A New Optical Angle Measurement Method Based on Second Harmonic Generation with a Mode-Locked Femtosecond Laser

Matsukuma, Hiraku; Madokoro, Shuhei; Astuti, Wijayanti Dwi; Shimizu, Yuki; Gao, Wei

doi:10.1007/s41871-019-00052-4

Cited by 30 publications

(21 citation statements)

References 31 publications

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“…Before discussing the theoretical approach, an overview of the present study and the difference from the previous research is shown in Figure 1 . In the previous research [ 25 ], the laser beam (FW light) is focused onto the nonlinear optical crystal (BBO), and converted to the SHW in the BBO. The power of the converted SHW is detected by a photodiode and recorded by an oscilloscope.…”

Section: Theoretical Approachmentioning

confidence: 99%

“…Since the wavelength of the focused light on an optical fiber varies with angular displacement, the angle can be determined by detecting the optical wavelength. Meanwhile, we have also developed an angular measurement method based on second harmonic generation (SHG) using high-intensity features [ 25 ]. In this method, a mode-locked laser is focused on a nonlinear optical crystal placed on the measurement target.…”

Section: Introductionmentioning

confidence: 99%

“…An angular measurement method based on SHG [ 25 ] produces the power change of the converted SHW when a mode-locked laser is focused on a nonlinear optical crystal, in which the SHW has half the wavelength of the mode-locked laser and is detected by a photodiode. The efficiency depends on the angle between the optic axis of the nonlinear optical crystal and the laser propagation direction.…”

Section: Introductionmentioning

confidence: 99%

“…In general, due to the dispersion relation of the refractive index, the matching angle depends on the wavelength. In a previous paper, beta-barium borate (BBO) was used as a nonlinear optical crystal, and the matching angle of BBO has a very small wavelength dependence over the spectral bandwidth from 1500 to 1620 nm of an Er-doped fiber laser [ 25 ]. Thus, the intensity of the SHW is not wavelength dependent but depends on the matching angle.…”

Section: Introductionmentioning

confidence: 99%

“…We present a feasibility study of angle measurements with a wide measurable range of angles based on calculations. In this study, we change from refractive optics to reflective optics to avoid the localization of SHG, which was a drawback of the focusing lens in the previous paper [ 25 ].…”

Section: Introductionmentioning

confidence: 99%

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An Optical Frequency Domain Angle Measurement Method Based on Second Harmonic Generation

Astuti

Matsukuma

Nakao

et al. 2021

Sensors

Self Cite

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This paper proposes a new optical angle measurement method in the optical frequency domain based on second harmonic generation with a mode-locked femtosecond laser source by making use of the unique characteristic of the high peak power and wide spectral range of the femtosecond laser pulses. To get a wide measurable range of angle measurement, a theoretical calculation for several nonlinear optical crystals is performed. As a result, LiNbO3 crystal is employed in the proposed method. In the experiment, the validity of the use of a parabolic mirror is also demonstrated, where the chromatic aberration of the focusing beam caused the localization of second harmonic generation in our previous research. Moreover, an experimental demonstration is also carried out for the proposed angle measurement method. The measurable range of 10,000 arc-seconds is achieved.

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Section: Theoretical Approachmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

An Optical Frequency Domain Angle Measurement Method Based on Second Harmonic Generation

Astuti

Matsukuma

Nakao

et al. 2021

Sensors

Self Cite

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108 fs high-power mode locked double-clad ytterbium-doped fiber laser using FePS3 saturable absorber

Ahmad,

Lutfi,

Samion

et al. 2024

Opt Quant Electron

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Angle Measurement Based on Second Harmonic Generation Using Artificial Neural Network

et al. 2023

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This article proposed an angle measurement method based on second harmonic generation (SHG) using an artificial neural network (ANN). The method comprises three sequential parts: SHG spectrum collection, data preprocessing, and neural network training. First, the referenced angles and SHG spectrums are collected by the autocollimator and SHG-based angle sensor, respectively, for training. The mapping is learned by the trained ANN after completing the training process, which solves the inverse problem of obtaining the angle from the SHG spectrum. Then, the feasibility of the proposed method is verified in multiple-peak Maker fringe and single-peak phase-matching areas, with an overall angle measurement range exceeding 20,000 arcseconds. The predicted angles by ANN are compared with the autocollimator to evaluate the measurement performance in all the angular ranges. Particularly, a sub-arcsecond level of accuracy and resolution is achieved in the phase-matching area.

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A New Optical Angle Measurement Method Based on Second Harmonic Generation with a Mode-Locked Femtosecond Laser

Cited by 30 publications

References 31 publications

An Optical Frequency Domain Angle Measurement Method Based on Second Harmonic Generation

An Optical Frequency Domain Angle Measurement Method Based on Second Harmonic Generation

108 fs high-power mode locked double-clad ytterbium-doped fiber laser using FePS3 saturable absorber

Angle Measurement Based on Second Harmonic Generation Using Artificial Neural Network

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