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The optical pickup unit (OPU) within a CD/DVD/Blu-ray drive integrates 780, 650, and 405 nm wavelength lasers, diffraction-limited optics, a high-bandwidth optoelectronic transducer up to 400 MHz, and a nano-resolution x-, z-axis and tilt actuator in a compact size. In addition, the OPU is a remarkable piece of engineering and could enable differen...
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... OPU for Biosensing. A conventional DNA microarray scanner requires microscale precision for xy positioning, laser excitation, precise optics for focusing, and optical sensing. Consequently, the resulting system is expensive and bulky. By replacing the OPU components with a single- mode optical fiber and attaching an external sensing setup, the OPU can be used as the head of a scanning confocal microscope to enable fluorescent-based biosensing. 69 Figure 12 shows an OPU-based DNA microarray scanner. The OPU is coupled to a photomultiplier tube (PMT) detector through a dichroic filter, such as that shown in Figure 2. The OPU−PMT setup can acquire signals from fluorescent dyes excited by the OPU laser of 650 nm. 24 The OPU VCM provides dynamic autofocusing that enables higher detection performance than conventional microarray scanners, as shown in Figure 13. The OPU−PMT-based DNA microarray scanner has been successfully used to measure a commercial bacterial artificial chromosome oligonucleotide DNA chip and a 32 12 Cy5 fluorescent dye calibration slide (DS01). 70 Combined with microfluidic chips, OPU−PMT fluorescence detection can measure 2.5 μm fluorescent beads inside a micro- channel, 71,72 as shown in Figure ...
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... However hacking, probing, reverse engineering and salvage have long been part of electronics maker practices. We find examples of these practices both in academia [1,9,17,38] and by numerous makers who share projects on websites like Hackaday, Instructables and Github. These practices involve disassembly to extract components, reprogramming Micro-controllers for added functionality and probing internal signals in closed systems for novel applications. ...
In our practice as educators, researchers and designers we have found that centering reverse engineering and reuse has pedagogical, environmental, and economic benefits. Design decisions in the development of new hardware tool-kits should consider how we can use e-waste at hand as integral components of electronics prototyping. Dissection, extraction and modification can give insights into how things are made at scale. Simultaneously, it can enable prototypes that have greater fidelity or functionality than would otherwise be cost-effective to produce.
... Thus, achieving a high-resolution portable low-cost microscopy system requires access to stable and adaptable sources of high numerical apertures (NAs) at reduced entry costs. In this regard, Blu-ray optical pickup units (OPUs) represent an attractive opportunity, as their implementation allows the use of three different wavelengths with up to NA = 0.85 and triple-axis integrated precision-movement actuators [21] in a single robust mechanical package that can be commercially acquired for less than $5 US, and whose implementation waives the need for delicate alignment procedures. However, using OPUs as a point source requires addressing some limitations, namely, acquiring control over its functions despite the secrecy of manufacturers and removing the undesired illumination artifacts produced by its internal diffraction gratings and the surface structure of the objective lens. ...
... Blu-ray OPUs are designed to produce a focalized spot of the order of 300 nm, which for the standard Blu-ray 405 nm wavelength, represents a NA = 0.85 [32]. Furthermore, those designed to be backward compatible with compact discs (CDs) and digital versatile discs (DVDs) include triple-wavelength emission capabilities, optimized optical components, and high-bandwidth triple-axis precision actuators [21]. With these properties being commercially available for less than $5 US in a compact and robust mechanical unit that waives the need for careful alignment, Blu-ray OPUs integrate all the benefits individually attributable to the aforementioned alternatives: they can produce the highest NA values available (NA > 0.8) with high optical performance and favor robust and stable setups without extensive optomechanical components while keeping a low commercial price. ...
... The former is generally incompatible with the academic research environment, while the latter is often impractical for researchers without a strong engineering background. Thankfully, a complete review by researchers Te Hwu and Boisen has openly detailed the OPU mechanism and components [21], laying the foundation for new low-cost and high-performance OPU-based applications, such as the one presented in this work. ...
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.
... The required kind of customized shape patterning requires a great amount of control over the optical pickup unit (OPU) inside the DVD-RAM optical drive along with the driver signal power level and pulse-width necessary to record and erase data. There are several open-source software packages available that offer access to the OPU inside the disc drive [70] and enable us to precisely control the laser diode positioning along with the signal power level to have the customized written pattern of our desired size and shape on the recording layer. When the required dimer-shaped amorphous patterning is done, rest of the tentative work-process to build the ultimate tunable biosensor design out of the patterned DVD-RAM has been illustrated stepwise in Fig. 9(a)-(e). ...
