Optical Part Research Articles

Functional gradient films on aluminum alloy to improve its laser‐induced damage ability and reduce pollutant particles’ generation

AbstractLaser‐induced damage on metal parts by stray light is a common issue for high‐energy laser systems, especially inertial‐confinement fusion (ICF) systems. Micro‐dust could be produced from the surface irradiated and adhere to and cause further damage of other optical parts like potassium dihydrogen phosphate (KDP) crystal. We propose a functional gradient film based on aluminum anodization to raise the laser‐induced damage threshold (LIDT). The number of particles produced by a 355‐nm nanosecond laser was considered a factor of LIDT. To investigate the interaction theoretically, a coupled model of electromagnetic radiation and heat conversion based on Ohm's law for a nanosecond laser pulse absorbed by the films was used to calculate the LIDT temperature. Films with different roughnesses and an untreated aluminum alloy (AA) were irradiated. The LIDT was 0.5 J/cm2, with a temperature of 5790 K, which largely prevented the laser damage of the AA and reduced particles produced while metal damaged. The combination of simulations and experiments provided a new and simple indication of LIDT for aluminum‐based functional gradient films. It also provided a guide for clean manufacturing with less particle generation, which is vital to the success of ICF systems that will generate sustainable energy.

Glass poling as a substrate surface pre-treatment for in situ metal nanoparticle formation by reduction of metal salt

Metal nanoparticles are used in optical coatings and sensors due to their absorption in optical part of spectrum and its sensitivity to the environment induced by localized surface plasmon resonance. Glass is the most common substrate used for optical coatings. However, its surface does not have optimal properties for coating with metal nanoparticles grown in situ by reduction of metal salt. Glass surface optimization methods may involve environmentally hostile chemicals or processes that have time limited or atmosphere sensitive effects. In this study it is demonstrated and discussed effectiveness, mechanisms and advantages of glass poling as pre-treatment method for improving glass surface properties for maximization of coatings plasmonic performance. Pre-treatment of glass surfaces by poling is highly efficient for the purpose. Glass poling quenches ion exchange between metal ions from the solution and alkali ions from glass, favouring nanoparticles formation. Surface prepared in such way is not affected by ageing in normal atmosphere and is effective even after coating with ultrathin dielectric or Cr layers.

Experimental use of precision replication technology to recover optical parts from rejects in batch production

Experimental use of precision replication technology to recover optical parts from rejects in batch production

An ultra-high sensitivity fluorescence sensor based on fluorescence technology

An ultra-high sensitivity fluorescence sensor with 1 ng/L-level detection limit was developed for water treatment applications, in which fluorescent tracing method is applied by using PTSA (1, 3, 6, 8-pyrenetetrasulfonic acid, sodium salt) to indicate the concentration of water treatment agents. This sensor consists of an optical part for fluorescence excitation and detection, as well as a signal processing and control circuit. The optical part employs a compound parabolic concentrator structure and achieves 6-fold increase in the collected fluorescence intensity. The circuit handles the determination procedures such as LED emission modulation, detector signal processing and concentration determination of water treatment agents. For PTSA with ultrapure water in ultra-low concentration range of 0 – 0.1 μg/L, a detection limit of 7 ng/L is demonstrated. The sensor has benefits of low cost, high accuracy and ease of deployment, which is promising for real-time detection of water treatment agents concentration in industrial cooling water circulation system.

Real-time contact angle’s measurement of molten solder balls in laboratory conditions

