Length Of Lens Research Articles

System of N Thin Coaxial Lenses

In geometrical optics, in a system of two thin coaxial lenses, there are several standard formulas, including “𝟏𝑭=𝟏𝒇𝟏+𝟏𝒇𝟐−𝒅𝒇𝟏𝒇𝟐”. The purpose of this paper is to generalize these formulas to the case of a system of an arbitrary number of thin lenses. In particular, this paper proves that the focal length Fn of a system of n thin coaxial lenses is given by 𝟏𝑭𝒏=Σ{(−𝟏)𝒎Π[(Σ𝟏𝒇𝒓𝒔𝒂𝒔𝒓𝒔=𝒂𝒔−𝟏+𝟏 𝟎=𝒂𝟎<𝒂𝟏<⋯<𝑎𝒎<𝒂𝒎+𝟏=𝒏;𝒅𝒏=𝟏 )𝒅𝒂𝒔]𝒎+𝟏𝒔=𝟏}𝒏−𝟏𝒎=𝟎, where, fr is the focal length of the rth lens, and dr is the distance between the rth lens and (r+1)th lens. For a fixed value of m, all combinations of values of the a’s (satisfying the condition “0 = a0 < a1 < … < am < am+1 = n”) are taken in the inner sum.

Electrode length effects on the performance of the electrostatic quadrupole triplet lens

The present work aims to better understand the relationship between the electrode length of the electrostatic quadrupole triplet lens (EQTL) and its optical properties, as well as the possibility of increasing efficiency by selecting the electrode length that produces the best results, as this topic has not been discussed in previous studies. The effects of electrode length on the performance of the quadrupole triplet lens (QTL) were studied. The quadrupole triplet lens (QTL) electrode voltage combinations were found to produce the stigmatic image, and the effects of electrode length on the image’s characteristics were examined. Two lenses with electrode lengths L of 80 mm and 90 mm were designed, and the comparisons were made to show the effects on the electrode voltages, electron beam trajectories, and aberration figures. The findings indicated that a 12.5% increase in electrode length resulted in a 60% increase in aberration figures for Δy in point object-to-point image focusing mode and an 80% increase for Δz in parallel object-to-point image focusing mode.

Calculating the focal length of a concave mirror computerically using mathematical algorithms using MATLAB

This study proposes the use of digital image processing technology to determine the focal lengths of simple concave mirror , as well as spherical mirrors. This method is simpler, faster to implement, and more accurate in calculating the focal length by taking several pictures at different distances for the image formed by the lens, then calculating the least point spread function for these pictures at that distance to determine the best image. In this work Image No. (7) represents the image that carries the least (psf) that was determined by algorithms and special mathematical equations through the (Matlab) program, then the focal length is calculated by employing algorithms and mathematical equations specific to calculating the focal length. A comparison was made with the traditional method by taking measurements of a group of students at the Optics laboratory of University of Wasit, College of Science (which depends on view to choose the best image). This method has proven to be superior in measuring the focal length of lenses. A statistical analysis was conducted for these measurements for the group of students and it was found that there was differences measurements with an error rate, which confirms the feasibility of this method in terms of measurement accuracy and time saving. Experimental results have confirmed this.

Adaptive contour-tracking to aid wide-field swept-source optical coherence tomography imaging of large objects with uneven surface topology.

High-speed and wide-field optical coherence tomography (OCT) imaging is increasingly essential for clinical applications yet faces challenges due to its inherent sensitivity roll-off and limited depth of focus, particularly when imaging samples with significant variations in surface contour. Here, we propose one innovative solution of adaptive contour tracking and scanning methods to address these challenges. The strategy integrates an electrically tunable lens and adjustable optical delay line control with real-time surface contour information, enabling dynamic optimization of imaging protocols. It rapidly pre-scans the sample surface to acquire a comprehensive contour map. Using this map, it generates a tailored scanning protocol by partitioning the entire system ranging distance into depth-resolved segments determined by the optical Raleigh length of the objective lens, ensuring optimal imaging at each segment. Employing short-range imaging mode along the sample contour minimizes data storage and post-processing requirements, while adaptive adjustment of focal length and reference optical delay line maintains high imaging quality throughout. Experimental demonstrations show the effectiveness of the adaptive contour tracking OCT in maintaining high contrast and signal-to-noise ratio across the entire field of view, even in samples with significantly uneven surface curvatures. Notably, this approach achieves these results with reduced data volume compared to traditional OCT methods. This advancement holds promise for enhancing OCT imaging in clinical settings, particularly in applications requiring rapid, wide-field imaging of tissue structures and blood flow.

