This PDF file contains the front matter associated with SPIE Proceedings Volume 9947, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and Conference Committee listing.

The art of lens design has long been divided into two camps: theorists and number crunchers. Both camps have vocal supporters, both manage to get the job done, and both occasionally voice disdain for the other. This paper presents the case for number crunching—while recognizing the important contributions that theorists have made and continue to make. We illustrate this case by designing a zoom lens with no starting design and minimum direction from the designer. To this end we use a feature called ZSEARCH™ found in the program SYNOPSYS™¹.

A hyperspectral imaging spectrometer covering the wavelength range from 420 nm to 1000 nm is designed for the purpose of monitoring Earth’s environmental change. It has an entrance slit length of 24 μm, f/# of 3, smile and keystone distortion smaller than 20% of the pixel pitch and a spectral resolution of 6.5 nm. We design and review thirteen systems including one Offner system, two Schwarzschild systems and ten TMA systems for such specifications. Freeform surface and aspheric surface are used in some of the systems to achieve the required system parameters. With all system performance being summarized and evaluated, advantages and disadvantages of three different system types are compared. We down select two systems for further fine adjustments and tolerancing analysis. Final systems with superior performance and detailed tolerancing analysis are given at the end.

An achromatic component shares a common focus at two wavelengths and is a commonly used device in optical assemblies. This work explores the cost versus performance tradeoff for several types of achromatic lenses: conventional doublets with homogenous glass elements, hybrid doublets with a diffractive surface, axial GRadient INdex (GRIN) lenses (where the index of refraction changes along the length of the lens), and radial GRIN lenses (where the index of refraction changes depending on radial position). First order achromatic principles will be reviewed and applied to each system as a starting point and refined through the use of ray trace software. Optical performance will be assessed in terms of focusing efficiency and imaging. Cost will then be evaluated by accounting for current manufacturing costs and retail price through several distributors.

The theoretical concept of a perfect thermal radiator, the blackbody, was first introduced by the German physicist Gustav Robert Kirchhoff in 1860. By the latter half of the nineteenth century it had become the object of intense theoretical and experimental investigation. While an attempt at trying to theoretically understand the behavior of radiation emitted from a blackbody was undertaken by many eminent physicists of the day, its solution was not found until 1900 when Max Planck put forward his now famous law for thermal radiation. Today, of course, understanding blackbody behavior is vitally important to many fields including infrared systems, illumination, pyrometry, spectroscopy, astronomy, thermal engineering, cryogenics, and meteorology. Mathematically, the form Planck’s law takes is rather cumbersome meaning calculations made with it before the advent of modern computers were rather tedious, dramatically slowing the process of computation. Fortunately, during those early days of the twentieth century researchers quickly realized Planck’s equation, and the various functions closely related to it, readily lend themselves to being given a graphical, mechanical, or numerically tabulated form for their evaluation. The first of these computational aids to appear were tables. These arose shortly after Planck introduced his equation, were produced in the greatest number, and remained unsurpassed in their level of accuracy compared to all other aids made. It was also not long before nomograms designed to aid thermal radiation calculations appeared. Essentially a printed chart and requiring nothing more than a straightedge to use, nomograms were cheap and extremely easy to use. Facilitating instant answers to a range of quantities relating to thermal radiation, a number were produced and the inventiveness displayed in some was quite remarkable. In this paper we consider the historical development of many of the nomograms and tables developed and used by generations of scientists and engineers before their sudden and irrevocable decline shortly after the arrival of affordable digital computers and hand-held electronic calculators during the mid-1970s. This work represents a continuation of our earlier work on a number of radiation slide rules developed and used for thermal radiation calculations, with all three of these computational aids being the subject of a forthcoming book.

We study the formation of caustic surfaces produced by bi-conic lenses, considering a plane wavefront propagating parallel to the optical axis. We have already seen that the shape of caustic surfaces can represent the monochromatic aberrations that we call image errors, furthermore the shape of the caustic can be modified by changing the parameters of the lens in such a way that if we are able to vanish the caustic, the optical system produces an image without spherical aberration, alternatively caustic surfaces having a large area could be applied to design non-imaging optical systems, such as diffusers of light. The shape of the caustic surface is a function of the indices of refraction involved in the process of refraction, and all the parameters of the bi-conic lens. We provide an analytic equation for the caustic surface in a meridional plane and some examples are presented.

