In recent years, with technological advances, head-mounted display systems (HMDs) for virtual reality (VR) and augmented reality (AR) have been adopted for their applications in the military, government, education, training, medical visualization, aerospace, entertainment industries, and tourism. For this reason, a compact and light HMD but without sacrificing their performance is necessary. In this paper, the optical design of a lightweight and compact head-mounted display (HMD) system is proposed. We use an off-axis three-mirror system (OTS) with freeform surfaces for the correction of the aberrations and obtain a wide field of view (FOV), a compact structure with an exit pupil size over 7 mm and eye relief of 25 mm.
We present a new optical design of an off-axis three-mirror system (OTS) that is corrected for spherical, coma, astigmatism, and field curvature aberrations. Our design methodology begins using paraxial theory and continues with the third-order approach for a coaxial three-mirror system (CTS) with a wide field of view and high resolution. We propose to use only two optical elements because the primary and tertiary mirrors will be integrated in a single optical element, the secondary mirror will be the other optical element. For our final design, we will use only off-axis surfaces. Thus it will be possible to obtain a compact, light, easy-to-align optical system with high stability. However, when the CTS is transformed into an OTS, new aberrations are generated. The last step in our methodology is to use freeform surfaces to compensate for new aberrations. With this methodology, a limited diffraction system is obtained.
This paper proposes the design of an anastigmatic three-mirror telescope using freeform surfaces for the correction of spherical aberration, coma, astigmatism, and field curvature, allowing a wide field of view (FOV) and high resolution. For the structure of this telescope, it is proposed to use only two optical elements where the primary and tertiary mirrors are integrated into an only optical element and the secondary mirror in the other, thus achieving a considerable reduction in the difficulty of alignment and assembly. To achieve a high performance of the telescope, the system was decentered (offaxis design), avoiding the loss of energy due to the obscuration of the M2 in the on-axis system. In addition, to solve the difficult access to the focus.
The design of a two-mirror telescope using a free-form surface for the primary mirror, to obtain a compensation of the spherical and coma aberrations, in the entire pupil of the telescope is proposed. In this design, the conic constant (𝑘1 ) of the primary mirror is a function of the heights, measure from the center to the edge of primary mirror. In this method, we use the exact ray tracing to find the optical path length (OPL) for each ray that intersect the primary mirror at different distances measured from the center of the primary mirror. The OPL is calculated with the sum of the distances that each ray travels until reaching the plane of the image, and the sum of the distances for a paraxial axial ray. From the optical path difference (OPD) of a set of rays, we obtain a set of values of the conic constant that guarantees that the OPD has a value of zero for each incident ray height. With the set of values of the conic constant it is possible to obtain the shape of the surface of the primary mirror.
The tendency in the manufacture of large telescopes that working in visible light, has improve the manufacture of large mirrors by the use off-axis segments, which must be aligned with very high precision in order of fractions of wavelength for the optimal operation. In this paper we present a new method for alignment segments of a big telescope, where the positions of the images produced by each off-axis segment, of a point source placed at center of curvature, the primary mirror. These positions can be known by exact rays tracing, considering the aberrations produce in each off-axis segment. Consequently, each point source is not on the optical axis of the system. Some numerical simulations are shown to establish the accuracy achieved with the proposed method.
Measuring large curvature radii of convex surfaces with high precision is a challenge because the spherometer’s focus must be positioned at the apex of the surface and at the center of curvature of the surface by moving the surface or the spherometer. If the radius of curvature is larger than the back focus of spherometer, then measurement is not possible. In this work, we propose to use the FOCOIVA system1 to move the focus of the spherometer in longitudinal way without modifying the f number by moving two lenses inside it, with this mechanism it is possible to measure radii of curvature of several meters in length. The curves of movement of the lenses and the optical parameters of the lenses that compose the spherometer are presented.
We report the construction and characterization at a wavelength of 633 nm of a polyurethane multi layered
phantom with optical properties similar to a stratified model of human skin. During the construction of this
phantom, integrating sphere technique was used to measure transmittance and reflectance, and using the inversion
method IAD, to ensure that the optical properties of each layer corresponds to those in the design, measuring an
exact replica of each one. A modified MCML code that includes the effects of lateral loss light and the spatial
distribution of intensity at the entrance of the sample was used to compare the experimental transmittance and
reflectance measurements of the whole phantom with the simulated ones obtained using the retrieved optical
parameters in each layer.
We present Raman spectra from a sample of 8 volunteers that have different type of blood. The experimental data were
carried out using a 785 nm excitation laser and an ocean optics spectrometer of 6 cm-1 resolution, with a used spectral
region from 1000 to 1800 cm-1. We find Raman features at 1000 and 1542 cm-1 regarded with hemoglobin and its
derivatives. Also we find Raman features at 1248 and 1342 cm-1 that are now regarded with pure fibrin. In this work, we
use Principal Component analysis (PCA) to determine all variations of our samples, which allows us to define a
classification of the influence of the blood type. Finally, we found vibrational lines of cholesterol, glucose and
triglycerides that are reported in literature.
