Tube Lens Research Articles

Ultracompact optical microscopes made of liquid crystal Pancharatnam–Berry optical elements

Ultracompact optical systems are increasingly sought after for applications such as consumer electronics and medical imaging. Here, we present a design and manufacturing approach for ultracompact bright- and dark-field optical microscopes entirely made of flat liquid crystal optical elements. Both systems utilize liquid crystal PB lenses as objective and tube lenses, while the dark-field optical microscope incorporates an additional Q-plate with a +1 topological defect to filter zero-order light. We demonstrate two optical microscopic systems with a numerical aperture of 0.25 and overall thickness of just 5 mm. The system can achieve high imaging performance with a resolution better than 7 µm. We further demonstrate an exemplary application in biological imaging to effectively enhance edge contrast in imaging onion epidermal cells. This work presents an example in exploiting the flatness and high quality of liquid crystal optical elements to achieve compactness and high-quality imaging promising for various applications.

Sensitive and isotopic interference-free analysis of Sb using hydride generation-microwave plasma torch-mass spectrometry under ambient condition

A sensitive and isotopic interference-free analysis method for Sb was developed based on hydride generation-microwave plasma torch-mass spectrometry (HG-MPT-MS). Compared to the conventional ICP-MS, MPT coupled to an ion trap mass spectrometer enabled much “softer” ionization of Sb under ambient condition, which provided multi-detection modes and various ion forms, such as Sb+, SbO+, SbO2−, SbO++H2O and so on. These ion formations can be easily regulated by tuning capillary voltage and tube lens voltage, which facilitated elimination of isotopic interference during analysis, for instance the interference of 123Te on 123Sb could be effectively excluded by optimizing parameters of capillary voltage and tube lens voltage. The potential application of HG-MPT-MS for Sb isotope ratio analysis was also demonstrated, which could be determined in different forms, e.g., 123Sb/121Sb or 123Sb16O/121Sb16O. The value of 123Sb/121Sb was determined to be 0.75110 ± 0.00038 (2σ, n > 50). In addition, the detection limit, linearity and spike recovery were also studied. Overall, HG-MPT-MS performed equally well on detection limit (0.05 μg/L) with ICP-MS or HG-AFS. The linearity (R2 = 0.998) was checked in the concentration range of 10–500 μg/L. Spike recovery were evaluated with two soil samples, and the obtained spike recovery ranged 90–100 %. In general, HG-MPT-MS was expected to be a versatile tool for study the biochemical or geochemical behaviors of Sb and other hydride forming elements under ambient condition in a much simpler and more efficient way.

Nested design and numerical simulation of ellipsoidal glass tube X-ray lens

This paper presents a nested optimization design scheme for ellipsoidal glass tubes. The lens, also known as a mirror, is composed of multiple ellipsoidal glass tubes with varying semi-major and semi-minor axes, nested within a larger-diameter ellipsoidal glass tube. Compared to Traditional Ellipsoidal Single-bounce Lens (TESL), the Nested Ellipsoidal Glass Tube X-ray Lens (NEXL) can utilize a smaller or even no beam stop at its input, mitigating the impact of the direct X-ray beam on the NEXL's focused beam and thereby enhancing X-ray source utilization. NEXLs can be designed with a large input focal distance, making them suitable for synchrotron radiation X-ray sources located significant distances from the source point to the sample. Simulation results show that for a synchrotron X-ray source 34,000 mm from the sample, a NEXL with six ellipsoidal sub-tubes offers a solid acceptance angle four times greater than a single ellipsoidal glass tube lens. Furthermore, for standard laboratory X-ray sources, a NEXL with three sub-tubes provides double the solid acceptance angle compared to a single-tube lens. These features position NEXLs as highly versatile in the field of X-ray technology.

