-
Lasers in Medical Science Mar 2020Deep tissue imaging using two-photon fluorescence (TPF) techniques have revolutionized the optical imaging community by providing in depth molecular information at the... (Review)
Review
Deep tissue imaging using two-photon fluorescence (TPF) techniques have revolutionized the optical imaging community by providing in depth molecular information at the single-cell level. These techniques provide structural and functional aspects of mammalian brain at unprecedented depth and resolution. However, wavefront distortions introduced by the optical system as well as the biological sample (tissue) limit the achievable fluorescence signal-to-noise ratio and resolution with penetration depth. In this review, we discuss on the advances in TPF microscopy techniques for in vivo functional imaging and offer guidelines as to which technologies are best suited for different imaging applications with special reference to adaptive optics.
Topics: Animals; Brain; Imaging, Three-Dimensional; Microscopy, Fluorescence; Neuroimaging; Optics and Photonics; Photons
PubMed: 31729608
DOI: 10.1007/s10103-019-02908-z -
Optics Letters Jul 2023We investigate the impact of collisions with two-frequency photonic molecules aiming to observe internal dynamic behavior and challenge their strong robustness....
We investigate the impact of collisions with two-frequency photonic molecules aiming to observe internal dynamic behavior and challenge their strong robustness. Versatile interaction scenarios show intriguing state changes expressed through modifications of the resulting state such as temporal compression and unknown collision-induced spectral tunneling. These processes show potential for efficient coherent supercontinuum generation and all-optical manipulation.
Topics: Photons; Fiber Optic Technology
PubMed: 37450741
DOI: 10.1364/OL.495682 -
Clinical & Experimental Optometry Jan 2020Stand magnifiers are still one of the most commonly prescribed classes of low vision devices. Their performance can be difficult to understand because stand magnifiers... (Review)
Review
Stand magnifiers are still one of the most commonly prescribed classes of low vision devices. Their performance can be difficult to understand because stand magnifiers usually do not give an image at infinity. This review summarises the methods of describing image enlargement for stand magnifiers, emphasising their relationship to equivalent viewing distance (EVD). This is done in terms of the underlying optical equations, and measurement methods, and methods of prescribing. In the past, methods of determining EVD have been somewhat indirect, requiring accurate measurement of lens power, and image position. The use of digital photography provides an alternative, more direct, simpler method of determining EVD, which can be accomplished in-office. This method is described and it is demonstrated how it gives comparable results to older methods with small, clinically non-meaningful differences, that may be due to differences in image distance reference planes. Describing the performance of stand magnifiers in terms of their dioptric power, or in terms of 'nominal magnification' or 'trade magnification', is imprecise and misleading. It is better to use indices such as equivalent viewing power and EVD, which take into account the magnifier dioptric power, the image position of the magnifier and the distance a patient is from the magnifier. While EVD is a useful index for prescribing stand magnifiers, manufacturers do not always provide sufficient technical details to determine EVD for their stand magnifiers, and available tables of EVDs are more than a decade old and are likely to need updating. Photographic comparison provides a method for determining EVD, and this method can also be applied to other low vision devices.
Topics: Equipment Design; Humans; Optics and Photonics; Prescriptions; Reading; Sensory Aids; Vision, Low
PubMed: 31429123
DOI: 10.1111/cxo.12948 -
Small (Weinheim An Der Bergstrasse,... Jul 2021As a nanoscale renewable resource derived from lignocellulosic materials, cellulose nanocrystals (CNCs) have the features of high purity, high crystallinity, high aspect... (Review)
Review
As a nanoscale renewable resource derived from lignocellulosic materials, cellulose nanocrystals (CNCs) have the features of high purity, high crystallinity, high aspect ratio, high Young's modulus, and large specific surface area. The most interesting trait is that they can form the entire films with bright structural colors through the evaporation-induced self-assembly (EISA) process under certain conditions. Structural color originates from micro-nano structure of CNCs matrixes via the interaction of nanoparticles with light, rather than the absorption and reflection of light from the pigment. CNCs are the new generation of photonic liquid crystal materials of choice due to their simple and convenient preparation processes, environmentally friendly fabrication approaches, and intrinsic chiral nematic structure. Therefore, understanding the forming mechanism of CNCs in nanoarchitectonics is crucial to multiple fields of physics, chemistry, materials science, and engineering application. Herein, a timely summary of the chiral photonic liquid crystal films derived from CNCs is systematically presented. The relationship of CNC, structural color, chiral nematic structure, film performance, and applications of chiral photonic liquid crystal films is discussed. The review article also summarizes the most recent achievements in the field of CNCs-based photonic functional materials along with the faced challenges.
