In a perfect world a good starting point should not be required. A Genetic Algorithm in powerful lens design software should find an optimum solution for us. As a practical matter a good starting point does matter. Time and resources may not be sufficient to generate a good design in a global optimizer quickly. In lens design a small glass catalog combined with the Hammer algorithm in ZEMAX moves the glass selection process in a search around the glass map forcing the design to consider many radically different forms in a short amount of time. From this starting point an expanded search can be undertaken by conventional design methods or in a global search algorithm. There are precedents in other fields for a narrow search method that still yields near infinite numbers of solutions. Mozart invented a game that narrows a search from a blank sheet paper and a set of notes to a single voice minuet by rolling dice. The results can be played and the dynamics manipulated to form the starting points for future compositions. Music composition software has, like lens design software, incorporated many powerful algorithms and search techniques. A simple comparison will be made. It is a long way from a protoplasm to Christie Brinkley. A good starting point means a lot whether you are an optical designer, a composer, or running the universe.
While researching various gradient index glass families for superb color correction using ZEMAX1 optical design program, the authors found that certain solutions could only be found using the Hammer routine2. Hammer is a genetic algorithm that breeds a particular lens configuration with variations of itself3. It is not intended to be a global search routine. Hammer is typically used after the best performance is obtained using the standard damped least squares (DLS) algorithm with the default merit function (MF) based on minimizing root mean square (RMS) spot size. Upon this discovery, the authors proceeded to explore the benefit of using the genetic Hammer algorithm on three different lens systems. To make the solution space more complicated, two axial gradient index (AGRIN) elements were used in each lens type; a bi- AGRIN cemented doublet; a bi-AGRIN air spaced triplet with CaF2 as the center element, and a double Gauss with four AGRIN elements and two CaF2 elements. AGRIN elements were used in each lens to provide a more complex solution space and to make optimization more difficult. After optimization, the performance of each lens was compared wiht the conventionally optimized counterpart using the default MF with a DLS algorithm. After this comparison was made, another trade study was done between the Hammer and DLS algorithms, but in this case, the optimization used a custom MF instead of the default MF. The authors believe this study shows the importance of MF construction over that of using the default RMS spot size metric. A significant improvement was obtained for all lenses with the default MF using the Hammer over the DLS technique, but that improvement was less obvious when a custom MF was used.
The optical design for an Infrared Multiple Object Spectrometer (IRMOS) intended for Astronomical research is presented. To accomplish spectroscopy of multiple objects simultaneous, IRMOS utilizes a Micro- Mirror array (MMA) as an electronically controlled slit device. This approach makes object selection simple and offers great versatility for performing spectral analysis on many objects within a field location. Furthermore, it allows a field location to be imaged without spectra prior to object selection. The optical design of IRMOS has two distinct stages. The first stage reduces an f/15 incoming beam to f/4.5, with a tilted focal plane located at the MMA (the MMA removes some of the tilt of the focal plane, since the micro-mirrors tilt individually). The second stage consists of the spectrometer, capable of resolutions of 300, 1000, and 3000 in the astronomical J, H and K bands. This stage transforms the tilted focal plane into a collimated pupil on a grating, and then re-images onto a HAWAII detector. When used with the Kitt Peak National Observatory 4 meter telescope, a plate scale of approximately equals 0.2 arcseconds per pixel is realized at both the MMA and the detector. A total of 6 mirrors are used, two flat fold mirrors, two off-axis concave aspheres, one off-axis convex asphere, and one off-axis concave biconic mirror. The selection of a biconic surface in this design helped reduce the overall size of the instrument by reducing the size and number of necessary mirrors, simplifying alignment.
New functional representations are needed for describing aspheric surfaces that can compensate for a high degree of wavefront asphericity and represent steeply sloped surfaces as the surface normal becomes perpendicular to the optical axis. The explicit definition of the standard aspheric surface limits the range of surfaces that it can properly describe. This paper presents both a parametrically defined surface approach and an implicitly defined surface approach. The utility of these novel approaches is demonstrated using examples of current interest. Additionally, this work shows that a Fourier series is not a useful optical surface.