In some vital organs of the human body the air bubbles are indicative of the presence of disease. On the other
hand, poor information has been published considering the effect of air bubbles on the optical properties of
tissue mimicking phantoms. The goal of this study was to investigate the influence of air bubbles on the optical
properties of polyurethane phantoms. A two-integrating spheres system (TISS) in combination with the IAD
method was used to determine the optical properties of a set of polyurethane phantoms fabricated with different
levels of air bubbles. Phantoms were characterized with a microscope and a fiber optic spectrometer using a two-fiber probe. Results indicate that the TISS in conjunction with the IAD method is insensitive to the level of air bubbles within polyurethane phantoms whereas that for the spectrometric system a noticeable difference was found for the spectra of phantoms prepared with different levels of air bubbles. A change of reflectance spectra above 25 % at 428 nm was found when degassing sample time changed from 5 to 10 minutes. This finding indicates that controlling the degassing step of phantoms is more critical when they are required for the validation and standardization of devices that have a robust working principle based on the probing of a localized volume such as it is the case of fiber optic probes.
Phantoms simulate optical characteristics of tissues. Phantoms use to mimic light distributions in living tissue. Several
Phantoms compositions made of silicone, polyester, polyurethane, and epoxy resin have been described in the literature.
These kinds of phantoms have the problem of long time preservation. In this work, we describe the fabrication and
characterization of phantoms with low concentrations of synthetic lipid using Raman spectroscopy. We fabricate four
phantoms made of Polydimethylsiloxane (PDMS). These phantoms have synthetic lipid content of cholesterol and
triglycerides.
The size of our phantoms is 1 x 1 cm and 5 mm of thickness.We used the point-to-point mapping technique. Finally, we
compared advantages and performance of made PDMS and gelatin phantoms.
In this study was made a comparison between the optical coherence tomography and microscope images. We obtain
images from different biological tissues, and from a designed epoxy phantom to analyze if the SR-OCT 930 can obtain
images similar to microscopy images. The result is that the OCT images and the microscopy images are similar. Also
developed a software to analyze the OCT images without distorting the structures in the image when the image is obtain
in different image sizes.
Determining optical properties of turbid media has been performed by many research groups using a technique
based on iteratively solving the radiative transport equation using the adding doubling technique (IAD). We
present a new, alternative method, GA-MCML, for determining optical properties based on a Monte Carlo tech-
nique for radiative transport (MCML) guided by a genetics algorithm. The Monte Carlo method is more
exible
than the adding-doubling technique and can be adapted to a wider range of sample geometries. The genetic
algorithm is a robust search technique that is well-adapted to avoiding the local minima in this optimization
problem. GA-MCML, has been implemented by modifying the MCML source code to account for two common
experimental problems: light losses due to the nite sample size and non-linear integrating sphere eects using
Mott's equations. GA-MCML was validated by comparing with IAD method for data acquired at 632.8 nm
on a set of phantoms using a single integrating sphere system. The GA-MCML results were equivalent to the
IAD technique.
Tunable liquid-filled lens (TLFL) is a lens that changing their focal length by modify the quantity of
liquid within the mount. Recent research shows that, the use of tunables lens makes lighter, simpler and
more compact optical devices in micro-ingineering. In the literature there are papers that present
simulations of the behavior of tunable micro-lenses composed slim membranes. We use a TLFL
composed a cylindrical metallic mount with a compartment for two transparent elastic membranes filled
with water between them. Membranes with plane, spherical and conic surfaces are employed. The
membranes are elaborated of Polydimethilsolixane and the mechanical mount is made of alluminium. In
this work, we present the opto-mechanical design, analysis and simulations of behavior de tunable liquid-filled
lenses composed thick membranes. The analysis is made in three TLFL with different types
membranes. The simulations and analysis of mechanical behavior were made with SolidWork™ software.
Moreover an application with genetic algorithms was development to obtain the geometrical parameters
of the lenses when a value of pressure is applied on the membrane surfaces. On the order hand, the
analysis of optical behavior of the lenses was made with the OSLO software. Finaly, results are shown.
Xochicalco is an archaeological site located in the state of Morelos in central Mexico. It flourished from 600 to 900 a.d. with numerous multicultural elements. There are several underground rooms carved into the hillside In particular, a room with a shaft that has a hole in the roof whose orientation towards the zenith supports its astronomical purpose. Our hypothesis is that the place was used as a tlayohualchieliztli or camera obscura for astronomical observations. This would be the first evidence of a pre-columbian image forming device. To explore the feasibility of this assertion, the conditions required to produce an image were studied. The aperture diameter in the top of the shaft is far too large to be used as a "pinhole" but it may have been covered with a screen containing a smaller bore-hole. We work out the optimum aperture size. The portion of the sky that could be observed due to the orientation of the shaft was also undertaken. The two most intense celestial objects should produce bright enough images thus suggesting that observation of the sun took place during day-time and observation of the moon during night-time. Amate paper or cloth could have been used to directly draw the position of celestial objects.
