Optical Pickup Research Articles

A Portable Fluorescent Lateral Flow Immunoassay Platform for Rapid Detection of FluA.

The spread of the FluA virus poses significant public health concerns worldwide. Fluorescent lateral flow immunoassay (LFIA) test strips have emerged as vital tools for the early detection and monitoring of influenza infections. However, existing quantitative virus-detection methods, particularly those utilizing smartphone-based sensing platforms, encounter accessibility challenges in resource-limited areas and among the elderly population. Despite their advantages in speed and portability, these platforms often lack user-friendliness for these demographics, impeding their widespread utilization. To address these challenges, this study proposes leveraging the optical pick-up unit (OPU) sourced from commercial optical drives as a readily available fluorescence excitation module for the quantitative detection of antibodies labeled with quantum-dot fluorescent microspheres. Additionally, we utilize miniaturized and high-performance optical components and 3D-printed parts, along with a customized control system, to develop an affordable point-of-care testing (POCT) device. Within the system, a stepping motor scans the test strip from the T-line to the C-line, enabling the calculation of the fluorescence-intensity ratio between the two lines. This simple yet effective design facilitates rapid and straightforward field or at-home testing for FluA. The proposed prototype platform demonstrates promising performance, achieving a limit of detection (LOD) of 2.91 ng/mL, a total detection time of no more than 15 min, and dimensions of 151 mm × 11.2 mm × 10.8 mm3. We believe that the proposed approach holds great potential for improving access to an accurate influenza diagnosis.

A low-cost and portable fluorometer based on an optical pick-up unit for chlorophyll-a detection

Chlorophyll-a (Chl-a) fluorescence detection is an important technique for monitoring water quality. In this work, we proposed an approach that employs the mass-produced low-cost optical pick-up unit (OPU) extracted from the high-definition digital versatile disc (HD-DVD) drive as the key optical component for our chlorophyll-a fluorometer. The built-in blue-violet 405 nm laser diode of the OPU acts as the excitation light to perform laser-induced fluorescence (LIF). The laser driver and a series of intrinsic lenses within the OPU, such as an objective lens with a numerical aperture (NA) of 0.65 and a collimating lens, help reduce the size, cost, and system complexity of the fluorometer. By integrating off-the-shelf electronic components, miniaturized optical setups, and 3D-printed assemblies, we have developed a low-cost, easy-to-make, standalone, and portable fluorometer. Finally, we validated the performance of the device for chlorophyll-a fluorescence detection under laboratory and on-site conditions, which demonstrated its great potential in water monitoring applications. The limit of detection (LOD) for chlorophyll-a is 0.35 μg/L, the size of the device is 151 × 100 × 80 mm3, and the total cost of the proposed fluorometer is as low as 137.5 USD.© 2023 Elsevier Science. All rights reserved.

3D image steganography using cellular automata transform and depth estimation network

Traditional 3D image steganography is cumbersome and difficult owing to the special structure of 3D image, imposing a practical limit for its applications. Herein, we propose a 3D image steganography scheme utilizing cellular automata transformation (CAT). By using CAT with various rule numbers to hide images, the weakness of previous algorithms with only one transformation plane is overcome, and the hidden image quality can be improved by reducing energy loss. In the 3D reconstruction process, we apply a depth estimation algorithm based on a convolutional network to obtain corresponding depth maps from a single RGB image, simplifying the elemental image array (EIA) pickup process and even overcoming the phase difference problem caused by the traditional optical pickup process using lens arrays. Before hiding, we use the maximum length cellular automata (MLCA) to encrypt a single RGB image instead of encrypting EIA images with huge data, which greatly reduces the complexity of the encryption algorithm and improves efficiency. Finally, we reconstruct the decrypted image optically and obtain a full color and full parallax 3D image through the display device.

Development of Structural Design Method for Twisted Wires Suspension

Copper alloy suspension wires are used in the optical pickups and image stabilization mechanisms of mobile cameras. The durability of suspension wires used in mobile cameras is greatly affected by the increase in the weight of the lens assembly as makers improve the image quality of the camera. Therefore, the durability of the wire needs improvement. In this study, the stress reduction effect of twisted suspension wires was investigated using finite element method (FEM) analysis. In addition, a practical equation was obtained to facilitate the structural design. From this study, the following conclusions were obtained. In contrast to the conventional single-wire structure, the twisted wire structure enables a significant reduction in the stress generated while maintaining the stiffness. A simple formula that approximates the results of many FEM analyses was developed to enable rapid product design.