Fabrication of liquid-filled zoom compound eyes with a tunable focal length

The conventional bionic compound eye system encounters challenges associated with a complex zoom structure, susceptibility to wear, and elevated costs. In this paper, a preparation method of liquid-filled zoom compound eyes is proposed. A polydimethylsiloxane (PDMS) film is integrated with a microfluidic chamber composed of polymethyl methacrylate (PMMA). The microlens array (MLA, hexagonal array, diameter 800 µm, center distance 850 µm) on the PDMS film is prepared by a wettability-guided dipping method. The sub-eye focal length on zoom compound eyes (ZCEs) is 1.42 mm. By controlling the volume of deionized (DI) water injected into the chamber from 2.41 to 2.71cm3, the focal length of the main lens is adjusted from infinity to 55.51 mm, and the FOV is adjusted from 32° to 58°. This large aperture ZCE combines the advantages of monocular and compound eyes. This method has great potential for advanced micro-optical devices with a wide field of view and tunable imaging capabilities.

Analysis of the zoom system of a microscope condenser and its modification using variable focus lenses

A detailed theoretical analysis and optimization of the classical three-element zoom (pancratic) microscope condenser according to a patent from the 1930s [Reichspatentamt Nr. 713188 (29 10 1936)] is performed and formulas are derived for calculating basic parameters and the displacement of lenses during zooming. Furthermore, the modification of the classical zoom microscope condenser is investigated using a simpler optical system of two lenses with variable focal lengths and fixed positions. The relations for the calculation of the focal lengths of both variable focus lenses and the basic parameters of the zoom system have been described. The proposed two-element zoom system consisting of a system of two lenses with variable focal lengths maintains a constant distance between the object and image planes and fixed position of both lenses during zooming. The basic parameters and third-order aberration coefficients of such a system are calculated using an example.

Focal length measurement based on vortex beam interference

This paper proposes a new method to measure the focal lengths of both convex and concave lenses based on vortex beam interference. Theoretical analysis illustrates that the maximum intensity distribution of the interferogram is in accordance with the Fermat's spiral, and the spiral coefficient is proportional to the difference between the focal length of the test lens and the distance from the test lens to the camera. In order to calculate the precise focal length, we separately block the light paths to obtain the reference and test beam spots, and get the ratio of these two spot sizes. Then, the ratio and the spiral coefficient are used to determine the focal length. For a biconvex lens with a focal length of 200 mm and a biconcave lens with a focal length of −100 mm, the relative measurement errors are 0.0892 % and 0.0800 %, respectively. This research provides a novel and convenient method for measuring the focal length, and no-sophisticated displacement devices and moving the lens to be measured are required in the measurement.

Ocular biometry in rabbits using computed tomography.

To describe a repeatable method of measuring ocular structures and to establish ocular biometry reference ranges in adult domestic rabbits (Oryctolagus cuniculus) without medical history or imaging findings consistent with ophthalmic disease using a 64-slice multidetector computed tomography scanner. In this retrospective and observational anatomic study, 100 eyes from 50 rabbits without medical history or imaging findings consistent with ophthalmic disease who received a head computed tomography scan were selected for measurement of globe length, width, and height using 3D multiplanar reconstruction. Lens width and length, the anteroposterior length of the anterior and vitreous chambers, and attenuation of the lens and vitreous chamber were collected. These parameters were compared against age, sex, weight, body condition, and ear conformation. A reference guide was established, with globe width being the largest dimension (18.03 ± 0.81 mm), followed by height (17.18 ± 0.69 mm) and then length (16.64 ± 0.66 mm). Increased weight was associated with an increase in globe height (p = 2.43 × 10-5 ), length (p = 1.63 × 10-4 ), and width (p = 7.0 × 10-3 ). Increased age was associated with increased lens attenuation (p = 1.28 × 10-7 ) and increased transverse lens width (p = 1.64 × 10-3 ). Inter- and intra-observer agreement was excellent. CT is a reliable modality for measurement of ocular biometry dimensions in rabbits. These reference values can be applied to aid in identifying diseases that affect the dimensions of the ocular structures in rabbits over 18 months of age.