Most optical systems may be understood as wave-transforming systems. One input wave is transformed into a corresponding output wave. The quality of the system is evaluated by merit functions applied to the output wave. In monofunctional or multifunctional design methods free parameters of the optical system are optimized with respect to one or more pairs of input waves and merit functions, respectively. Laser beam shaping may be understood as the transformation of waves originated by laser sources. In this paper we present a strategy for the systematic design of systems to realize monofunctional wave transformations. By this method we obtain not only a suitable phase-only transmission, which must be realized by a suitable element or module, but also their position, the number of transmissions/elements necessary to maximize the conversion efficiency of the system, and the upper limit of the conversion efficiency for a specific number of introduced transmissions/elements. We call this strategy amplitude matching. It is based on an inverse design approach. The input field is propagated forward and a desired output field is propagated backward. The system is designed with the goal to find a plane in which the magnitudes of both fields match perfectly. If required more than one element are introduced in the optical system by synthesis of phase-only transmission functions.
The double expansion of wavefront deformation in Zernike polynomials over pupil and field-of-view coordinates is a powerful tool for lens design, testing and alignment. It provides a compact description of wavefront deformation of centered and decentered optical systems over the field-of-view. Understanding the structure of this expansion provides a solution for determining the optimum position and minimum number of field-of-view points for wavefront approximation. This can significantly reduce the computational burden of lens design and is especially important for time consuming wavefront testing before lens alignment.
A strategy for designing optical systems that are optimized for multiple optical functions on the basis of wave optics is presented. Each optical function is composed of an input field, a set of fixed system parameters, and a merit function. A design algorithm is proposed which is applicable for optical systems consisting of an transmission operator followed by an arbitrary linear operator. The goal is to find the transmission operator which is optimal for all optical functions simultaneously. In later design steps, the found transmission operator can be transformed to real optical elements, for instance by using the thin element approximation. It is shown that the algorithm is efficiently applicable by investigating two sample applications for multifunctional wave optical design: the design of tolerant systems and 3D beam shaping.
As fiber optics transformed the telecommunications industry, integrated optics is enabling dramatic advances in the speed of optical networks. This new technology is also leading to compact optical sensors for physics, chemistry and biology. Ideally, an integrated optics sensor would be self-contained, with the light source, detectors, and other electronic elements incorporated on the same integrated optics platform as the optical waveguides themselves. However, many challenges remain in the fabrication of fully integrated optoelectronic sensors. In this paper, we present innovative approaches in integrated optics packaging technology we have developed for fabricating integrated optics sensors for navigation, guidance, and combustion microdiagnostics. As an example, we will focus on the development of the RB-3, a three-axis rotation sensor we developed under funding from the U.S. Army Yuma Proving Ground. Besides innovations in optical layout, our design approach presents new possibilities as well as challenges for photonic integrated,incorporating active detection elements directly onboard the integrated optics chip (IOC) platform. Eliminating the fiber pigtails which would normally carry the optical output to an external detection scheme not only adds ruggedness to the sensor, it also allows a reduction in size and mass. With this configuration, the incorporation of the IOC into a larger system only requires electrical inputs and output to the IOC, eliminating all but the input fiber pigtail from the light source. In describing the on-board detectors system, we include a description of the chemical dry etching and micropositioning techniques we have developed, as well as the wirebonding schemes we used to interface the detectors with external electronics. We also briefly discuss the engineering of the sensor package and the external housing. We finally give a summary of some of the challenges that remain to the practical implementation of fully integrated optics sensors which include onboard light sources and other electronic components.
The design and optimization of a retinal exposure detector for measuring the total amount of light entering the human eye and falling on the retina is presented. The retinal exposure device was designed by first determining the spatial efficiency function of the human eye system. This is accomplished by combining the spatial response function of the average human eye with a standard facial cutoff function. The eye's spatial efficiency function is ascertained through ray trace analysis with optical modeling software of published theoretical and biometric wide-angle eye models. All major factors affecting light propagation, such as volume attenuation, the gradient index of the lens, aspheric surface curvatures, partial reflection, and vignetting are included in the simulation. A practical metering device that mimics the calculated total eye system spatial response function was designed and optimized by again employing optical simulation software. The final design consisted of baffles, a lens system, a decentered aperture, an optical diffuser, optical filters, and a silicon photodiode. The response of the prototype retinal exposure detector device design was shown to match that of the theoretical eye response to within three percent.