Maskless, Reusable Visible-Light Direct-Write Stamp for Microscale Surface Patterning.

We report a straightforward method for creating large-area, microscale resolution patterns of functional amines on self-assembled monolayers by the photoinduced local acidification of a flat elastomeric stamp enriched with photoacid. The limited diffusivity of the photoactivated merocyanine acid in poly(dimethylsiloxane) (PDMS) enabled to confine efficient deprotection of N-tert-butyloxycarbonyl amino group (N-Boc) to line widths below 10 μm. The experimental setup is very simple and is built around the conventional HD-DVD optical pickup. The method allows cost-efficient, maskless, large-area chemical patterning while avoiding potentially cytotoxic photochemical reaction products. The activation of the embedded photoacid occurs within the stamp upon illumination with the laser beam and the process is fully reversible. Preliminary positive results highlight the possibility of repeatable use of the same stamp for the creation of different patterns.

Adapting a Blu-ray optical pickup unit as a point source for digital lensless holographic microscopy.

The adaptation of an off-the-shelf Blu-ray optical pickup unit (OPU) into a highly versatile point source for digital lensless holographic microscopy (DLHM) is presented. DLHM performance is mostly determined by the optical properties of the point source of spherical waves used for free-space magnification of the sample's diffraction pattern; in particular, its wavelength and numerical aperture define the achievable resolution, and its distance to the recording medium sets the magnification. Through a set of straightforward modifications, a commercial Blu-ray OPU can be transformed into a DLHM point source with three selectable wavelengths, a numerical aperture of up to 0.85, and integrated micro-displacements in both axial and transversal directions. The functionality of the OPU-based point source is then experimentally validated in the observation of micrometer-sized calibrated samples and biological specimens of common interest, showing the feasibility of obtaining sub-micrometer resolution and offering a versatile option for the development of new cost-effective and portable microscopy devices.

Label-Free Optical pH Measurement Based on Chitosan-TEOS-PDMS Hydrogel Layer for Microfluidic Applications

The optical pH sensor based on smart hydrogel material was designed for use in microfluidic applications. The chitosan-tetraethyl orthosilicate (chitosan-TEOS) interpenetrating network was synthesized as a pH-sensitive part of the sensor. This chitosan-TEOS-PDMS layer was bonded by oxygen plasma treatment to a thin layer of polydimethylsiloxane (PDMS), which enabled easily integrating of the sensor layer into the microfluidic chips. Also, the thickness of this PDMS layer worked as an adjustable parameter to control the sensitivity of the sensor. In addition, the optical astigmatism method (the method used in CD/DVD optical pickup unit) was utilized to measure the pH-induced variations of the sensor layer by monitoring the laser beam profile on a charge-coupled device (CCD). The experimental results showed that the fabricated sensor responded to pH changes and became stable in less than 90 s. It showed a sensitivity of 54 and 94 pixel/pH using the spin-coated PDMS thickness of 75 and 28 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> , respectively.

A study on signal enhancement of a Raman probe using an optical pickup unit

A simplified fabrication method for an optical pickup unit (OPU)-based Raman probe was introduced. The use of OPU tracking mode was examined to increase the Raman signal and reduce background signals. Unlike most Raman systems, the tracking mode of the OPU moves the objective lens in the x (or y) direction, thus resulting in a significantly reduced background signal and increased Raman signal intensity. These results can be explained by two factors, such as reducing the surface scattering of the incident light from the objective lens and decreasing signal blocking by a dot mirror, which depends on the horizontal position of the objective lens. The reproducibility of the OPU Raman in tracking mode is higher than the OPU Raman in normal mode. The peak position deviation was calculated to be around ±3 cm−1. The Raman spectra of normal organic samples were obtained under the same conditions and recorded as per the applied voltage in the OPU tracking mode to validate the fabricated device. The objective lens shifts resulted in increased Raman peaks and reduced background signals. The maximum peak-position difference for all samples was 10 cm−1 compared to reference peaks obtained using a commercial Raman system.

Development of Ultrasmall Optical Pickup by Employing the Six Sigma Methodology

Development of Ultrasmall Optical Pickup by Employing the Six Sigma Methodology

Real-Time Reflectance Measurement Using an Astigmatic Optical Profilometer.

