• Title/Summary/Keyword: Precision Engineering

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Technological Trends for Precision Optical Metrology (광계측의 기술동향)

  • 김승우
    • Journal of the Korean Society for Precision Engineering
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    • v.17 no.6
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    • pp.7-16
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    • 2000
  • 정밀공학에서 측정은 필수적인 의미를 갖는다. 측정할 수 없는 제품 치수는 체계적인 가공이 불가능하며, 이는 설사 가공자의 특수한 기능에 의해 가공이 되더라도 체계적인 양산방식에 의한 생산이 될 수 없음을 의미한다. 이러한 중요성을 갖는 측정기술은 가공기술의 발랄과 더불어 꾸준한 진보를 이루어 왔다.(중략)

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Quality Analysis on Computer Generated Hologram Depending on the Precision on Diffraction Computation (회절연산 정밀도에 따른 CGH 기반 홀로그램 생성 품질 분석)

  • Jaehong Lee;Duksu Kim
    • Journal of Broadcast Engineering
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    • v.28 no.1
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    • pp.21-30
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    • 2023
  • Computer-generated holography requires much more computation costs and memory space rather than image processing. We implemented the diffraction calculation with low-precision and mixed-precision floating point numbers and compared the processing time and quality of the hologram with various precision. We compared diffraction quality with double, single and bfloat16 precision. bfloat16 shows 5.94x and 1.52x times faster performance than double precision and single precision. Also, bfloat16 shows lower PSNR and SSIM and higher MSE than other precision. However, there is no significant effect on reconstructed images. These results show low precision, like bfloat16, can be utilized for computer-generated holography.

Absolute Distance Measurements Using the Optical Comb of a Femtosecond Pulse Laser

  • Jin, Jong-Han;Kim, Young-Jin;Kim, Yun-Seok;Kim, Seung-Woo
    • International Journal of Precision Engineering and Manufacturing
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    • v.8 no.4
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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.