scholarly journals The difference between the mechanical and optical lengths of a steel end-gauge

1929 ◽  
Vol 122 (789) ◽  
pp. 122-133 ◽  
Keyword(s):  
Optical Length ◽  
Interference Fringes ◽  
Light Waves ◽  
Fabry Perot ◽  
The Difference ◽  
Block Gauge

The two lapped surfaces whose separation defines the length of a good end-gauge or block-gauge generally approach a degree of optical flatness and parallelism sufficient for their use in interferometry. If, therefore, such a gauge is supported between the semi-transparent mirrors of a Fabry-Perot étalon of greater length than the gauge, with its surfaces parallel to the mirrors, the gauge may be standardised in terms of light waves by the methods usually applied to Fabry-Perot étalons. In fig. 1 L is the optical separation of the étalon mirrors, l 1 and l 2 are respectively the optical separations of a gauge surface and an adjacent étalon mirror at each end of the figure, and O is the optical length of the gauge: therefore O = L — ( l 1 + l 2 ), (1) L is measured either directly or indirectly in terms of light waves, the choice depending upon the magnitude of L, while both l 1 and l 2 are measured directly in terms of light waves by observation of the reflected system of circular interference fringes; thus O may be obtained in terms of light waves.

Quanitative aspects of electron diffraction using electron holography

1995 ◽  
Vol 53 ◽  
pp. 616-617
Author(s):  
E. Völkl ◽  
L.F. Allard ◽  
B. Frost ◽  
T.A. Nolan
Keyword(s):  
Electron Beam ◽  
Electron Diffraction ◽  
Software Package ◽  
Spatial Coherence ◽  
Electron Holography ◽  
Image Intensity ◽  
Interference Fringes ◽  
Complex Image ◽  
The Difference ◽  
Recorded Image

Off-axis electron holography has the well known ability to preserve the complex image wave within the final, recorded image. This final image described by I(x,y) = I(r) contains contributions from the image intensity of the elastically scattered electrons IeI (r) = |A(r) exp (iΦ(r)) |, the contributions from the inelastically scattered electrons IineI (r), and the complex image wave Ψ = A(r) exp(iΦ(r)) as:(1) I(r) = IeI (r) + Iinel (r) + μ A(r) cos(2π Δk r + Φ(r))where the constant μ describes the contrast of the interference fringes which are related to the spatial coherence of the electron beam, and Φk is the resulting vector of the difference of the wavefront vectors of the two overlaping beams. Using a software package like HoloWorks, the complex image wave Ψ can be extracted.

scholarly journals Thermal Characteristics of Positive Leaders under Different Electrode Terminals in a Long Air Gap

Energies ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 4024 ◽  
Author(s):  
Du ◽  
Tang ◽  
Li ◽  
Zou ◽  
Ma ◽  
...  
Keyword(s):  
High Speed ◽  
Thermal Characteristics ◽  
Video Camera ◽  
Air Gap ◽  
Radius Of Curvature ◽  
Gas Temperature ◽  
Gas Density ◽  
Interference Fringes ◽  
High Speed Video Camera ◽  
The Difference

The thermal characteristics of the positive leader discharges occurring under the different electrode terminals in a 1 m rod-plate air gap were studied quantitatively using Mach–Zehnder interferometry and a high-speed video camera. When disturbed by the discharge channel, the interference fringes are distorted because of the change in the refractive index of air, which is related to the gas density. Therefore, the gas temperature and gas density distribution in the leader channel can be retrieved from the offset of the interference fringes. Based on these results, the thermal characteristics of the leader channel were studied under different electrode terminals with a radius of curvature of 2.5 mm and 5 mm for cone electrodes and a diameter of 40 mm for a spherical electrode. The results show that the gas temperature in the leader channel increased while the gas density decreased as the radius of curvature of the electrode terminal decreased. Additionally, a smaller radius of curvature leads to a larger thermal diameter, but the difference in the thermal diameter is not obvious; for the terminals used in this paper, the difference is within 2 mm.

scholarly journals Casimir force induced by electromagnetic wave polarization in Kerr, Gödel and Bianchi–I spacetimes

2020 ◽  
Vol 80 (11) ◽  
Author(s):  
Felipe A. Asenjo ◽  
Sergio A. Hojman
Keyword(s):  
Electromagnetic Waves ◽  
Casimir Force ◽  
Polarized Light ◽  
Casimir Forces ◽  
Circularly Polarized Light ◽  
Bianchi I ◽  
Phase Velocities ◽  
Light Waves ◽  
Waves Propagation ◽  
The Difference