PurposeThe purpose of this paper is to show a possibility to measure a change of a contact angle during the melting in real-time and to reveal significant factors of a wettability. Influence of the flux with combination of plasma on copper surface was investigated in experiment as well.Design/methodology/approachLaboratory equipment consists of heating and optical part that was developed and tested for real-time contact angle’s measurements. Solder balls based on Sn96.5/Ag3/Cu0.5 and Sn63Pb37 spread out on a copper substrate during a melting process. The wettability of pure copper surface was compared with copper surface treated with flux or combination plasma–flux. The contact angle and spreading rate of a melted solder balls observed by the charged-coupled device camera were analyzed in real-time and measured using the JavaScript.FindingsLaboratory equipment allows for analysis of contact angle and spreading rate in real-time during the melting process. The contact angle decreases more noticeable after applying the plasma-flux treatment in contrast to no flux or flux treatment only. Using the plasma treatment before application of the flux improves the wettability and the effectivity of the flux activity on the copper surface during the melting process.Originality/valueThe interpretation of the results of such a comprehensive measurement leads to a better understanding of the mutual relation between flux and combination plasma–flux of the wetting during the melting process. The simple, cheap, fast and accurate laboratory equipment, which consists of the heating and the optical part, allows for the wettability evaluation of the melting process in real-time.

Impact of Intraocular Lens Decentration on the Near Vision Performance of a Wavefront-Correcting Extended Depth of Focus IOL

PURPOSE: To examine the impact of intraocular lens (IOL) decentration on the near vision performance of a wavefront-correcting extended depth of focus (EDOF) IOL. METHODS: Case report. RESULTS: A 77-year-old man presented with poor unaided visual function at near (20/125) and intermediate (20/100) distances after cataract surgery in the right eye with implantation of a wavefront-correcting EDOF IOL. Uncorrected distance visual acuity was 20/25. A 0.4-mm decentration of the central optical component of the IOL was noted and assumed to be the underlying reason for the poor near/intermediate visual function. After reassessing the patient's expectations for spectacle independence for reading, IOL exchange by a multifocal diffractive IOL with capsular tension ring implantation was performed 3 months after surgery. The patient was satisfied, and uncorrected near (20/32) and intermediate (20/32) visual function was restored. CONCLUSIONS: Correct centration of the central 2.2-mm optical part of the wavefront-correcting EDOF IOL seems to play a critical role in achieving satisfactory vision for both intermediate and near distances. The authors suggest the routine implantation of a capsular tension ring together with this lens to minimize the risk for such a complication. [ Journal of Refractive Surgery Case Reports. 2022;2(2):e29–e31.]

Clinical Study of Intraocular Lens Implantation by Scleral Suture Fixation after Lensectomy and Vitrectomy

Objective: To investigate the surgical techniques and clinical significance of intraocular lens implantation by scleral suture fixation after lensectomy and vitrectomy. Methods: According to the inclusion and exclusion criteria, 19 cases (20 eyes) were selected for IOL implantation by scleral suture fixation after lensectomy and vitrectomy. The uncorrected visual acuity (VA), best-corrected visual acuity (BCVA), intraocular pressure (IOP), preoperative IOL position and surface clarity, and complications were recorded, analyzed and compared. Results: In 20 eyes of 19 patients who underwent IOL implantation by scleral suture fixation in this study, both VA and BCVA after surgeries were significantly improved compared with those before surgeries (P<0.05). 11 eyes of 10 patients had IOP ≥ 21mmHg before surgeries. Three months after surgeries, IOP of all these affected eyes were within 21 mmHg, and no affected eyes required the application of ocular hypotensive drugs. Three months after surgeries, 17 eyes of 16 patients (85%) had centered IOL position and 3 eyes of 3 patients (15%) had slightly tilted IOL, all of these tilted IOLs were in patients with ocular trauma and all of them were found to be caused by scar adhesion in the peripheral part. In two eyes, the IOL optical edge was completely blocked by the pupil, which was only found after dilating the pupil. The pupil of one eye was traumatic and irregularly dilated, and the edge of the optical part of IOL was exposed. In two eyes of two patients who underwent silicone oil removal and IOL fixation during the same surgery, a small number of silicone oil droplets were found on the surface of IOL in the early stage after surgeries, and in the later stage, small flakes of pigment granules were observed. During the 3-month postoperative follow-up period, no patient had complications such as IOL dislocation, exposure of fixation suture, retinal detachment and corneal endothelial decompensation. Conclusion: For patients ....

