Optical Lens Research Articles

Additive effects of narrowband light and optical defocus on chick eye growth and refraction

BackgroundIn the past decade and during the COVID pandemic, the prevalence of myopia has reached epidemic proportions. To address this issue and reduce the prevalence of myopia and its complications, it is necessary to develop more effective interventions for controlling myopia. In this study, we investigated the combined effects of narrowband lights and competing defocus on eye growth and refraction in chicks, an important step in understanding the potential for these interventions to control myopia. This is the first time these effects have been characterized.MethodsThree groups of five-day-old chicks (n = 8 per group) were raised in three different lighting conditions: white, red, and blue for 13 days in a 12/12-h light/dark diurnal cycle. One eye was randomly selected for applications of a dual-power optical lens (− 10 D/ + 10 D, 50∶50), while another eye was left untreated as control. Vitreous chamber depth (VCD), axial length (AL), choroidal thickness (CT) and refractive errors were measured at pre-exposure (D0) and following 3 (D3), 7 (D7), 10 (D10), and 13 days (D13) of light exposure.ResultsUnder white light, the dual-power lens induced a hyperopic shift [at D13, mean spherical equivalent refraction (SER), treated vs. control: 4.81 ± 0.43 D vs. 1.77 ± 0.21 D, P < 0.001] and significantly reduced the progression of axial elongation (at D13, change in AL, treated vs. control: 1.25 ± 0.04 mm vs. 1.45 ± 0.05 mm, P < 0.01). Compared to white light alone, blue light alone induced a hyperopic shift (at D13, mean SER, blue vs. white: 2.75 ± 0.21 D vs. 1.77 ± 0.21 D, P < 0.01) and significantly reduced axial elongation (at D13, change in AL, blue vs. white: 1.17 ± 0.06 mm vs. 1.45 ± 0.05 mm, P < 0.01) in control eyes. When comparing all conditions, eyes exposed to blue light plus dual-power lens had the least axial elongation (at D13, change in AL, 0.99 ± 0.05 mm) and were the most hyperopic (at D13, mean SER, 6.36 ± 0.39 D).ConclusionsBoth narrowband blue light and dual-power lens interventions were effective in inducing a hyperopic shift in chicks, and provided protection against myopia development. The combination of these interventions had additive effects, making them potentially even more effective. These findings support the use of optical defocus interventions in combination with wavelength filters in clinical studies testing their effectiveness in treating myopia in children.

Computational Optical Microscopy Using Algorithm

Like a mobile phone camera, optical microscopy typically relies on optical lenses that convert a plane wave to a spherical wave or vice versa. In such conventional imaging scheme, light from an object point propagates through a set of lenses and creates a tight focus on a camera, resulting in 1 to 1 relation between the object point and the camera pixel. Recently, this conventional imaging paradigm has been challenged by a new paradigm where computational algorithms replace the role of lenses. Here, I will introduce the concept of computational optics and some novel microscopy techniques based on algorithms.

Probing the conserved roles of cut in the development and function of optically different insect compound eyes.

Astonishing functional diversity exists among arthropod eyes, yet eye development relies on deeply conserved genes. This phenomenon is best understood for early events, whereas fewer investigations have focused on the influence of later transcriptional regulators on diverse eye organizations and the contribution of critical support cells, such as Semper cells (SCs). As SCs in Drosophila melanogaster secrete the lens and function as glia, they are critical components of ommatidia. Here, we perform RNAi-based knockdowns of the transcription factor cut (CUX in vertebrates), a marker of SCs, the function of which has remained untested in these cell types. To probe for the conserved roles of cut, we investigate two optically different compound eyes: the apposition optics of D. melanogaster and the superposition optics of the diving beetle Thermonectus marmoratus. In both cases, we find that multiple aspects of ocular formation are disrupted, including lens facet organization and optics as well as photoreceptor morphogenesis. Together, our findings support the possibility of a generalized role for SCs in arthropod ommatidial form and function and introduces Cut as a central player in mediating this role.

