Meniscus Lens Research Articles

Flexible solid immersion meniscus lens (SIMlens) approach for enhancing biological imaging of cleared samples.

Tissue-clearing techniques have revolutionized the field of biological imaging by rendering biological specimens transparent and enabling inside optical detection. Light-sheet fluorescence microscopy (LSFM) is a powerful tool for three-dimensional imaging of large biological samples. Combining tissue-clearing techniques with LSFM has advanced the efficient 3D visualization of these samples. A crucial challenge with LSFM is the requirement for the objective to operate within the clearing reagent, which can cause aberrations. To address this issue, we introduce a novel, to our knowledge, approach for the flexible design of the solid immersion refractive meniscus lens (SIMlens), facilitating the use of air objectives with cleared samples. Compared to the previous SIMlens, this method not only eliminates aberrations but also offers customized options for enhancing the numerical aperture and working distance of the objective lens, achieving at least a 10% improvement. We have demonstrated the feasibility of this new method using mouse brain samples.

Direct observation of negative dysphotopsia in a physical model of the pseudophakic eye

Introduction: Negative dysphotopsia (ND) is a phenomenon affecting pseudophakic eyes where a dark crescent or shadow is perceived in the peripheral temporal visual field. Although is it understood that the size and position of the intraocular lens (IOL) creating a space between the IOL's optic and the iris are involved, the exact aetiology and conditions remains unclear. The purpose of this study was to develop a physical model of the pseudophakic eye and to record ND at the retinal plane in a variety of conditions.Methods: The eye model resembles anatomically the human eye with an aspheric cornea made of PMMA (R = 7.73 mm, Q = −0.24) an exchangeable iris and an IOL holder with variable distance (0.5 to 1.5 mm) from the pupil, representing a pseudophakic anterior chamber depth (pACD) ranging from 4.05 to 5.05 mm. The eye model is filled with distilled water. A camera, in a water‐tight housing is used to record images at the retinal plane. Negative dysphotopsia was investigated using both point sources and extended surfaces for two different pACD values (4.05 and 5.05 mm) and two pupil diameters (3 and 6 mm).Results: A characteristic crescent appeared next to the point spread function (PSF) in the periphery, representing light that was propagated beyond the edge of the IOL. This crescent was more prominent in greater pupil diameters and greater pACD values. When testing with an extended field, a relatively dark band appeared at a specific location at approximately 75 degrees of field angle. Various optical strategies to eliminate negative dysphotopsia can be envisaged including inverted meniscus lenses that ‐naturally‐ have a narrower peripheral gap and allow optical propagation until greater field angles as well as formations that block peripheral light.Conclusion: A peripheral crescent, corresponding to light that misses the IOL's optic results to a double‐peaked PSF for field angles as small as 45 degrees in some conditions (large pupil diameter, deep pACD). Yet, a dark band does not appear until much greater angles, where effectively the part of light passing through the IOL is eliminated while the peripheral crescent persists.

Parametric multiphysics study of focus-variable silicone lenses.

By exploiting their inherent elasticity, focus-variable silicone lenses shift their focal length reversibly when deformed. Although biconcave and meniscus lenses contribute to optical systems just as well as biconvex lenses, studies primarily revolve around the latter. Thus, we aim to reveal the focal length shifting potential of all aforementioned lens types. Covering a wide parameter range of varying lens curvature radii, we present a coupled mechanical and optical simulation in which a lens deformation is applied. The results show significant differences in focal length shifting effectiveness for different lens types. Within the domains of specific lens types, trends in this effectiveness emerge for different combinations of curvature radii. Matching these radii when incorporating adaptive silicone lenses in optical systems may guide optics engineers toward more effective system designs through this study.

Method of initial design of a two-element double-sided telecentric optical system.

An algebraic method for finding fundamental parameters of a starting design of a two-element double-sided telecentric lens is introduced in this work. The telecentric lens is formed by two objectives composed of an afocal meniscus lens followed by a cemented doublet. It is used the third-order aberration theory to find the fundamental parameters of the starting configuration of a given optical system. The method gives results which make possible to obtain a good initial design of such a telecentric lens for further optimization using optical design software. The proposed method is presented on an example of finding initial design parameters of the double-sided telecentric lens.

Underwater determination of calcium and strontium ions in oilfield produced water by laser-induced breakdown spectroscopy (LIBS).