Topics: Cellulose; Liquid Crystals; Nanoparticles; Nanostructures; Optics and Photonics
PubMed: 34047461
DOI: 10.1002/smll.202007306 -
Chemical Reviews Dec 2019The extraordinary properties of biological materials often result from their sophisticated hierarchical structures. Through multilevel and cross-scale structural... (Review)
Review
The extraordinary properties of biological materials often result from their sophisticated hierarchical structures. Through multilevel and cross-scale structural designs, biological materials offset the weakness of their individual building blocks and enhance performance at multiple length scales to match the multifunctional needs of organisms. One essential merit of hierarchical structure is that it can optimize the interfacial features of the "building blocks" at different length scales, from the molecular level to the macroscale. Understanding the roles of biological material interfaces (BMIs) on the determination of properties and functions of biological materials has become a growing interdisciplinary research area in recent years. A pivotal aim of these studies is to use BMIs as inspiration for developing bioinspired and biomimetic materials and devices with advanced structures and functions. Given these considerations, this review aims to comprehensively discuss the structure-property-function relationships of BMIs in nature. We particularly focus on the discussion of BMIs and their inspired materials from mechanical and optical perspectives because these two directions are the most well-investigated and closely related. The challenges and directions of design and fabrication of BMI-inspired mechanical and optical materials are also discussed. This review is expected to garner interest from advanced material communities as well as environmental, nanotechnology, food processing, and engineering fields.
Topics: Animals; Biological Products; Biomimetic Materials; Biomimetics; Nanofibers; Optics and Photonics; Structure-Activity Relationship
PubMed: 31793285
DOI: 10.1021/acs.chemrev.9b00416 -
Scientific Reports Aug 2022Herein, we theoretically suggest one-dimensional photonic crystal composed of polymer doped with quantum dots and porous silicon. The present simulated design is...
Herein, we theoretically suggest one-dimensional photonic crystal composed of polymer doped with quantum dots and porous silicon. The present simulated design is proposed as a refractive index biosensor structure based on parity-time symmetry. Under the parity-time conditions, the transmittance of the resonant peaks is magnified to be 57,843% for refractive index 1.350, 2725% for 1.390, 2117% for 1.392, 1502% for 1.395, 1011% for 1.399, and 847% for 1.401. By magnification, we can distinguish between different refractive indices. The present design can record an efficiency twice the published designs as clear in the comparison table. Results clear that the sensitivities are 635 nm/RIU and 1,000,000%/RIU. So, it can be used for a broader range of detection purposes.
Topics: Biosensing Techniques; Optics and Photonics; Photons; Refractometry; Silicon
PubMed: 35961999
DOI: 10.1038/s41598-022-17676-0 -
Small (Weinheim An Der Bergstrasse,... Nov 2022Low-dimensional organic crystals (LOCs) have attracted increasing attention recently for their potential applications in miniaturized optoelectronics and integrated... (Review)
Review
Low-dimensional organic crystals (LOCs) have attracted increasing attention recently for their potential applications in miniaturized optoelectronics and integrated photonics. Such applications are possible owing to their tunable physicochemical properties and excellent charge/photon transport features. As a result, the precise synthesis of LOCs has been examined in terms of morphology modulation, large-area pattern arrays, and complex architectures, and this has led to a series of appealing structure-dependent properties for future optoelectronic applications. This review summarizes the recent advances in the precise synthesis of LOCs in addition to discussing their structure-property relationships in the context of optoelectronic applications. It also presents the current challenges related to organic crystals with specific structures and desired performances, and the outlook regarding their use in next-generation integrated optoelectronic applications.