Experimental and computational phase behavior investigation for the CO2 + 1H, 1H-perfluorooctyl acrylate and CO2 + 1H, 1H-perfluorooctyl methacrylate systems at high pressure

The solubility information of fluoro-monomer (meth) acrylate in organic solvents is an important factor affecting their use in numerous engineering practices. This study investigated the phase equilibria of 1H, 1H-perfluorooctyl acrylate (PFOA) and 1H, 1H-perfluorooctyl methacrylate (PFOMA) in supercritical CO2 using optical fiber and contact lenses. The solubility curves investigations were conducted at different temperatures (313.2 to 393.2) K and pressures (3.31 to 16.84) MPa, and the mole fraction of (0.032 to 0.630).Results revealed that the PFOA + SC-CO2 and PFOMA + SC-CO2 systems exhibited a type-I behavior. The RMSD (%) for the PFOA + SC-CO2 [kij = 0.075, ηij = 0.0], and PFOMA + SC-CO2 [kij = 0.075, ηij = 0.0] models using two factors determined at 353.2 K evaluated with the alterable parameters at each T were 5.08 %, and 5.36 %, respectively. The correlation of the experimental response for the PFOA + SC-CO2 and PFOMA + SC-CO2 two component models were examined using Peng-Robinson (PR) equation of state (EOS) involving two parameters (kij, ηij) base on a fluid mixture rule. Additionally, the critical properties (pc, Tc and ω) and vapor pressure of PFOA and PFOMA were assessed using the Joback-Lyderson group impact.

Volumetric light sheet imaging with adaptive optics correction.

Light sheet microscopy has developed quickly over the past decades and become a popular method for imaging live model organisms and other thick biological tissues. For rapid volumetric imaging, an electrically tunable lens can be used to rapidly change the imaging plane in the sample. For larger fields of view and higher NA objectives, the electrically tunable lens introduces aberrations in the system, particularly away from the nominal focus and off-axis. Here, we describe a system that employs an electrically tunable lens and adaptive optics to image over a volume of 499 × 499 × 192 μm3 with close to diffraction-limited resolution. Compared to the system without adaptive optics, the performance shows an increase in signal to background ratio by a factor of 3.5. While the system currently requires 7s/volume, it should be straightforward to increase the imaging speed to under 1s per volume.

Evaluating clinical near-infrared surgical camera systems with a view to optimizing operator and computational signal analysis.

As clinical evidence on the colorectal application of indocyanine green (ICG) perfusion angiography accrues, there is also interest in computerizing decision support. However, user interpretation and software development may be impacted by system factors affecting the displayed near-infrared (NIR) signal. We aim to assess the impact of camera positioning on the displayed NIR signal across different open and laparoscopic camera systems. The effects of distance, movement, and target location (center versus periphery) on the displayed fluorescence signal of different systems were measured under electromagnetic stereotactic guidance from an ICG-albumin model and in vivo during surgery. Systems displayed distinct fluorescence performances with variance apparent with scope optical lens configuration (0deg versus 30deg), movement, target positioning, and distance. Laparoscopic system readings fitted inverse square function distance-intensity curves with one device and demonstrated a direction dependent sigmoid curve. Laparoscopic cameras presented central targets as brighter than peripheral ones, and laparoscopes with angled optical lens configurations had a diminished field of view. One handheld open system also showed a distance-intensity relationship, whereas the other maintained a consistent signal despite distance, but both presented peripheral targets brighter than central ones. Optimal clinical use and signal computational development requires detailed appreciation of system behaviors.

Angular Superoscillatory Metalens Empowers Single‐Shot Measurement of OAM Modes with Finer Intervals

AbstractDistinct from conventional optical lenses suffering from the diffraction limit, the superoscillatory lens offers an alternative approach to realize far‐field sub‐diffraction focusing and find significant applications in both microscopy and telescopy. During the past few years, planar micro/nanostructures are unitized to precisely manipulate the optical fields through a standard lens to realize a superoscillatory field along the radial direction of the pupil. Here, an angular superoscillatory metalens (ASOM) is demonstrated by combining the superoscillatory phase and angular metalens phase in a single metasurface. To the best of the authors’ knowledge, this is the first work that focuses on the angular superoscillatory phenomenon. As a proof‐of‐concept application demo, this study shows the ASOM can map the received orbital angular modes (OAMs) into focusing patterns at the focal plane with different azimuth angles. Therefore, the OAM spectrum incorporating multiple modes can be determined with a single‐shot measurement according to the precalibrated mapping relationship. This study shows that the OAM resolution is scaled up about 3.2 times compared with a normal angular metalens, thanks to the shrinkage of the focal patterns. This approach may push the development of integrated and high‐dimensional optical and quantum systems.

