• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.569-572
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• 2005

Technological feasibility of using recently-available femtosecond ultra short pulse lasers for advanced precision length metrology is investigated with emphasis on absolute distance measurements with $10{\mu}m$ ??resolution over extensive ranges. The idea of using femtosecond lasers for the measurement of absolute distances is based on the fact that a short pulse train is a mode-locked combination of discrete monochromatic light components spanning a wide spectral bandwidth. The synthetic wavelength is created from the repetition frequency, $f_r$ of the femtosecond laser and for more precise resolution, higher-order harmonics of the repetition frequency may be selected as the synthetic wavelength by using appropriate electronic filters.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.188-191
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• 2005

A common feature in various methods of optical interferometry for absolute distance measurements is the use of multiple monochromatic light components either in sequence or in parallel at the same time. Two or multiple wavelength synthesis has been studied though its performance is vulnerable to the frequency instability of the light source. Recently continuous frequency modulation is considered a promising method with availability of wide band tunable diode lasers, which also have frequency instability errors. We can lock frequencies of these third-party light sources to the modes of the femtosecond laser which is stabilized to the precision of the standard radio frequency. To this end, we have stabilized all the modes of the femtosecond laser to the atomic frequency standard by using powerful tools of frequency-domain laser stabilization.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 추계학술대회 논문집
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• pp.139-140
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• 2008

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 춘계학술대회 논문집
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• pp.369-370
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• 2007

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 춘계학술대회 논문집
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• pp.53-54
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• 2007

• 한국정밀공학회지
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• 제27권6호
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• pp.7-16
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• 2010

Physical fundamentals of ultrashort femtosecond lasers are addressed along with emerging applications for precision manufacturing and metrology. Femtosecond lasers emit short pulses whose temporal width is in the range of less than a picosecond to a few femtoseconds, thereby enabling extremely high peak-power machining with less thermal damages. Besides, the broad spectral bandwidth of femtosecond lasers constructed in the form of frequency comb permits absolute distance measurements leading to ultraprecision positioning control and dimensional metrology.

• International Journal of Precision Engineering and Manufacturing
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• 제8권4호
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• pp.22-26
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• 2007

We describe a new way of implementing absolute displacement measurements by exploiting the optical comb of a femtosecond pulse laser as a wavelength ruler, The optical comb is stabilized by locking both the repetition rate and the carrier offset frequency to an Rb clock of frequency standard. Multiwavelength interferometry is then performed using the quasi-monochromatic beams of well-defined generated wavelengths by tuning an external cavity laser diode consecutively to preselected light modes of the optical comb. This scheme of wavelength synthesizing allows the measurement of absolute distances with a high precision that is traceable to the definition of time. The achievable wavelength uncertainty is $1.9{\times}10^{-10}$, which allows the absolute heights of gauge blocks to be determined with an overall calibration uncertainty of 15 nm (k = 1). These results demonstrate a successful industrial application of an optical frequency synthesis employing a femtosecond laser, a technique that offers many possibilities for performing precision length metrology that is traceable to the well-defined international definition of time.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.195-198
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• 2002

Demand for high precision measurement of large area is increasing in many industrial fields. White-light Scanning Interferometer(WSI) is a well-known method for 3D profile measurement. However WSI has some limitations in a measurement range because of the sensing mechanism. Therefore, in this paper we use a heterodyne laser interferometer to get over the limitations of a short measurement range in WSI, We suggest a new WSI system combined with heterodyne laser interferometer. This system is aimed at eliminating Abbe error with measuring the focus point directly. With the use of triggering functionality of WSI, we can use this system as a probe of a precision stage such as a probe of CMM. The suggested system gives a repeatability of 87 nm in the absolute distance measurement test under the laboratory environment.