A 6-DOF camera motion correction method using IMU sensors for photogrammetry and optical measurements

Environmental conditions such as wind and ground traffic introduce motion in camera measurement systems and affect measurement accuracy. Conventional camera motion correction methods track static reference points with one or multiple cameras, reducing applicability. This study proposes a novel 6-degree-of-freedom (DOF) camera motion correction method using only an inertial measurement unit (IMU) sensor. A Kalman filter is adopted as a data fusion method to estimate the camera orientation and translation using IMU data. Six pinhole camera models are built to evaluate and correct 6-DOF camera motions. The motion correction efficiency and robustness are tested for different object distances and focal lengths of optical lenses. The motion correction ratio is statistically analysed and reaches approximately 80%. The object distance has little effect on the motion correction ratio. The rotation-induced pixel movement is independent of the object distance. More than 90% of the pixel movement noise is caused by camera rotation. The translation-induced pixel movement is inversely correlated with the object distance.

Perbandingan Lama Adaptasi Lensa Bifokal Dan Progressive Addition Lens (Pals) Terhadap Kenyamanan Pasien Di Optik Kota Padang

This paper discusses the comparison of the length of adaptation bifocal lenses and Progressive Addition Lenses (PALs) to patient comfort in optics Pariaman City. This study aims to reveal: (1) The effect of the use bifocal lenses and PALs on patient comfort in the optics Pariaman City, (2) The process of adaptating bifocal lenses and PALs to the comfort of activities patients in optics Pariaman City. The type of research used is a quantitative descriptive approach. The population in this study were presby Contents lists available at Journal ARO YLPTK Padang Journal of Optometry, Health and Education Research ISSN: XXXX-XXXX (Print)ISSN: XXXX-XXXX(Electronic) Journal homepage: https://jurnal-aropadang.org/index.php/jophr/index opia patients who used bifocal lens glasses and PALs. Sampling using the Slovin formula. Data were collected through questionnaires and research instruments using a check list. The results of the research of respondents in the optics Pariaman City were 53 respondents including 18 respondents who wore bifocal lenses and 35 respondents who wore PALs. Respondents who felt the effect of using bifocal lenses and PALs in the optics of Kota Pariaman were 0 respondents (0%) and those who did not feel the effect of using bifocal lenses were 18 respondents (100%) and PALs were 35 respondents (100%). While the respondents who felt the process of adapting the use of bifocal lenses in the optics Pariaman City were 18 respondents (100%) and PALs were 35 respondents (100%) and 0 respondents (0%) did not feel the process of adaptation to the use of bifocal lenses and PALs. Based on the results of this study, there are several suggestions, namely: (1) It is recommended for researchers and RO to learn more material about lenses and lens adaptation process, (2) It is hoped the academy will add books reference sources about lenses and lens adaptation processes, (3) It is hoped that the public will ask the RO for education about lenses and lens adaptation before buying glasses.

Dynamic thermal analysis of pulsed blue diode pumped Ti:Sapphire amplifiers

We simulated the time-dependent temperature profiles inside a blue diode pumped Ti:Sapphire (Ti:Sa) laser amplifier for several different pulsed pump configurations using a discrete element method, including temperature-dependent thermal conductivity and specific heat capacity of Ti:Sa crystals. Furthermore, we calculated the resulting focal length of the thermal lenses using the optical path differences through the crystal.

382 mW External-Cavity Frequency Doubling 461 nm Laser Based on Quasi-Phase Matching

To rapidly improve strontium optical clocks, a high-power, high-efficiency, and high-beam-quality 461 nm laser is required. In blue lasers based on periodically poled KTiOPO4 crystals, the optical absorption in the crystals can induce thermal effects, which must be considered in the design of high-efficiency external-cavity frequency doubling lasers. The interdependence between the absorption and the thermally induced quasi-phase mismatch was taken into account for the solution to the coupled wave equations. By incorporating multilayer crystal approximation, a theoretical model was developed to accurately determine the absorption of the frequency doubling laser. Based on experimental parameters, the temperature gradient in the crystal, the influence of the boundary temperature on the conversion efficiency, and the focal length of the thermal lens were simulated. Theoretical calculations were employed to optimize the parameters of the external-cavity frequency doubling experiment. In the experiment, in a bow-tie external cavity was demonstrated by pumping a 10 mm long periodically poled KTiOPO4 crystal with a 922 nm laser, a 461 nm laser with a maximum output power of 382 mW. The conversion efficiency of the incident fundamental laser was 66.2%. The M2 factor of the frequency doubling beam was approximately 1.4.