A high sensitive, low foot print, SU-8 material-based, light intensity modulated MOMS accelerometer

A high sensitive optical MEMS accelerometer is proposed, which works by changing the effective refractive index of a microring relied on intensity modulation of light wave. The proposed optical sensing system consists of a microring, waveguide, and a proof mass. Acceleration causes lateral displacement of the proof mass. The proof mass is in the optical coupling length of the microring, and the displacement of the proof mass changes effective refractive index of the microring. Changes of the effective refractive index of the microring result in wavelength shift. The mechanical and optical parts of the proposed accelerometer are designed, and the obtained functional characteristics are compared with other accelerometers. Simulation shows functional characteristics of the proposed design are as follows: mechanical resonant frequency of 3.7 kHz, operating bandwidth of 2.6 kHz, mechanical sensitivity of 2 nm/g, optical sensitivity of 0.7%/nm, overall sensitivity of 1.4%/g, foot print of less than 150 μm * 170 μm, measurement range of ∓ 50 g, and mechanical noise density of 3.1 ( mg / Hz ) . These functional characteristics make the design very interesting for a wide range of applications, ranging from consumer electronics and automobile to inertial navigation.

Fabrication of silicon-tipped fiber-optic temperature sensors using aerogel-assisted glass soldering with precise laser heating.

We demonstrate the fabrication of fiber-optic Fabry-Perot interferometer (FPI) temperature sensors by bonding a small silicon diaphragm to the tip of an optical fiber using low melting point glass powders heated by a 980 nm laser on an aerogel substrate. The heating laser is delivered to the silicon FPI using an optical fiber, while the silicon temperature is being monitored using a 1550 nm white-light system, providing localized heating with precise temperature control. The use of an aerogel substrate greatly improves the heating efficiency by reducing the thermal loss of the bonding parts to the ambient environment. A desirable temperature for bonding can be achieved with relatively small heating laser power. The bonding process is carried out in an open space at room temperature for convenient optical alignment. The precise temperature control ensures minimum perturbation to the optical alignment and no induced thermal damage to the optical parts during the bonding process. For demonstration, we fabricated a low-finesse and high-finesse silicon FPI sensor and characterized their measurement resolution and temperature capability. The results show that the fabrication method has a good potential for high-precision fabrication of fiber-optic sensors.

Fabrication of a diffractive optical element by the precision diamond micro-turning method

The paper considers the manufacturing process of a diffractive optical element by precision diamond micro-turning using a diffractive lens as an example. The process consists of a preparatory stage and the stage of manufacturing a given diffractive element on specialized equipment with computer program control. The preparatory stage includes selection of a special diamond cutter with a response offset of the cutter angle relative to the calculated microstructure of the diffractive element, the preparation and manufacture of the necessary equipment, including fasteners, with the help of which the optical part is installed and adjusted, on the surface of which a diffractive lens is formed. After that, the specified values of the parameters of the lens zones, the values of the parameters of the diamond cutter are entered into the computer software, and the process of manufacturing a diffractive lens is started.

CONTROL OF THE OPTICAL SURFACE PURITY OF THE ELEMENTS BY THE ELLIPSOMETRIC METHOD

The possibility of controlling the chemical purity of the surface of optical elements by the ellipsometric method has been analyzed. The rationale of the possibility of measuring the parameters of contaminating films on the optical surface of elements by the ellipsometric method has been given simplification has been
 shown of the process of determining the thickness of the contaminating film while expanding the possibility of its measurement on an optical element made of different materials. Ellipsometric studies of freshly polished and used metal mirrors made of copper and copper alloy (zirconium bronze), aluminum and its alloys AMG-6, AL-9, AL-24 have been carried out. Research has also been conducted on elements made of K-8 and
 K-108 (State Standard 3514-94) optical glasses, which are the most typical materials used for manufacture of optical parts for laser technique of visible and near IR-range, from single crystals of NaCl, BaF2 and sapphire (Al2O3). Parameters of contaminating films on the surface of these elements have been measured.
 It has been concluded that it is advisable to use the ellipsometry method during the input (before carrying out physicochemical cleaning) and during the output (after cleaning) control of the optical element to assess the contamination of the optical surface and also for the quantitative analysis of the concentration of contaminants on the optical surface of the elements while working off the technology of their physicochemical cleaning.

