Comb-referenced laser distance interferometer for industrial nanotechnology

Jang, Yoon-Soo; Wang, Guochao; Hyun, Sangwon; Kang, Hyun Jay; Chun, Byung Jae; Kim, Young‐Jin; Kim, Seung-Woo

doi:10.1038/srep31770

“…the air refractive index will deviate from the value (n air − 1)10 8 = 27403.6 [84]. According to [67] the relative uncertainty of the distance can be estimated to be about δz obj /z obj = 2 · 10 −8 . For our experimental conditions the influence of the uncertainty of n air needs to be considered only for z obj > 5 m.…”

Section: The Detection Systemmentioning

confidence: 99%

“…An interesting line of more recent development is based on Hänsch-type frequency combs, often with sub-mm accuracy, some of them developed for applications over very long distances in space (e.g. [60,61,62,63,64,65,66,67]). One common feature of most of the techniques discussed in those reviews is the need to accurately measure, in one way or another, intensities returned from the object.…”

Section: Laser-based Distance Measurementsmentioning

confidence: 99%

Ranging with frequency-shifted feedback lasers: from $$\upmu$$ μ m-range accuracy to MHz-range measurement rate

Kim¹,

Ogurtsov²,

Bonnet³

et al. 2016

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We report results on ranging based on frequency shifted feedback (FSF) lasers with two different implementations: (1) An Ytterbium-fiber system for measurements in an industrial environment with accuracy of the order of 1 µm, achievable over a distance of the order of meters with potential to reach an accuracy of better than 100 nm; (2) A semiconductor laser system for a high rate of measurements with an accuracy of 2 mm @ 1 MHz or 75 µm @ 1 kHz and a limit of the accuracy of ≥ 10 µm. In both implementations, the distances information is derived from a frequency measurement.The method is therefore insensitive to detrimental influence of ambient light. For the Ytterbium-fiber system a key feature is the injection of a single frequency laser, phase modulated at variable frequency Ω, into the FSFlaser cavity. The frequency Ω max at which the detector signal is maximal yields the distance. The semiconductor FSF laser system operates without external injection seeding. In this case the key feature is frequency counting that allows convenient choice of either accuracy or speed of measurements simply by changing the duration of the interval during which the frequency is measured by counting.

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“…As a result, conventional schemes of multi-wavelength interferometers were not capable of achieving absolute distance measurements over several meters without losing the superb sub-wavelength measurement resolution of laser-based phase-measuring interferometers. Figure 3 shows the basic concept of multi-wavelength interferometry implemented by generating four wavelengths with reference to the frequency comb of a modelocked laser [49,50]. Each wavelength k i (i = 1,2,3,4) is phase-locked individually to its pre-assigned modes of the frequency comb, so the target distance L is given in terms of k i as L i = (k i /2n i )/(m i ?…”

Section: Comb-based Multi-wavelength Interferometermentioning

confidence: 99%

“…Besides, e i denotes the excess fraction that can be calculated directly from the measured interferometric phase divided by 2p. Then the exact value of the target length L is determined by optimizing the integer value m i so as to minimize the sum of |L -L i | for all k i through a sequence of numerical iterations [50]. This metrological principle of multi-wavelength interferometry is well suited to exploit the frequency comb of a mode-locked laser as the wavelength ruler, i.e., the multiple wavelengths are extracted from the frequency comb with high selectivity as well as stability.…”

Section: Comb-based Multi-wavelength Interferometermentioning

confidence: 99%

“…In recent years, in order to meet evergrowing industrial demands on the measurement precision and functionality, quit a few attempts have been made worldwide. Examples include synthetic wavelength interferometry [43][44][45], multi-wavelength interferometry [46][47][48][49][50], spectrally resolved interferometry [51][52][53][54], timeof-flight measurement [55][56][57][58][59] and dual-comb interferometry [60][61][62][63][64].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Distance Measurements Using Mode-Locked Lasers: A Review

Jang

¹

,

Kim

²

2018

Self Cite

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We present a progress review on the advance of distance measurements made at KAIST by making use of mode-locked lasers as the light source to meet ever-growing industrial demands on the measurement precision and functionality. Diverse principles exploited for the progress are described in this review with focus on four attributes: first, the optical spectrum of a mode-locked laser, distinctively called the frequency comb, permits multi-wavelength interferometry to be realized for absolute distance measurement up to several meters without losing the nanometer precision of well-established laser-based phase-measuring displacement measurement. Second, the frequency comb enables spectrally resolved interferometry for absolute distance measurement to be conducted with a nanometer resolution by Fourier transform analysis of the dispersive interference data captured using a spectrometer. Third, the mode-locked laser in the time domain appears as a train of ultrashort pulses, of which the time-of-flight is measured with a picosecond resolution by control of the pulse repetition rate with reference to the radio-frequency atomic clock. Fourth, the pulse-to-pulse cross-correlation occurring in the optical frequency domain is down-converted to the radio-frequency domain to achieve femtosecond pulse timing precision by means of dual-comb interference. All these principles based on unique spectral and temporal characteristics of ultrashort mode-locked lasers are anticipated to make contributions to the advance of nanotechnology particularly in manufacturing and metrology.

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Ranging with Frequency-Shifted Feedback Lasers: From μm-Range Accuracy to MHz-Range Measurement Rate

Kim¹,

Ogurtsov²,

Bonnet³

et al. 2018

Exploring the World With the Laser

0

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We report results on ranging based on frequency shifted feedback (FSF) lasers with two different implementations: (1) An Ytterbium-fiber system for measurements in an industrial environment with accuracy of the order of 1 µm, achievable over a distance of the order of meters with potential to reach an accuracy of better than 100 nm; (2) A semiconductor laser system for a high rate of measurements with an accuracy of 2 mm @ 1 MHz or 75 µm @ 1 kHz and a limit of the accuracy of ≥ 10 µm. In both implementations, the distances information is derived from a frequency measurement.The method is therefore insensitive to detrimental influence of ambient light. For the Ytterbium-fiber system a key feature is the injection of a single frequency laser, phase modulated at variable frequency Ω, into the FSFlaser cavity. The frequency Ω max at which the detector signal is maximal yields the distance. The semiconductor FSF laser system operates without external injection seeding. In this case the key feature is frequency counting that allows convenient choice of either accuracy or speed of measurements simply by changing the duration of the interval during which the frequency is measured by counting. 2 J. I. Kim et al.

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Comb-referenced laser distance interferometer for industrial nanotechnology

Cited by 53 publications

References 43 publications

Ranging with frequency-shifted feedback lasers: from $$\upmu$$ μ m-range accuracy to MHz-range measurement rate

Ranging with frequency-shifted feedback lasers: from $$\upmu$$ μ m-range accuracy to MHz-range measurement rate

Distance Measurements Using Mode-Locked Lasers: A Review

Ranging with Frequency-Shifted Feedback Lasers: From μm-Range Accuracy to MHz-Range Measurement Rate

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