Design of an Internal Focusing Tube Lens for Optical Inspection Systems

The numerical aperture (NA) of objective lens optical (inspection) systems has been increased to achieve higher resolution. However, the depth of focus decreases with an increase in the NA, and focusing becomes difficult. Therefore, the entire optical lens in currently developed optical inspection systems must be moved to focus within the depth of focus. To achieve a high resolution, many lenses are used in optical inspection systems, increasing the size and weight of the optical systems. To address this issue, a focus control group was placed on a tube lens that could adjust its focus based on the movement of the sample in front of the objective lens. Therefore, we developed a focus range increment to focus on the range of the optical inspection system. Using objective lenses with focal lengths of 30 and 60 mm and tube lenses with a focal length of 300 mm, optical systems for 10× and 5× inspection were constructed. In the designed optical systems, the weights of the objective lenses with focal lengths of 30 and 60 mm were calculated to be approximately 844 and 570 g, respectively. These values confirm that the weight of the moving group can be reduced.

Selective Laser Melting Process and Structure Optimization of Invar Alloy Lens Tube

Selective Laser Melting Process and Structure Optimization of Invar Alloy Lens Tube

Miniaturized high-resolution dual 2D MEMS mirror scanning confocal Raman microscopy for topographic and Raman mapping

A novel dual 2D MEMS mirror scanning confocal Raman microscopy (D-2D-MEMS-CRM) method is proposed to realize the miniaturized design of the confocal Raman microscopy. This method uses two 2D MEMS mirrors to realize beam telecentric scanning, which eliminates the relay system consisting of a scan lens and tube lens, significantly shortens the optical length of the system, and improves the detection efficiency of Raman signal. Moreover, this method uses reflected light to construct a real-time focus tracking system, which improves the spatial resolution of the confocal Raman detection system. Based on this method, a miniaturized D-2D-MEMS-CRM system was established, which had an axial focusing capability of 50 nm using an objective lens with NA of 0.6, and the lateral resolution of 500 nm for both topographic and Raman mapping. In addition, the system achieved simultaneous topographic imaging and Raman mapping of carbonaceous chondrite, demonstrating its effectiveness in extraterrestrial sample detection.

Alignment and characterization of remote-refocusing systems.

The technique of remote refocusing is used in optical microscopy to provide rapid axial scanning without mechanically perturbing the sample and in techniques such as oblique plane microscopy that build on remote refocusing to image a tilted plane within the sample. The magnification between the pupils of the primary (O1) and secondary (O2) microscope objectives of the remote-refocusing system has been shown previously by Mohanan and Corbett [J. Microsc.288, 95 (2022)JMICAR0022-272010.1111/jmi.12991] to be crucial in obtaining the broadest possible remote-refocusing range. In this work, we performed an initial alignment of a remote-refocusing system and then studied the effect of axial misalignments of O1 and O2, axial misalignment of the primary tube lens (TL1) relative to the secondary tube lens (TL2), lateral misalignments of TL2, and changes in the focal length of TL2. For each instance of the setup, we measured the mean point spread function F W H M xy of 100nm fluorescent beads and the normalized bead integrated fluorescence signal, and we calculated the axial and lateral distortion of the system; all of these quantities were mapped over the remote-refocusing range and as a function of lateral image position. This allowed us to estimate the volume over which diffraction-limited performance is achieved and how this changes with the alignment of the system.

Low-coherence and broadband confocal refractometry: reducing the measurement time

This paper describes the steps taken to improve the measurement speed of a combined low-coherence and confocal refractive index measurement system. The instrument measures the refractive index and thickness of transparent plates using a fibre-based low-coherence interferometer with a line-scan spectrometer. The spectrometer allows on-line dispersion measurement which is necessary to derive the sample thickness t as well as both the phase and group refractive indices n p, n g. The measurements were performed on a sample with six surfaces consisting of three glass windows mounted in a lens tube. Experimental results show that a measurement time of 4.4 s for the multi-layered object, which has a total thickness of approximately 10.5 mm, can be achieved whilst maintaining an accuracy of better than 0.1% for n p, n g, and t. This represents an approximately hundredfold improvement over previously published measurements.

Dependence of ghost on the incident light angle into dichroic mirror.