Laser-induced breakdown spectroscopy (LIBS) was applied to the determination of scaling ions in oilfield-produced water employing underwater measurements. Initially, the stability of plasma was verified using four different optical setups and expansion of the laser beam, and a combination of an achromatic lens with a meniscus lens were necessary to stabilize the plasma. Preliminary experiments demonstrated that only the determinations of Ca(II) and Sr(II) ions were feasible while the signal for the Mg(II) ion was absent and the sensitivity for Ba(II) was very low. The laser pulse repetition rate was evaluated and rates of 10 and 20 Hz provided a more stable breakdown in water compared to repetition rates of 2 to 7 Hz, besides imparting higher intense signals. The increase in salinity showed a small matrix effect, decreasing the sensitivities of the calibration curves by 8-13% when standard solutions with a salinity of 30‰ were used instead of water. Under optimized conditions with a laser pulse energy of 31 mJ, gate delay of 300 ns, gate width of 5.0 μs, repetition rate of 10 Hz, and accumulation of 500 laser shots, a linear range from 25 to 150 mg L-1 was obtained, with limits of detection of 0.58 and 0.85 mg L-1 for Ca(II) and Sr(II), respectively. The underwater determination of scaling ions in produced water by LIBS provided results that do not significantly differ from those obtained by inductively coupled plasma atomic emission spectroscopy (ICP OES) at a confidence level of 95%, with relative errors of up to 5.2%. These results demonstrate the potential of underwater LIBS measurements as an analytical tool for the determination of alkaline-earth metal ions in produced water, which can help the oil industry to overcome the problems related to scale formation.

Effect of preform shape on formability and internal stress for glass molded concave meniscus lens

Effect of preform shape on formability and internal stress for glass molded concave meniscus lens

Algebraic method for finding the initial design parameters of a two-element optical system with an afocal meniscus lens.

This work introduces an algebraic method of the calculation of an initial design of a two-element optical system composed of a thick afocal meniscus lens and a thin lens element, which can be formed, for example, by a cemented doublet. The third-order aberration theory is used to find the fundamental parameters of the starting configuration of a given optical system. The method gives results that make it possible to obtain a good starting design for further optimization of such imaging systems using optical design software. The proposed method is presented on two examples of finding the initial design parameters of the objective with an afocal meniscus lens and a cemented doublet.

Интерференционный метод контроля выпуклых гиперболических поверхностей с использованием дифракционного оптического элемента

Interference control methods are making it possible to evaluate with high accuracy errors in the shape of the optical part surface profile. The interference pattern processing allows obtaining a map of the surface deviations at each of its points with an accuracy of half the wavelength. An interference method is proposed for testing the convex hyperbolic surfaces, which could be introduced to control mirrors with large aperture angles in the imaginary geometric focus. The proposed auto-collimation control scheme consists of a helium-neon laser with the wavelength of 632.8 nm, a meniscus lens and a planar axisymmetric diffractive optical element to correct the meniscus spherical aberration. Numerical method is presented for calculating the optical diffraction element using a phase profile on the example of the secondary hyperbolic mirror of the Millimetron space telescope. The developed scheme was simulated in the Zemax OpticStudio program. The approximation error of the calculated phase profile was evaluated depending on the number of phase coefficients. The Fizeau interferometer optical system is proposed to implement the developed method. The influence of errors in installing a controlled mirror on the interference pattern for axial displacement, transverse displacement and tilt was determined. The residual wave aberration was evaluated in the control system

Compact zooming optical systems for panoramic and telescopic applications based on curved image sensor

Biological eyes in nature have strongly inspired novel optical systems. In this regard, imaging systems mimicking fish eyes and human eyes have been reported for having a wide field-of-view (FoV) and relatively higher magnification properties, respectively. However, most of these systems have complex lens configurations because of their flat image sensors. As these optical systems are bulky, heavy, and expensive, they have limited application in small devices (e.g., drones and mobile phones). In addition to a simplistic design, multi-functionality is essential for broad applications. Therefore, this study proposes a compact zooming optical system (CZOS) that combines the properties of natural vision systems (i.e., human and fish eyes) using a curved focal plane. The CZOS controls the zoom range through the modification of the distances between the single front lens (i.e., negative meniscus) and dual rear lens (i.e., bi-convex/positive meniscus lenses) groups. In the proposed system, the panoramic mode had an FoV of 200 deg and a magnification of 0.23, whereas the conversion of the system to the high magnification mode increased the magnification over two times with an FoV of 70 deg. These promising results demonstrate that the proposed simple imaging system is applicable to small-scale electronics.

Aplanatic meniscus lens corrector for Ritchey-Chrétien telescopes.

An analytically designed aplanatic meniscus lens is proposed for increasing the field of view (FoV) of Ritchey-Chrétien (RC) telescopes. Compared to other field correctors, the proposed solution does not affect the initial RC telescope's aplanatic properties, and it can be added or removed from an existing RC telescope without changing the mirrors' shape. The final system features less astigmatism, which is balanced to flatten the image surface.

