Cylindrical Lens Research Articles

Optical beam steering and distance measurement experiments through an optical phased array and a 3D printed lens

We present beam steering experiments based on the wavelength tuning of edge-coupled 1D optical phased arrays (OPAs) on a 3 µm silicon on insulator (SOI) platform. Two versions of 512-channel OPA with different pitch values, namely 2 µm and 3 µm, are designed, fabricated, and characterized. For the 2 µm pitch, the width of the output array is 1 mm, steering sensitivity is measured to be 1°/nm, and the maximum beam steering angle is 45°. For the 3 µm pitch, the output array is 1.5 mm wide, the steering sensitivity is 0.6°/nm, and the maximum beam steering angle is 30°. Since the chip doesn’t offer vertical collimation, both a cylindrical (2D-shaped) lens and a 3D printed (3D-shaped) lens were tested with the OPA chips. The high number of output channels results in a wide width of the output array, therefore enabling frequency-modulated continuous-wave (FMCW) distance measurements up to a few meters. The ability to achieve precise steering angles and distance measurements with up to 5 cm accuracy improves the efficiency of light detection and ranging (LiDAR) systems in various fields, such as autonomous vehicles, robotics, and environmental mapping.

Effect of induced astigmatism on vestibulo-ocular reflex

ABSTRACT Clinical relevance The vestibular-ocular reflex stabilises the retinal image and maintains balance during head movement. Astigmatism is one of the common refractive errors that can reduce the quality of visual inputs. Background The purpose of this study was to investigate the effect of induced astigmatism on the function of the vestibular-ocular reflex. Methods This prospective semi-experimental study was conducted on 48 participants aged 20 to 40 years who had no history of neurological, vestibular, or eye disorders. Simple myopic astigmatism was induced using three positive cylindrical lens powers of + 0.50D, +1.50D, and + 2.50D at three axes of 180, 45, and 90 degrees in both eyes. The vestibular-ocular reflex was evaluated by the ocular Vestibular Evoked Myogenic Potential (oVEMP) through acoustic stimulation (a 500 hz tone burst at an intensity of 95 dBnHL) of the ear, with potentials recorded from the lower oblique muscle. The latency of the N1 and P1 waves and the amplitude of N1-P1 were recorded for all participants in the baseline condition (without any induced astigmatism) and under different induced astigmatism conditions. Results The latencies of N1 and P1 significantly increased with the increasing power of induced astigmatism; however, the powers of astigmatism had no effect on the amplitude of N1-P1. The axes of induced astigmatism did not have a significant effect on the latencies and amplitude of N1-P1. Conclusions Induced astigmatism due to retinal image blur can deteriorate the function of the vestibular-ocular reflex by increase in the latencies of N1 and P1 oVEMP waves.

Spatially Selective Imaging in Color: What You See is What You Want.

Spatially selective imaging (SSI) involves sampling a group of pixels from different positions on an encoded object to display a decoded image. Here, SSI is achieved by using off-axis cylindrical Fresnel lens arrays to decode multiple images from an encoded print of structural color pixels. Each image is optically retrieved by separately placing different "keys" (arrays of lenses in different pseudorandom configurations) over the same encoded print, and then each image is digitally reconstructed for visualization. In addition, a detailed analysis is presented on the designed lenses and pixels, which are all fabricated by two-photon polymerization lithography. Though Fresnel lenses are susceptible to chromatic aberrations, the results show that they can be used for imaging pixels that produce a wide range of colors at low numerical aperture (NA ≈0.2). The images have acceptable color contrast, corresponding to a simulated normalized modulation transfer function (MTF) of ≈0.6 averaged across wavelengths in the visible spectrum. This work can find applications in optical information security devices.

Effect of astigmatism and spherical equivalent correction on contrast sensitivity.