The temporal resolution of a confocal laser microscope, by which three- dimensional data of specimens are obtained, usually suffers the slow speed of image acquisition devices, such as CCDs, or scanning mirrors. Here we propose a confocal microscope system where parallel optoelectronic devices are employed aiming at obtaining high frame rate of three-dimensional data that provides real time analysis of dynamical properties and adaptive feedback control of the specimen. A smart pixel yields pixel-parallel data processing capability owing to its integrated optical devices and electronic processing circuits fabricated on the same chip. A vertical-cavity surface-emitting laser (VCSEL) array is introduced for the parallel probing beams by which the optical system is simplified. In addition, pixel parallel illumination control is achievable. We have performed basic experiments on a syst em composed on an 8x8x VCSEL array, a silicon photodetector array, and processing element (PE) array. Each PE contains an arithmetic logic unit (ALU), 24- bit local memory, and electrical connections to neighboring pixels, that provides fast processing versatility such as the moving object recognition. Vibrating a sample by a piezo micro stage, we have successfully obtained a dynamical property, which is a one-dimensional moment of the moving sample, on the basis of the data obtained by the experimental system over the range of conventional video frame rate.
We developed a standard credit card-shaped general-purpose data carrier, a reflective Holographic Memory Card (HMC), and the appropriate equipment for its handling. Data recording and retrieval are accomplished by polarisation Fourier holography using a thin layer of photo-anisotropic polymer as the storage material. The data density is about 1 bit/micrometers 2, the maximum storage capacity of the card is around 10 Mbytes assuming a 10 x 10 mm storage area. Data is stored in the form of microholograms, from which 40x40 pieces are recorded on the HMC. The optical system involved performs data writing/reading/erasing and also locates the position of the microholograms. Main components of the optical system are an SLM and CCD for opto-electronic conversion, a frequency-doubled solid-state laser source, a beam shaping system that provides homogeneous illumination of the SLM, an interferometer for hologram construction, special Fourier transforming objectives and a random-phase mask for optimised hologram recording. Our results include conceptual planning, design, fabrication and assembling of the optical system. In the present paper we describe principle of operation including layout of the elements, and explain the operation of the equipment in detail.
In this paper, the geometric configuration of recording beams and the orientation of crystal axis is optimized for optical holographic storage in order to achieve the preferable effective dynamic range and angle selectivity simultaneity. The influences of the defocusing amount of record crystal on data retrieval in the Fourier transform configuration are studied theoretically. The field lens is used in the optical path for Fourier transform to reduce the length of optical path and the distortion. T he optimization results are used to design the optical architecture for miniaturizing the optical holographic storage system.
An investigation on methods to capture dual waveband image with CCD camera has been conducted. A split image concept has been identified after reviewing different possible configurations. A prototype development has been presented and the experimental image captured by the prototype has proven the proposed split image design concept. This concept can also be applied to middle or long wave infrared waveband. It has potential applications in surveillance, target classification or identification.
Nonimaging reflectors designed with rays other than the edge rays allow the designer to tailor the irradiance distribution at the target surface, especially for targets located at a finite distance from the source. An iterative approach of the development of the reflector shape allows for both uniform and asymmetric light distributions to be generated. The defining rays are chosen due to the characteristics of the prescribed source and the desired light distribution at the target, or in other words the final reflector design is dependent on the required application. Two-dimensional reflector (2D) shapes (i.e. troughs) are developed herein, but the method can be extended to three- dimensional (3D) reflectors (i.e., wells). Two examples employing specular reflectors for diode pumping of a solid-state laser rod are presented. These cases use a pseudo-imaging technique to direct the light to the preferred target. A final example develops a plastic lightguide that uses total-internal reflection (TIR) to obtain uniform illumination over a target plane.