CLEAR interactive – 5

Neil Retallic and Bill Harvey offer feedback from the last interactive CPD exercise based on the BCLA CLEAR publication focusing on contact lens optics. (C104243)

Acousto-optical camera for super-resolution imaging

I will present a hybrid acousto-optical imaging system that probes the environment with acoustic waves, converts the back-scattered sound into a coherent optical field on an aperture using an acousto-optical metasurface, and focuses the latter into an image with existing optical lenses. Preliminary theoretical analysis and experiments show that this approach can produce images of significantly higher resolution than possible with conventional methods, thus enabling high quality images produced with low frequency probing sound. Our imaging approach takes advantage of the best properties of optic and acoustic waves, namely, (1) the high image quality produced by existing optical systems and (2) the ability of low frequency acoustic waves to penetrate most materials. An additional advantage of our method is that it puts essentially no constraints on the sound source. For example, the source could have low directivity and may consist of a single transducer or it could even miss when imaging noisy environments. In the latter scenarios, our imaging method becomes purely passive.

Beam Shaping Technique for 5-mm Fiber-coupled Laser Diode Bars with Lens Group

In the last few years, fiber-coupled diode lasers have shown massive applications in many fields of communication and scientific research. Particularly, the pumping of solid-state lasers is a key application for more powerful diode lasers enabling good solutions in various laser micro methods like metal cutting, sintering, structuring as well as drilling. In this work, a simple beam shaping method is demonstrated for coupling a high-power semiconductor laser diode into multi-mode fiber optic using optical lenses. The optical lenses as beam transformation components are utilized to reshape the asymmetrical irradiation of the diode laser bar and to circularize the laser beam. Using this simple method, compact, high-output-power, and high-brightness fiber-coupled laser diode systems are achieved. The obtained results show that the entire optical coupling efficiency of the system is more than 65%.

Development of an Active Optical Lens for Arc Flashing Detection.

This paper contains the design of active optical lenses used for the detection of arc flashing emissions. The phenomenon of an arc flashing emission and its characteristics were contemplated. Methods of preventing these emissions in electric power systems were discussed as well. The article also includes a comparison of commercially available detectors. An analysis of the material properties of fluorescent optical fiber UV-VIS-detecting sensors constitutes a major part of the paper. The main purpose of the work was to make an active lens using photoluminescent materials, which can convert ultraviolet radiation into visible light. As part of the work, active lenses with materials such as Poly(methyl 2-methylpropenoate) (PMMA) and phosphate glass doped with lanthanides, such as terbium (Tb3+) and europium (Eu3+) ions, were analyzed. These lenses were used to make optical sensors, which were supported by commercially available sensors in their construction.

A single-vision dual imaging optical system in flip chip alignment

In the case of flip-chip, the key to high-quality packaging is the high-precision alignment of the chip to the PCB. High-precision alignment is usually achieved using vision. Since the lens and camera are expensive and the camera coordinates system conversion is cumbersome, the single-vision system is proposed. However, there are defects in that the loss of light source is large, and the coaxial optical lens cannot be used. In this paper, a new single-vision dual-imaging optical system is proposed based on Zemax, which effectively solves the defects of the old single-vision system. The results show that the system can reduce the use of the lens and camera, reduce the use cost of the equipment, and easily convert the camera coordinate system to ensure the imaging quality.

Enhancing the optical path inside a capillary without sacrificing light intensity: application to a compact and highly sensitive photometer.

In order to increase the optical path and related sensitivity of photometers, multiple axial-reflection of parallel light-beam inside a capillary cavity is one of the most effective ways. However, there is a non-optimum trade-off between optical path and light intensity, e.g., smaller aperture on cavity mirror can increase multiple axial-reflection times (i.e., longer optical path) due to the lower cavity-loss, but it would also reduce coupling efficiency, light intensity, and related signal-to-noise ratio. Herein, an optical beam shaper, which is composed of two optical lenses with an apertured mirror, was proposed to focus the light beam (i.e., increasing coupling efficiency) without deteriorating beam parallelism and related multiple axial-reflection. Thus, by combining the optical beam shaper with a capillary cavity, large optical path enhancement (10-fold of capillary length) and high coupling efficiency (>65%) can be realized simultaneously, where the coupling efficiency was improved 50-fold. An optical beam shaper photometer (with a 7 cm long capillary) was fabricated and applied to detect water in ethanol with a detection limit of 12.5 ppm, which is 800-fold and 32∼80 fold lower than that of the commercial spectrometer (1 cm cuvette) and previous reports, respectively.