To investigate the effect of astigmatism and spherical equivalent (SE) correction on contrast sensitivity (CS). In this cross-sectional study, 103 visually normal subjects aged 18 to 36y with bilateral regular astigmatism in range of 1.00 diopter cylinder (DC) to 4.00 DC and normal best-corrected visual acuity (20/20) were recruited. Binocular CS was assessed by linear sine-wave gratings at 1.5, 3, 6, 12, and 18 cycles per degree (cpd), before correction of astigmatism, after full correction of astigmatism by cylindrical spectacle lenses, and after SE of refractive error. The repeated measures ANOVA and Bonferroni test were used to compare the effects of astigmatism correction on logCS. Totally 39 patients were male and 64 patients were female with the mean age of 28.25±5.38y. The average degree of astigmatism in right and left eye was 2.03±0.83 and 2.10±0.78, respectively. Increases in uncorrected astigmatic power correlated with decreases in the logCS, especially at high spatial frequencies. A statistically significant difference in logCS was found between these three cases: before correction of astigmatism, after SE of refractive error, and after full correction of astigmatism by cylindrical spectacle lenses at all frequencies (P<0.001), except at 18 cpd. At 18 cpd, there was no statistically significant difference between logCS before and after SE of refractive error (P=1.0). Also, there was no statistically significant difference in mean CS between with-the-rule (WTR) and against-the-rule (ATR) astigmatism, before correction of astigmatism, after correction of astigmatism with cylindrical lenses, and after SE of refractive error. Binocular astigmatism defocus decreases CS depending on the degree of astigmatism power; correction of this will improve patent's quality of vision. Although high astigmatism refractive error (more than 2.00 DC) that is fully corrected by cylindrical spectacle lenses doesn't increase the CS to the maximum value, especially at higher spatial frequencies (12 and 18). Also SE refractive error effects on improving CS in low astigmatism power (less than 2.00 DC), especially at lower spatial frequencies.

Optical method for dissolution/diffusion process multiparameters simultaneous measurement based on liquid-core cylindrical lenses.

The dissolution/diffusion process of solid in a liquid is a kind of widespread physical phenomenon. Parameters involved in this process include the dissolution rate (dC/dt), dissolution rate constant (K), and diffusion coefficient (D), whose accurate measurement is particularly important in fields such as biopharmaceuticals, materials science, agriculture, etc. However, the commonly used measurement methods at present cannot obtain these parameters simultaneously. Besides that, the measurement process is always not intuitive and time-consuming. This study introduces a method for measuring the multiple parameters of potassium dihydrogen phosphate (KDP) dissolving and diffusing in water under three states (powder, solid, and crystal) based on a compound liquid-core cylindrical lens (SLCL-Doublet) using a real-time optical image feature extraction method. Based on the relationship between the dissolution/diffusion image width and the solution concentration, dynamic spatiotemporal distribution of the solution concentration can be established, which can be used to calculate the D values based on Fick's second law, and the dC/dt, K values based on Noyes-Whitney equation, accordingly. At last, the area of solid-liquid contact surfaces is determined based on the relationship between K and D in the Nernst-Brunner equation, confirming the accuracy of the measurement data from the side. The optical method for simultaneously measuring the multiple parameters in the dissolution/diffusion process introduced in this study can be widely used to quickly expand the basic data required for chemical and pharmaceutical industries.

A Cylindrical Lens Spectrometer with Parallel Detection for Reflection Electron Energy Loss Spectroscopy.

Reflection electron energy loss spectroscopy (REELS) has played a pivotal role in allowing researchers to explore the characteristics of various bulk materials. This study presents results for the low-loss region of REELS with a new cylindrical lens spectrometer integrated into a low-voltage scanning electron microscope. The operational principles and implementation of the spectrometer are explained through comparisons between electron optical simulations and experimental results. Notably, the analysis shows the ability to distinguish samples in film and bulk forms. Graphene and graphite, despite their identical elemental composition and crystalline structure, are found to have distinct energy spectra as indicated by plasmon peaks. Furthermore, the study explores the bandgap measurement of SiO2 at low-energy conditions of 2.5 keV, highlighting the proposed instrument's advantages in the measurement without the harmful effect of Cherenkov loss. Additionally, this method reaffirms the capability to measure multiple plasmon peaks from the energy spectra of bulk gold samples, thus introducing a pioneering avenue in energy spectrum measurement. Leveraging the compact size and simple experimental setup of the spectrometer for REELS, the method enables the measurement of energy spectra of both bulk- and film-formed samples under low electron energy conditions, marking a significant advancement in the field.