An astigmatic optical profilometer with a commercial optical pickup head provides benefits, such as high resolution, compact size, and low cost. To eliminate artifacts caused by complex materials with different reflectances, a z-axis modulation mode is proposed to obtain quantitative surface morphology by measuring S curves on all image pixels. Moreover, the slope of the linear region in the S curve shows a positive relationship with the surface reflectance. However, the slope was calculated using an offline curve fitting method, which did not allow real-time reflectance imaging. Furthermore, quantitative reflectance data were unavailable because of the lack of calibration. In this study, we propose a novel method for real-time reflectance imaging by measuring the amplitude of a focus error signal (FES). The calibration results displayed a linear relationship between the FES amplitude and reflectance. The reflectance image of a grating sample with chrome patterns on a glass substrate demonstrates accurate reflectance measurements with a micrometer spatial resolution.

Development of Defocus Atomic Force Microscope (DeF-AFM)

ABSTRACT In this study, a novel measuring instrument named defocus atomic force microscope (DeF-AFM) is presented. A Gaussian beam intensity measuring method is proposed for this optical pickup unit (OPU)-based AFM. Only partial components inside the OPU such as the laser diode, the objective, and the photodiode IC (PDIC) are required for this method. The displacement of the cantilever can be acquired by analyzing the exponential intensity change, which is along the optic axis of the laser, reflected to the PDIC. A support controller for the DeF-AFM is also designed and developed. The dynamic measuring ranges of this AFM in X, Y, and Z-axis are designed to be 12,000 nm, 12,000 nm, and 1400 nm, respectively. The horizontal and the vertical resolution are approximately 3.3 nm and 0.34 nm, respectively. The spatial resolution of the DeF-AFM is also verified by resolving the single atomic layer of the highly ordered pyrolytic graphite (HOPG).

Open-source force analyzer with broad sensing range based on an optical pickup unit

In the pharmaceutical field, oral drug delivery devices continue to shrink down to the micrometer scale, driving a trending demand to investigate ex vivo mucoadhesive force down to the micro-Newton scale. However, owing to the limitation of measuring sensitivity, conventional methods (e.g., a texture analyzer) lack reliability while measuring forces in this range. Herein, we report on an open-source force analyzer that utilizes an optical-pickup-unit (from a DVD player) to detect cantilever-based force transducers and thereby, achieves a wide force-sensing range from 1.1 N to 0.99 nN. The cantilever force transducers can easily be adjusted to fit different force ranges by adjusting the steel shim, magnets, and 3D printed components. To validate the analyzer, we conducted a preliminary study to investigate the effect of time and humidity of mucoadhesion of porcine intestinal tissues. Besides, we measured the mucoadhesive force of a single oral drug delivery microdevice with an average force of 93.7 µN on the top sides of the device. This analyzer offers the possibility of measuring e.g. mucoadhesion of individual microdevices in the micro-Newton range. Hence, the analyzer can assist in the development of miniaturized oral drug delivery devices but has a much wider field of potential force sensing applications.

A Study on Signal Enhancement of a Raman Probe Using an Optical Pickup Unit

A Study on Signal Enhancement of a Raman Probe Using an Optical Pickup Unit

Integrated self-referencing single shot digital holographic microscope and optical tweezer

Digital holographic microscopy is a single-shot technique for quantitative phase imaging of samples, yielding thickness profiles of phase objects. It provides sample features based on their morphology, leading to their classification and identification. However, observing samples, especially cells, in fluids using holographic microscopes is difficult without immobilizing the object. Optical tweezers can be used for sample immobilization in fluids. The present manuscript provides an overview of our ongoing work on the development of a compact, low-cost microscopy system for digital holographic imaging of optically trapped samples. Integration of digital holographic microscopy system with tweezers is realized by using the optical pickup unit extracted from DVD burners to trap microsamples, which are then holographically imaged using a highly compact self-referencing interferometer along with a low-cost, in-house developed quadrant photodiode, providing morphological and spectral information of trapped particles. The developed integrated module was tested using polystyrene microspheres as well as human erythrocytes. The investigated system offers a multitude of sample features, including physical and mechanical parameters and corner frequency information of the sample. These features were used for sample classification. The proposed technique has vast potential in opening up new avenues for low-cost, digital holographic imaging and analysis of immobilized samples in fluids and their classification.