The dichroic mirror (DM) is a key component in microscope. We found ghost in the reflection channel of a dual-channel fluorescence microscope, and studied the relationship between the ghost and the incidence angle 𝜃 into the DM. The DM emission surface reflection generated ghost if the 𝜃 is not 45◦ . We analyzed the distance and intensity relationship between the ghost and the primary image, which is 𝜃-dependent and was demonstrated by imaging live cells and stage micrometer. The ghost can be eliminated by placing the DM between objective and tube lens, but not between tube lens and detector, ensuring that the incident light into the DM is approximately parallel. Furthermore, the transmitted light of the DM is shifted towards longer wavelength with increasing 𝜃. Collectively, microscopists must carefully optimize the 𝜃 when designing a microscope to avoid the ghost. This article is protected by copyright. All rights reserved.

Comparative Analysis of Optical Quality of Monofocal, Enhanced Monofocal, Multifocal, and Extended Depth of Focus Intraocular Lenses: A Mobile Model Eye Study.

To use the revised model eye to observe and compare how the world is perceived by patients with monofocal intraocular lens (IOL), Eyhance, bifocal IOL, and Symfony, and check its performance. The new mobile model eye consists of an artificial cornea, an IOL, a wet cell, an adjustable lens tube, a lens tube, an objective lens, a tube lens, and a digital single-lens reflex camera. We collected photographs of distant buildings and streets at night, videos of the focusing process, and videos of United States Air Force resolution target from 6m to 15 cm and analyzed them quantitatively. In this revised model eye using an objective lens, an artificial cornea similar to the human cornea could be used. Using a digital single-lens reflex camera, high-resolution imaging was possible without an additional computer. Fine focusing was possible using an adjustable lens tube. For monofocal IOL, the contrast modulation was 0.39 at 6m and decreased consistently. It was nearly 0 as the model eye got closer than 1.6m. For Eyhance, the contrast modulation was 0.40 at 6m. It then decreased and increased again. At 1.3 m, it was 0.07 and then decreased again. For Symfony, the contrast modulation was 0.18 at 6m. Symfony showed the characteristics of a bifocal IOL with low add diopter. Halos (234 pixels) were observed around lights, although smaller than those seen with bifocal IOL (432 pixels). We could objectively observe and compare how patients with monofocal IOL, Eyhance, bifocal IOL, and Symfony perceived the world using this revised model eye. Data obtained by this new mobile model eye can be used to help patients select their IOLs before cataract surgeries.

Live Cell Light Sheet Imaging with Low- and High-Spatial-Coherence Detection Approaches Reveals Spatiotemporal Aspects of Neuronal Signaling

Light sheet microscopy in live cells requires minimal excitation intensity and resolves three-dimensional (3D) information rapidly. Lattice light sheet microscopy (LLSM) works similarly but uses a lattice configuration of Bessel beams to generate a flatter, diffraction-limited z-axis sheet suitable for investigating subcellular compartments, with better tissue penetration. We developed a LLSM method for investigating cellular properties of tissue in situ. Neural structures provide an important target. Neurons are complex 3D structures, and signaling between cells and subcellular structures requires high resolution imaging. We developed an LLSM configuration based on the Janelia Research Campus design or in situ recording that allows simultaneous electrophysiological recording. We give examples of using LLSM to assess synaptic function in situ. In presynapses, evoked Ca2+ entry causes vesicle fusion and neurotransmitter release. We demonstrate the use of LLSM to measure stimulus-evoked localized presynaptic Ca2+ entry and track synaptic vesicle recycling. We also demonstrate the resolution of postsynaptic Ca2+ signaling in single synapses. A challenge in 3D imaging is the need to move the emission objective to maintain focus. We have developed an incoherent holographic lattice light-sheet (IHLLS) technique to replace the LLS tube lens with a dual diffractive lens to obtain 3D images of spatially incoherent light diffracted from an object as incoherent holograms. The 3D structure is reproduced within the scanned volume without moving the emission objective. This eliminates mechanical artifacts and improves temporal resolution. We focus on LLS and IHLLS applications and data obtained in neuroscience and emphasize increases in temporal and spatial resolution using these approaches.