Plasmonic meniscus lenses

Controlling and manipulating the propagation of surface plasmons has become a field of intense research given their potential in a wide range of applications, such as plasmonic circuits, optical trapping, sensors, and lensing. In this communication, we exploit classical optics techniques to design and evaluate the performance of plasmonic lenses with meniscus-like geometries. To do this, we use an adapted lens maker equation that incorporates the effective medium concepts of surface plasmons polaritons travelling in dielectric-metal and dielectric-dielectric-metal configurations. The design process for such plasmonic meniscus lenses is detailed and two different plasmonic focusing structures are evaluated: a plasmonic lens with a quasi-planar output surface and a plasmonic meniscus lens having a convex-concave input–output surface, respectively. The structures are designed to have an effective focal length of 2λ0 at the visible wavelength of 633 nm. A performance comparison of the two plasmonic lenses is shown, demonstrating improvements to the power enhancement, with a 22% and 16.5% increase when using 2D (ideal) or 3D (realistic plasmonic) meniscus designs, respectively, compared to the power enhancement obtained with convex-planar lenses. It is also shown that the depth of focus of the focal spot presents a 19.8% decrease when using meniscus lenses in 2D and a 34.3% decrease when using the proposed 3D plasmonic meniscus designs. The broadband response of a plasmonic meniscus lens (550–750 nm wavelength range) is also studied along with the influence of potential fabrication errors on the generated effective focal length. The proposed plasmonic lenses could be exploited as alternative focusing devices for surface plasmons polaritons in applications such as sensing.

Uniformity of Surface Film Thickness of Meniscus Lens in Third-Order Common Rotation Planetary System

Uniformity of Surface Film Thickness of Meniscus Lens in Third-Order Common Rotation Planetary System

Optical Design of Improved Offner Imaging Spectrometer

An improved Offner imaging spectrometer was proposed based on the optical system characteristics of Offner imaging spectrometer, which can ensure perfect imaging quality in a wider annular region. The operating wavelength of the improved Offner imaging spectrometer ranges from 900nm to 1700nm, and the magnification is 1. Improved Offner imaging spectrometer can be obtained by changing the meniscus lens position and further optimizing the design. The results indicate that the improved Offner imaging spectrometer can effectively improve compactness and lightweight, and reduce the difficulty of optical adjustment, which is conducive to the stability of practical application.

GRINCU lens with conicoid iso-indicial surfaces: application for modeling the crystalline lens.

We introduce a new type of lens with two gradients of refractive index (GRIN) and of curvature (GRCU) of iso-indicial surfaces, i.e., GRINCU. The inner structure of the lens resembles that of an onion. Each layer is a meniscus lens with infinitesimal thickness, which coincides with an iso-indicial surface characterized by a conicoid shape and a constant refractive index. The internal distribution automatically adapts to the external geometry. Here, we consider the simplest case of a constant gradient of the curvature radius -G, which indicates a linear decrease as we move along the optical axis. The formulation of this type of lens is presented, including its generalization to nonrotationally symmetric conicoid surfaces. The formulation is then applied to model the crystalline lens; the code corresponding to the numerical computation of the 3D refractive index distribution as well as its gradient is provided as a supplementary file. Finally, we confirmed a refractive power increase of nearly 14% when G changes from 0 to 3.

A novel fluorescent cardiac imaging system for preclinical intraoperative angiography

BackgroundIntraoperative coronary angiography can tremendously reduce early coronary bypass graft failures. Fluorescent cardiac imaging provides an advanced method for intraoperative observation and real-time quantitation of blood flow with high resolution.MethodsWe devised a system comprised of an LED light source, special filters, lenses and a detector for preclinical coronary artery angiography. The optical setup was implemented by using two achromatic doublet lenses, two positive meniscus lenses, a band-pass filter, a pinhole and a CCD sensor. The setup was optimized by Zemax software. Optical design was further challenged to obtain more parallel light beams, less diffusion and higher resolutions to levels as small as arterioles. Ex vivo rat hearts were prepared and coronary arteries were retrogradely perfused by indocyanine green (ICG). Video angiography was employed to assess blood flow and plot time-dependent fluorescence intensity curve (TIC). Quantitation of blood flow was performed by calculating either the gradient of TIC or area under curve. The correlation between blood flow and each calculated parameters was assessed and used to evaluate the quality of flow.ResultsHigh-resolution images of flow in coronary arteries were obtained as precise as 62 µm vessel diameter, by our custom-made ICG angiography system. The gradient of TIC was 3.4–6.3 s−1, while the area under curve indicated 712–1282 s values which ultimately gained correlation coefficients of 0.9938 and 0.9951 with relative blood flow, respectively.ConclusionThe present ICG angiography system may facilitate evaluation of blood flow in animal studies of myocardial infarction and coronary artery grafts intraoperatively.