In this paper, we have presented a novel plasmonic Refractive Index (RI) sensing scheme based on a rewritable optical disc structure with customized dimer-like nanopatterns. We have performed the finite-difference time-domain (FDTD) simulation for this work to exhibit the optical resonant response and sensing performance of our proposed sensing platform. We have also investigated how the changes in the different structural parameters affect the resonant wavelength. The high refractive index sensitivity of 768nm/RIU allowed our sensing system to achieve a resolution limit for blood Hemoglobin(Hb) detection superior to most Hb sensors previously reported. The use of the built-in grating structure of the optical disc, the ability to create customized patterns, and the high resolution achieved in blood Hb detection suggest the potential of our proposed RI sensor as a cost-efficient, reliable sensing technology for medical applications.
... Many attempts have been made to use an OPU as a base and apply it to various types of optical devices. For example, previous studies have reviewed its feasibility for use with optical microscopes [17][18] precise devices for determining refractive index at the femtoliter volume level [18][19] and in biosensing (micro or nanoscale biological sensors) [20], high-speed contact-mode atomic force microscopy [21], and optical imaging modules for astigmatic detection systems [22]. ...
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.
... By adopting a commercial digital versatile disk (DVD) pickup head, the astigmatic profilometer is equipped with the advantages of small beam spot size, compact size, and high bandwidth [14][15][16]. For sensing small data pits, the focal laser spot on the DVD pickup head has a small full width at half maximum (FWHM) of 530 nm [17]. Therefore, the astigmatic profilometer is able to provide a high spatial resolution image, which has been utilized for various applications, such as bio-molecular sensing and cell imaging [18][19][20]. ...
... The reflectance measurement is currently limited to the red-light wavelength. By adopting a Blu-ray pickup head, three wavelengths, 405, 650, and 780 nm, can be obtained [17]. ...
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.
... 1×1 cm 2 ) of a data track layer (from a rewritable DVD) was used as a low-cost sample to calibrate the HS-AFM scanner. The DVD data tracks have a fixed period of 740 nm and a defined depth of 160 nm [60]. The scanning area and Z sensitivity of the FES can be ...
High-speed atomic force microscopes (HS-AFMs) with high temporal resolution enable dynamic phenomena to be visualized at nanoscale resolution. However, HS-AFMs are more complex and costlier than conventional AFMs, and particulars of an open-source HS-AFM controller have not been published before. These high entry barriers hinder the popularization of HS-AFMs in both academic and industrial applications. In addition, HS-AFMs generally have a small imaging area that limits the fields of implementation. This study presents an open-source controller that enables a low-cost simplified AFM to achieve a maximum tip-sample velocity of 5,093 µm/s (9.3 s/frame, 512×512 pixels), which is nearly 100 times higher than that of the original controller. Moreover, the proposed controller doubles the imaging area to 46.3×46.3 µm² compared to that of the original system. The low-cost HS-AFM can successfully assess the severity of atopic dermatitis (AD) by measuring the nanotexture of human skin corneocytes in constant height DC mode. The open-source controller-based HS-AFM system costs less than $4,000, which provides resource-limited research institutes with affordable access to high-throughput nanoscale imaging to further expand the HS-AFM research community.
... The decreasing thermal conductance towards the center of the microstring leads to an increase in the average temperature, and the resulting thermal expansion was measured by detuning the resonance frequency, as shown in Fig. 14D. The nanopositioner has also been applied in a digital video disc (DVD) optical pick-up unit (OPU) sensing system [37][38][39][40][41][42][43][44][45]-based vibrometer, as reported previously [46]. ...
