Development of an Optical Angle Sensor With a Mode-Locked Femtosecond Laser Source for Surface Profile Measurement

2020 ◽  
Author(s):  
Yuki Shimizu ◽  
Shota Takazono ◽  
Yuri Kanda ◽  
Hiraku Matsukuma ◽  
Wei Gao ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Surface Profile ◽  
Single Mode ◽  
Single Mode Fiber ◽  
Laser Source ◽  
Profile Measurement ◽  
Angle Sensor ◽  
Optical Setup ◽  
Optical Modes ◽  
Optical Angle Sensor

Abstract Angle sensors based on the laser autocollimation are often employed to evaluate surface profiles of a target of interest. The authors have developed a femtosecond laser angle sensor, in which a spectrometer or an optical spectrum analyzer with a single-mode fiber is employed as the photodetector for simultaneous capturing of the multiple optical modes. In this paper, the concept of the femtosecond laser angle sensor is applied to evaluate the surface profile of a target of interest. An optical setup is designed in such a way that each mode in the spectrum of the mode-locked femtosecond is utilized as the laser beam to measure the local slope of a measurement target at each different point to evaluate the surface profile. Some basic experiments are carried out by using the developed optical setup with a mode-locked femtosecond laser source to evaluate basic performances of the developed optical setup as an optical angle sensor.

Profile Measurement by Using a Femtosecond Laser Chromatic Confocal Probe

2020 ◽  
Author(s):  
Ryo Sato ◽  
Yuki Shimizu ◽  
Hiraku Matsukuma ◽  
Wei Gao
Keyword(s):  
Thermal Stability ◽  
Femtosecond Laser ◽  
Surface Profile ◽  
Sample Surface ◽  
Measurement Range ◽  
Laser Source ◽  
Profile Measurement ◽  
Experimental Setup ◽  
Chromatic Confocal Probe ◽  
Surface Profile Measurement

Abstract Confocal probes are widely employed in many industrial fields due to the depth-sectioning effect. The author’s group has also proposed a chromatic confocal probe employing a mode-locked femtosecond laser source which can realize an axial resolution of 30 nm and a measurement range of 40 μm Efforts have also been made to improve the thermal stability of the developed femtosecond laser chromatic confocal probe so that the probe can be applied for long-term displacement measurement or surface profile measurement. Meanwhile, surface profile measurement has not been carried out by using the developed femtosecond laser chromatic confocal probe. For the verification of the performance of developed probe in profile measurement, in this paper, an experimental setup is built and a basic experiment is carried out. By using the probe with further improved thermal stability, the measurement of a sample surface profile is carried out. In this paper, the development of the experimental setup with the femtosecond laser chromatic confocal probe, as well as the results of the surface profile measurements, is presented.

scholarly journals Investigation and Improvement of Thermal Stability of a Chromatic Confocal Probe with a Mode-Locked Femtosecond Laser Source

2019 ◽  
Vol 9 (19) ◽  
pp. 4084 ◽  
Author(s):  
Ryo Sato ◽  
Yuki Shimizu ◽  
Chong Chen ◽  
Hiraku Matsukuma ◽  
Wei Gao
Keyword(s):  
Thermal Stability ◽  
Thermal Expansion ◽  
Femtosecond Laser ◽  
Thermal Instability ◽  
Theoretical Calculations ◽  
Surface Profile ◽  
Laser Source ◽  
Profile Measurement ◽  
Chromatic Confocal Probe ◽  
Thermal Stability Of