Generation of pseudo-nondiffracting symmetrical Layer beams using cylindrical lenses

The pseudo-nondiffracting behavior of optical caustic beams makes them potentially useful in precise component alignment at CERN. This paper introduces an innovative method for generating one and two-dimensional symmetrical Airy-like beams, known as Layer beams, utilizing a specific configuration of plano-convex cylindrical lenses. Simulations and experimental results have validated this method, demonstrating its potential for scalable and cost-effective beam production with tunable properties, making it practical for a wide range of scientific applications.

Rydberg atom-based microwave electrometry using polarization spectroscopy

Abstract In this study, we investigated Rydberg atom-based microwave (MW) electrometry using polarization spectroscopy in a room-temperature vapor cell. By measuring Autler-Townes splitting in the electromagnetically induced transparency (EIT) spectrum, we determined that the minimum measurable MW electric field is approximately five times lower than conventional EIT techniques. The results are well reproduced by a full optical Bloch equation model, which takes into account all the hyperfine levels involved. Subsequently, the EIT setup was used to characterize a custom MW cylindrical lens, which increases the field at the focus by a factor of three, decreasing the minimum measurable MW electric field by the same amount. Our results indicate that the combination of polarization spectroscopy and a MW lens may enhance MW electrometry, and may allow its use as a secondary standard.

Tunable enhancement of the cylindrical Luneburg lens focusing ability with the aid of a conformal graphene strip.

We consider the plane wave focusing characteristics of the layered cylindrical Luneburg lens equipped with a conformal strip of graphene, in the H-polarization case. The angular width and location of the strip is arbitrary, and its surface impedance is characterized with the aid of the quantum-physics Kubo formalism. We use a mathematically accurate full-wave analytical regularization technique, which is based on the explicit inversion of the problem static part and yields a Fredholm second-kind matrix equation. This guarantees the convergence of the resulting meshless numerical algorithm. We compute the focusing ability of a microsize lens as a function of the frequency in the wide range up to 60 THz. This analysis shows that a graphene strip, placed into the focal area of the Luneburg lens, enhances its focusing ability at the resonance frequency of the strip plasmon mode proportionally to the quality factor. This frequency is defined by the strip width and is tunable with the aid of graphene's chemical potential.

Sensory experience steers representational drift in mouse visual cortex

Representational drift—the gradual continuous change of neuronal representations—has been observed across many brain areas. It is unclear whether drift is caused by synaptic plasticity elicited by sensory experience, or by the intrinsic volatility of synapses. Here, using chronic two-photon calcium imaging in primary visual cortex of female mice, we find that the preferred stimulus orientation of individual neurons slowly drifts over the course of weeks. By using cylinder lens goggles to limit visual experience to a narrow range of orientations, we show that the direction of drift, but not its magnitude, is biased by the statistics of visual input. A network model suggests that drift of preferred orientation largely results from synaptic volatility, which under normal visual conditions is counteracted by experience-driven Hebbian mechanisms, stabilizing preferred orientation. Under deprivation conditions these Hebbian mechanisms enable adaptation. Thus, Hebbian synaptic plasticity steers drift to match the statistics of the environment.

Study on the diffraction light field of two special beams through a cylindrical lens

Study on the diffraction light field of two special beams through a cylindrical lens

Estimation of stresses in 1D structures via inverse wavenumber analysis

The ANR ITHERATE project proposes to develop identification procedures of residual stresses in additive manufacturing via in-situ and non destructive methods using the wide band wave response of structures. This work presents a proof on concept on one-dimensional waveguides, as a preliminary results to more complex configurations. An original experimental setup is implemented using a cylindrical lens to optically amplify the vibrations of the structure in the transverse direction, allowing to resolve the wave propagation with a high-speed low-resolution camera. The dispersion of the wave velocity with the frequency, obtained via high-resolution wavenumber analysis (HRWA), is compared to predictions given by the acousto-elastic theory. In particular, the effects of the quasi-static initial stress and the elasticity of the material can be separated and estimated seperately via an inverse method that is independent from the boundary conditions and applied loads. Interestingly, this wave-based estimation does not necessitate an a-priori knowledge of the material constitutive law, overcoming the limitations of most stress estimation techniques of the state of the art, that are based on a measurement of the strain. Finally, perspectives for the generalization of the method to more complex situations, as plates under thermal loads, will be presented.

