scholarly journals A New Method for Airborne Sound Detection Using Total Internal Reflection and Its Application to Microphone

2011 ◽  
Vol 2011 ◽  
pp. 1-9
Author(s):  
Yasushi Suzuki ◽  
Ken'iti Kido
Keyword(s):  
Atmospheric Pressure ◽  
Total Internal Reflection ◽  
Sound Pressure ◽  
Total Reflection ◽  
Internal Reflection ◽  
New Method ◽  
Air Density ◽  
Reflected Light ◽  
Sound Detection ◽  
Curved Interface

A new method for detecting the sound pressure in air, which uses the total internal reflection at the curved interface between glass and air, is proposed, and its application to microphone is discussed. The critical angle for total reflection changes by the refractive index of air, which depends on the air density. The density changes by the sound pressure. Therefore, the sound pressure is measurable by detecting the intensity of the reflected light from the total reflection area. The sound pressure sensitivity of the proposed method is investigated theoretically and experimentally. Experimental results show that the microphone using the method is feasible though its sensitivity is low in the present stage. When the sensitivity is improved dramatically for practical use, the microphone becomes very sensitive to the surrounding conditions. A method to compensate the fluctuation of atmospheric pressure or temperature is presented.

Novel Attenuated Total Reflection Fourier Transform Infrared Microscopy Using a Gem Quality Diamond as an Internal Reflection Element

2005 ◽  
Vol 59 (10) ◽  
pp. 1236-1241 ◽  
Author(s):  
Sanong Ekgasit ◽  
Pimthong Thongnopkun
Keyword(s):  
Fourier Transform ◽  
Total Internal Reflection ◽  
Fourier Transform Infrared ◽  
Normal Incidence ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Internal Reflection ◽  
The Novel ◽  
Infrared Microscope ◽  
Ft Ir

A novel technique for attenuated total reflection Fourier transform infrared (ATR FT-IR) spectral acquisition by an infrared microscope with a gem-quality faceted diamond as an internal reflection element (IRE) is introduced. Unlike conventional IREs, the novel diamond IRE has a sharp tip configuration instead of a flat tip configuration. Light at normal incidence was coupled into the diamond while the transflected radiation from the diamond was collected through the table facet by the built-in 15× Cassegrainian objective. The number of reflections in the novel diamond IRE equals two. The evanescent field generated under total internal reflection at the pavilion facet was exploited for ATR spectral acquisition of materials attached to the IRE. The observed ATR spectra were compared to those obtained via a traditional zinc selenide IRE.

Acoustic tunnelling

1978 ◽  
Vol 81 (1-2) ◽  
pp. 1-21 ◽  
Author(s):  
D. S. Jones
Keyword(s):  
Circular Cylinder ◽  
Acoustic Waves ◽  
Total Internal Reflection ◽  
Internal Reflection ◽  
Reflection And Transmission ◽  
Curved Interface ◽  
Transmission And Reflection

SynopsisGeneral formulae are obtained for the reflection and transmission of harmonic acoustic waves by a curved interface between two media when the frequency is high. In addition to refracted rays there turn up tunnelling rays, if the surface is concave to the source, which are emitted from an evanescent region when the phenomenon of total internal reflection would be anticipated. Uniformly valid formulae dealing with the transition from refraction to tunnelling in both transmission and reflection are derived.The theory is applied to the circular cylinder and to the top-hat circular jet. In the latter case it is suggested that radiation may tend to be more significant at inclinations of 50°-65° (downstream) and 25°-40° (upstream) to the axis of the cylinder. The augmentation due to tunnelling rays in propagation upstream is mentioned.

scholarly journals Attenuated Total Reflection at THz Wavelengths: Peculiarities of Total Internal Reflection and Polariscopy