AbstractElectromagnetic waves propagation on either rotating or anisotropic spacetime backgrounds (such as Kerr and Gödel metrics, or Bianchi–I metric) produce a reduction of the magnitude of Casimir forces between plates. These curved spacetimes behave as chiral or birefringent materials producing dispersion of electromagnetic waves, in such a way that right– and left–circularly polarized light waves propagate with different phase velocities. Results are explicitly calculated for discussed cases. The difference on the wavevectors of the two polarized electromagnetic waves produces an abatement of a Casimir force which depends on the interaction between the polarization of electromagnetic waves and the properties of the spacetime.

scholarly journals Quasi-Distributed Active-Mode-Locking Laser Interrogation with Multiple Partially Reflecting Segment Sensors

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4128
Author(s):  
Chang Park ◽  
Gyeong Kim ◽  
Suck Hong ◽  
Hwi Lee ◽  
Chang-Seok Kim
Keyword(s):  
Laser Cavity ◽  
Length Change ◽  
Mode Locking ◽  
Segment Length ◽  
Length Variation ◽  
Active Mode ◽  
Distributed Sensor ◽  
Fabry Perot ◽  
New Type ◽  
The Difference

A new type of quasi-distributed sensor system is implemented using an active mode locking (AML) laser cavity with multiple partially reflecting segments. The mode locking frequency of the AML laser is linearly proportional to the overall lasing cavity length. To implement multiple resonators having multiple reflection points installed in a sensing fiber, two types of partial reflectors (PRs) are implemented for an in-line configuration, one with fiber Bragg grating and the other with a fiber Fabry–Perot interferometer. Since the laser has oscillated only when the modulation frequencies for the mode locking frequency match with the corresponding resonator lengths, it is possible to read the multiple partially reflecting segments along the sensing fiber. The difference between two corresponding mode locking frequencies is changing proportionally with the segment length variation between two PRs upon strain application. The segment length change caused by the applied strain can be successfully measured with a linear sensitivity between mode locking frequency and displacement, linearity over 0.99, and spatial position resolution below meter order.

The Interferometer of Mach Zehnder and Its Applications

2021 ◽  
Vol 19 (8) ◽  
pp. 125-130
Author(s):  
Nawras Ali. Salman
Keyword(s):  
Optical Sensors ◽  
Fundamental Principle ◽  
Optical Switches ◽  
Interferometric Sensors ◽  
Fabry Perot ◽  
All Optical ◽  
Different Types ◽  
The Difference ◽  
Interferometric Sensor ◽  
Temperature Strain

Fiber optic interferometers have been studied extensively for sensing various physical characteristics such as temperature, strain, pressure, and refractive index. Fabry-Perot, Mach-Zehnder, Michelson, and Sagnac are the four different types. In this case, in this study, the operational principles of Mach-Zehnder interferometric sensor are examined. fabrication techniques, as well as application sectors. The technologies of interferometric sensors are described in detail to demonstrate their great potential in practical uses. Mach-Zehnder The interferometer is a device that measures the difference in phase shifts Between two coherent collimated beams. According to this fundamental Principle, various devices can be designed. Several devices, including various types of in-line MZI optical sensors, all-optical switches and modulator, can be created using this basic principle are discussed in this paper.

Novel Electrochemical-Emission Spectroscopy of Metals by White Light Interferometry

2021 ◽  
Vol 1026 ◽  
pp. 189-196
Author(s):  
Khaled Habib
Keyword(s):  
Sulfuric Acid ◽  
Aqueous Solutions ◽  
Current Density ◽  
White Light ◽  
Emission Spectroscopy ◽  
Rate Change ◽  
Fiber Optic Sensor ◽  
White Light Interferometry ◽  
Fabry Perot ◽  
The Difference

A white light, i.e., Fabry-Perot, interferometry was unprecedently applied to determine the rate change of the current density (J) of aluminum samples during the anodization processes of the samples in aqueous solutions. The current density(J) values were obtained by Fabry-Perot interferometry rather than the direct current (DC) or alternating current (AC), methods. Therefore, the abrupt rate change of the J was called electrochemical-emission spectroscopy. The anodization of the aluminum samples was conducted by an external DC source in 0.0,2,4,6,8,10% sulfuric acid (H2SO4) solutions at room temperature. In the meantime, the Fabry-Perot interferometry was used to determine the difference between the J of two subsequent values, dJ, as a function of the elapsed time of the DC experiment for the aluminum samples in 0.0,2,4,6,8,10% H2SO4 solutions. The Fabry-Perot interferometry was based on a fiber-optic sensor in order to make real time-white light interferometry possible at the aluminum surfaces in the sulfuric acid solutions. As a result, a new spectrometer was developed based on the combination of the Fabry-Perot, i.e., white light, interferometry and DC method for studying in situ the electrochemical behavior of metals in aqueous solutions.