Dual-band and wide-band lenses covering both the MWIR and LWIR spectral bands are increasingly needed as dualband MWIR/LWIR detectors have become prevalent and broadband applications have expanded. Currently in dual-band /wide-band applications, the use of more than three elements per lens group and the use of chalcogenide glass is common. This results in expensive systems. Also, many chalcogenides are available only in small diameters, which is a problem for large aperture broadband lenses. In this paper an investigation of cost-effective designs for dual-band MWIR/LWIR lens using only widely available IR materials, specifically Ge, ZnSe and ZnS were performed. An athermalized dual-band MWIR/LWIR using these three materials is presented. The performance analysis of this lens shows that this design form with these three common IR materials works well in certain applications. The required large size blanks of these materials can be easily obtained. Traditional chromatic aberration correction without diffraction for either wide-band or dual-band application was employed. In addition, the methods of harmonic diffraction for dual-band applications, especially with one narrow band, were used for two different presented designs.

Traditionally, Raman spectroscopy is done in a specialized lab, with considerable requirements in terms of equipment, time and manual sampling of substances of interest. We present the modeling, the design and the fabrication process of a microfluidic device incorporation Raman spectroscopy, from which one enables confocal Raman measurements on-chip. The latter is fabricated using ultra precision diamond tooling and is tested in a proof-of-concept setup, by for example measuring Raman spectra of urea solutions with various concentrations. If one wants to analyze single cells instead of a sample solution, precautions need to be taken. Since Raman scattering is a weak process, the molecular fingerprint of flowing particles would be hard to measure. One method is to stably position the cell under test in the detection area during acquisition of the Raman scattering such that the acquisition time can be increased. Positioning of cells can be done through optical trapping and leads to an enhanced signal-to-noise ratio and thus a more reliable cell identification. Like Raman spectroscopy, optical trapping can also be miniaturized. We present the modeling, design process and fabrication of a mass-manufacturable polymer microfluidic device for dual fiber optical trapping using two counterpropagating singlemode beams. We use a novel fabrication process that consists of a premilling step and ultraprecision diamond tooling for the manufacturing of the molds and double-sided hot embossing for replication, resulting in a robust microfluidic chip for optical trapping. In a proof-of-concept demonstration, we characterize the trapping capabilities of the hot embossed chip.

In the article some methods for processing the information contained in a database are offered with the purpose of extraction of the knowledge, the experience and the intuition of the designers, coded in the database. It gives much attention to the methods for determinating limit potential image quality of optical systems of various complexities.

This paper presents a methodology for designing an athermalised dual field of view zoom lens in long wave infrared (8μm - 12μm) spectral band by using the benefits of paraxial optics. By using this design methodology the optical designer can develop many types of complex optical systems in a straightforward way. The key feature of this design methodology relies on utilization of paraxial optics for defining the initial positions of the optical elements. The optical design is based on moving a single lens for changing the optical system’s FOV thereby reducing the number of moving parts and simplifying the assembly procedure of the system. The optical design begins with optimization process using paraxial optics. Then the optical design using paraxial optics is used as a template for designing the final optical system by lens material selection for compensating the shift in system’s focus due to thermal effects and lens thickness tuning.

In this work, an optical design approach is presented to design an ultrashort throw distance projection system by combination of an off-the-shelf refractive lens and two off-axis freeform mirrors. These two freeform mirrors are used to greatly shorten the projection distance by more than three times compared to conventional (rotationally symmetric) systems, while still maintaining a good imaging quality. Firstly, a direct design method that enables the simultaneous calculation of two off-axis freeform-profile mirrors by partially coupling more than three fields is introduced. The specifications of the conventional refractive lens are taken into account during this procedure. The pupil matching principle is applied to ensure good performance between the two sub-systems. The calculated mirrors then serve as a good starting point for optimization using commercial optical design software. To step from freeform profiles to freeform surfaces, the calculated two profiles are fitted into odd polynomials to evaluate the image quality and then re-fitted into XY polynomials for further optimization. Finally, the polynomial coefficients of the two freeform mirrors are imported into the optical design program. The merit function is built from RMS spot radii over the full field, and additional constraints are made for correcting distortion. After optimization, the calculated initial design quickly converges to a well performing imaging system. As an example, an ultrashort throw distance projection lens with a large 80-inch diagonal image at 400mm throw distance is designed, analyzed and compared with literature data. The values of MTF are over 0.6 at 0.5 lp/mm and the distortion is less than 1.5%: showing a very good and well balanced imaging performance over the entire field of view.

