The forward tracing technique for diffraction analysis (FFTD) is a numerical technique for ray-tracing environments
inspired by the Boundary Diffraction Wave. The technique was developed specifically considering circular apertures in
imaging systems. In previous work the technique was applied to a simple optical system. The value of the method has
been geared towards aiding optical design where diffraction effects not produces at the aperture stop are important. In
this work the technique is applied and evaluated as a tool for analyzing a complex system where only circular apertures
are present. The chosen system is an IR endoscope on the MWIR region. The system requirements make for circular
apertures aside from the stop where diffraction becomes important. FFTD is applied for obtaining irradiance information
at the image plane. The key parameters affecting the simulation are described on axis and field.
The optics industry in Spain pooled together to create the Southern European Cluster in
Photonics and Optics - SECPhO, founded in April 2009, with the mission to help the sector increase
competitiveness, specially through collaboration. From 10 founding members, SECPhO no incorporates
over 40 members, which is nearly 40% of the optics industry in the region. From the beginning of
operations the cluster has focused on three strategic challenges: R&D+i and Productivity, Visibility and
Internationalization, and Betterment and Retention of Talent. A brief summary of the clusters activities is
given. In this article, the focus will be on R&D and innovation, through industry driven collaborative
initiatives and the tools and actions that lead to successful partnerships. Topics discussed in this work are
will be a cluster's role in promoting strategic change, the value chain approach to partnerships,
international collaboration in projects and specific cluster activities. Some practical examples of
initiatives relating to effective collaboration are described, focusing on one of the mayor challenges of our
time: the greening of the planet. Examples will be addressed in smart cities, efficient LASER applications
and lightweight optical sensors for civil security. In all cases the collaboration between the public and
private sectors is shown.
Lately the short-wave infrared (SWIR) has become very important due to the recent appearance on the market of
the small detectors with a large focal plane array. Military applications for SWIR cameras include handheld and
airborne systems with long range detection requirements, but where volume and weight restrictions must be
considered. In this paper we present three different designs of telephoto objectives that have been designed
according to three different methods. Firstly the conventional method where the starting point of the design is an
existing design. Secondly we will face design starting from the design of an aplanatic system. And finally the
simultaneous multiple surfaces (SMS) method, where the starting point is the input wavefronts that we choose.
The designs are compared in terms of optical performance, volume, weight and manufacturability. Because the
objectives have been designed for the SWIR waveband, the color correction has important implications in the
choice of glass that will be discussed in detail.
A high-precision, low-cost tool for optimal alignment of a compensator group in anamorphic objectives is presented. The
system provides highly accurate information by analyzing the axis and field PSFs in the focal plane of the optical system
under test. The PSFs are provided by a bundle of 9 different pigtailed laser diodes placed in the object field, and they are
recorded by a lensless 2/3" CCD camera. The comparison of the simulated and obtained PSFs allows determining the
optical element introducing the differences so action may be taken precisely on that element. The system is especially
useful in non-rotationally symmetrical systems, where errors in axis position result into asymmetries of the PSF images.
The tool is used for precise alignment of the cylindrical lenses in the compensator group of an anamorphic objective
prior to sealing. Results show the system is able to detect misalignments of 100μm and axis positioning errors of just
30arcsec using off-the-shelf components without the need of high-precision positioning equipment.
Digital taking systems for HDTV and now for the film industry present a particularly challenging design problem for rear
adapters in general. The thick 3-channel prism block in the camera provides an important challenge in the design. In this
paper the design of a 1.33x rear anamorphic attachment is presented. The new design departs significantly from the
traditional Bravais condition due to the thick dichroic prism block. Design strategies for non-rotationally symmetric
systems and fields of view are discussed. Anamorphic images intrinsically have a lower contrast and less resolution than
their rotationally symmetric counterparts, therefore proper image evaluation must be considered. The interpretation of the
traditional image quality methods applied to anamorphic images is also discussed in relation to the design process. The
final design has a total track less than 50 mm, maintaining the telecentricity of the digital prime lens and taking full
advantage of the f/1.4 prism block.
The Schmidt-Cassegrain configuration has advantages from the point of view of the packaging constraint but doesn't
provide enough optical quality through the full field of view when a larger F-number (3.6) and a FOV of 1° are necessary
to reach the minimum illumination threshold in the sensor. Moreover, to improve the global performance the telescope's
window must be spherical instead of flat. All these factors produce a poor image optical quality that must be increased.
We had overcome those problems introducing two changes in the traditional Schimdt-Cassegrain configuration. First, we
had changed the spherical primary mirror to a Mangin mirror. This introduces a second surface and an extra thickness
that can be used to optimize the system without adding new elements. Secondly, as the Mangin mirror is the entrance
pupil of the system with a 200 mm diameter, the use of aspherical surfaces on it is too expensive. Instead we have aspherized the telescope's secondary mirror to obtain the required image quality.
This aspheric coefficient of the secondary mirror, introduced in an element with a diameter not larger than 50 mm, replaces the third order coefficient of the second surface of the telescope window.