Optical Simulation Design of a Short Lens Length with a Curved Image Plane and Relative Illumination Analysis.

This study proposes a three-lens design with a short lens length and explores the curved imaging plane and performs a relative illumination analysis. There are two ways to reduce the lens length: shortening the back focal and lens group lengths. We derived the relevant parameter relationships of three lenses using the first-order geometric optics theory. The optical lens length can be controlled within 2 mm. The shorter the lens length, the larger the angle of the chief ray in the image space, resulting in an increase in the field curvature and astigmatism. Third-order Seidel aberrations can be effectively reduced by a curved image plane. We also derived the equations for relative illuminance, solid angle, surface transmittance, and internal transmittance for the short three-lens design. The optical lens design uses a curved image plane to shorten the distance from the off-axis beam image space to the image plane and reduce the incident angle of the chief ray on the image plane. The formula and design results verified by Code V software (version 11.2) show that both the solid angle and relative contrast of the lens can be increased. For the proposed three-lens design with a short lens length, the semi-field angle is 32°, F/# is 2.7, the effective focal length is 1.984 mm, the image plane area is 2.16 mm × 1.22 mm, and the curvature radius of the concave image plane is 3.726 mm. Moroever, the MTF (100 lp/mm) is larger than 52%, the lateral color aberration is less than 2.12 μm, the optical distortion is less than 2.00%, and the relative illumination is greater than 68%.

Effect of the Outer Pole Length on the Optical Properties in Gemini Lens

In order to get some of the most important optical and geometrical properties of scanning electron microscope lens, Such as focal length, lens aberration (spherical and chromatic aberration), Axial magnetic field distribution, trajectory of the electron beam, diameter of the electron probe in this work. A computer programs used to achieve the results in objective lens which called Gemini lens.by changing the outer pole length of lens to get a better optical property. The results under constant lens excitation (NI=1000 A-t) and accelerating voltage (Vr=8 KV) are (f=3.93mm, Cs=2.59mm, Cc=2.87mm) and the magnetic field distribution Bz =1.72 tesla

Smartphone photography based determination of refractive index of liquid

A simple but useful method is presented to measure the refractive index of a liquid using the smartphone camera. We have measured the image lengths by utilizing the ImageMeter application (free online) and determine the refractive index directly. We mention some striking points based upon which this simple method can be considered robust and novel: (i) no extra device other than the smartphone is required; (ii) there is no need to know the focal length of the camera lens of the smartphone; (iii) instead of finding the size of the object, only the image sizes of the object in different conditions are to be measured in pixel units to determine the refractive index of the liquid.

Exploring the Femtosecond Filamentation Threshold in Liquid Media Using a Mach-Zehnder Interferometer.

We experimentally studied the supercontinuum induced by femtosecond filamentation in different liquid media. Using a Mach-Zehnder interferometer, we determined the relative filamentation thresholds (Pth) of these media. Research has shown that the value of the filamentation threshold is greater than that of Pcr (critical power for self-focusing), which can mainly be attributed to the strong dispersion effect. Changing the focal length of the focusing lens affects filamentation dynamics, thereby affecting the measured results regarding the filamentation threshold. With shorter focal lengths, the linear focusing (i.e., geometrical focusing) regime dominates, and the measured values of Pth for different liquid media are almost the same; as the focal length becomes larger, self-focusing starts to play a role, making the values of Pth for different media different from each other. This study presents an efficient method for investigating the femtosecond filamentation phenomenon in liquid media, helpful to provide further insights into the physical mechanism of supercontinuum generation via femtosecond filamentation in liquid media.