Head-up Display (HUD) is a safety feature for automobile drivers. Although there have been some HUD systems in commercial product already, their images are too small to show assistance information. Another problem, the volume of HUD is too large. We proposed a HUD including micro-projectors, rear-projection screen, microlens array (MLA) and the light source is 28 mm x 14 mm realized a 200 mm x 100 mm image in 3 meters from drivers. We want to use the MLA to reduce the volume by virtual image stitching. We design the HUD’s package dimensions is 12 cm x 12 cm x 9 cm. It is able to show speed, map-navigation and night vision information. We used Liquid Crystal Display (LCD) as our image source due to its brighter image output required and the minimum volume occupancy. The MLA is a multi aperture system. The proposed MLA consists of many optical channels each transmitting a segment of the whole field of view. The design of the system provides the stitching of the partial images, so that we can see the whole virtual image.

The advances in the field of adaptive optics and in the fabrication of tunable optical components capable to automatically modify their physical features are of great interest in areas like machine vision, imaging systems, ophthalmology, etc. Such components like tunable lenses are used to reduce the overall size of optical setups like in small camera systems and even to imitate some biological functions made by the human eye. In this direction, in the last years we have been working in the development and fabrication of PDMS-made tunable lenses and in the design of special mechanical mounting systems to manipulate them. A PDMS-made tunable lens was previously designed by us, following the scheme reported by Navarro et al. in 1985, in order to mimic the accommodation process made by the crystalline lens of the human eye. The design included a simulation of the application of radial stress onto the lens and it was shown that the effective focal length was indeed changed. In this work we show the fabrication process of this particular tunable lens and an optimized mechanism that is able to automatically change the curvature of both surfaces of the lens by the application of controlled stress. We also show results of a study and analysis of aberrations performed to the Solid Elastic Lens (SEL).

In this paper, a new approach to fabricate a liquid crystal (LC) microlens array with spherical-shaped electrode is demonstrated, which can create the inhomogeneous electric field. Inkjet-printing, hydrophilic confinement, self-assemble and replication process is used to form the convex microlens array on glass. After the spherical-shaped electrode is done, we assemble it with ITO glass to form a liquid crystal cell. We used Zemax® to simulate the liquid crystal lens as a Gradient-index (GRIN) lens. The simulation results show that a GRIN lens model can well match with the theoretical focal length of liquid crystal lens. The dimension of the glass is 1.5 cm x 1.5 cm x 0.7 mm which has 7 concave microlens on the top surface. These microlens have same diameter and height about 300 μm and 85 μm. The gap between each other is 100 μm. We first fabricate microlens array on silicon substrate by hydrophilic confinement, which between hydrophilicity of silicon substrate and hydrophobicity of SU-8, and inkjet printing process. Then we start replication process with polydimethylsiloxane (PDMS) to transfer microlens array form silicon to glass substrate. After the transparent conducted polymer, PEDOT:PSS, is spin-coated on the microlens arrays surface, we flatten it by NOA65. Finally we assemble it with ITO glass and inkjet liquid crystal. From measuring the interference rings, the optical power range is from 47.28 to 331 diopter. This will be useful for the optical zoom system or focus-tunable lens applications.

Tunable lenses have become very popular elements due their capacity of change their focal length by only modifying their shape. This characteristic is very useful in different applications in the field of optics. The development of tunable lenses consists on several phases: first, to find a suitable material, second, to obtain an optimal analysis and design, and third, to find the way to change the lens shape and characterization. In this work we present the characterization of a tunable lens, formed by spherical profiled elastic membranes and a liquid medium between them. The proposed liquidfilled tunable has a design such that the spherical aberration is the least to different focus. The development of an optomechanical system to change the lens shape is presented.

A low-cost and fully automated process for phase-shifting interferometry by continuously changing and turning on-off the input voltage of a laser diode under the scheme of an unbalanced Twyman-Green interferometer setup is presented. The input signal of a laser diode is controlled by a Data Acquisition (NI-DAQ) device which permits to change its wavelength according to its tunability features. The automation and data analysis will be done using LabVIEW in combination with MATLAB. By using Carré algorithm the phase map is obtained. Measurements of visibility and phase-shift to verify the PSI requirements are also shown.