Optical projection tomography of fluorescent microscopic specimens using lateral translation of tube lens.

Optical projection tomography (OPT) is a three-dimensional (3D) fluorescence imaging technique, in which projection images are acquired for varying orientations of a sample using a large depth of field. OPT is typically applied to a millimeter-sized specimen, because the rotation of a microscopic specimen is challenging and not compatible with live cell imaging. In this Letter, we demonstrate fluorescence optical tomography of a microscopic specimen by laterally translating the tube lens of a wide-field optical microscope, which allows for high-resolution OPT without rotating the sample. The cost is the reduction of the field of view to about halfway along the direction of the tube lens translation. Using bovine pulmonary artery endothelial cells and 0.1 µm beads, we compare the 3D imaging performance of the proposed method with that of the conventional objective-focus scan method.

Разработка и валидация методики количественного определения метопролола в плазме крови пациентов методом ВЭЖХ-МС/МС

INTRODUCTION: Metoprolol is a selective β1-adrenoblocker without intrinsic sympathomimetic activity. The effectiveness of metoprolol has been proven in numerous clinical studies in the treatment of arterial hypertension, stable angina, myocardial infarction, chronic heart failure. To improve the efficiency and safety of the therapy, it is advisable to carry out therapeutic drug monitoring of metoprolol, which requires a sensitive method for its quantitative determination. AIM: To develop, validate and test a method for the determination of metoprolol in human plasma using high performance liquid chromatography (HPLC) with tandem mass spectrometric detection (MS/MS). MATERIALS AND METHODS: The work was performed on Ultimate 3000 TSQ Fortis HPLC-MS/MS (Thermo Fisher, USA). For sample preparation, acetonitrile was used with fexofenadine hydrochloride at a concentration of 10 ng/ml as an internal standard, which was added to plasma samples in 3:1 ratio. The volume of the injected sample was 5 μl. Separation was performed on UCT Selectra C18 4.6 mm × 100 mm, 3 um, 100 A column with a similar pre-column at 35°C, in gradient elution mode in proportion of 0.1% formic acid solution/acetonitrile: 0 min — 80%/20%, 0.1 min — 45%/55%, 5 min — 10%/90%, 10 min — 80%/20%, at flow rate of 300 µl/min. Detection was performed in positive electrospray ionization mode, electrospray voltage 4000 V, sheath gas 50 arb, auxiliary gas 10 arb, purge gas 1 arb, evaporator temperature 350°C, ion transport tube temperature 300°C, using the multiple reaction monitoring mode (MRM) at argon flow rate 2 mTorr, 268 m/z → 115.5 m/z, Collision Energy 18 V, Tube lens 95 V, 268 m/z → 191 m/z, Collision Energy 17 V, Tube lens 95 V. The blood plasma of healthy volunteers served as matrix. RESULTS: The analytical range of the technique was 2–1000 ng/ml. The developed technique was tested on a patient with arterial hypertension. During the analysis, an equilibrium concentration of metoprolol of 12.0 ng/ml was detected in the patient's blood plasma (previously, the patient took metoprolol tartrate at a dose of 12.5 mg twice a day for a week), and in 2 hours after taking the drug — 31.0 ng/ml. CONCLUSION: A method for the quantitative determination of metoprolol in human blood plasma using HPLC-MS/MS has been developed, validated and tested.

Smartphone-based fluorescent sensing platforms for point-of-care ocular lactoferrin detection