An intentional investigation on the thermal stability of a mode-locked femtosecond laser chromatic confocal probe, which is a critical issue for the probe to be applied for long-term displacement measurement or surface profile measurement requiring long-time scanning, is carried out. At first, the thermal instability of the first prototype measurement setup is evaluated in experiments where the existence of a considerably large thermal instability is confirmed. Then the possible reasons for the thermal instability of the measurement setup are analyzed quantitatively, such as the thermal instability of the refractive index of the confocal lens and the thermal expansion of mechanical jigs employed in the probe. It is verified that most of the thermal instability of the measurement setup is caused by the thermal expansion of mechanical jigs in the probe. For the improvement of the thermal stability of the probe, it is necessary to employ a low thermal expansion material for the mechanical jigs in the measurement setup and to shorten the optical path length of the laser beam. Based on the analysis result, a second prototype probe is newly designed and constructed. The improved thermal stability of the second prototype probe is verified through theoretical calculations and experiments.

scholarly journals An Off-Axis Differential Method for Improvement of a Femtosecond Laser Differential Chromatic Confocal Probe

2020 ◽  
Vol 10 (20) ◽  
pp. 7235
Author(s):  
Chong Chen ◽  
Yuki Shimizu ◽  
Ryo Sato ◽  
Hiraku Matsukuma ◽  
Wei Gao
Keyword(s):  
Femtosecond Laser ◽  
Focal Plane ◽  
Signal To Noise Ratio ◽  
Single Mode ◽  
Measurement Range ◽  
Single Mode Fiber ◽  
Differential Method ◽  
Laser Source ◽  
Dual Detector ◽  
Chromatic Confocal Probe

This paper presents an off-axis differential method for the improvement of a femtosecond laser differential chromatic confocal probe having a dual-detector configuration. In the proposed off-axis differential method employing a pair of single-mode fiber detectors, a major modification is made to the conventional differential setup in such a way that the fiber detector in the reference detector is located at the focal plane of a collecting lens but with a certain amount of off-axis detector shift, while the fiber detector in the measurement detector is located on the rear focal plane without the off-axis detector shift; this setup is different from the conventional one where the difference between the two confocal detectors is provided by giving a defocus to one of the fiber detectors. The newly proposed off-axis differential method enables the differential chromatic confocal setup to obtain the normalized chromatic confocal output with a better signal-to-noise ratio and approaches a Z-directional measurement range of approximately 46 μm, as well as a measurement resolution of 20 nm, while simplifying the optical alignments in the differential chromatic confocal setup, as well as the signal processing through eliminating the complicated arithmetic operations in the determination of the peak wavelength. Numerical calculations based on a theoretical equation and experiments are carried out to verify the feasibility of the proposed off-axis differential method for the differential chromatic confocal probe with a mode-locked femtosecond laser source.

scholarly journals Characterization of small-signal intensity modulation of single-mode fiber grating Fabry-Perot laser source

2012 ◽  
Vol 19 (2) ◽  
pp. 64-70 ◽  
Author(s):  
Hisham Kadhum Hisham ◽  
Ahmad Fauzi Abas ◽  
Ghafour Amouzad Mahdiraji ◽  
Mohd Adzir Mahdi ◽  
Ahmad Shukri Muhammad Noor
Keyword(s):  
Signal Intensity ◽  
Single Mode ◽  
Single Mode Fiber ◽  
Intensity Modulation ◽  
Laser Source ◽  
Fiber Grating ◽  
Small Signal ◽  
Fabry Perot

Wavelength-tunable picosecond laser source based on filtering and amplifying broadband dissipative soliton pulse

Laser Physics ◽  
2021 ◽  
Vol 32 (1) ◽  
pp. 015103
Author(s):  
Jing Li ◽  
Chuncan Wang ◽  
Peng Wang ◽  
Pengtao Liu ◽  
Junhao Lan ◽  
...  
Keyword(s):  
Picosecond Laser ◽  
Single Mode ◽  
Single Mode Fiber ◽  
Picosecond Pulse ◽  
Dissipative Soliton ◽  
Laser Source ◽  
Seed Pulse ◽  
Practical Applications ◽  
Wavelength Tunable ◽  
Wavelength Control