Use of Fiber Interferometer for AFM Cantilever Probe Displacement Control

2005 ◽  
Vol 295-296 ◽  
pp. 77-82 ◽  
Author(s):  
N.C. Shie ◽  
T.L. Chen ◽  
Kai Yuan Cheng
Keyword(s):  
Light Intensity ◽  
Theoretical Equation ◽  
Displacement Sensor ◽  
Phase Array ◽  
Fibre Optic ◽  
Core Diameter ◽  
Atomic Force ◽  
Interference Fringes ◽  
Fabry Perot ◽  
Afm Cantilever

This investigation presents a fibre-optic Fabry-Perot interferometer as a displacement sensor in an atomic force microsope (AFM). A simple model of light wave transmission between two fibres with the same core diameter is proposed to determine the theoretical equation of light intensity of interference fringes from the fibre-optic Fabry-Perot interferometer. By replacing an AFM cantilever with a movable reflective mirror, the variations of relative light intensity of the interference fringes with the spacing between the fibre and the mirror were recorded. The theoretical equation for the light intensity of interference fringes was close to those obtained experimentally. Finally, a fibre-optic Fabry-Perot interferometer was operated in an AFM to image a two-dimensional phase array with a pitch of 4 µm and a depth of 150 nm.

Measuring Line Centers from Digitally Recorded Spectra Using a Minicomputer

1974 ◽  
Vol 28 (4) ◽  
pp. 362-368 ◽  
Author(s):  
S. C. Hurlock ◽  
J. R. Hanratty
Keyword(s):  
High Resolution ◽  
Infrared Spectra ◽  
High Accuracy ◽  
Digital Form ◽  
Measuring Line ◽  
Local Section ◽  
Standard Methods ◽  
Interference Fringes ◽  
The Difference ◽  
Very High

A system is described for determining spectral positions from high resolution infrared spectra which have been recorded in digital form on magnetic tape. The system employs a minicomputer located in the laboratory and line centers are determined by an interactive procedure in which the operator makes judgments based on information displayed on the CRT screen of the computer. This information consists of the spectrum, a reflection of a local section of the spectrum at a vertical line through the center of the screen, a plot of the difference between the spectrum and its reflection, and the square of the area under the difference curve. Very high accuracy is demonstrated for locating the centers of single lines as well as the centers of the components of incompletely resolved double lines. Determinations of spectral positions (wavenumber calibration) parallel operations that were previously performed as batch jobs by a much larger computer. Spectral positions are determined by standard methods of calibration of interference fringes and interpolation.

scholarly journals Monitoring the Growth of a Microbubble Generated Photothermally onto an Optical Fiber by Means Fabry–Perot Interferometry

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 628
Author(s):  
J. Gabriel Ortega-Mendoza ◽  
Placido Zaca-Morán ◽  
J. Pablo Padilla-Martínez ◽  
Josué E. Muñoz-Pérez ◽  
José Luis Cruz ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Ccd Camera ◽  
Single Mode ◽  
Laser Source ◽  
Photothermal Effect ◽  
Interference Fringes ◽  
Time Period ◽  
Fabry Perot ◽  
The Time Domain ◽  
Practical Demonstration

In the present paper, we show the experimental measurement of the growth of a microbubble created on the tip of a single mode optical fiber, in which zinc nanoparticles were photodeposited on its core by using a single laser source to carry out both the generation of the microbubble by photothermal effect and the monitoring of the microbubble diameter. The photodeposition technique, as well as the formation of the microbubble, was carried out by using a single-mode pigtailed laser diode with emission at a wavelength of 658 nm. The microbubble’s growth was analyzed in the time domain by the analysis of the Fabry–Perot cavity, whose diameter was calculated with the number of interference fringes visualized in an oscilloscope. The results obtained with this technique were compared with images obtained from a CCD camera, in order to verify the diameter of the microbubble. Therefore, by counting the interference fringes, it was possible to quantify the temporal evolution of the microbubble. As a practical demonstration, we proposed a vibrometer sensor using microbubbles with sizes of 83 and 175 µm as a Fabry–Perot cavity; through the time period of a full oscillation cycle of an interferogram observed in the oscilloscope, it was possible to know the frequency vibration (500 and 1500 Hz) for a cuvette where the microbubble was created.

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