Zoom Lens System Research Articles

A qualitative validation of an in-situ monitoring system for EHD inkjet printing via laser diffraction

Electrohydrodynamic inkjet printing enables high-resolution patterning for nano features. In-flight dynamics of EHD inkjet printing play an essential role in the quality control of printing results. We applied a laser diffraction/scattering in-situ analyzing setup for the EHD inkjet printing system to replace the zoom lens and high-speed camera imaging system. In contrast to conventional imaging systems, the laser diffraction/scattering system is based on analyzing the diffraction pattern and scattering intensity, respectively, which provided higher resolution for micro-scale jetting measurement and enabled sub-micron level jetting correlation between the voltage applied to the electrode and printing results. Furthermore, Taylor cone information from the nozzle head could also be analyzed in real-time to make adjustments to the printing process. In this work, we successfully validated the feasibility of laser diffraction analysis in-situ monitoring for EHD inkjet printing at micron and sub-micron levels.

Intraoperative zoom lens calibration for high magnification surgical microscope

Background and objectivesAn augmented reality (AR)-based surgical guidance system is often used with high-magnification zoom lens systems such as a surgical microscope, particularly in neurology or otolaryngology. To superimpose the internal structures of relevant organs on the microscopy image, an accurate calibration process to obtain the camera intrinsic and hand–eye parameters of the microscope is essential. However, conventional calibration methods are unsuitable for surgical microscopes because of their narrow depth of focus at high magnifications. To realize AR-based surgical guidance with a high-magnification surgical microscope, we herein propose a new calibration method that is applicable to the highest magnification levels as well as low magnifications. MethodsThe key idea of the proposed method is to find the relationship between the focal length and the hand–eye parameters, which remains constant regardless of the magnification level. Based on this, even if the magnification changes arbitrarily during surgery, the intrinsic and hand–eye parameters are recalculated quickly and accurately with one or two pictures of the pattern. We also developed a dedicated calibration tool with a prism to take focused pattern images without interfering with the surgery. ResultsThe proposed calibration method ensured an AR error of < 1 mm for all magnification levels. In addition, the variation of focal length was within 1% regardless of the magnification level, and the corresponding variation with the conventional calibration method exceeded 20% at high magnification levels. ConclusionsThe comparative study showed that the proposed method has outstanding accuracy and reproducibility for a high-magnification surgical microscope. The proposed calibration method is applicable to various endoscope or microscope systems with zoom lens.

Tunable metalensing based on plasmonic resonators embedded on thermosresponsive hydrogel.

Metalenses of adjustable power and ultrathin flat zoom lens system have emerged as a promising and key photonic device for integrated optics and advanced reconfigurable optical systems. Nevertheless, realizing an active metasurface retaining lensing functionality in the visible frequency regime has not been fully explored to design reconfigurable optical devices. Here, we present a focal tunable metalens and intensity tunable metalens in the visible frequency regime through the control of the hydrophilic and hydrophobic behavior of freestanding thermoresponsive hydrogel. The metasurface is comprised of plasmonic resonators embedded on the top of hydrogel which serves as dynamically reconfigurable metalens. It is shown that the focal length can be continuously tuned by adjusting the phase transition of hydrogel, the results reveal that the device is diffraction limited in different states of hydrogel. In addition, the versatility of hydrogel-based metasurfaces is further explored to design intensity tunable metalens, that can dynamically tailor the transmission intensity and confined it into the same focal spot under different states, i.e., swollen and collapsed. It is anticipated that the non-toxicity and biocompatibility make the hydrogel-based active metasurfaces suitable for active plasmonic devices with ubiquitous roles in biomedical imaging, sensing, and encryption systems.

Paraxial design of four-component zoom lens system with fixed distance between focal points by matrix optics

In this paper, we propose a systematic approach to design a four-component zoom system with fixed spacing between focal points based on matrix optics to achieve a relatively high zoom ratio. In the method, the zoom trajectory under each chosen paraxial design is determined through matrix method, which is challenging but meaningful to achieve a globally optimized design for the complex zoom system. The elements of the system matrix imply the working state of the optical system, and axial displacement equation for the desired zoom system are derived by restricting specific matrix elements. Properly selected trajectory of the particular component described by means of a parametric function can make the model become solvable explicitly. Then the paraxial design problem is transformed into the optimization of these parameters with regard to the merit functions encompassing the primary aberration terms, compactness, smoothness of the trajectories. We adopt Particle Swarm Optimization (PSO) algorithm to globally optimize the parameters to retrieve the optimum zoom trajectory in specific design criteria. The proposed method is demonstrated through two specific examples under different configurations, both of which have acquired a final zoom ratio of 8X. The simulation results demonstrate that our proposed method can be a practical and powerful tool for paraxial design of complex multi-group zoom optical systems.