Semiconductor laser collimation and shaping design based on the combination of a rotationally symmetrical lens and a cylindrical lens

A dual-lens collimation and shaping system which is composed of a rotationally symmetric lens and an aspherical cylindrical lens is proposed in this paper. The system design method is discussed in detail, and the divergent elliptical laser beams are finally converted into collimated circular beams. The simulation results show that the maximum divergence angle of the beams can be collimated to 2.58 µrad, the standard deviation of the edge beam radius samples (SDRS) can be decreased from the original 4.227 to 0.135 mm, and the ratio of beam waist (RBW) drops from 1.554 to 1.0093 in the case of the output beam radius of 40 mm. The effects of transmission distance, astigmatism, wavelength deviation, light source offset, and lens offset on the collimation shaping effect are discussed. The collimation system can be widely used in long-distance optical communication systems and the design method in this paper can provide some new ideas for optical design researchers.

Variational approach to learning photonic unitary operators

Structured light, light tailored in its internal degrees of freedom, has become topical in numerous quantum and classical information processing protocols. In this work, we harness the high dimensional nature of structured light modulated in the transverse spatial degree of freedom to realize an adaptable scheme for learning unitary operations. Our approach borrows from concepts in variational quantum computing, where a search or optimization problem is mapped onto the task of finding a minimum ground state energy for a given energy/goal function. We achieve this by a pseudo-random walk procedure over the parameter space of the unitary operation, implemented with optical matrix-vector multiplication enacted on arrays of Gaussian modes by exploiting the partial Fourier transforming capabilities of a cylindrical lens in the transverse degree of freedom for the measurement. We outline the concept theoretically, and experimentally demonstrate that we are able to learn optical unitary matrices for dimensions d = 2, 4, 8, and 16 with average fidelities of &gt;90%. Our work advances high dimensional information processing and can be adapted to both process and quantum state tomography of unknown states and channels.

Rapid measurement of liquid diffusion coefficients for different concentrations based on compound liquid-core cylindrical lenses and the finite element method.

Liquid diffusion coefficients are usually concentration-dependent (D(C)), and current methods for measuring the D(C) relationship suffer from long measurement times and large repetitive experimental workloads. This paper consequently proposes a new method for rapid measurement of D(C), which can eliminate the need to measure uncalibrated diffusion coefficients corresponding to concentration by comparing the theoretical concentration distribution of diffusion solution obtained by the finite element method and the experimental concentration distribution. The core diffusion and imaging setup is a compound liquid-core cylindrical lens, which can offer the advantages of high refractive index resolution and imaging quality, guaranteeing the accurate measurement concentration distribution. The D(C) relationship can be obtained by simply gathering an appropriate diffusion image in one experiment profiting from taking full use of the solution concentration spatiotemporal distribution information using the finite element molding fitting method, reducing the measurement time greatly from several days in traditional methods to within 2 hours, characterized by short measurement time, high measurement accuracy and small experimental workload. The D(C) relationship of NaCl solution at 25 °C was measured using this method, and the result was in accord with the instantaneous image method and the literature values.

The laser screen imaging measurement system based on arrayed fibers

This paper presents a laser screen imaging measurement system (LSIMS) based on arrayed fibers to measure the velocity and dimension of a flying object. A laser diode is connected to the emission module of the laser screen via a single-mode fiber, then the emitted light beam is collimated into a parallel beam with a lens, this structure is arrayed to form the laser screen. The receiving module of the laser screen employs a cylindrical lens array to converge the collimated beams into a focal line. The input ends of the plastic fibers are arrayed along this focal line, while the output ends are imaged on the sensor of a line scan camera (LSC) through a lens. The LSIMS effectively modulates the process of a flying object passing through the laser screen into the light intensity change in the plastic fibers. The velocity and dimension of the flying object are subsequently measured through the analysis of the image obtained by the LSC. The timing accuracy of the LSIMS is verified through experiments. The velocity and diameter of pellets launched by a slingshot are measured and analyzed for errors.