Optical spectroscopy allows the characterization, recognition and differentiation of subcutaneous tissues
healthy and no-healthy, to facilitate the diagnosis or early detection for breast cancer are studied white
adipose tissue by the subcutaneous region with the help of the diffuse reflection spectroscopy in the visible
areas (400 to 700 nm) of electromagnetic spectrum for them using a spectrometer portable of integrating
sphere, Hunter lab Model Mini-Scan. The problem to be solved for cancer detection by optical techniques is
to find the solution to the inverse problem of scattering of radiation in tissue where it is necessary to solve the
equation of energy transfer. us through the trigonometric interpolation and by the data adjustment by least
squares using Fourier series expansion to parameterize the spectral response curves of each sample of breast
adipose tissue then correlated with histological grades established by the optical biopsy for each one of the
samples, allowing use this technique to the study of anomalies in White Adipose Tissue Breast, changes are
evident in the spectral response for Breast Adipose Tissue carcinogens with respect to healthy tissues and for
the different histological grades.
The non-invasive clinic method of diffuse reflectance spectroscopy (DRS), for the diagnosis of human skin lesions
can be performed by using spectrometric devices together with fiber optics probes. However, the operation of
most of these devices commercially available is not specifically designed for clinical applications. As a result, the
commercial software and the optical hardware of these spectrometers are impractical when trying to conciliate the
requirements of a clinical procedure with their operation to perform the DRS for diagnosis purposes. Therefore,
the development of home-built acquisition software will impact in a more reliable and practical spectrometric
system for clinical environment. In this work is presented the development of an automation system that includes
both a user graphical interface and a control system that enable a more reliable and faster acquisition of clinical
spectra. The software features a voice control to perform the acquiring spectra process. The impact of this work
is mostly the use of available programming platforms to implement a preliminary spectra processing tool that
will lead to real-time acquisition of skin reflectance spectra of a given patient.
Precision machining is as a very precise and effective method for micro-structure optical components fabrication. In this
paper, the mechanical structure of one XYZ and spindle axis of freedom machine with 250 nm of resolution in linear
axes is described, details of the homemade mechanical mounts are given; also components of the electronic system such
as hardware, firmware and software are included in the description.
Determination of tissue optical parameters is fundamental for application of light in either diagnostics or therapeutical
procedures. However, in samples of biological tissue in vitro, the optical properties are modified by
cellular death or cellular agglomeration that can not be avoided. This phenomena change the propagation of
light within the biological sample. Optical properties of human blood tissue were investigated in vitro at 633 nm
using an optical setup that includes a double integrating sphere system. We measure the diffuse transmittance
and diffuse reflectance of the blood sample and compare these physical properties with those obtained by Monte
Carlo Multi-Layered (MCML). The extraction of the optical parameters: absorption coefficient μa, scattering
coefficient μs and anisotropic factor g from the measurements were carried out using a Genetic Algorithm, in
which the search procedure is based in the evolution of a population due to selection of the best individual,
evaluated by a function that compares the diffuse transmittance and diffuse reflectance of those individuals with
the experimental ones. The algorithm converges rapidly to the best individual, extracting the optical parameters
of the sample. We compare our results with those obtained by using other retrieve procedures. We found that
the scattering coefficient and the anisotropic factor change dramatically due to the formation of clusters.
The optical coherence tomography images are useful to see the internal profile and the structure of material samples. In
this work, OCT images were recorded in 10 volunteers with different skin tone which were related to Raman spectra.
The areas where we obtained OCT images and Raman spectra were a) index finger nail, b) between index finger and
middle finger, c) middle finger tip, d) half of middle finger, e) the thumb finger tip and f) between index finger and
thumb, areas measured were for the purpose of finding extracellular fluids with contain triglycerides, cholesterol and
glucose that are reported in the literature. The excitation wavelength used for this work was 785 nm, a spectrometer of
6 cm-1 resolution. The spectral region used ranges from 300 to 1800 cm-1. We use an OCT with 930 nm of Central
Wavelength, 1.6 mm of Image Depth, 6 mm of image width and 6.2 μm of axial resolution.