High-precision Sr and Nd isotope measurements using a dynamic zoom lens-equipped thermal ionisation mass spectrometer

Techniques for the determination of radiogenic strontium (87Sr/86Sr) and neodymium (143Nd/144Nd) isotope ratios by Thermal Ionisation Mass Spectrometry (TIMS) are presented in this study. We have developed a 5 lines acquisition routine for both elements, taking advantage of the 16 Faraday cups available on the Nu Instruments TIMS in conjunction with an efficient zoom lens system. This allows increased flexibility regarding the number of lines in a multidynamic acquisition routine whilst maintaining optimal peak alignment and peak shape for every measurement line despite the fact that the detectors are not movable. The long-term reproducibility obtained for our Sr (NBS 987) and Nd (Rennes-Ames) standard solutions gives a (87Sr/86Sr)multidyn of 0.7102467 ± 0.0000043 (6.0 ppm, 2 s.d., n = 38) and a (143Nd/144Nd)multidyn of 0.5119537 ± 0.0000022 (4.2 ppm, 2 s.d., n = 31), respectively. We also report (87Sr/86Sr)multidyn and (143Nd/144Nd)multidyn for a set of terrestrial rock standards (including 5 basalts (BCR-2, BHVO-2, BIR-1, Be-N and BR-24), one rhyolite (RGM-1) and one andesite (AGV-2)) with the same, or greater, level of precision as for the pure standards solutions. This level of precision is 2 to 3 times better than the literature data for Sr isotope ratios, and comparable to the latest high precision data reported for Nd isotope ratios. This is the first paper reporting such high precisions for radiogenic Sr and Nd data generated using a TIMS from Nu Instruments. Significant statementHigh precision Sr and Nd isotopic measurements are of key importance in the field of Earth Sciences because they are powerful tools to trace sources of materials and to date them. Here, we report the first high-precision data for 87Sr/86Sr and 143Nd/144Nd (external error of 5–6 ppm for Sr and 4–5 ppm for Nd) measured using a Nu Instruments TIMS. Such precisions will open new opportunities in fields such as geochemistry, geochronology, cosmochemistry, archaeology or forensics.

Design of IR zoom lens system for long-range detection in uncooled LWIR camera

A new compact optical zoom lens system with variable focal length 100–200 mm for uncooled LWIR (8–12 μm) camera is designed. It is used for long-range detection. The optimized IR zoom lens consists of four group elements. The F/# of the zoom system is F/1.4 at all zoom positions. Its performance reaches the diffraction limit at each focal length position. Moreover, optical design and image quality are calculated by ZEMAX optical software. The imaging quality performance is steady during zoom process. In addition to the above benefits, the optimized IR zoom lens is light and compact (200 mm) with 4 lenses and only one of them has diffractive surface to lower production cost. Upon applying anti-reflection coating, the total transmittance of the optical system is enhanced from 2 to 99% at λ = 10 µm.

多组元全动型大孔径及超大视场变焦系统设计

多组元全动型大孔径及超大视场变焦系统设计

Computation of Analytical Zoom Locus Using Padé Approximation

When the number of lens groups is large, the zoom locus becomes complicated and thus cannot be determined by analytical means. By the conventional calculation method, it is possible to calculate the zoom locus only when a specific lens group is fixed or the number of lens groups is small. To solve this problem, we employed the Padé approximation to find the locus of each group of zoom lenses as an analytic form of a rational function consisting of the ratio of polynomials, programmed in MATLAB. The Padé approximation is obtained from the initial data of the locus of each lens group. Subsequently, we verify that the obtained locus of lens groups satisfies the effective focal length (EFL) and the back focal length (BFL). Afterwards, the Padé approximation was applied again to confirm that the error of BFL is within the depth of focus for all zoom positions. In this way, the zoom locus for each lens group of the optical system with many moving lens groups was obtained as an analytical rational function. The practicality of this method was verified by application to a complicated zoom lens system with five or more lens groups using preset patents.