This paper describes an integrated stray light model of each Science Instrument (SI) in the Integrated Science Instrument Module (ISIM) of the James Webb Space Telescope (JWST) and the Optical Telescope Element Simulator (OSIM), the light source used to characterize the performance of ISIM in cryogenic-vacuum tests at the Goddard Space Flight Center (GSFC). We present three cases where this stray light model was integral to solving questions that arose during the testing campaign – 1) ghosting and coherent diffraction from hardware surfaces in the Near Infrared Imager and Slitless Spectrograph (NIRISS) GR700XD grism mode, 2) ghost spots in the Near Infrared Camera (NIRCam) GRISM modes, and 3) scattering from knife edges of the NIRCam focal plane array masks.

In a previous work, we described the theoretical fundamentals for the design of radiance meters. There, we observed that the length between the first and the second aperture of the instrument plays an important role in the performance of the meter. Such a length is a parameter related with the instrument response to variations of the size of the source and of the distance between the instrument and the source. Such dependences are not predicted by the theory of geometrical optics, normally used in the instrument design. Even the approximation of wave optics gives a partial understanding of the propagation of optical radiation. A more general treatment, based in the theory of partial coherence, gives a better description of the propagation.

The main goal of nuclear safety is to protect from accidents in nuclear power plant (NPP) against radiation arising during normal operation of nuclear installations, or as a result of accidents on them. The most important task in any activities aimed at the maintenance of NPP is a constant maintenance of the desired level of security and reliability. The periodic non-destructive testing during operation provides the most relevant criteria for the integrity of the components of the primary circuit pressure. The objective of this study is to develop a system for forming a color image on the television camera on vidicon which is used to conduct non-destructive testing in conditions of increased radiation at NPPs.

Over the past decade, 3M has developed a number of mobile projectors, with a goal towards providing the world’s smallest, most efficient projection systems. Compact size and efficiency are required characteristics for projection systems used in mobile devices and more lately, in augmented reality systems. In this paper we summarize the main generations of 3M light engine optical designs. We present the optical architectures of four light engines, including the rationale behind the illumination designs and the projection systems. In particular, we describe various configurations relating to the 3M polarizing beam splitter (PBS) which is key to enhanced efficiency of the miniature projection systems.

We consider the collinear backward light scattering as one of potential physical mechanisms for creating an advanced collinear acousto-optical filter with significantly improved spectral resolution. Within co-directional crystalline collinear acousto-optical filters, the resolution is inversely proportional to the material’s birefringence, which is ~0.1 in the best case of LiNbO₃-crystal. For the backward light scattering this parameter is replaced by the twice refractive index, so that the gain achieves > 45 times in LiNbO₃-crystal. Thus, one can expect the resolution ~0.002 Å instead of the value ~0.1 – 0.2 Å recently obtained by us experimentally for co-directional geometry in that crystal. Moreover, the collinear backward light scattering can be implemented in an extended amount of available materials. However, the main limitation for applying the phenomenon is the acoustic attenuation in ultra-high frequency range peculiar to the materials for acousto-optical filters. Linear acoustic attenuation reduces the length of acousto-optical interaction and limits the spectral resolution. At an initial stage, our studies are concentrated on physical aspects of this phenomenon as well as on possibilities of its application to creating the acousto-optical filters of a high resolution. In particular, the frequency band-shapes of the scattered light intensity exhibit a tendency to specific acousto-optical nonlinearity, i.e. to more and more rectangular profile as the acoustic power density grows. Results of this analysis confirm the above-noted estimations for a triplet of trigonal acousto-optical crystals, having possibly lower acoustic attenuation.

In every optical testing method, the time taken to process data, the precision of the results and the sensitivity are among the most relevant aspects to be taken into account when the viability of its implementation is been under consideration. An accuracy and sensitivity analysis of a topographer based on a conical null-screen with a semi-radial distribution of targets is presented. On the other hand, we proposed a custom evaluation algorithm in order to reduce the time in the calculation of the normal to the corneal surface. Finally, we perform some corneal topographical measurements.