In this work we carried out a comparison and localization of skin Raman spectra. Measurements were
made in regions where Raman scatter is caused by the excitation source; we used the spectra overlap in a
comparative way. Ten volunteers with different skin colors participated in the experiment; body parts
sampled were palm and dorsum of the hand. The excitation wavelength used for this work was 785nm. A spectrometer with 6cm-1 resolution and spectral region range 0 to 2000 cm-1 was utilized. We used Matlab® to overlap and compare the differences between Raman spectra form different samples. We found spectral variations that were caused by differences on the surface of the skin, such as scars and moles. This work helps to identify potential undesirable behavior on the epidermis.
The transparent elastomer Polydimethylsiloxane (PDMS) Sylgard 184 is increasingly used in optical applications, as in the manufacture of microlens, waveguides (optical fibers) and to elaborated phantoms (simulator of biological tissue); The wide range of applications is due to its excellent physic-chemical properties, its low cost, easy operation and null toxicity. This paper describes the manufacturing process and physic-chemical characterization of Phantoms prepared with PDMS as grid and doped with some elements present as Gliceryl, ink, glucose 10% and melanin provided by sigma aldrich. We made phantoms with different concentrations and elements; we measured their profiles, and thicknesses. Finally, we obtained their Raman Spectra. We present the experimental results obtained of the physic-chemical parameters of the phantoms and the conclusions.
There has been a considerable recent increase in the use of variable focal length lenses (VFLLs), especially as microlenses in photographic objectives, endoscopes, microscope objectives, etc. One distinguishing feature of these VFLLs is the presence of a mechanism whereby the shape of the lens and its geometrical parameters can be changed. A new type of variable focal length lens is introduced made from elastic material. It is placed inside a mechanical mount where radial forces can be applied to its perimeter. We also present the optomechanical design and the measurement of wavefront aberrations to the third and fifth order of a solid elastic lens (SEL). A point-diffraction interferometer is used as a wavefront sensor to test changes of the lens. Geometrical changes in the lens produce changes in the aberrations. Finally, the aberrations found in the SEL (without any application of stress) are compared with aberrations obtained by means of numerical ray trace. Some experimental results are also shown.
In this work, we present the optical design of a tunable focus liquid lens composed with meniscus
surfaces. The surfaces are elaborated of PDMS. Analysis of the opto-mechanical behavior of the lens is
presented.
We present a novel method to diffractive null lens designs to test parabolic mirrors. The phase coefficients control the
diffracted ray which hits normally the aspheric surfaces. The spherical and coma aberrations are corrected. The
equations are exact and optimization process is not required.
Recently in the micro-optical engineering area has been a grown in use of tunable liquid lenses because this
lenses us allow versatility in the focusing range, also an easy handling and implementation. In the literature,
many tunable lens models have been reported, but most of this work has been on describing the optical quality
of the images, the opto-mechanical analysis is neglected. In this paper, an analysis of opto-mechanical of a
tunable liquid lens is presented, for this; we show a finite element simulation of mechanical behavior and
estimate how this influences in the optical performance of the lens. The liquid lens is composed of two elastic
transparent membranes and of a cylindrical metallic mount.
In this work we developed a novel technique to remove the fluorescence background in the
Raman spectrum. This technique permit us to obtain better accuracy in the spectrum peaks,
it is based in the wavelets theory, using symlets and biothogonals wavelets, therefore it is
adapting with the Raman Spectrum. We use a spectral range from 300 to 1800(cm-1), 785 nm laser excitation source and Oceans optics spectrometer was used. The experimental samples were people with different kinds of skin, like brown, black and white. We compare the differences between each Raman spectra, which permitted us to identified persons due to accuracy of Raman spectroscopy. This results shows that Raman spectroscopy has greatly precision in this field of biomedical optics.
In this study, the opto-mechanical design and functional characterization of a Variable Focal
Liquid Length Lens (VFLLL) are presented. This VFLLL is formed by a hydro-pneumatic
system, a mount with two elastic membranes and the liquid medium between them. The hydropneumatic
system allows the entrance and exit of the liquid at any moment to change the shape
of the surfaces as well as the axial thickness of the lens. The functional characterization consists
in measure the spherical aberrations present in VFLLL when changes on the amount of liquid
medium are made. We used the Zygo interferometer to measure the spherical aberration. The
changes of aberration as function of the focal length are shown. Finally the experimental results
are presented.
This paper presents a sensor of liquids using Raman spectroscopy. Results are displayed using 96
degrees alcohol mixed with collagen, moreover we used samples of acetone with alcohol, acetone
with collagen. Raman spectrum noise is decreased using a matlab ® algorithm that works with
wavelets symmlets. The results show main spectral lines for each of the samples used.
Today elastic membranes are being used more frequent as optical surfaces in the science or in the industry. This
due to the advantages that they display in their handling and in their cost of production. These characteristics
make them ideals to apply them in micro-optical components and Tunable Focus Liquid Filled Length Lens
(TFLFLL). In order to know if a membrane of PDMS (PDMS Sylgard 184) is feasible for a specific application
within the field of the optics, it is necessary to know its mechanical, optical and chemical properties. In this
work the parametric membrane characterization is reported for an optical application. An important factor in
the performance of these membranes is related with their scattering factor that is produced due to the roughness
and impurities (micro-bubbles or dust particles). These membranes are used as refractive surface in TFLFLL. Experimental results of the characterization process and device performance are presented.