Nanoscale positioning has numerous applications in both academia and industry. A growing number of applications require devices with long working distances and nanoscale resolutions. Friction-inertia piezoelectric positioners, which are based on the stick-slip mechanism, achieve both nanometer resolution and centimeter-scale travel. However, the requirements of complex preload mechanism, precision machining, and precise assembly increase the cost of conventional friction-inertia nanopositioners. Herein we present the design of an open-source XYZ-axis nanopositioning system. Utilizing a magnet-based stick-slip driving mechanism, the proposed XYZ nanopositioner provides several advantages, including sub-nanometer resolution, a payload capacity of up to 12 kg (horizontal), compact size, low cost, and easy assembly; furthermore, the system is adjustment-free. The performance tests validate the precision of the system in both scanning and stepping operation modes. Moreover, the resonant spectra affirm the rigidity and dynamic response of the mechanism. In addition, we demonstrate the practical applications of this nanopositioner in various measurement techniques, including scanning electron microscopy, vibrometry, and atomic force microscopy. Furthermore, we present 11 variations of the nanopositioner designs that are either compatible with ultra-high-vacuum systems and other existing systems, 3D printable, or hacking commercial linear slides.
... The OPU emits a laser with a wavelength of 650 nm, and a built-in voice coil motor actuates an objective lens in the z-axis direction to precisely focus the laser on the mirror. Furthermore, the OPU integrates an astigmatic optical path and a sensor to generate a focus error signal (FES) [13]. While the mirror approaches along the z-axis to a laser focal point, the FES appears as an Sshaped curve (S-curve) (Fig. 2b). ...
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.
... In its most common implementation, as shown in panel (a) of Fig. 2, a laser beam is focalized into a pinhole spatial filter with an aperture diameter in the order of the illumination wavelength ( ). However, the use of alternative sources has been amply studied; for instance, Optical Pickup Units [50], engineered step-index optical fibers [51], gradient-index lenses [52], aspheric lenses [53], and Light-Emitting Diodes [54]. In all design cases, the Numerical Aperture (NA) is the critical parameter as it determines the effective resolution of the system [55], given by ...
In this work, the contributions that the research group of Optics and Opto-Digital Processing have developed to democratize digital holographic microscopy (DHM) are reviewed. The said group, based on the Universidad Nacional de Colombia Sede Medellin, has focused its work on developing tools, both of software and hardware, for DHM architectures, both without and with lenses, with the aim of making these cutting-edge technologies of microscopy accessible to many people. Cost-effective hardware designs, open-source processing software, and user-friendly modeling platforms are the main contributions of our research group to the democratization of DHM. The fundamentals of DHM, both without and with lenses, are briefly recalled to introduce the above-mentioned review.
... The structure was used for RI sensing. Additional works on SPR based DVD structures can be found in [37][38][39][40][41]. Theoretical and experimental study of the SPR supported by CDs can be found in [42], biosensing application of different types of CDs is discussed in [43]. ...
... Many other applications can be implemented using CDs-based structures, for example, SERS-based CDs have been described by the authors of [32,44,45]. Moreover, schematic, SEM, and AFM characterization of the CDs-based structures and the materials used to manufacture the different types of CDs have been described by the authors of [30,[32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47], including the treatment methods made on the sample to prepare them for sensing applications. The main treatment method is exposure to metallic film. ...
Resonant-based sensors are attractive optical structures due to the easy detection of shifts in the resonance location in response to variations in the analyte refractive index (RI) in comparison to non-resonant-based sensors. In particular, due to the rapid progress of nanostructures fabrication methods, the manufacturing of subwavelength and nano-scale gratings in a large area and at a low cost has become possible. A comparative study is presented involving analysis and experimental work on several subwavelength and nanograting structures, highlighting their nano-scale features’ high potential in biosensing applications, namely: (i) Thin dielectric grating on top of thin metal film (TDGTMF), which can support the excitation of extended surface plasmons (ESPs), guided mode resonance, or leaky mode; (ii) reflecting grating for conventional ESP resonance (ESPR) and cavity modes (CMs) excitation; (iii) thick dielectric resonant subwavelength grating exhibiting guided mode resonance (GMR) without a waveguide layer. Among the unique features, we highlight the following: (a) Self-referenced operation obtained using the TDGTMF geometry; (b) multimodal operation, including ESPR, CMs, and surface-enhanced spectroscopy using reflecting nanograting; (c) phase detection as a more sensitive approach in all cases, except the case of reflecting grating where phase detection is less sensitive than intensity or wavelength detection. Additionally, intensity and phase detection modes were experimentally demonstrated using off-the-shelf grating-based optical compact discs as a low-cost sensors available for use in a large area. Several flexible designs are proposed for sensing in the visible and infrared spectral ranges based on the mentioned geometries. In addition, enhanced penetration depth is also proposed for sensing large entities such as cells and bacteria using the TDGTMF geometry.