Lactoferrin is a critical glycoprotein that accounts for the major component in tear protein composition. Tear lactoferrin has been indicated as a potential biomarker in ocular health screening, such as dry eye disease diagnosis. Fluorescent biosensors are a desirable alternative to current diagnostic methods, due to their high selectivity and sensitivity, and rapid and cost-effective detection technologies at point-of-care (POC) platforms. Herein, fluorescent lactoferrin sensing is examined and applied on nitrocellulose membrane, capillary tube, and contact lens platforms in cooperation with a developed smartphone software for data collection and analysis. Fluorescent sensors based on trivalent terbium (TbCl3) are integrated into different platforms, including nitrocellulose membranes, capillary tubes, and contact lenses, and tested in artificial tear fluid. A bespoke 3D printed readout device integrated with a smartphone camera was employed for image acquisition and readout. The detection range of the lactoferrin sensors could be varied from 0 to 5 mg mL−1 with a strong linear relation and yielded a limit of detection (LOD) of 0.57 mg mL−1 for lateral flow sensing, 0.12 mg mL−1 for capillary tube sensing, and 0.44 mg mL−1 for contact lens sensing. The contact lens sensor obtained the highest linear regression, while the capillary tube sensor achieved a lowest LOD. This work could pave the way towards accessible lactoferrin monitoring at POC and could induce hospitalization at the UK national health service (NHS) for future clinical trials and examinations.

Computational single-objective scanning light sheet (cSOLS)

Single-objective scanning light sheet (SOLS) imaging has fueled major advances in volumetric bioimaging because it supports low phototoxic, high-resolution imaging over an extended period. The remote imaging unit in the SOLS does not use a conventional epifluorescence image detection scheme (a single tube lens). In this paper, we propose a technique called the computational SOLS (cSOLS) that achieves light sheet imaging without the remote imaging unit. Using a single microlens array after the tube lens (lightfield imaging), the cSOLS is immediately compatible with conventional epifluorescence detection. The core of cSOLS is a Fast Optical Ray (FOR) model. FOR generates 3D imaging volume (40 × 40 × 14 µm3) using 2D lightfield images taken under SOLS illumination within 0.5 s on a standard central processing unit (CPU) without multicore parallel processing. In comparison with traditional lightfield retrieval approaches, FOR reassigns fluorescence photons and removes out-of-focus light to improve optical sectioning by a factor of 2, thereby achieving a spatial resolution of 1.59 × 1.92 × 1.39 µm3. cSOLS with FOR can be tuned over a range of oblique illumination angles and directions and, therefore, paves the way for next-generation SOLS imaging. cSOLS marks an important and exciting development of SOLS imaging with computational imaging capabilities.

Double-layer focal plane microscopy for high throughput DNA sequencing.

Throughput is one of the most important properties in DNA sequencing. We propose a novel double-layer focal plane microscopy that doubles the DNA sequencing throughput. Each fluorescence channel is divided into two tube lens channels by energy splitting, and the camera is adjusted to take images corresponding to different defocus positions of the objective, thus doubling the information capacity of the microscopy. The microscopy is applied to gene chip, which has high spatial frequency and good uniformity, so the simultaneous imaging of the two tubes has little influence on each other due to the spatial averaging effect. Experimental results show that the image signal to noise ratio (SNR) is reduced by 1%, while the sequencing throughput is doubled.

A miniaturized, low-cost lens tube based laser-induced fluorescence detection system for automated microfluidic analysis of primary amines.

In situ analyses are essential to ascertain potential past or present habitability in celestial bodies. One technique that provides the sensitivity and miniaturization needed to successfully detect trace organics in the outer Solar System is laser-induced fluorescence (LIF) detection, which, when coupled with microfluidic systems, provides a powerful wet chemistry platform that can meet the size and resource consumption constraints of a remote analysis mission. Herein, a portable LIF detection module (44-mm long, 18-mm wide) was prototyped and utilized to quantify bulk organics in a liquid sample via manual and automated analysis utilizing a programmable microfluidic architecture. The experimental limit of detection (LOD) for primary amines was 11.8μM. A sample (Y31B) collected from the Atacama Desert in Yungay, Chile, was analyzed manually and found to contain 300±50μM of bulk primary amine organics, while the automated microfluidic protocol found the sample to contain 289±4μM of primary amines. Automated analyses showed no statistically significant differences when compared to the manual analyses (t-test, C.I. 95%). Our results demonstrate that the coupling of programmable microfluidic devices with a custom lens tube-based LIF detector enables automated analysis of primary amines using a protocol appropriate for remote analyses. This technique is an invaluable tool for in situ analysis applications in distant, resource-restricted environments.

