scholarly journals Structure and pigment make the eyed elater’s eyespots black

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8161 ◽  
Author(s):  
Victoria L. Wong ◽  
Paul E. Marek
Keyword(s):  
Specular Reflection ◽  
Incident Light ◽  
Natural World ◽  
Multiple Reflections ◽  
Anatomical Structures ◽  
Click Beetle ◽  
Combine Structure ◽  
Absorption Of Light ◽  
Complete Absorption ◽  
Vertically Aligned

Surface structures that trap light leading to near complete structural absorption creates an appearance of “super black.” Well known in the natural world from bird feathers and butterfly scales, super black has evolved independently from various anatomical structures. Due to an exceptional ability to reduce specular reflection, these biological materials have garnered interest from optical industries. Here we describe the false eyes of the eyed elater click beetle, which, while not classified as super black, still attains near complete absorption of light partly due to an array of vertically-aligned microtubules. These cone-shaped microtubules are modified hairs (setae) that are localized to eyespots on the dorsum of the beetle, and absorb 96.1% of incident light (at a 24.8° collection angle) in the spectrum between 300–700 nm. Filled with melanin, the setae combine structure and pigment to generate multiple reflections and refractions causing light to travel a greater distance. This light-capturing architecture leaves little light available to receivers and the false eyes appear as deep black making them appear more conspicuous to predators.

scholarly journals Super black eyespots of the Eyed elater

2019 ◽  
Author(s):  
Victoria L Wong ◽  
Paul E Marek
Keyword(s):  
Incident Light ◽  
Natural World ◽  
Surface Structures ◽  
Anatomical Structures ◽  
Scattering Of Light ◽  
Click Beetle ◽  
Absorption Of Light ◽  
Complete Absorption ◽  
Vertically Aligned ◽  
Scatter Light

Scattering of light by surface structures leading to near complete structural absorption creates an appearance of “super black.” Well known in the natural world from bird feathers and butterfly scales, super black has evolved independently from various anatomical structures. Due to an exceptional ability to harness and scatter light, these biological materials have garnered interest from optical industries. Here we describe the false eyespots of the Eyed elater click beetle, which attains near complete absorption of light by an array of vertically-aligned microtubules. These cone-shaped microtubules are modified hairs (setae) that are localized to eyespots on the dorsum of the beetle, and absorb 96.1% of incident light (at a 24.8° collection angle) in the spectrum between 300 – 700 nm.

scholarly journals Super black eyespots of the Eyed elater

2019 ◽  
Author(s):  
Victoria L Wong ◽  
Paul E Marek
Keyword(s):  
Incident Light ◽  
Natural World ◽  
Surface Structures ◽  
Anatomical Structures ◽  
Scattering Of Light ◽  
Click Beetle ◽  
Absorption Of Light ◽  
Complete Absorption ◽  
Vertically Aligned ◽  
Scatter Light

Scattering of light by surface structures leading to near complete structural absorption creates an appearance of “super black.” Well known in the natural world from bird feathers and butterfly scales, super black has evolved independently from various anatomical structures. Due to an exceptional ability to harness and scatter light, these biological materials have garnered interest from optical industries. Here we describe the false eyespots of the Eyed elater click beetle, which attains near complete absorption of light by an array of vertically-aligned microtubules. These cone-shaped microtubules are modified hairs (setae) that are localized to eyespots on the dorsum of the beetle, and absorb 96.1% of incident light (at a 24.8° collection angle) in the spectrum between 300 – 700 nm.

Electrochemical preparation of vertically aligned, hollow CdSe nanotubes and their p–n junction hybrids with electrodeposited Cu2O

Nanoscale ◽  
2014 ◽  
Vol 6 (15) ◽  
pp. 9148-9156 ◽  
Author(s):  
Joyashish Debgupta ◽  
Ramireddy Devarapalli ◽  
Shakeelur Rahman ◽  
Manjusha V. Shelke ◽  
Vijayamohanan K. Pillai
Keyword(s):  
Charge Carriers ◽  
Type Ii ◽  
Electrochemical Preparation ◽  
Enhanced Absorption ◽  
Absorption Of Light ◽  
Vertically Aligned ◽  
P Type

Heterojunction (type II) of self standing, vertically aligned CdSe NTs (n-type) with electrodeposited Cu2O (p-type) exhibits excellent photoresponse, resulting from enhanced absorption of light and faster transport of photogenerated charge carriers by CdSe NTs.

