In this work we calculate the effect caused by roughness on the light reflected by an optical surface like a mirror, the numerical calculation is carry out within the Rayleigh approximation. We focus our study in the comparison of the results obtained numerically using different roughness parameters and calculate its effect on the aberrations of the wavefront, which without the effect of the roughness is considered a ideal surface.
In this work we calculate the effect caused by roughness on the light reflected by an optical surface like a mirror, the numerical calculation is carry out within the Rayleigh approximation. We focus our study in the comparison of the results obtained numerically using different roughness parameters and calculate its effect on the aberrations of the wavefront, which without the effect of the roughness is considered perfect surface.
In this paper, we propose a method to detect the valid phase pixels of fringe patterns obtained with phase shifting interferometry. From a set of simulated interferogram images, we obtain a set of equations to discriminate between valid and invalid wavefront phase pixels, which allow us to compute the wavefront aberration. This method is useful for testing any converging optical system in a quantitative way with either a small or large focal ratio, with either polished or rough surfaces and with wavefront or lateral shear interferograms.
Vein patterns can be used for accessing, identifying, and authenticating purposes; which are more reliable than classical identification way. Furthermore, these patterns can be used for venipuncture in health fields to get on to veins of patients when they cannot be seen with the naked eye. In this paper, an image acquisition system is implemented in order to acquire digital images of people hands in the near infrared. The image acquisition system consists of a CCD camera and a light source with peak emission in the 880 nm. This radiation can penetrate and can be strongly absorbed by the desoxyhemoglobin that is presented in the blood of the veins. Our method of analysis is composed by several steps and the first one of all is the enhancement of acquired images which is implemented by spatial filters. After that, adaptive thresholding and mathematical morphology operations are used in order to obtain the distribution of vein patterns. The above process is focused on the people recognition through of images of their palm-dorsal distributions obtained from the near infrared light. This work has been directed for doing a comparison of two different techniques of feature extraction as moments and veincode. The classification task is achieved using Artificial Neural Networks. Two databases are used for the analysis of the performance of the algorithms. The first database used here is owned of the Hong Kong Polytechnic University and the second one is our own database.
When strong Jaundice is presented, babies or adults should be subject to clinical exam like “serum bilirubin” which can cause traumas in patients. Often jaundice is presented in liver disease such as hepatitis or liver cancer. In order to avoid additional traumas we propose to detect jaundice (icterus) in newborns or adults by using a not pain method. By acquiring digital images in color, in palm, soles and forehead, we analyze RGB attributes and diffuse reflectance spectra as the parameter to characterize patients with either jaundice or not, and we correlate that parameters with the level of bilirubin. By applying support vector machine we distinguish between healthy and sick patients.
Human skin has been studied in numerous investigations, given the interest in knowing information about physiology, morphology and chemical composition. These parameters can be determined using non invasively optical techniques in vivo, such as the diffuse reflectance spectroscopy. The human skin color is determined by many factors, but primarily by the amount and distribution of the pigment melanin. The melanin is produced by the melanocytes in the basal layer of the epidermis. This research characterize the spectral response of the human skin using the coefficients of Fourier series expansion. Simulating the radiative transfer equation for the Monte Carlo method to vary the concentration of the melanocytes (fme) in a simplified model of human skin. It fits relating the Fourier series coefficient a0 with fme. Therefore it is possible to recover the skin biophysical parameter.
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.
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.
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.
MEGARA is a multi-object spectrograph project for the 10.4m Gran Telescopio Canarias with medium to high
resolution: R ~ 5600 - 17000. The instrument operates in three modes that cover different sky areas and that can run
simultaneously: (1) the compact mode through a large central Integral Field Unit with minimum fiber pitch, covering a
field of view on sky of 12 arcsec × 14 arcsec, (2) the sparse mode with fibers covering 1 arcmin × 1arcmin in three
pointings and (3) the dispersed mode with a grid of nearly 100 robotics positioners able to place 7-fiber minibundles
over a large field of view of 3.5 arcmin × 3.5 arcmin. The spectrograph is composed by a pseudo-slit, where the fibers
are placed simulating a long slit; a slit shutter is placed just behind the pseudo-slit, a collimator, a 162mm pupil where
the volume phase holographic gratings are placed, and the camera with the detector. Here we describe the spectrograph
optical rationale, the conceptual optical design and the expected system performance.
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.
We use the profile of a parabolic mirror to calculate the scattered electromagnetic field, this mirror can be used
in the design and construction of a reflector telescope. We calculate the effect caused by the roughness on the
performance of this optical elements, the calculation is done within the Rayleigh approximation. In another work
presented in this meeting we show a comparison of the results obtained numerically using different roughness
parameters and calculate its effect on the aberrations of the wavefront.
In this paper we show the results as well as the description of the followed process to calculate the electromagnetic
field scattered by optical surface elements, where the optical surface is not considered as a flat surface that follows
a shape, but as a rough one, roughness that in general may be regarded as random. We use the profile of a
parabolic mirror to calculate the scattered electromagnetic field, this mirror can be used in the design and
construction of a reflector telescope. We calculate the effect caused by the roughness on the performance of
this optical elements, the calculation is done within the Rayleigh approximation. In another work presented in
this meeting we show a comparison of the results obtained numerically using different roughness parameters and
calculate its effect on the wavefront.
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.
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.
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.
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 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.
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.
In this work we describe a lithographic technique for fabrication of Fresnel lenses. This technique is achieved using a photo mask and Norland Optical Adhesive No. 65. The main characteristics of this lens are his low cost and its flexibility due to the material. Some experimental results are shown.
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.
We designed and built an electro-optical sensor to detect human bodies. The aim of this paper is to describe a device to make easier the localization of lost people in natural disasters or in dangerous environments. The detection is realized in base of the infrared radiation emitted by the human body. We employ point commercial pyloric quantum sensors, the electronic assembly integrates the captured infrared energy by using low noise chip. The optical device include a Cassegrain antenna, a diffraction grating which besides to choose in automatic way the correct wavelength emitted by the human body, it is useful as optical filter.
The Ronchi test is one of the simplest and most effective methods used for evaluating and measuring aberrations. Employed in optical shops, its use is limited to qualitative analysis. Few methods in use today produce quantitative results. What follows are explained both the development and the guidelines for manufacturing a Ronchi tester based on quantitative analysis which also has the advantage to receive automatic input and output of data. In order to achieve this goal, phase shifting interferometry and a square Ronchi ruling with a variable intensity LED were used. It is important to note that with the set up described only one movement of the motor which supports the square ruling is needed to simultaneously obtain both the X and Y components of the wave front aberration.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.