Comparison of Three Prototypes of PPG Sensors for Continual Real-Time Measurement in Weak Magnetic Field.

This paper is focused on investigation of three developed prototypes of sensors based on the photoplethysmography (PPG) principle for continual measurement of the PPG signal in the magnetic field environment with the inherent radiofrequency and electromagnetic disturbance. The tested prototypes differ in the used optical part of the PPG sensor and their working mode, control unit, power supply, and applied Bluetooth (BT) communication methods. The main aim of the current work was motivated by finding suitable and universal parameter settings for PPG signal real-time recording in different working mode conditions. Comparative measurements in laboratory conditions by certified commercial pulse oximeter and blood pressure monitor (BPM) devices show good stability and proper accuracy of finally determined heart rate values. The supplementary investigation certifies the necessity of the placement of the pressure cuff of the BPM device on the opposite arm than the tested PPG sensor. Measurement experiments inside the scanning area of the running weak field magnetic resonance scanner verify proper function and practical usability of sensed PPG signals for further processing and analysis in all three prototype cases. Additional testing shows that the BT transmission in the scanning area has no visible influence on the quality of the finally obtained scanner images.

Review on Surface Polishing Methods of Optical Parts

With the extensive application of optical parts in many high-tech fields such as high-power laser, space optics, and aerospace, the requirements for the surface quality of optical parts are also increasing, which requires not only high surface qualities but also low defects including low subsurface damage and strict wavefront errors. As an essential link in the precision and ultraprecision optical manufacturing, various surface polishing methods and techniques have always attracted researchers’ continuous study and exploration. Considering the development of optical part surface polishing technology in recent years, this study analyzes the principle and development process of typical processing methods represented by each kind of polishing technology, expounds the specific research progress of optical part surface polishing technology, including the iterative renewal of traditional technologies and the research development of new technologies, and gives examples for typical applications. Finally, the development trend of optical part surface polishing technology is prospected, which provides a reference for follow-up intensive research in optical manufacturing.

The eVe reference polarisation lidar system for the calibration and validation of the Aeolus L2A product

Abstract. The eVe dual-laser/dual-telescope lidar system is introduced here, focusing on the optical and mechanical parts of the system's emission and receiver units. The compact design of the linear–circular emission unit along with the linear–circular analyser in the receiver unit allows eVe to simultaneously reproduce the operation of the ALADIN lidar on board Aeolus as well as to operate it as a traditional ground-based polarisation lidar system with linear emission. As such, the eVe lidar aims to provide (a) ground reference measurements for the validation of the Aeolus L2A aerosol products and (b) the conditions for which linear polarisation lidar systems can be considered for Aeolus L2A validation, by identifying any possible biases arising from the different polarisation state in the emission between ALADIN and these systems, and the detection of only the co-polar component of the returned signal from ALADIN for the L2A products' retrieval. In addition, a brief description is given concerning the polarisation calibration techniques that are applied in the system, as well as the developed software for the analysis of the collected signals and the retrieval of the optical products. More specifically, the system's dual configuration enables the retrieval of the optical properties of particle backscatter and extinction coefficients originating from the two different polarisation states of the emission and the linear and circular depolarisation ratios, as well as the direct calculation of the Aeolus-like backscatter coefficient, i.e. the backscatter coefficient that Aeolus would measure from the ground. Two cases, one with slightly depolarising particles and one with moderately depolarising particles, were selected from the first conducted measurements of eVe in Athens in September 2020, in order to demonstrate the system's capabilities. In the slightly depolarising scene, the Aeolus-like backscatter coefficient agrees well with the actual backscatter coefficient, which is also true when non-depolarising particles are present. The agreement however fades out for strongly depolarising scenes, where an underestimation of ∼18 % of the Aeolus like backscatter coefficient is observed when moderately depolarising particles are probed.