Abstract A method for obtaining picosecond pulse sources with continuously tunable central wavelengths is demonstrated numerically and experimentally. A dissipative soliton (DS) mode-locked erbium-doped fiber (EDF) laser based on the nonlinear polarization rotation provides the seed pulse with a flat-top spectral profile and a 55 nm spectral bandwidth. Then it is filtered by a wavelength-tunable super-Gaussian bandpass filter and amplified by two segments of EDFs with different doping concentrations. The output DS pulse from the EDF laser can be compressed from 5.532 ps to 0.291 ps by using a single-mode fiber (SMF-28e), while the pulse energy is about 1.6 nJ. Furthermore, the about 4 ps and 6.84 nJ pulses with continuously tunable central wavelengths ranging from 1535 to 1580 nm can be obtained by amplifying the spectrally filtered pulses. The tunable picosecond pulse source based on the extra-cavity filtering method is very useful for many practical applications because of its flexible wavelength control.

Femtosecond Laser Precision Machining of Micropores in Single-Mode Fiber and Sensing Application

2020 ◽  
Vol 57 (11) ◽  
pp. 111425
Author(s):  
王解 Wang Jie ◽  
赵宗晨 Zhao Zongchen ◽  
江超 Jiang Chao ◽  
刘昌宁 Liu Changning ◽  
孙四梅 Sun Simei
Keyword(s):  
Femtosecond Laser ◽  
Single Mode ◽  
Single Mode Fiber ◽  
Precision Machining ◽  
Sensing Application

Laser Linewidth Measurements Using Self-Heterodyne Detection with Total-Reflected Delay Line

2012 ◽  
Vol 571 ◽  
pp. 467-470 ◽  
Author(s):  
Jian Li ◽  
Nan Xu ◽  
Jian Wei Li ◽  
Zhi Xin Zhang
Keyword(s):  
Delay Line ◽  
Detection Method ◽  
Tunable Laser ◽  
Single Mode ◽  
Single Mode Fiber ◽  
Heterodyne Detection ◽  
Laser Source ◽  
Laser Communication ◽  
Narrow Linewidth ◽  
Fiber Delay Line

As an important parameter in the laser communication system, the narrow linewidth of tunable laser source (TLS) must be measured accurately. Therefore, the linewidth of a TLS was measured with the delayed self-heterodyne detection method in the present work. The total-reflected delay line was used in the measurement system for make full use of 25km single-mode fiber delay line. The measured linewidth of the 1550 TLS is of 127 kHz, in agreement with the nominal value.

scholarly journals Optical Angle Sensor Technology Based on the Optical Frequency Comb Laser

2020 ◽  
Vol 10 (11) ◽  
pp. 4047 ◽  
Author(s):  
Yuki Shimizu ◽  
Hiraku Matsukuma ◽  
Wei Gao
Keyword(s):  
Femtosecond Laser ◽  
Frequency Comb ◽  
Angle Measurement ◽  
Optical Frequency Comb ◽  
High Peak Power ◽  
Optical Frequency ◽  
Absolute Distance ◽  
Angle Sensor ◽  
The Absolute ◽  
Optical Angle Sensor

A mode-locked femtosecond laser, which is often referred to as the optical frequency comb, has increasing applications in various industrial fields, including production engineering, in the last two decades. Many efforts have been made so far to apply the mode-locked femtosecond laser to the absolute distance measurement. In recent years, a mode-locked femtosecond laser has increasing application in angle measurement, where the unique characteristics of the mode-locked femtosecond laser such as the stable optical frequencies, equally-spaced modes in frequency domain, and the ultra-short pulse trains with a high peak power are utilized to achieve precision and stable angle measurement. In this review article, some of the optical angle sensor techniques based on the mode-locked femtosecond laser are introduced. First, the angle scale comb, which can be generated by combining the dispersive characteristic of a scale grating and the discretized modes in a mode-locked femtosecond laser, is introduced. Some of the mode-locked femtosecond laser autocollimators, which have been realized by combining the concept of the angle scale comb with the laser autocollimation, are also explained. Angle measurement techniques based on the absolute distance measurements, lateral chromatic aberration, and second harmonic generation (SHG) are also introduced.

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