Versatile thin layer spectroelectrochemical cell employing specular reflectance

1987 ◽  
Vol 65 (5) ◽  
pp. 919-923 ◽  
Author(s):  
A. Scott Hinman ◽  
Brad J. Pavelich
Keyword(s):  
Thin Layer ◽  
Specular Reflection ◽  
Incident Light ◽  
Tetrabutylammonium Perchlorate ◽  
Specular Reflectance ◽  
Advantages And Disadvantages ◽  
Ftir Characterization ◽  
Sandwich Type

A versatile thin layer spectroelectrochemical cell employing specular reflection of the incident light beam from the electrode surface is described. Its application to in-situ uv–vis and FTIR characterization of the products of electrochemical reactions and to thin layer voltammetry and coulometry as well as conventional cyclic voltammetry is demonstrated for the oxidation of tetraphenylporphinatozinc in dichloroethane/tetrabutylammonium perchlorate solution. The advantages and disadvantages of this type of cell as compared to more conventional sandwich type optically transparent thin layer electrodes are discussed.

Dye-Improved Optical Absorption of Vertically Aligned Silicon Nanowire Arrays Synthesized by Electroless Etching of Silicon Wafer

2014 ◽  
Vol 895 ◽  
pp. 200-203 ◽  
Author(s):  
Hui Chiang Teoh ◽  
Sabar Derita Hutagalung
Keyword(s):  
Silicon Nanowires ◽  
High Performance ◽  
Silicon Nanowire ◽  
Incident Light ◽  
Electroless Etching ◽  
Dye Sensitized ◽  
Silicon Nanowire Arrays ◽  
Wide Range ◽  
Vertically Aligned ◽  
Si Wafer

Silicon nanowires (SiNWs) are important candidate for high performance electronic and optoelectronic devices due to their unique structures, electrical and optical properties. SiNWs were fabricated by silver-assisted electroless etching of Si wafer. Vertically aligned SiNW arrays with length about 8.75 μm and diameter of less than 90 nm have been fabricated. The reflectance of SiNWs without dye (12%) is greatly lower compared to bare Si wafer (25%). Therefore, SiNWs on Si substrate can be used as a good anti-reflection layer for a wide range of incident light. The reflectance of dye-sensitized SiNWs with red, green and blue dyes is 7%, 5.5%, and 5% respectively. The results confirmed that the reflectance of SiNWs with dye is much lower compared to SiNWs without dye and bare Si wafer. It was proven that dye on SiNWs can be used to reduce the reflectance (improved absorption) about 40% compared to SiNWs without dye.

scholarly journals A Fabry-Pérot cavity coupled surface plasmon photodiode for electrical biomolecular sensing

2021 ◽  
Author(s):  
Giles Allison ◽  
Amrita Sana ◽  
Yuta Ogawa ◽  
Hidemi Kato ◽  
Kosei Ueno ◽  
...  
Keyword(s):  
Surface Plasmon ◽  
Specular Reflection ◽  
Incident Light ◽  
Near Field ◽  
Photovoltaic Cell ◽  
Plasmon Mode ◽  
Label Free ◽  
Plasmonic Sensor ◽  
Label Free Detection ◽  
Fabry Perot

Abstract Surface plasmon resonance (SPR) is a well-established technology for real-time highly sensitive label-free detection and measurement of binding kinetics between biological samples. A common drawback, however, of SPR detection is the necessity for far field angular resolved measurement of specular reflection, which increases the size as well as requiring precise calibration of the optical apparatus. Here we present an alternative optoelectronic approach in which the plasmonic sensor is integrated within a photovoltaic cell. Incident light generates an electronic signal that is sensitive to the refractive index (RI) of a solution via interaction with the plasmon. The photogenerated current is enhanced due to the coupling of the plasmon mode with Fabry-Pérot (FP) modes in the absorbing layer of the photovoltaic cell. The near field electrical detection of SPR we demonstrate will enable a new generation of cheap, compact and high throughput biosensors.

scholarly journals BRDF of human skin in the visible spectrum

Sensor Review ◽  
2017 ◽  
Vol 37 (4) ◽  
pp. 390-395
Author(s):  
Ali Sohaib ◽  
Laurence Broadbent ◽  
Abdul Rehman Farooq ◽  
Lyndon Neal Smith ◽  
Melvyn Lionel Smith
Keyword(s):  
Human Skin ◽  
Specular Reflection ◽  
Incident Light ◽  
Visible Spectrum ◽  
Light Transport ◽  
Angle Of Incidence ◽  
Spectral Simulation ◽  
Fibre Optics ◽  
Content Type ◽  
Skin Reflectance