Variable immersion microscopy with a high numerical aperture.

Three-dimensional (3D) optical microscopy with a high numerical aperture (NA) remains challenging for thick biological specimens owing to aberrations arising from interface refractions. We developed a variable immersion lens (VIL) to passively minimize these aberrations. A VIL is a high-NA concentric meniscus lens and was used in combination with an aberration-corrected high-NA reflecting objective (TORA-FUJI mirror). Wave-optics simulation at a wavelength of 488 nm showed that a VIL microscope enables diffraction-limited 1.2-NA imaging in water (refractive index of 1.34) at a depth of 0.3 mm by minimizing aberrations due to refraction of a sample interface. Another aberration due to the refractive index mismatching between a mounting medium, and an object can also be corrected by the VIL system, because various fluids with different refractive indices can be used as mounting media for the VIL. As a result of correcting the two aberrations at the same time, we experimentally demonstrated that a 6 µm diameter fluorescent bead can be imaged to the true dimensions in 3D.

Effect of preform shape on formability and residual stress for glass molded concave meniscus lens

Effect of preform shape on formability and residual stress for glass molded concave meniscus lens

Multi-resolution open-top light-sheet microscopy to enable efficient 3D pathology workflows.

Open-top light-sheet (OTLS) microscopes have been developed for user-friendly and versatile high-throughput 3D microscopy of thick specimens. As with all imaging modalities, spatial resolution trades off with imaging and analysis times. A hierarchical multi-scale imaging workflow would therefore be of value for many volumetric microscopy applications. We describe a compact multi-resolution OTLS microscope, enabled by a novel solid immersion meniscus lens (SIMlens), which allows users to rapidly transition between air-based objectives for low- and high-resolution 3D imaging. We demonstrate the utility of this system by showcasing an efficient 3D analysis workflow for a diagnostic pathology application.

Suitability of Different Observational Lenses for Viewing the Macular Area Through Multifocal Intraocular Lenses in a Model of the Human Eye.

PurposeMultifocal intraocular lenses (IOLs) can potentially affect the intraoperative view of the retina. We investigated the suitability of different lenses for viewing the macular area through two multifocal intraocular lenses in a human eye model.MethodsThis study compared the image quality of graduated index (0.1 mm) in a model eye when viewed through refractive or diffractive multifocal IOLs with a meniscus or flat contact lens, and a wide field 60 diopter non-contact lens or wide field contact lens (Super Macula®).ResultsImages acquired through the meniscus contact lens or flat contact lens via the central optical zone of the refractive multifocal IOL or the diffractive multifocal IOL were well focused. However, images viewed through these lenses near the center were warped and out of focus. All images viewed through a wide-field 60 diopter non-contact lens at the central optical zone and near the center were slightly out of focus. All images viewed through the Super Macula at the central optical zone and near the center were well focused.ConclusionA wide field contact lens (Super Macula®) made it possible to obtain clear images of the macular area at multiple focal points through refractive or diffractive multifocal IOLs.

Transmissive resonant fiber-optic gyroscope employing Kagome hollow-core photonic crystal fiber resonator.

A novel scheme for a double closed-loop resonant fiber-optic gyroscope (R-FOG) employing a high-performance transmissive Kagome hollow-core photonic crystal fiber (HCPCF) resonator is proposed. We use specially designed Kagome HCPCFs and a meniscus lens module to form a resonator, whose finesse is 58.2 with a length of 5.6 m and a diameter of 13 cm; the theoretical sensitivity of the R-FOG is better than 0.05°/h. Based on the novel Kagome HCPCF resonator, a double closed-loop R-FOG is set up and the performance of the R-FOG system is experimentally studied. It demonstrates that white noise dominates in the output at the integration time of 200 s and a bias stability of 0.15°/h and angle random walk coefficient of $0.04^{\circ}\,{\rm h}^{1/2}$0.04∘h1/2 are achieved. Over a dynamic range of ${-}{100}^\circ {\rm /s}$-100∘/s to 100°/s, the scale factor nonlinearity of the FOG is 310 ppm, which shows significant improvement compared with the single closed-loop R-FOG system. The novel double closed-loop R-FOG proposed is quite feasible for tactical grade applications.