In recent years there has been a considerable increase in the use of variable focal length lenses (VFLL), due to
the fact that they are used as micro lenses in photographic cameras, endoscope, etc. The VFLL's come mainly in
three types, one of them are formed of two transparent elastic membranes with a liquid medium between them,
those made of an elastic material inside a mount which allow radial forces to be applied on its perimeter, and
finally those which are made of a dielectric liquid medium. In these VFLL always have a mechanism that allows
the shape of the lens and its geometrical parameters can be changed. In this study, we implement a mechanical
mount to applied radial force, in the perimeter of a solid elastic lens. We measure the aberrations of wavefront
present in deformable solid elastic lens (VFLL), when we change the radial forces applied on its borders. The
wave sensor used were the Point Diffraction Interferometer (PDI) and null screen tests. Theoretical and
experimental results are presented.
Recent times have seen the production of normal and micro liquid lenses with variable focal length. These have been
specially made with transparent elastic materials and liquid medium between them, or with a dielectric liquid medium
inside the cavity. Change in the volume of the liquid medium, in the first case, or the application of an electric field as in
the second, produced a change in the optical parameters of the lens. The present study offers the opto-mechanical design,
manufacture and characterization of a solid elastic lens made of Polydimethylsiloxane (PDMS). To do so, we have
prepared a mechanical support frame to hold all of the components of the lens and also allow for the application of radial
stress on its periphery. In order to ensure a well-finished lens surface a high quality optical glass mold has also been
constructed. Finally, we will present an analysis of the properties of this type of lens when it undergoes variations of
radial stress. The experimental results are presented.
The design and construction of next-generation telescopes involves the development of new technologies capable of
fabricating and testing large dimension mirrors with small f-numbers in order to get rapid surfaces. Secondary mirrors in
Cassegrain-type telescopes are convex and hyperbolic. When the dimensions are increased and its f-number is reduced,
the difficulty in testing the surface increases exponentially and traditional optical testing is no longer feasible. The
present study offers a technique developed to test a mould to be used in fabricating the secondary mirror of the Large
Millimeter Telescope (LTM). The mould is a hyperboloid surface with a conic constant of -1.1474, a paraxial curvature
radius of 1764.94 mm and a diameter of 1600 mm. Since the telescope will work within wavelengths ranging from 1 to 3
mm, surface errors must be less than 15 μm in rms. The mould was evaluated by measuring the coordinates of 53,824
points on its surface using an advanced coordinates measurement machine (CMM) at the National Institute of
Astrophysics, Optics and Electronics (INAOE) in Mexico. From this we obtained the shape of the conic surface that
better fits this distribution of points, using a Genetic Algorithms (GA) program developed for this purpose. Finally, the
results obtained are shown.
The inability of an optical spherometer to measure large curvature radii in optical convex surfaces is well known. This is
because the movement of the optical component or the instrument cannot be physically carried out since this would
involve crossing each other. This study proposes the opto-mechanical design of a spherometer that will have a source
light, a beam splitter, and a liquid lens composed of a plane surface and a transparent elastic membrane with a liquid
medium between them. By changing the volume of the liquid the shape of the membrane and the thickness of the lens
will change. The present study offers a paraxial analysis of the relationships obtained to measure the curvature radius
together with its uncertainty as a function of changes in the volume. The study also presents the work range of the
instrument. The instrument is focused on the vertex of the surface and on the center of curvature with aid an intensity
detector.
We propose a novel method to correct the spherical and coma aberration using a hybrid element (refractive-diffractive).
The refractive surface is used to correct the coma, we obtain this condition curving the second principal plane and
centred it on the axial point image. The diffractive element is used to correct the spherical aberration using an exact ray
trace and the diffractive coefficients as variables. The optimization routine is no required. This method can be used for
any conjugates position.
Studies on adaptive lenses formed of two transparent elastic surfaces with a transparent liquid medium between them
have focused mostly on the characterization, analysis and the optical performance of the proposed lenses. No attention,
however, has been given to the mechanical design to generate a user-friendly functional mounting as well as being
adaptable to conventional optical systems. This work, therefore, presents the design and manufacturing processes of the
parts of the mounting for a biconvex adaptive lens with a 20 mm diameter. It also presents an analysis of the membranes
used as elastic surfaces as well as images formation of the proposed lens.