A Novel Intraocular Lens Simulator that Allows Patients to Experience the World Through Multifocal Intraocular Lenses Before Surgeries.

PurposeThe purpose of this study was to investigate whether the intraocular lens (IOL) simulator can simulate how the world appears to patients with multifocal IOLs by allowing the patients to see far and near objects through the IOL simulator.MethodsTwenty eyes from 20 patients (age = 50–70 years old) were included in the study. The IOL simulator we developed consists of a trial lens frame adapter, a lens tube, a concave lens, a spacer, a wet cell, and an IOL. We used two IOLs: Tecnis monofocal and Tecnis bifocal IOL (add +3.25 diopter [D]). Patients wore a trial lens frame with an IOL simulator on distant corrected trial lenses and underwent the following tests: defocus curve, satisfaction with distance and near vision, halo around the light, and near point accommodation (NPA). To check how the world appears to the patients through this simulator, a machine vision lens and a scientific camera were attached to the simulator, and far and near objects were photographed.ResultsIn the defocus curve of multifocal IOL, the visual acuity showed the second peak at –4 D. Compared to monofocal IOL, satisfaction with distant vision was slightly worse, more halos were felt, satisfaction with near vision was higher, and the NPA was shorter in multifocal IOL. In the scientific camera test, through the multifocal IOL, the waiting room was blurry, the halo around the ceiling light was prominent, and the characteristics on the near visual acuity chart were clear.ConclusionSubjects could experience the functions of multifocal IOLs with our newly developed IOL simulator.Translational RelevanceThis IOL simulator using geometric optics allows patients to experience the function of multifocal IOLs before cataract surgery.

Automatic tube lens design from stock optics for microscope remote-refocusing systems.

The remote-refocusing approach of Botcherby et al. [Opt. Lett.32, 2007 (2007)10.1364/OL.32.002007] has been applied widely to 2D and 3D fluorescence microscopes to enable rapid refocusing of the optical system without mechanically perturbing the sample. In order for this approach to operate correctly, it requires that the overall magnification of the first two microscope systems matches the ratio of the refractive indices in sample and intermedia image spaces. However, commercially available tube lenses are not always suitable to produce the desired overall magnification. Therefore, a practical approach to produce tube lenses with low expense and diffraction-limited performance is required. Tube lenses can be formed using a pair of stock achromatic doublets, however, selecting appropriate pairs of achromatic doublets from stock optics is a time-consuming process, as many combinations can be considered. In this paper, we present two software packages (Catalogue Generator and Doublet Selector) developed in MATLAB that use the application programming interface (ZOS-API) to the Zemax OpticStudio optical design software to realise an automatic search of stock achromatic doublets to produce microscope tube lenses with a specified focal length, entrance pupil diameter and maximum design field angle. An algorithm to optimise principal plane positions in versions of OpticStudio before 20.2 was also introduced to enable the use of older software versions. To evaluate the performance of Catalogue Generator and Doublet Selector, we used them to generate ten tube lens designs. All of the software-produced tube lenses have a better optical performance than those using manually selected pairs of stock doublets lenses.

Quantification of the NA dependent change of shape in the image formation of a z-polarized fluorescent molecule using vectorial diffraction simulations.

The point spread function of a fixed fluorophore with its dipole axis colinear to the optical axis appears donut‐shaped when seen through a microscope, and its light distribution in the pupil plane is radially polarized. Yet other techniques, such as photolithography, report that this same light distribution in the pupil plane appears as a solid spot. How can this same distribution lead to a spot in one case but a donut in the other? Here, we show how the tube lens of the system plays a critical role in determining this shape. Using a vectorial treatment of image formation, we simulate the relative contributions of both longitudinal and radial components to the image of a dipole emitter and thus show how the donut (typically reported for z‐polarized single molecule fluorescence microscopy) transforms into a solid spot (as commonly reported for photolithography) as the numerical aperture of the tube lens increases. We find that the transition point occurs around 0.7 NA, which is significantly higher than used for most microscopy systems and lower than for common photolithography systems, thus resolving the seeming paradox of dipole shape.