Recently, the display device was developed to apply to the transparency display device(TDD), but the TDD was no brightness. The purpose of this paper was introduced a double layer optical film to improve luminance of the TDD. The film was doped micro metal oxide particles to increase the effect of scattering and refraction, and the micro structure was fabricated between the top and bottom film to enhance the light into the TDD. This research provided a transparent double layer optical film. The transparency of the film was achieved to 70 %, and the brightness efficiency up to 60 %.

In this paper, we propose a multi-channel imaging system which combines the principles of an insect’s compound eye and optical cluster eye. The system consists of two curved structure lens arrays with different pitches. Both of them have the same curvature and the radiuses of the lenses in the arrays are optimized to focus rays on the retina. The optical axes of different channels are tilted to each other in order to reduce the optical system volume and transmit a wide field of view. Each channel of an array of multiple optical system transfers only a part of the field of view. Each partial image passes through each channel and stitches together on the retina to reconstruct a complete image. In order to simulate the image stitching, we also build an eye model. The thickness from the panel to the last surface of lens group is less than 25mm. The panel size is designed to be 4 inch which is the scale of eyeglass. The system can provide a large field of view about 150 degrees which is much wider than the commercial products. By using the 3D printer, we can make a model of lens array to achieve our design.

Thermal dissipation had an important influence in the quantum effect and life of light emitting diodes (LED) because it enabled heat transfer away from electric devices to the aluminum plate for heat removal. In the industrial processing, the quality of the thermal dissipation was decided by the gumming technique between the PCB and aluminum plate. In this study, we made the ceramic thin films of diamond like carbon (DLC) by vacuum sputtering between the substrate and high power light emitting diodes (HPLED) light to check the influence of heat transfer by DLC thin films. The ceramic dielectric coatings were characterized by several subsequent analyses, especially the measurement of real work temperature of HPLEDs. The X-Ray photoelectron spectroscopy (XPS) patterns revealed that ceramic phases were successfully grown onto the substrate. At the same time, the real work temperatures showed the thickness of DLC thin film coating effectively affected the thermal conduction of HPLEDs.

Gluing technology has been widely used in aerospace, optical, electrical and mechanical and other related industries, and already has excellent bonding strength, mechanical properties and airtightness, gluing material selection and process which is a key issue. In this paper, we choice EC2216 glue to assemble a reflective telescope primary mirror. In this study, a lightweight aluminum mirror with a diameter of 566 mm with three stainless parts have been taken as the gluing and assembly benchmark. We control the thickness of the glue between 0.35 ± 0.15 mm by a 0.3 mm shim, and control stainless parts on the Neutral plane effectively at the same time, after the installation of bipod in the future, this assembly can ensure effective verification to avoid stress is transmitted to the mirror distortion caused by the optical system. This paper aims to provide assembly and aligning by coordinate measurement machine (CMM). In order to obtain more accurate optimization results, we trace parts and the measurement results of CMM.

The paper overviews the advantages and disadvantages of various inverse solutions methods for the Risley-prism-based scanner. According to some given target trajectories, the calculation precisions and calculation consuming time by four different inverse solution methods are investigated, respectively, which reflect the computing complexities and condition applicability. Meanwhile, the corresponding scanning precisions for the same target trajectory by four methods are compared to each other. The paper overviews the limits of different inverse solution methods and evaluates different inverse solution methods for specific beam scanning applications.

Retinal images are obtained by simultaneously illuminating and imaging the retina, which is achieved using a fundus camera. This device meets low light illumination of the fundus with high resolution and reflection free images. Although the current equipment presents a sophisticated solution, it is complex to align due to the high number of off-axis components. In this work, we substitute the complex illumination system by a ring of LEDs mounted coaxially to the imaging optical system, positioning it in the place of the holed mirror of the traditional optical design. We evaluated the impact of this substitution regarding to image quality (measured through the modulation transfer function) and illumination uniformity produced by this system on the retina. The results showed there is no change in image quality and no problem was detected concerning uniformity compared to the traditional equipment. Consequently, we avoided off-axis components, easing the alignment of the equipment without reducing both image quality and illumination uniformity.

In this work, we will present some improvements to the conical null-screen based corneal topographer, for testing aspheric surfaces without rotational symmetry. We present the formulae to design the conical null-screen in such a way that the image on the CCD is a perfect array of spots; departures from this geometry are due to deformation or misalignment of the surface. Additionally, we will explain how to improve the algorithms to find the normals of corneal surface. Finally, we will evaluate the topography of a spherical surface.