KEYWORDS: Solar concentrators, Mirrors, Radon, Algorithm development, Systems modeling, Optical testing, Solar energy systems, Optical design, Aspheric optics, Solar processes
In this work we present the optical design of a solar concentrator for an High-Flux solar furnace of a solar laboratory, these concentrator is compound for an aspheric mirror surface sectioned in 121 hexagonal facets to simplify the construction process, its total diameter is 6.6 m and a focal length is 3.68 m, also was developed the corresponding algorithm to determine the correct position and orientation of each hexagonal section that compound the arrangement. We present the results of the focused energy of this configuration and we propose a modification on the original position of the mirrors for optimizing the focusing of energy by the sun furnace. These modifications produces an increment on the energy focused on a small area in a remarkable way similar to used a parabolic mirror.
The algorithm before mentioned was programmed in MathCAD and it calculates the modification of the original position of each hexagonal mirror giving us a file that ZEMAX can read. This file contains the information of each 121 mirrors from the arrangement and also the correct form, position and direction, simplifying the traditional input process one by one.
A method based on a hybrid genetic algorithm is proposed to obtain the wavefront aberrations of a real interferogram. By solving an optimization problem, the proposed method fits a set of Zernike polynomials to the experimental data. The results show that, compared to a conventional genetic algorithm, the hybrid genetic algorithm not only improves the searching ability but also accelerates the convergence. The proposed method is robust to spatial variation of the illumination.
This study presents results obtained from the exact tracing of rays of an adaptive lens, that is, a liquid lens with transparent elastic surfaces. Because the elastics surfaces are deformed by a liquid, they acquire different curvatures depending on the difference in pressures of the liquid and of the environment. Images generated by this type of lens are simulated with a ray-tracing computer program, considering that each surface can be modeled with concentric spherical rings with different curvatures; this is because the elastic coefficients of the plastic materials used are non-linear.
This study presents the design and analysis of a lens with a variable focal length, which we will call an adaptative lens. This lens is formed of two transparent elastic surfaces with a transparent liquid medium between them. The mechanical design of the lens considers the variation of liquid pressure between the surfaces. This causes changes in curvature radii and in the axial thickness, generating variations in the focal length of the lens. An analysis is given of changes in lens power with respect to changes in pressure. Finally, a model of the human eye is presented using this adaptative lens as crystalline.
There are many optical techniques to evaluate and calculate the shape of any concave surface, including lateral shear or
phase lock interferometry tests. In this work we employ a Twymann Green interferometer to obtain several
interferograms of any mirror under test, and by using a computer program and a piezo electric device, we apply the
phase shifting technique to obtain several interferograms and with them we obtain the phase by applying several phase
unwrapping methods, also we realize an experimental comparison between the methods employed to unwrap the phase.
Finally results concerned with the advantages or disadvantages of the studied methods are discussed.
In this work we present a method to design compact and anastigmatic telescopes using tree mirrors, in the
proposed system two of the mirrors are build in the same substratum to reduce the size of the telescope. The
tree conic constants are used to correct the spherical aberration, comma and the astigmatism. In this work the
equations are presented for the design to first order, to third order and we propose a method to calculate the
conic constants exactly, Using our equations a telescope is designed and the obtained parameters are used in the
optical design program, OSLO, to verify the quality of the image.
In this work, we propose an alternative method for design diffractive lenses controlling the spherical aberration for monochromatic imaging. These diffractive lenses are designed on a rotationally symmetrical surface. Our method calculates the surface profiles for any substrate, for any f-number and any object position. The calculations are exact and an optimization process is not required.
We present a method to compensate the spherical aberration for any optical system and any object position, with this method the spherical aberration could be zero in several pupil positions at the same time. The aspheric coefficients are used to compensate the spherical aberration and they are calculated solving a system of first grade equations.
The Large Millimeter Telescope (LMT)1 is a 50 m diameter millimeter-wave telescope designed for principal operation at wavelengths between 1mm and 4mm. The LMT secondary mirror will have a diameter of approximately 2.6 meters and focal ratio of .35. The purpose of this study was to implement the incoherent fringe projection technique and the spatial phase synchronous method to measure the secondary mirror mold profiling. The obtained topography is compared with the conic surface generated synthetically. We considered that mold should be hyperboloid surface with paraxial curvature of 1764.9 mm and conic constant of -1.1474. We will discuss the preliminary results where it is obtained a RMS of 0.624 cm.
We proposed an optical system called ACOAS as a scanner in two dimensions and we present the analysis to first order
and the final optical design for two versions, glass and plastic versions, this scanner will be used as a writing system for
a digital documents reader. The image quality fulfills the requirements because the final designs are diffraction limited
systems.
In this work an alternative is presented to design a noncontact profiler using diffractive optical elements in substitution of the traditional optical elements (refractive, reflective). With these elements is possible to have lenses with large numerical aperture and high control of the spherical aberration that is most important in the case of the profilers. Also, the optical design of a profiler that we are presenting, it will be used in a large coordinate measuring machine allowing us to scan surfaces in a continuous way. We also present the algorithms for recover the form of the surface starting from the date obtained with the profiler.