变焦鱼眼镜头系统设计

The zoom fish-eye lens had the characteristics of much larger field-of-view angle, much larger relative aperture, and much larger anti-far ratio. In the work described in this paper, the initial structure of a fish-eye lens with fixed focal length was firstly designed using the theory of a plane symmetric optical system. And then the initial structure components of the fish-eye lens were divided into two groups, the former-group and the rear-group, and then the entire zoom fish-eye lens system was optimized using Gaussian optical theory. Finally, a zoom fish-eye lens system with good imaging quality was obtained. This fish-eye lens system had a field-of-view angle of 180° with an 8 mm short focal length and a field-of-view angle of 90° with a 16 mm long focal length. Its relative aperture was 1/3.5. The design results show that the modulation transfer function of this zoom lens system at different focal lengths is no less than 0.45 when the spatial frequency is 50 lp/mm. This zoom fish-eye photographic objective lens had higher imaging quality than other zoom fish-eye lenses.

Globally optimal first-order design of zoom systems with fixed foci as well as high zoom ratio.

In this paper, we propose a systematic approach to automatically retrieve the first-order designs of three-component zoom systems with fixed spacing between focal points based on Particle Swarm Optimization (PSO) algorithm. In this method, equations are derived for the first-order design of a three-component zoom lens system in the framework of geometrical optics to decide its basic optical parameters. To realize the design, we construct the mathematical model of the special zoom system with two fixed foci based on Gaussian reduction. In the optimization phase, we introduce a new merit function as a performance metric to optimize the first-order design, considering maximum zoom ratio, total optical length and aberration term. The optimization is performed by iteratively improving a candidate solution under the specific merit function in the multi-dimensional parametric space. The proposed method is demonstrated through several examples, which cover almost all the common application scenarios. The results show that this method is a practical and powerful tool for automatically retrieving the optimal first-order design for complex optical systems.

Thin lens aberrations for anamorphic lenses.

This paper provided thin lens aberrations for anamorphic lenses, including the central thin lens aberrations, the central Lagrange invariant shift, the central conjugate shift, and the central pupil shift. Based on thin lens theory and the paraxial lens module, the aberration of the anamorphic lens system can be easily corrected. The central Lagrange invariant shift can be used for aberration correction for an anamorphic zoom lens system. In order to make a concise expression for the central conjugate shift, eight aberration coefficients are introduced: D¯3x, D¯5x, D¯6x, D¯10x, D¯11y, D¯12x, D¯15x, and D¯16y. Similarly, four aberration coefficients are introduced for the central pupil shift: D11x, D¯11x, D16x, and D¯16x. A simulation is conducted that proves numerically the validity of the thin lens aberrations for an anamorphic lens system.

Displaceable and focus-tunable electrowetting optofluidic lens.

A conventional optofluidic lens usually has one liquid-liquid (L-L) interface, which can be deformed to achieve variable focal length. Such a single lens cannot be used alone to realize optical zooming because its back focal distance keeps changing. Here, we report a novel displaceable and focus-tunable electrowetting optofluidic lens. In comparison with the conventional optofluidic lens, our new lens has a different working principle and it can function as an optical zoom lens. The L-L interface can be displaced by a voltage. The object distance and image distance can be adjusted by shifting the L-L interface position to achieve the desired magnification, yet the lens can refocus the image by reshaping the L-L interface with another voltage. Under such condition, only one lens is adequate to realize the zooming functionality. To prove the concept, we fabricate an optofluidic lens whose largest displaceable distance is ~8.3 mm and the zooming ratio is ~1.31 ×. The proposed optofluidic lens greatly simplifies the zoom lens system. Widespread application of such an adaptive zoom lens is foreseeable.

Programmable Zoom Lens System with Two Spatial Light Modulators: Limits Imposed by the Spatial Resolution

In this work we present an experimental proof of concept of a programmable optical zoom lens system with no moving parts that can form images with both positive and negative magnifications. Our system uses two programmable liquid crystal spatial light modulators to form the lenses composing the zoom system. The results included show that images can be formed with both positive and negative magnifications. Experimental results match the theory. We discuss the size limitations of this system caused by the limited spatial resolution and discuss how newer devices would shrink the size of the system.

Design and analysis of an 8x four-group zoom system using focus tunable lenses.

We present an 8x four-group zoom lens system for a compact camera without any moving groups by employing a focus tunable lens (FTL). We locate the FTLs at the second and fourth groups as a variator and a compensator. In the initial design stage, paraxial analysis for the zoom position was numerically determined by examining the solutions for various first group and third group powers, to achieve a physically meaningful and compact zoom system at a zoom ratio of 8x. The designed zoom lens has focal lengths of 4-31 mm and the apertures of F/3.5 to F/4.5 at wide and tele positions, respectively.