Since their development in the mid-1960's, the luminous efficiency and range of available output wavelengths of light-emitting diodes (LEDs) have increased to such a degree that an enormous number of new applications for LED sources are now being pursued. For these applications, it is critically important to design the illumination optics to achieve high flux-transfer efficiency. In this paper we describe a nonimaging projection lens design to efficiently collect and transfer flux from a Hewlett-Packard LED source to a rectangular target at a distance from the Led and tilted with respect to the lens' symmetry axis. The source was experimentally characterized using a technique that captures its full four-dimensional luminance distribution. The lens was then designed by implementing a constrained global optimization procedure over a parametrization search space with variables that determine the positional and aspheric geometrical properties of the lens. The optimization was performed subject to constraints arising from packaging and fabrication considerations. The resulting lens employs a combination of refraction and total-internal reflection (TIR) mechanisms to achieve a total flux-transfer efficiency of 40%.
It has been shown that it is possible to fabricate very small lenses by melting islands of inorganic photoresist on a glass substrate. The inorganic photoresist composited in our laboratory is suitable to be exposed by Electron Beam (EBE) or X-Ray. We have obtained the lithophotography pattern with 0.6 micrometers line width by EGE exposure. Because the resist pattern will not swell and distort during the processing, there is no problem of shelf life. We have made lenses with diameter from 0.8 mm to 1.0 mm, in the form of spheres, and have studied their optical properties.
The unique C60 atoms configuration known as buckyball have attracted notice for their ability to quench light, but layered buckyballs can be used in novel laser nanointerferometers. These nanointerferometers have the wide area of applications: manufacturing, metrology, biology, medicine, industry, space equipment, astronomy, physics, biophysics, biochemistry, pharmacology, cell research, biometrics, microelectronics, etc. The nanointerferometers are proposed with this aims and can be very small. A nanointerferometers consists of a laser, special equipment with layered buckyballs and image receiver. The layered buckyball surface are used in laser nanointerferometers for making a reference and a working beams. One part of the beam of laser reflects from one side of the layered buckyball-this is a reference arm. The last part of the laser beam reflects from the other side of the layered buckyball and goes to a mirror, - the working arm of the interferometer. Then working beam of the interferometer passes back from mirror and interfere with reference arm. The interferometers pictures can be recorded by means of the image receiver, for example, CCD. The equipment must be made of zero-expansion material. These new nanointerferometers are simple in use, have the low cost and easily/fastly manufactured in quantity. These new nanointerferometers are use in extremely wide region of spectrum. The novel unique buckyballs call and do new sciences of novel buckyballs laser nanointerferometry and new buckyballs high technology in the aforementioned very wide area of applications.
A novel integrated optical biosensor, that combines optical planar waveguides for illumination with microlens arrays for collection of fluorescence, is presented in this paper. This sensor is based on laser induced fluorescence detection and will be applied for biochemical or chemical applications such as fluorescence labeled DNA affinity assay. An evanescent field is generated by the optical planar waveguides, which illuminate DNA arrays on the surface of the waveguide. High signal to noise ratio and sensitivity can be achieved since the evanescent field is tightly confined within the neighborhood of the surface of waveguides and laser noise will scarcely reach the detector. Micro lens arrays with large numerous aperture are combined into the sensor to collect more fluorescent lights from DNA samples induced by the evanescent field. A high sensitive CCD is used for this multi-channel system. The sensor has advantages of compactness, multi-dimensional channel detection simultaneously, high sensitivity and good compatibility with biology samples, so it is not only suitable to be used in detection of fluorescent labeled DNA arrays, but also can be used in other life science research like fluorescence immunoassays. The compact design of the sensor allows it to be integrated in a micro total analysis system ((mu) -TAS) such as a portable DNA diagnostics device.
Increased performance for optical telescopes has historically come from larger apertures, from technological advances for the telescope components, such as detectors, and from access to better sites, such as space. Little has changed in the basic telescope design for a century. These conventional designs have served us well and will continue to do so with the Next Generation Space Telescope. There is an upper limit to the size of thsi type of telescope, set by the capacity to launch the required mass. For future space telescopes of 50, 100, 500 meter apertures, we have developed a new type of optical design. We use a primary reflector made from segments of flat and near-flat membranes. The secondary reflector and subsequent optics are supported in separate spacecraft, flying in formation with the primary reflector. In addition, each spacecraft maintains sunshields to keep the optics shaded from the sun. This paper explores the optical design issues for this type of giant space telescope.