In this work we propose the optical design of Galilean telescopes for low vision people using hybrid optical components. By use of these new optical components we have obtained compact and lightweight optical systems without detriment of the optical quality of the images. We present the optical design of telescopes for three different magnifications, as well as the evaluation of the image quality using the eye model proposed by Bruce H. Walker.
We obtained novel analytic expressions which permit us to realize the optical design of any thick lens, this analysis include both first and exact order design. We employ the conic constant of the first surface to correct the marginal spherical aberration. We analyzed both finite and infinite conjugates cases. Examples done with our methodology also show good agreement with commercial optical design programs.
Working with big mirrors always is a great challenge, even more if the surfaces have great roughness. In this work we present a technique to verify the quality for surfaces around 3 meters in diameter and with roughness around 30 microns. In order to reach our goal we made an analysis of the grating pitch to avoid the roughness and we implement a common source light, which is independent of the angle of illumination of the surface under test. Also we implement the shadow moire and the phase shift method to obtain the wave front aberrations.
We report on the experimental verification of an alternative method to the conventional least-squares fit method to obtain the phase of real interferograms. The proposed method performs an automatic polynomial fitting by solving an optimization problem, where an objective function is minimized and the solution to the irradiance equation is considered as an inverse problem. In this work, we consider fundamental concepts by comparing the performance of the least-squares fit method and the evolutionary algorithm. It is important to point out that the experimental verification of interferograms with the proposed method is applied to confirm the quality of some manufactured optical surfaces at the Instituto Nacional de Astrofísica, Optica y Electrónica.
The new astronomical instruments; spectrographs, cameras, focal reducers, telescopes, etc., requires to work in more and more wide spectral ranges and with very large fields of vision. Therefore, the chromatic aberrations and the field curvature are aberrations very difficult to correct and to balance in the process of optical design. For that problem, in the stage of optical design is necessary to add more optical components in the instrument, also we need to use more aspherical surfaces and we need more time of optical design, etc. In this work we propose to use the technique of wavefront coding using a cubic phase mask to obtain optical systems with an extended depth of field that corrects the chromatic aberration and the field curvature automatically. In this paper we present preliminary results of this technique.
We report the experimental verification of an alternative method to the conventional least squares fit method for obtaining the phase of real interferograms, making an automatical polynomial fitting on exprimental data in accurate form. The process can be realized solving an optimization problem using an evolutionary algorithm, where the solution to the irradiance equation should be considered like an inverse problem and an objective function should be minimized. In this work we review the fundamental concepts comparing the performance of the least squares fit method and the evolutionary algorithm used in the experimental interferogram analysis.
People with visual weakness, besides the typical refraction problems as myopia (shortsightedness), lose much of the light that enters to their eyes because their retina has many useless cones. For this reason the traditional ophthalmic lenses cannot solve the problem of these people, therefore, we are required of optical systems that collect a big quantity of light, we also need these systems to be of small dimensions and lightweight so they can be used for a long time. In this work we propose the optical design of telescopes using hybrid components, using this new optical components we have obtained compact and lightweight optical systems without decreasing the optical quality of the images. We present the optical design of telescopes for three different magnifications, as well as the analysis of the quality of their images.
Nowadays there are a lot of optical interferometric tests, but there is no doubt the most used, among the lateral shear interferometry is the Ronchi test. In this work we implement the Bi-Ronchi test by generating a square Ronchi ruling onto a LCD. Phase shifting interferometry and a matrix method were used to recover the wavefront aberration. Plots of the surface under test and wavefront abberations are also shown.
The star test is conceptually perhaps the most basic and simplest of all methods of testing image-forming optical systems, the irradiance distribution at the image of a point source (such as a star) is give for the Point Spread Function, PSF. The PSF is very sensitive to aberrations. One way to quantify the PSF is measuring the irradiance distribution on the image of the source point. On the other hand, if we know the aberrations introduced by the optical systems and utilizing the diffraction theory then we can calculate the PSF. In this work we propose a method in order to find the wavefront aberrations starting from the PSF, transforming the problem of fitting a polynomial of aberrations in a problem of optimization using Genetic Algorithm. Also, we show that this method is immune to the noise introduced in the register or recording of the image. Results of these methods are shown.
In this work we present an alternative to design a noncontact profiler using diffractive optical elements in substitution of the traditional optical elements (refractive, reflective). With these elements we have lenses with large numerical aperture and high control of the spherical aberration that is most important in the case of the profilers. In this work, the optical design of a profiler is presented that will be used in a large coordinate measuring machine. The optical design allows to this profiler scan the surface in a continuous way. We also present the algorithms for recovering the form of the surface starting from the date obtained with the profiler.