Topics: Optics and Photonics
PubMed: 36057992
DOI: 10.1002/smll.202203961 -
Faraday Discussions Oct 2020Photonic structures in ordered, quasi-ordered or disordered forms have evolved across many different animal and plant systems. They can produce complex and often... (Review)
Review
Photonic structures in ordered, quasi-ordered or disordered forms have evolved across many different animal and plant systems. They can produce complex and often functional optical responses through coherent and incoherent scattering processes, often too, in combination with broadband or narrowband absorbing pigmentation. Interestingly, these systems appear highly tolerant of faults in their photonic structures, with imperfections in their structural order appearing not to impact, discernibly, the systems' optical signatures. The extent to which any such biological system deviates from presenting perfect structural order can dictate the optical properties of that system and, thereby, the optical properties that system delivers. However, the nature and extent of the optical costs and benefits of imperfect order in biological systems demands further elucidation. Here, we identify the extent to which biological photonic systems are tolerant of defects and imperfections. Certainly, it is clear that often significant inherent variations in the photonic structures of these systems, for instance a relatively broad distribution of lattice constants, can consistently produce what appear to be effective visual appearances and optical performances. In this article, we review previously investigated biological photonic systems that present ordered, quasi-ordered or disordered structures. We discuss the form and nature of the optical behaviour of these structures, focusing particularly on the associated optical costs and benefits surrounding the extent to which their structures deviate from what might be considered ideal systems. Then, through detailed analyses of some well-known 1D and 2D structurally coloured systems, we analyse one of the common manifestations of imperfect order, namely, the extent and nature of positional disorder in the systems' spatial distribution of layers and scattering centres. We use these findings to inform optical modelling that presents a quantitative and qualitative description of the optical costs and benefits of such positional disorder among ordered and quasi-ordered 1D and 2D photonic systems. As deviation from perfectly ordered structures invariably limits the performance of technology-oriented synthetic photonic processes, we suggest that the use of bio-inspired fault tolerance principles would add value to applied photonic technologies.
Topics: Crystallization; Optics and Photonics; Photons; Scattering, Radiation
PubMed: 33000817
DOI: 10.1039/d0fd00101e -
Macromolecular Rapid Communications Jul 2022Living organisms have evolved fascinating structural colors to survive in complex natural environments. Artificial photonic composites developed by imitating the... (Review)
Review
Living organisms have evolved fascinating structural colors to survive in complex natural environments. Artificial photonic composites developed by imitating the structural colors of organisms are applied in displaying, sensing, biomedicine, and many other fields. As emerging materials, photonic composites mediated by supramolecular chemistry, namely, supramolecular photonic composites, are designed and constructed to meet emerging application needs and challenges. This review mainly introduces the constructive strategies, properties, and applications of supramolecular photonic composites. First, constructive strategies of supramolecular photonic composites are summarized, including the introduction of supramolecular polymers into colloidal photonic array templates, coassembly of colloidal particles (CPs) with supramolecular polymers, self-assembly of soft CPs, and compounding photonic elastomers with functional substances via supramolecular interactions. Supramolecular interactions endow photonic composites with attractive properties, such as stimuli-responsiveness and healability. Subsequently, the unique optical and mechanical properties of supramolecular photonic composites are summarized, and their applications in emerging fields, such as colorful coatings, real-time and visual motion monitoring, and biochemical sensors, are introduced. Finally, challenges and perspectives in supramolecular photonic composites are discussed. This article provides general strategies and considerations for the design of photonic materials based on supramolecular chemistry.
Topics: Elastomers; Optics and Photonics; Photons
PubMed: 35255176
DOI: 10.1002/marc.202100867 -
Journal of Visualized Experiments : JoVE Sep 2022Recent advances in optical bioimaging and optogenetics have enabled the visualization and manipulation of biological phenomena, including cellular activities, in living...
Recent advances in optical bioimaging and optogenetics have enabled the visualization and manipulation of biological phenomena, including cellular activities, in living animals. In the field of neuroscience, detailed neural activity related to brain functions, such as learning and memory, has now been revealed, and it has become feasible to artificially manipulate this activity to express brain functions. However, the conventional evaluation of neural activity by two-photon Ca imaging has the problem of low temporal resolution. In addition, manipulation of neural activity by conventional optogenetics through the optic fiber can only simultaneously regulate the activity of neurons with the same genetic background, making it difficult to control the activity of individual neurons. To solve this issue, we recently developed a microscope with a high spatiotemporal resolution for biological applications by combining optogenetics with digital holographic technology that can modify femtosecond infrared laser beams. Here, we describe protocols for the visualization, evaluation, and manipulation of neural activity, including the preparation of samples and operation of a two-photon holographic microscope (Figure 1). These protocols provide accurate spatiotemporal information on neural activity, which may be useful for elucidating the pathogenesis of neuropsychiatric disorders that lead to abnormalities in neural activity.
Topics: Animals; Brain; Holography; Microscopy; Neurons; Optogenetics; Photons
PubMed: 36190272
DOI: 10.3791/64205