The task of this research project is to define the extent of applicability of such 3D self-manufacture approach to the production of optical fastenings. The resulting lack of equipment, to be used for demonstration of simple experiments, which would be both competitive in performance and cheap to produce, led to the decision to research opportunities for self-manufacturing.

Introduction of coefficients defining the relationship of the radii of curvature of the surfaces of concentric optical systems, allowed the transformation of the obtained analytical relations in a system of two equations with two unknowns. It is shown that the existence of the solution of the system of equations determined by the optical constants of the selected lens material. The results of the analysis of the conditions of the chromatic aberration correction position and the sequence of obtaining of the system equations define the theoretical basis of the engineering method of parametric synthesis of concentric lens systems. Application of the developed method is illustrated by examples of calculation particular systems design build.

The theoretical basis for the mirror high-aperture optical system synthesis, based on the properties of the reflecting surface accepted as the base having a shape of a paraboloid of rotation are considered in the work Design parameters and residual aberrations tables of the few design solutions for considered optical systems are presented. From the analysis of aberration correction of the image formed by the considered optical system, it follows that the angular value image space is limited, primarily, the image surface curvature. To compensate for curvature of the image surface can be applied Smith lens. The additional condition that determines a high aperture ratio of the optical system of the considered lens as a whole was introduced, but it complicates the process of correcting the aberrations of a wide beam of rays. It is shown that the use of afocal Mersenne system with known anaberration properties, allows you to build a series of compact and SLR mirror-lens systems with aplanatic, anastigmatic and plananastigmatic aberration correction formed the image, at the same time the length of the system is about four times smaller than the diameter of its entrance pupil. Importantly, when applying the lens for using in a long wavelength range emission, the requirements for aberration correction image formed by the lens are reduced, and accordingly, manufacturability are increases.

The properties of optical surfaces generated by diffraction are studied analyzing the changes in the curvature function of the boundary condition. The study leads to establish a classification for the optical fields as elliptical, hyperbolical or parabolic. The elliptical regions are separated from hyperbolic regions by a region of parabolic type, which corresponds to optical focusing regions. The main result of the analysis leads us to describe and to control bifurcations and vortices effects allowing to geometrize and to control the topological properties of the optical field. For this feature is important to control the geometry of the parabolic region, obtained by controlling the curvature function in the boundary condition. The model is implemented experimentally applying a linear transformation in transmittances of zone plate type. The experimental results corroborate the theoretical predictions.

Ametropies of the human eye, are refractive defects hampering the correct imaging on the retina. The most common ways to correct them is by means of spectacles, contact lenses, and modern methods as laser surgery. However, in any case it is very important to identify the ametropia grade for designing the optimum correction action. In the case of laser surgery, it is necessary to define a new shape of the cornea in order to obtain the wanted refractive correction. Therefore, a computational tool to calculate the focal length of the optical system of the eye versus variations on its geometrical parameters is required. Additionally, a clear and understandable visualization of the evaluation process is desirable. In this work, a model of the human eye based on geometrical optics principles is presented. Simulations of light rays coming from a punctual source at six meter from the cornea are shown. We perform a ray-tracing in three dimensions in order to visualize the focusing regions and estimate the power of the optical system. The common parameters of ametropies can be easily modified and analyzed in the simulation by an intuitive graphic user interface.

The physical shape of the hand vascular distribution contains useful information that can be used for identifying and authenticating purposes; which provide a high level of security as a biometric. Furthermore, this pattern can be used widely in health field such as venography and venipuncture. In this paper, we analyze different IR imaging systems in order to obtain high visibility images of the hand vein pattern. The images are acquired in the range of 400 nm to 1300 nm, using infrared and thermal cameras. For the first image acquisition system, we use a CCD camera and a light source with peak emission in the 880 nm obtaining the images by reflection. A second system consists only of a ThermaCAM P65 camera acquiring the naturally emanating infrared light from the hand. A method of digital image analysis is implemented using Contrast Limited Adaptive Histogram Equalization (CLAHE) to remove noise. Subsequently, adaptive thresholding and mathematical morphology operations are implemented to get the vein pattern distribution.