The fiber Raman amplifier employs the intrinsic properties of silica fiber to obtain the amplification, thus they use the transmission fiber as the amplification medium, where the gain is created along the transmission line. The amplification is realized by Stmulated Raman Scattering (SRS). This nonlinear process occurs when a sufficiently powerful pump is within the same fiber as the signal. In this paper, we showed experimental and numerical analysis of SRS in optical fibers. We obtain a continuous spectral when we plot the energy content in each Stokes sublines with the wavelength, which are self-pump between them. The numerical results are in agreement with the experimental results, just as the waveform in the time of optical fiber end and the energy is transferred from the signal pump to the Stokes sublines. With the simulations, we can obtain several parameters of this optical amplifier like the optical fiber effective length to obtain the amplification.
The Point Spread Function (PSF) or star test is one of the main criteria to be considered in the quality of the image formed by a telescope. In a real system the distribution of irradiance in the image of a point source is given by the PSF, a function which is highly sensitive to aberrations. The PSF of a telescope may be determined by measuring the intensity distribution in the image of a star. Alternatively, if we already know the aberrations present in the optical system, then we may use diffraction theory to calculate the function. In this paper we propose a method for determining the wavefront aberrations from the PSF, using Genetic Algorithms to perform an optimization process starting from the PSF instead of the more traditional method of adjusting an aberration polynomial. We show that this method of phase recuperation is immune to noise-induced errors arising during image aquisition and registration. Some practical results are shown.
The primary reflective surface of the Large Millimeter Telescope (LMT), it will be formed by a set of trapezoidal panels. Each panel has a paraboloid off-axis form and it is constructed with carbon fiber. The paraboloid off-axis surfaces is obtained copying by contact to a mold with the required form. One proposal in order to manufacture each mold, is made it of graphitizing steel fused. And after that, it lathing with a numerical control machine for obtain the paraboid off-axis section. But due to the dimensions of the sections, 5x3 meters for the biggest section; the mold of steel will be formed by two small segments. In consequence, it is necessary in the first place, alignment these segments in order to obtain a mold with a surface approximately continuous, with a minimum precision of 5mm. In this work we present a method in order to alignment these two molds' segments, as well as, the results of alignment obtained for the prototype mold.
We propose a novel optical system that can scan simultaneously in perpendicular and longitudinal directions to the optical axis, which we have named the FOCOIVA lens system. We give the equations for the first order analysis and also the equations of motion for the lenses. Examples calculated with these equations are presented and finally we give the optical design for the writing system that will be used for a reader of digital documents.
Hybrid elements contained optical power with both diffractive and refractive components are shown to be useful for obtaining achromatic dispersive characteristics. In the achromatic case, the optical power of both refractive and DOE components are of the sem sign resulting in much smaller glass curvatures than in all-refractive achromatic doublets. A comparison is made between Hybrid achromatic and equivalent traditional system in the visible wave band to seek advantages and disadvantages.
We present a method for obtaining the phase of a noisy synthetic interferogram. We find the wave-front aberrations by transforming the problem of fitting a polynomial in an optimization problem, which is then solved using an evolutionary algorithm. Our experimental results show that with our method more accurate results are obtained than with other methods commonly used to solve this problem.
We proposes the optical design of a 3D scanner using only two off-axis conic mirrors. We scan in transversal directions with rotations of one of the mirrors and the longitudinal scan with displacements along the axis of the other mirror. Within the principal parameters for the design of the conic mirrors is considered the entrance pupil diameter, the f-number of the primary mirror and the distance from the vertex of the primary mirror to the image plane. For the analysis of the image awe are considering the following characteristic: Spot Size, the RMS of the wavefront, the point-spread-function and the Strehl ratio. Finally, we calculate the maximum scan volume for the designed scanner.
Usually the fabrication of a conic or aspheric surfaces begins with the best-fit sphere and by removing the glass surplus the desired aspheric surface can be obtained. If the aspherical surface have a large focal ratio and small conic constant the manufacture process is easy. But when the focal ratio is small or the conic constant is large this process is very hard. We propose to use two-wavelengths interferometry for testing the surface in the grinding process, because with this method is possible to obtain interference fringes of rough surfaces.
When optical systems are designed, the final stage corresponds to the optimization of an initial design, and frequently the methods of damped least squares are used. However, some methods as the one mentioned find local minimums and not the global one. Therefore, the solution depends mainly of the initial design. The method proposed in this work, is based in the genetic algorithms that find the global minimum, and besides an initial design is not necessary to begin the optimization process.
When optical systems are designed, the final stage corresponds to the optimization of an initial design, and frequently the methods of damped least squares are used. However, some methods, such as the one mentioned, find local minimums and not the global one. Therefore, the solution depends mainly on the initial design. The method proposed in this work, is based in the genetic algorithms that find the global minimum, and besides an initial design is not necessary to begin the optimization process.
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