Smartphone-based hand-held polarized light microscope for on-site pharmaceutical crystallinity characterization.

Polarized light microscopy (PLM) is a common but critical method for pharmaceutical crystallinity characterization, which has been widely introduced for research purposes or drug testing and is recommended by many pharmacopeias around the world. To date, crystallinity characterization of pharmaceutical solids is restricted to laboratories due to the relatively bulky design of the conventional PLM system, while little attention has been paid to on-site, portable, and low-cost applications. Herein, we developed a smartphone-based polarized microscope with an ultra-miniaturization design ("hand-held" scale) for these purposes. The compact system consists of an optical lens, two polarizers, and a tailor-made platform to hold the smartphone. Analytical performance parameters including resolution, imaging quality of interference color, and imaging reproducibility were measured. In a first approach, we illustrated the suitability of the device for pharmaceutical crystallinity characterization and obtained high-quality birefringence images comparable to a conventional PLM system, and we also showed the great promise of the device for on-site characterization with high flexibility. In a second approach, we employed the device as a proof of concept for a wider application ranging from liquid crystal to environmental pollutants or tissues from plants. As such, this smartphone-based hand-held polarized light microscope shows great potential in helping pharmacists both for research purposes and on-site drug testing, not to mention its broad application prospects in many other fields.

Polarization-dependent metalens with flexible and steerable bifocal spots

Lenses are an important part of modern optical systems. We propose metalenses with bifocal spots, which realizes the beam focusing with controllable intensity ratio and free deflection of the bifocal spots. The metalens consists of an array of titanium dioxide (TiO2) nanopillars, which can provide two different propagation phases for x-linear polarization (XLP) and y-linear polarization (YLP) incidence, respectively. Therefore, by precisely choosing the size of the nanopillars, it is possible to produce two different focal spots for the two orthogonal input polarized light. And the intensity of the two focal points can be adjusted by changing the polarization angle of the incident light. Superimposing the initial phase distribution of the metalens and the phase distribution of the beam deflector metasurface enables multi-dimensional adjustment of the two focal points and realizes the free deflection characteristics of the metalens. The deflection angle of the focal spot is close to the theoretical deflection angle. In addition, multiple superposition can produce more deflection angles or deflect the focus to a two-dimensional plane. The method of controlling the targeting phase of the metalens by superimposing additional phases gives us the ability to fully manipulate the phase and wavefront of the metalens, providing a new idea for the continuous angle change of future optical lenses.

Electric Field‐Driven Dielectrophoretic Elastomer Actuators

AbstractDielectrophoresis is the electro‐mechanical phenomenon where a force is generated on a dielectric material when exposed to a non‐uniform electric field. It has potential to be exploited in smart materials for robotic manipulation and locomotion, but to date it has been sparsely studied in this area. Herein, a new type of dielectrophoretic actuator exploiting a novel electroactive polymer is described, termed as dielectrophoretic elastomer (DPE), which undergoes electric field‐driven actuation through dielectrophoresis. Unique deflection and morphing behavior of the elastomer induced by controlling the dielectrophoretic phenomenon, such as out‐of‐plane deformation and independence of electric field polarity, are illustrated. The dielectric and mechanical properties of the DPE are studied to gain insight into the influence of materials composition on deformation. Actuation performance using different electrode parameters is experimentally investigated with supplementary analysis through finite element simulation, revealing the relationship between electric field inhomogeneity and deflection. The applications of DPE actuators in a range of robotic devices is demonstrated, including a pump, an adjustable optical lens, and a walking robot. This diverse range of applications illustrates the wide potential of these new soft‐and‐smart electric field‐driven materials for use in soft robotics and soft compliant devices.

A Study on the Development of a White Light Source Module for a Large-Capacity Searchlight Using a Blue Laser Diode

In this paper, a large-capacity white light source module using a high-power blue laser diode and a reflective spaced phosphor was designed. The reflective spacing phosphor ensured thermal stability. The proposed white light module is a reflective phosphor structure with a bi-directional optical system based on a rhombus prism lens. The rhombus prism optical system can greatly narrow the blue laser beam width and a long-wavelength band-pass filter of 500 nm or more is applied to change the movement path of the laser beam and transmit white light excited by the phosphor. A dichroic filter was applied to the fold mirror part and a planar convex lens was designed to focus the blue laser beam so that the phosphor was irradiated. Finally, a high-power white light source is obtained from the pre-optics unit to which the dichroic filter is applied. In order to use the proposed white light source as a searchlight, a divergence angle of 4° or less is required. For this implementation, a large-area collimating lens combining an aspheric condensing lens and an achromatic lens was applied. It was confirmed that the divergence angle of 4 degrees or less was satisfied at the focal length (FL) of 38.5 to 42.5 mm of the optical lens of the laser white light module emitter and the collimating optical system.