Method of first-order analysis of a three-element two-conjugate zoom lens

A method is described for the first-order analysis of a two-conjugate zoom lens composed of three movable elements. Such an optical system satisfies the requirement that the object, image, and pupil planes are fixed within the change of its magnification. General formulas are derived for the calculation of parameters of a three-component two-conjugate zoom lens system, which enable us to calculate the optical power of individual optical elements and their distances for a different range of magnification and imposed conditions. The application of derived formulas is presented on three examples of optical systems with different parameters.

Nonmechanical zoom lens based on the Pancharatnam phase effect.

We present a nonmechanical zoom lens system based on the Pancharatnam phase effect, which is controlled by the state of circularly polarized light. The device is shown to allow for a compact design for a wide range of zoom ratios. A demonstration system is shown, which has a 4× zoom ratio between its two electrically switchable states. We show its observed image quality experimentally and compare it with calculated expectations.

Test and analysis of the dynamic procedure for electrowetting-based liquid lens under alternating current voltage

An experimental setup used to measure the important optical properties of electrowetting liquid lens is proposed. The simple and precise method of measuring dynamic responses and focal lengths of liquid lens under different excitation signals is based on Gaussian beam transmission theory. The measurement method can be widely used in all kinds of zoom lens systems. The device is simple and economical, and also has the advantages of convenient operation, high measurement precision and wide range measurement. This work provides a new way to study the dynamic response of electrowetting liquid lens and the the mechanism of electrowetting liquid lens. The fabrication process and some relevant noticeable points for the homemade liquid lens are introduced. The testing device of dynamic process of lens consists of a He-Ne laser, an electrowetting lens, a circular diaphragm, a phototube, a digital storage oscilloscope and a computer. The change of the focal length of liquid lens due to the applied voltage will affect the flux detected by the photoelectric receivers. It is proved according to Gaussian beam transmission theory that the light flux received by the phototube changes with time, which represents the relationship between the focal length and time and the dynamic characteristics of the liquid lens. Therefore, the intensity of output signal of photoelectric receiver reflects the focal length of liquid lens. A dynamic changing process of the focal length of a self-regulating varifocal liquid lens based on electrowetting technology is tested under alternating current signal. It shows that the focal length of the liquid lens changes with the corresponding amplitude and polarity of the sine voltage. In one cycle, 4 peak signals of 50 Hz appear in turn, and the peak amplitude increases with the increase of voltage. Peaks 1 and 2 are caused by the voltage polarity, while peaks 3 and 4 by the oscillation modes. This is due to the fact that the liquid surface changes with time in the spherical shape under low voltage, but it will generate new oscillation mode when the amplitude is high.

Optical Design and Fabrication of a Large Telephoto Zoom Lens with Fixed f/2.8 and Light Autofocus Lens

Compact system cameras (CSCs) are commonly used nowadays and feature enhanced video functions and thin yet light interchangeable lenses. They differ from digital single-lens reflex (DSLR) cameras in their lack of mirror boxes. CSCs, however, have autofocus (AF) speeds lower than those of conventional DSLRs, requiring weight reduction of their AF groups. To ensure the marketability of large telephoto zoom lenses with fixed f/2.8 regardless of field angle variation, in particular, light weight AF groups are essential. In this paper, we introduce a paraxial optical design method and present a new, large, telephoto zoom lens with f/2.8 regardless of the field angle variation, plus a lightweight AF group consisting of only one lens. Using the basic paraxial optical design and optimization methods, we fabricated a new and lighter zoom lens system, including a single-lens, lightweight AF group with almost the same performance.

P‐143: 4‐D Floating Holographic‐Like Image Display

There are various methods in producing 3‐D floating holographic‐like images that are stationary in space. This paper presents a floating holographic‐like image display optical system with a 4th dimension in which as the object moves in space, the image will move at the same time in space at another location based on the configuration of the optical system. A zoom lens system will be described such that the motion of the object is created by the zoom lens system without actual movement of the object resulting a movement of the image as if the object is actually moving. A single panel display system will also be described such that a floating holographic‐like image from a portion of the display will be made floating in front of another portion of the display using the 4‐D optical system folded to provide a thin profile. These systems will be suitable for theme parks, display windows, kiosks, and for security purposes.

连续变焦系统的一阶结构设计方法研究

连续变焦系统的一阶结构设计方法研究