Purpose Significant research has been carried out in terms of development of new bidirectional reflectance distribution function (BRDF) instruments; however, there is still little research available regarding spectral BRDF measurements of human skin. This study aims to investigate the variation in human skin reflectance using a new fibre optic-based spectral-BRDF measurement device. Design/methodology/approach Design of this system mainly involves use of multiple fibre optics to illuminate and detect light reflected from a sample, whereas a hemispherical dome was 3D printed to mount the fibres at various slant/tilt angles. To investigate the spectral differences in BRDF of human skin, 3 narrowband filters in the visible spectrum were used, whereas measurements were taken from the back of the hand for Caucasian and Asian skin types. Findings The experiments demonstrate that the BRDF of human skin varies with wavelengths in the visible spectrum and it is also different for Caucasian and Asian skin types. Both skin types exhibit off-specular reflection with increase in angle of incidence and show less variation with respect to viewing angles when the angle of incidence is normal to the surface. Research implications A database of spectral BRDF measurements of human skin will help not only in creating realistic skin renderings but also in development of novel skin reflectance models for biomedical and machine vision applications. The measurements would also provide means to validate the predictions from existing light transport/spectral simulation models for human skin and will ultimately help in the accurate diagnosis and simulation of various skin disorders. Originality/value The proposed system provides fast scatter measurements by utilising multiple fibres to detect light simultaneously at different angles while also allowing easy switching between incident light directions. Due to its flexible design and contact-based measurements, the device is independent of errors due to sample movements and does not require any image registration. Also, measurements taken from the device show that the BRDF of skin varies significantly in the visible spectrum and it is different for Caucasian and Asian skin types.

scholarly journals Laser second-harmonic generation from an overdense plasma slab

2017 ◽  
Vol 35 (3) ◽  
pp. 379-385
Author(s):  
M. Kaur ◽  
P. C. Agarwal ◽  
S. Kaur
Keyword(s):  
Second Harmonic ◽  
Short Pulse ◽  
Specular Reflection ◽  
Plasma Boundary ◽  
Harmonic Amplitude ◽  
Angle Of Incidence ◽  
Multiple Reflections ◽  
Short Pulse Laser ◽  
Plasma Slab ◽  
Overdense Plasma

AbstractA s-polarized short-pulse laser impinged obliquely on an overdense plasma slab is shown to produce very significant second harmonic in the direction of specular reflection and transmission. The laser induces a non-linear current on electrons, which is curl free. However, with sharp plasma boundary, it gives rise to electromagnetic radiation at the second harmonic. Our formalism includes multiple reflections of the incident and second-harmonic waves from both the front and rear surfaces. The present work includes finiteness of the slab. The normalized second-harmonic amplitude acquires a sharp peak at some specific angle of incidence for a particular set of parameters dependent on thickness of the slab and plasma density.

scholarly journals A Fabry-Pérot cavity coupled surface plasmon photodiode for electrical biomolecular sensing

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Giles Allison ◽  
Amrita Kumar Sana ◽  
Yuta Ogawa ◽  
Hidemi Kato ◽  
Kosei Ueno ◽  
...  
Keyword(s):  
Surface Plasmon Resonance ◽  
Surface Plasmon ◽  
Plasmon Resonance ◽  
Specular Reflection ◽  
Incident Light ◽  
Photovoltaic Cell ◽  
Label Free ◽  
Plasmonic Sensor ◽  
Label Free Detection ◽  
Fabry Perot

AbstractSurface plasmon resonance is a well-established technology for real-time highly sensitive label-free detection and measurement of binding kinetics between biological samples. A common drawback, however, of surface plasmon resonance detection is the necessity for far field angular resolved measurement of specular reflection, which increases the size as well as requiring precise calibration of the optical apparatus. Here we present an alternative optoelectronic approach in which the plasmonic sensor is integrated within a photovoltaic cell. Incident light generates an electronic signal that is sensitive to the refractive index of a solution via interaction with the plasmon. The photogenerated current is enhanced due to the coupling of the plasmon mode with Fabry-Pérot modes in the absorbing layer of the photovoltaic cell. The near field electrical detection of surface plasmon resonance we demonstrate will enable a next generation of cheap, compact and high throughput biosensors.

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