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 A Method for Expansion of Z-Directional Measurement Range in a Mode-Locked Femtosecond Laser Chromatic Confocal Probe

2019 ◽  
Vol 9 (3) ◽  
pp. 454 ◽  
Author(s):  
Chong Chen ◽  
Ryo Sato ◽  
Yuki Shimizu ◽  
Taku Nakamura ◽  
Hiraku Matsukuma ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Femtosecond Laser ◽  
Intensity Ratio ◽  
Theoretical Calculations ◽  
Expansion Method ◽  
Measurement Range ◽  
Laser Source ◽  
Peak Wavelength ◽  
Dual Detector ◽  
Chromatic Confocal Probe

A method is proposed to expand the Z-directional measurement range of a fiber-based dual-detector chromatic confocal probe with a mode-locked femtosecond laser source. In the dual-detector chromatic confocal probe, the Z-directional displacement of a measurement target is derived from the peak wavelength in the normalized intensity ratio from the two light intensities obtained by the two identical fiber detectors. In this paper, a new method utilizing the main-lobe and side-lobes of axial responses acquired from both the normalized intensity ratio Ia and the invert normalized intensity ratio In, which is the inverse of Ia, is proposed to obtain the seamless relationship between the peak wavelength and the Z-directional displacement of a measurement target. Theoretical calculations and experimental investigation are carried out to demonstrate the feasibility of the proposed measurement range expansion method.

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.

A chromatic confocal probe with a mode-locked femtosecond laser source

2018 ◽  
Vol 103 ◽  
pp. 359-366 ◽  
Author(s):  
Xiuguo Chen ◽  
Taku Nakamura ◽  
Yuki Shimizu ◽  
Chong Chen ◽  
Yuan-Liu Chen ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Laser Source ◽  
Chromatic Confocal Probe

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

scholarly journals Microdrilled tapers to enhance optical fiber lasers for sensing

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
R. A. Perez-Herrera ◽  
M. Bravo ◽  
P. Roldan-Varona ◽  
D. Leandro ◽  
L. Rodriguez-Cobo ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Optical Fibers ◽  
Fiber Lasers ◽  
Signal To Noise Ratio ◽  
Power Level ◽  
Single Mode ◽  
Optical Signal ◽  
Single Mode Fiber ◽  
Output Power Level ◽  
Linear Cavity

AbstractIn this work, an experimental analysis of the performance of different types of quasi-randomly distributed reflectors inscribed into a single-mode fiber as a sensing mirror is presented. These artificially-controlled backscattering fiber reflectors are used in short linear cavity fiber lasers. In particular, laser emission and sensor application features are analyzed when employing optical tapered fibers, micro-drilled optical fibers and 50 μm-waist or 100 μm-waist micro-drilled tapered fibers (MDTF). Single-wavelength laser with an output power level of about 8.2 dBm and an optical signal-to-noise ratio of 45 dB were measured when employing a 50 μm-waist micro-drilled tapered optical fiber. The achieved temperature sensitivities were similar to those of FBGs; however, the strain sensitivity improved more than one order of magnitude in comparison with FBG sensors, attaining slope sensitivities as good as 18.1 pm/με when using a 50 μm-waist MDTF as distributed reflector.

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.

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