Illumination engineering is a field that spans many topics and the number industries that actively work in the field is
expanding. In this field the efficiency of the design is only a part of the design. Of nearly the same importance is the
distribution of the light at the target. Many times the factors that are necessary to develop an illumination system will
contradict one another, thus making the design of illumination systems complex and demanding. Optical modeling plays
a basic role in obtaining new models. In general, the LED optical model obtains its parameters as a mathematical
transformation or the average of a large set of measured experimental data. The main goal of this paper is to measure
directly the parameters of the LED optical model. We use the typical LED spatial distribution model based on ray
distribution. The basic parameters of this model are: the slope of the ray and the energy of each ray. The measurement
system incorporates the slope measuring method used in deflectometry into an energy measurement technique. The
method was tested using the measured data of two LEDs to analyze the illumination distribution provided at the image
screen of standard Köhler illumination system.
In this work a numerical technique for calculating the influence of diffraction of an electromagnetic wave by a boundary in an optical system within a ray-tracing environment is presented. The technique was inspired by the theory of Boundary Diffraction Waves applied at circular apertures. The numerical technique presented here is intended to analyze diffraction of a wavefront at a circular aperture within an optical system, but not restricted to being the aperture stop. At the diffractive aperture discrete sampling of the wavefront permits the selection of a geometrical wave and separates this wave from an assumed boundary wave that will direct luminous energy from the incident wave into the geometrical shadow. Sampling requirements are also discussed since three sampling periods need to coexist. A pseudo-random sampling technique is applied to sample the diffracted rays in order to reduce aliasing in the final irradiance distribution. The technique is incorporated into a traditional ray tracing environment to allow future generalization of the technique. Two cases were simulated. First the far-field diffraction due to a circular aperture was simulated. The results were close to the analytical solution of diffraction by a circular aperture in the Fraunhofer region. The comparison was feasible in a ray-tracing environment due to the incorporation of perfect imaging lens that acted as a phase element in that appropriate phase correction was introduced. Finally a thick bi-convex lens was simulated such that the aperture was placed before the bi-convex lens.
The reduction of contrast due to scattering by optical mounts and buffers was studied, especially for the systems that must work in the infrared region. When a particular optical system is optimized [1,2] up a specified field value the scattering effects introduced by optical mounts and buffers must be taken into account. The scattering effect plays an important role in the IR region where the influence of off-field effects is important. The contrast reduction due to scattering effects is not uniform with the object position, in other words the influence of scattering effects has field dependence. The scattering model used is based on the classical point of view of the scattering electromagnetic wave and it is adapted for optical evaluation using ray-tracing techniques. In order to test the validity of our scattering model we calculated the distribution of illumination produced for a laser beam in a plane-parallel plate with perfect scattering properties at the back surface. The comparison between the results obtained form our model and the analytical models permit us to extrapolate the use of our model in systems that involve more complex geometry. The model was applied in a four element IR objective with germanium and silicon lenses. In all the situations the contrast as a function of the field value was calculated, with and without the scattering effects. By contemplating the contrast loss, a better choice of materials, geometries and buffer positions can be made possible.
In this paper we present a robust pseudo-random method for propagating an electromagnetic wavefront through an arbitrary optical system. The wavefront at an arbitrary plane is obtained by the discrete sampling of the wavefront in regular regions equally distributed on the entrance pupil and the appropriate modelling of the optical properties of the system. The discretization permits us to treat each region as a plane wave, so long as the area is small compared to the area of the pupil, therefore allowing us to apply the electromagnetic approximations of refraction and reflection during the transfer through an optical system. We can therefore account for amplitude and phase modulation of the wavefront due to the optical system, without making any assumptions about the shape of the optical elements. Furthermore, our numerical integration method on an arbitrary plane avoids singularities due to the classical analytical integrals, while still obtaining results comparable to rigorous electromagnetic theory. We have applied the method to simulating the propagation of both plane waves and spherical waves. The well known interference patterns of classical experiments such as Young's interference fringes or Newton's rings were reproduced accurately, with respect to results obtained applying analytical methods. We then successfully applied the method to analyze a Michelson interferometer set-up, demonstrating the robustness of the calculations. Since the propagation of the wavefront is possible with this method, in the future we plan to apply the method to simulating electrically large diffractive optical elements within a complex optical system, for which rigorous analytical methods may not be available, and other numerical methods generally require large computer resources.
Progressive ophthalmic lenses involve high resolution technological manufacturing processes, due to the particular non-symmetrical, aspherical form of their convex surface. However, the testing of the surfaces is not usually performed using whole-field methods because of the high dynamic range and resolution required for the slope changes in the convex surface. Applying some simple enhancements, a robust Ronchi test technique can be used to obtain accurate power distribution maps of commercial progressive lenses. In this technique, a CCD detector is used as a high resolution slope map, which combined with multiple acquisition techniques, allow for high resolution measurements of both lateral displacement (10<sup>-4</sup> m) and slope measurements (10<sup>-5</sup> rad) with the required dynamic range in slope measurements for progressive power lenses. The power maps of different types of progressive lenses are presented, showing the differences between lens design and manufacturing. The ability of the enhanced Ronchi test technique to quantitatively map power variations with important slope changes is demonstrated.