI unit of time, the second. Four ultra-stable optical telecommunication wavelengths near 1556 nm are obtained by locking a narrow-tuning-range fiber laser to a fiber-based femtosecond frequency comb. Since the GB calibration system does not operate at this region of spectrum, the superior frequency stability of the laser is transferred to the 778 nm region by using a waveguide periodically poled lithium niobate crystal. After applying the locking scheme, the stability and accuracy of the laser become better than 8×10(-12). The frequency-doubled light is sent through 30 m optical fiber to a GB interferometer, which is installed at a different laboratory in the same building. Using this calibration scheme, a GB with a nominal length of 100 mm is calibrated with an uncertainty of ±52 nm. This uncertainty value is still comparable to or even better than other metrology laboratories for a similar block length.

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Fractional Fringe Order Method Using Fourier Analysis for Absolute Measurement of Block Gauge Thickness

Cited by 15 publications

References 18 publications

Comb-referenced laser distance interferometer for industrial nanotechnology

Comb-referenced laser distance interferometer for industrial nanotechnology

Real-time absolute distance measurement by comb-based generation of multiple wavelengths

Absolute gauge block calibration using ultra-precise optical frequency synthesizer locked to a femtosecond comb

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