Comparative Effect of Cylindrical Lenses Versus Spherical Equivalent on Contrast Sensitivity

Background: Astigmatism is a common refractive error that affects visual acuity and contrast sensitivity. Cylindrical lenses and spherical equivalents are commonly prescribed to correct these errors, but their comparative effects on contrast sensitivity are not well-documented.Objective: To compare the effects of cylindrical lenses versus spherical equivalents on contrast sensitivity in individuals with astigmatism.Methods: A randomized controlled trial was conducted involving 68 participants with astigmatism, aged 15 to 30 years. Participants were randomly assigned to receive either cylindrical lens correction or spherical equivalent correction. Contrast sensitivity was measured using the Pelli-Robson chart at baseline and during two follow-ups over three months. Data were analyzed using Friedman's Two-Way Analysis of Variance and the Wilcoxon Signed Ranks Test, with p ≤ 0.05 considered statistically significant.Results: The mean contrast sensitivity decreased from 1.95 ± 0.07 to 1.93 ± 0.09 over three months. Cylindrical lenses resulted in higher contrast sensitivity scores (2.00 in 67.6% of cases at final visit) compared to spherical equivalents (44.1%, p &lt; 0.001).Conclusion: Cylindrical lenses significantly improve contrast sensitivity compared to spherical equivalents, particularly in moderate to high astigmatism.

Investigation into NSAW excitation and modulation utilizing the grating mask technique

Narrowband surface acoustic wave (NSAW) method is a promising ultrasonic detection technique, with its laser-induced excitation technology offering the advantages of non-contact and flexible regulation. This paper proposes an NSAW excitation and modulation system based on the grating mask method to detect the nonlinear characteristics of the spectra caused by the variation in material surface properties. According to Doyer’s sharp line excitation theory, a strip line source array excitation model formed by superposition principle is established, and the effects of duty ratios of the masks on NSAW spectra amplitude characteristics are interpreted. An NSAW excitation and B-scan experimental system that can realize line source spacing changes is developed, and the effects of cylindrical lens height and masks with different duty ratios on NSAW spectra modulation are studied. The experimental results show that the amplitude ratios (the ratio of the double frequency amplitude to the second harmonic amplitude) are consistent with the results of the Doyer superimposed strip line source array excitation model in which the excitation light source energy is evenly distributed. The second-order nonlinear coefficients extracted from the experimental spectra can effectively characterize the surface properties of 6061 aluminum alloy at different annealing temperatures.

Cascaded spectral light field tomography.

We present cascaded spectral light field tomography for multicolor imaging in three dimensions (3D). Building upon light field tomography, our method uses a Dove prism array and a cylindrical lens array to transform a 3D scene into one-dimensional (1D) projections. To further enhance the reconstructed image quality, we incorporate a rotating Dove prism to increase the number of projection angles and a scanning light sheet to sparsify the sample along the depth axis. The resulting 1D projections are then spectrally dispersed for parallel spectral measurements. We demonstrate the effectiveness of our system in both fluorescence and scattering microscopy applications.

Hundred-watt Ho:YAG oscillator pumped by high-power Tm:YLF laser with orthogonal cylindrical lenses spot shaping

A hundred-watt, linearly-polarized Ho:YAG oscillator, pumped by a 200 W, home-made and s-polarized Tm:YLF laser, was demonstrated. By utilizing a combination of a half-wave plate (HWP) and a thin-film polarizer (TFP), the Tm:YLF laser was split into two orthogonally polarized parts. Each part was significantly reshaped by a system of orthogonally arranged cylindrical lenses and subsequently used to dual-end pump the oscillator. With a total incident pump power of 183 W, a continuous wave (CW) output power of 101 W at 2.1 μm was achieved, with corresponding slope efficiency and optical-to-optical conversion efficiency (OOCE) of 61.6 % and 55.2 %, respectively. Additionally, the beam quality factors, measured in the x and y directions, were 1.59 and 1.35, respectively. Finally, under Q-switched operation at a repetition rate of 20 kHz, a maximum output power of 97 W was achieved, with a corresponding pulse width of less than 34 ns. The central wavelength of the laser was measured to be 2090.2 nm.