Broadband ultrafast ultraviolet laser output by using β-BaB2O4 crystal

In this paper, a broadband ultrafast ultraviolet (UV) laser was generated through sum-frequency method with β-BaB2O4 (BBO) crystal by using a femtosecond (fs) Ti:sapphire laser as the fundamental laser source. We studied the influence of the power ratio between the fundamental frequency and second harmonic laser beams on output power and conversion efficiency of UV laser. The time delay method was used to change the optical path difference in the sum-frequency generation (SFG). At the same time, the cutting angle of the crystal was optimized and the effect of different focal lengths of lenses on the experimental results was studied. Finally, we obtained a tunable UV laser beam with a tuning range from 226.7 nm to 360 nm generated by the BBO crystal. The laser had high conversion efficiency, and the maximum output power was 540 mW at 270 nm.

A Bidirectionally Focus-Tunable Optofluidic Microlens With Miniature Thermoelectric Coolers

The design and fabrication of a novel bidirectionally optofluidic tunable microlens actuated by thermoelectric coolers (TECs) are reported. A high-resolution three-dimensional printing technology is adopted to fabricate the truly three-dimensional structure of an optofluidic chip. Owing to the bidirectional thermal property of the TECs, both upward and downward membrane profiles are available under the control of a programmable direct-current power supply. The focal length of the liquid lens decreases from 25 to 5mm as the voltage is increased from 0.2 to 1.1V whereas the focal length changes from -25 to -5mm as the current is applied in the opposite direction. A finite element simulation with COMSOL software is conducted to assess the temperature distribution on the device. The response functions of the TECs are investigated for the heating and cooling processes, and the imaging properties are characterized.

Corneal parameters, ocular biometers, and retinal and choroidal thickness in acromegaly patients

BackgroundTo compare ocular findings of acromegaly patients with healthy individuals and investigate the relation of serum levels of insulin-like growth factor (IGF-1) along with growth hormone (GH) and pituitary tumor (adenoma) dimensions (TD) with specific ocular parameters. MethodsThe ocular parameters of acromegaly patients (n = 38) were compared with those of healthy subjects (n = 36). These parameters were intraocular pressure, keratometric (K1–K2) values, central corneal thickness (CCT), total axial length along with anterior chamber-lens-vitreous length, retinal nerve fiber layer (RNFL) thickness, central foveal thickness (CFT), choroidal thickness (CT), ganglion cell layer thickness (GCLT), and inner plexiform layer thickness (IPLT). Also investigated was whether there was a correlation between disease duration, TD, GH, IGF-I, CCT, RNFL, CFT, GCLT, IPLT, and CT. ResultsThe lens length of the acromegaly group was increased (p = 0.014). GH and IGF-1 levels were positively correlated with CT and CCT, respectively (p = 0.041, r = 0.343) (p = 0.03, r = 0.347). Analysis of TD also found a highly negative correlation with the mean RNFL thickness of the acromegaly patients (p < 0.01, r = -0.603). The mean value of the inner parts of GCLT and IPLT was negatively correlated with TD (p = 0.041, r = -0.343 and p = 0.025, r = -0.379, respectively). ConclusionSerum IGF-1 and GH levels might be determinant factors in CCT and CT, respectively. The pituitary adenoma size increasing may be prone to lead RNFL, ganglion cell layer, inner plexiform layer thinning. Increased lens thickness was found in the acromegaly group.

Numerical investigations of influence on thermal conductive heating in DNAPL-impacted soils by heterogeneity

The treatment of dense non-aqueous phase liquid (DNAPL) source zones is challenging, particularly in heterogeneous media. Thermal conductive heating (TCH) has the potential to treat DNAPL source zones for its ability to enhance mass transfer. This study uses numerical modeling combined with Monte Carlo simulation to examine the influence of heterogeneity of the permeability field on the DNAPL distribution and TCH remediation. It is found that the longer horizontal correlation length of high-permeable clay lens would contribute to accelerate multiphase convection and then heat conduction in horizontal direction. The presence of DNAPL (both in NAPL phase and dissolved), pressure, and permeability are all contributory factors to phase change. Realizations with shorter horizontal correlation lengths always have a larger vertical spreading of DNAPL. As a shallow vapor extraction well was applied in this study, higher TCE removal rate can be obtained in the realizations with a shorter horizontal correlation length when NAPL phase of TCE is existed in the domain.