2021 ◽  
Author(s):  
Meguya Ryu ◽  
Soon Hock Ng ◽  
Vijayakumar Anand ◽  
Stefan Lundgaard ◽  
Jingwen Hu ◽  
...  
Keyword(s):  
Refractive Index ◽  
Biological Samples ◽  
Total Internal Reflection ◽  
Refractive Index Change ◽  
High Refractive Index ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Internal Reflection ◽  
Optical Elements ◽  
Frustrated Total Internal Reflection

Capabilities of the Attenuated Total Reflection (ATR) at THz wavelengths for increased sub-surface depth characterisation of (bio-)materials is presented. The penetration depth of a THz evanescent wave in biological samples is dependent on the wavelength and temperature and can reach 0.1-0.5 mm depth due to strong refractive index change ∼0.4 of the ice-water transition; this is quite significant and important when studying biological samples. Technical challenges are discussed when using ATR for uneven, heterogeneous, high refractive index samples with possibility of frustrated total internal reflection (a breakdown of the ATR reflection-mode into transmission-mode). Local field enhancements at the interface are discussed with numerical/analytical examples. Maxwell’s scaling was used to model behaviour of absorber-scatterer inside materials at the interface with ATR prism for realistic complex refractive indices of bio-materials. Modality of ATR with polarisation analysis is proposed and its principle illustrated, opening an invitation for its experimental validation. The sensitivity of the polarised ATR mode to the refractive index between the sample and ATR prism is revealed. Design principles of polarisation active optical elements and spectral filters are outlined. The results and concepts are based on experiments carried out at the THz beamline of the Australian Synchrotron.

scholarly journals Attenuated Total Reflection at THz Wavelengths: Prospective Use of Total Internal Reflection and Polariscopy

2021 ◽  
Vol 11 (16) ◽  
pp. 7632
Author(s):  
Meguya Ryu ◽  
Soon Hock Ng ◽  
Vijayakumar Anand ◽  
Stefan Lundgaard ◽  
Jingwen Hu ◽  
...  
Keyword(s):  
Refractive Index ◽  
Biological Samples ◽  
Total Internal Reflection ◽  
Refractive Index Change ◽  
High Refractive Index ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Internal Reflection ◽  
Experimental Conditions ◽  
Frustrated Total Internal Reflection

Capabilities of the attenuated total reflection (ATR) at THz wavelengths for increased sub-surface depth characterisation of (bio-)materials are presented. The penetration depth of a THz evanescent wave in biological samples is dependent on the wavelength and temperature and can reach 0.1–0.5 mm depth, due to the strong refractive index change ∼0.4 of the ice-water transition; this is quite significant and important when studying biological samples. Technical challenges are discussed when using ATR for uneven, heterogeneous, high refractive index samples with the possibility of frustrated total internal reflection (a breakdown of the ATR reflection mode into transmission mode). Local field enhancements at the interface are discussed with numerical/analytical examples. Maxwell’s scaling is used to model the behaviour of absorber–scatterer inside the materials at the interface with the ATR prism for realistic complex refractive indices of bio-materials. The modality of ATR with a polarisation analysis is proposed, and its principle is illustrated, opening an invitation for its experimental validation. The sensitivity of the polarised ATR mode to the refractive index between the sample and ATR prism is numerically modelled and experimentally verified for background (air) spectra. The design principles of polarisation active optical elements and spectral filters are outlined. The results and proposed concepts are based on experimental conditions at the THz beamline of the Australian Synchrotron.

The Velocity of Energy Transport for Normal Modes Near Total Internal Reflection

1971 ◽  
Vol 26 (1) ◽  
pp. 124-127
Author(s):  
John S. Nicolis
Keyword(s):  
Total Internal Reflection ◽  
Energy Transport ◽  
Normal Modes ◽  
Total Reflection ◽  
Internal Reflection ◽  
Monochromatic Wave ◽  
Transparent Layer ◽  
Velocity Of Propagation ◽  
Modal Equation

Abstract The problem of the velocity of propagation of the various normal modes of a spherical electro­ magnetic quasi-monochromatic wave in a transparent layer near total reflection is examined, and a formula giving the velocity of the energy transport as a function of the eigenvalues of the modal equation is derived

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