Design of a four-sided magnetic circuit for an optical pickup actuator for multilayer high-density optical disks

Large-capacity optical storage materials have reached a stage of relative maturity, but progress in the design of optical pickup actuators is currently slow. To improve the reading and writing capabilities of optical recording systems, we propose a design for a four-sided magnetic circuit for an optical pickup actuator for multilayer high-density optical disks that make full use of the space around the actuator. The basic magnetic circuit model in this design, which is derived by the equivalent magnetic charge method, can be applied to the design of all such actuators. The static and dynamic magnetic circuit evaluation parameters established in this paper can be used conveniently and directly to improve the magnetic circuit performance of the actuator. The design was verified by finite element simulation, and linear working ranges of ±2.6 mm, ±0.6 mm, and ±16° were found in the focusing, tracking, and tilting degrees of freedom. This is sufficient to compensate for errors in phase-change optical disks with more than 50 layers in high-speed rotation. The theoretical servo accuracy of the actuator can reach tens of nanometers. This can be used with a dual-objective-lens layout that can support layer-skip reading and writing of optical disks with an effective working bandwidth greater than 10 000 Hz.

Micro and nanoscale 3D printing using optical pickup unit from a gaming console

Conventional photopolymerization-based 3D printing still requires developing a concise and cost-effective method to improve the printing resolution at the nanoscale. Here, we propose the use of a gaming console optical drive pickup unit for 3D photopolymerization. This mass-produced optical pickup unit features a finely adjustable diode laser, allowing us to adjust the printing resolution from tens of micrometres down to hundreds of nanometres without requiring oxygen radical scavenging or costly femtosecond lasers. We evaluate the 3D printing performance using a commercial photopolymer under different laser exposure parameters. The proposed printing system achieves a resolution of 385 nm along the lateral direction and XYZ nano-resolution linear stages enable a printing volume of up to 50 × 50 × 25 mm3. Finally, we demonstrate the fabrication of 3D stereoscopic microstructures. The substantially simplified optics proposed here paves the way for affordable high-resolution micro/nanoscale 3D fabrication.

Development of Micromirror Array for Miniaturized Optical Pickup by Employing the Six Sigma Methodology

Development of Micromirror Array for Miniaturized Optical Pickup by Employing the Six Sigma Methodology

Model-Based Design and Simulation of Paraxial Ray Optics Systems

A model-based design allows representing complex, multi-domain systems as interconnected functional blocks, yielding graphical, intuitive information about the overall project, besides simplifying simulation. This work proposes using the modular approach as an optical engineering design and educational tool for developing paraxial ray optics setups, providing further integration with mechatronics subsystems and control loops. An expanded version of the ABCD transfer matrix modeling is implemented in MATLAB Simulink environment to simultaneously perform ray tracing and dynamic simulations. The methodology is validated for different problems, including paraxial cloaking, transmission through a multimode optical fiber, a Fabry–Perot interferometer, and an optical pickup with automatic focus, yielding reliable results with prospective applications in optical engineering design and for creating virtual labs devoted to multiphysics and mechatronics engineering courses.

Compact and low-cost instrument for digital holographic microscopy of immobilized micro-particles

A compact and low-cost system capable of Digital Holographic Microscopic (DHM) imaging of immobilized micro-particles is presented. The proposed design, integration, and manufacturing can lead to wider use and increased accessibility of this device for research, education, and biomedical applications. The optical tweezer system for particle immobilization is built using the optical pickup unit taken from a DVD burner. DHM is integrated into the system through the addition of a glass plate which enables one arm of the system to operate as a lateral shearing digital holographic interferometer. The operation of the system is confirmed by trapping, quantitative phase imaging and analysis of polystyrene micro-spheres for which the corner frequency measurements, carried using an in-house developed low-cost Quadrant Photodiode, compare favorably with simulated results. Furthermore, the system is illustrated for trapping and simultaneous quantitative phase imaging of micro-particles, including biological specimen such as red blood cells. The use of a low-cost easily implementable DHM integrated optical tweezer system provides vast information content, which enable in-depth analysis of immobilized micro-particles.

Study on a Raman spectrometer utilizing an optical pickup unit and pulsed power

A number of Raman spectra obtained for liquid and solid samples according to various electrical signals were analyzed to increase the resolution of a Raman system utilizing an optical pickup unit and pulse power. The wavelength of the laser marginally changed in response to modifications in the duty and frequency, and the accuracy of the Raman spectra changed accordingly. Intriguingly, after converting the spectrum based on the laser wavelength, an error in the Raman peak position dependent on the duty and frequency of power remained. Overall, lower duty ratio and higher frequency resulted in more accurate Raman spectra.