Development of a laser-based angle-resolved-photoemission spectrometer with sub-micrometer spatial resolution and high-efficiency spin detection.

Angle-resolved photoemission spectroscopy with sub-micrometer spatial resolution (μ-ARPES), has become a powerful tool for studying quantum materials. To achieve sub-micrometer or even nanometer-scale spatial resolution, it is important to focus the incident light beam (usually from synchrotron radiation) using x-ray optics, such as the zone plate or ellipsoidal capillary mirrors. Recently, we developed a laser-based μ-ARPES with spin-resolution (LMS-ARPES). The 177nm laser beam is achieved by frequency-doubling a 355nm beam using a KBBF crystal and subsequently focused using an optical lens with a focal length of about 16mm. By characterizing the focused spot size using different methods and performing spatial-scanning photoemission measurement, we confirm the sub-micron spatial resolution of the system. Compared with the μ-ARPES facilities based on the synchrotron radiation, our LMS-ARPES system is not only more economical and convenient, but also with higher photon flux (>5 × 1013 photons/s), thus enabling the high-resolution and high-statistics measurements. Moreover, the system is equipped with a two-dimensional spin detector based on exchange scattering at a surface-passivated iron film grown on a W(100) substrate. We investigate the spin structure of the prototype topological insulator Bi2Se3 and reveal a high spin-polarization rate, confirming its spin-momentum locking property. This lab-based LMS-ARPES will be a powerful research tool for studying the local fine electronic structures of different condensed matter systems, including topological quantum materials, mesoscopic materials and structures, and phase-separated materials.

Microsphere-based photoexcited efficient terahertz radiation at room temperature enhanced by Ag/PI/PMMA/ZnO circle hollow waveguide resonance

The discovery and development of efficient terahertz sources at room temperature could lead to comprehensive application foreground. Here, ZnO mesocrystal microspheres were prepared by hydrothermal method through self-assembly of nanosheets. High-frequency mechanical vibrations of charged nanostructures excited by a continuous 514.5 nm laser at room temperature can lead to radiative emission at 0.36 THz, conversion efficiency of which was only 0.015%. A sandwich-structured Ag/PI/PMMA/ZnO circle hollow terahertz waveguide was fabricated to obtain high-power terahertz radiation source. Nano Ag thin film effectively localized terahertz light in the waveguide and reduced diffusion losses because of high reflection. Then, Optical lenses were placed before and after the waveguide to form a resonant cavity, so that terahertz light was resonantly enhanced at certain length. Meanwhile, the thickness of the PI thin film was designed to enhance the interference of terahertz light. Besides, the incident angle of green laser had a great influence on its reflection path within the waveguide, which in turn affected the number of excitations of ZnO. The above comprehensive reasons have successfully improved the conversion efficiency by 5.5 and 8.3 times when the angle of incident laser was 0° and 30°, respectively. This work revealed a new strategy to design and fabricate terahertz sources with excellent properties simultaneously such as room temperature operation, stable performance, and high power output.

Deep learning-based weak micro-defect detection on an optical lens surface with micro vision.

To solve limited efficiency and reliability issues caused by current manual quality control processes in optical lens (OL) production environments, we propose an automatic micro vision-based inspection system named MVIS used to capture the surface defect images and make the OL dataset and predictive inference. Because of low resolution and recognition, OL defects are weak, due to their ambiguous morphology and micro size, making a poor detection effect for the existing method. A deep-learning algorithm for a weak micro-defect detector named ISE-YOLO is proposed, making the best for deep layers, utilizing the ISE attention mechanism module in the neck, and introducing a novel class loss function to extract richer semantics from convolution layers and learning more information. Experimental results on the OL dataset show that ISE-YOLO demonstrates a better performance, with the mean average precision, recall, and F1 score increasing by 3.62%, 6.12% and 3.07% respectively, compared to the YOLOv5. In addition, compared with YOLOv7, which is the latest version of YOLO serials, the mean average precision of ISE-YOLO is improved by 2.58%, the weight size is decreased by more than 30% and the speed is increased by 16%.