Disaggregation and cloudification of metropolitan area networks: enabling technologies and impact on architecture, cost, and power consumption [Invited

The deployment of the new 5G system and ultra-broadband access networks, on one side, and the advent of network disaggregation and cloudification paradigms, on the other, are producing disruptive changes in metropolitan area networks (MANs). The new central offices will be more like small data centers than traditional Telco-type central offices. The presence of general-purpose servers, in partial or total replacement of specialized equipment or cards, and also hosting new functions and services, significantly changes the way the central office is organized and how the equipment internetworks. After having defined a reference architecture named cloudified-MAN, the paper briefly introduces the enabling technologies that include information technology (IT) systems, packet switches, and optical equipment. A disaggregated model is applied to all layers and systems. In the optics field, special insight on high data rate (up to 1.6 Tb/s) transceiver technology developed by the TERIPHIC project is provided as an example of low-cost and low-power technology. Through a quantitative techno-economic case study on a realistic network scenario aimed at short-term and medium-term time horizons, the paper provides indications on what could be the impact of the new architecture on costs and energy consumption. The main outcome of the study is that the IT and optical parts are those with the highest fractions of overall cost, and specifically for the optics, the cost of wavelength division multiplexing transceivers increases significantly in the medium term due to the demand for high-capacity connections ( > 400 G b / s ), while the line system cost (reconfigurable optical add-drop multiplexer) decreases in percentage. Another significant result is that in terms of energy consumption, the IT component has been found to be the dominant one (70%–75% of the total), followed by packet devices (about 20%–25%) and optical systems, the latter with significantly lower percentage values (less than 5%) in all cases analyzed.

Development of a Fringe Printer With 0.35 μm Pixel Pitch

The development of computational devices can provide computer-generated holograms (CGH) of over 100 Giga-pixel easily. The performance improvement of the graphical processing unit makes calculations faster with a normal personal computer. In contrast, the output device of CGH is not reported much. Since CGH is a fringe pattern, high resolution and fine pixel pitch are required for the output device. We have been developing a direct fringe printer, which consists of a laser, an X-Y stage, an SLM, and optical parts available on the market. Our previous report presented a liquid crystal panel, which was used for SLM that had full HD resolution and 7 μm pixel pitch. Since the Pixel pitch of the liquid crystal panel is not small enough for CGH, the optical setup works to demagnify the pixel pitch of the printed fringe pattern. To record high resolution CGH, the calculated fringe pattern is split and exposed in tiles by the X–Y stage. The results showed a 0.44 μm pixel pitch and over 100 Gpixel CGHs. However, to output more high-quality CGH, the development of pixel pitch and resolution is very important. In this paper, we review the optical system of a fringe printer that achieved an output of 0.35 μm pixel pitch CGH. We also investigate the performance of the new fringe printer.

Gamma distribution excess minority carrier concentration model for solar cell performance modeling

Concentrated photovoltaic (PV) technology represents a growing market in the field of terrestrial solar energy production. As the demand for renewable energy technologies increases, further importance is placed on the modeling, design, and simulation of these systems. Given the cultural shift toward energy awareness and conservation, several concentrated PV systems have been installed across the world. This research presents a new model for carrier concentration within a solar cell. The goal of this innovation is to facilitate the determination of the steady-state operating temperature as a function of the concentration factor for the optical part of the concentrated PV system, to calculate the optimum concentration that maximizes power output and efficiency. This model will be shown to produce a more realistic estimate of the current through a solar cell, which will enable further research into dynamic thermal modeling.

The analysis of the errors of the dynamic interferometry method
 in the control of local surface inhomogeneities of the nanometer level of the profiles of optical parts

The analysis of the errors of the dynamic interferometry method
 in the control of local surface inhomogeneities of the nanometer level of the profiles of optical parts

The analysis of the influence of limiting factors in the method
 of differential scattering in the control of surface nhomogeneities
 of the subnanometer level of the profiles of optical parts

The analysis of the influence of limiting factors in the method
 of differential scattering in the control of surface nhomogeneities
 of the subnanometer level of the profiles of optical parts

INNOVATIVE WASHING TECHNOLOGY IN PIEZOTECHNICS

The analysis of known detergents used for cleaning electronic products: electrical and optical parts, printed circuit assemblies is carried out. Developed and patented a universal detergent for cleaning piezo products. The detergent is recommended for wider applications in the electronics industry.