Proceedings Volume 7428

Current Developments in Lens Design and Optical Engineering X

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Proceedings Volume 7428

Current Developments in Lens Design and Optical Engineering X

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Volume Details

Date Published: 21 August 2009
Contents: 8 Sessions, 23 Papers, 0 Presentations
Conference: SPIE Optical Engineering + Applications 2009
Volume Number: 7428

Table of Contents

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Table of Contents

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  • Front Matter: Volume 7428
  • Plenary Session
  • Invited Session: Joint Session with Conference 7429
  • Modeling and Optimization
  • Optical Design I
  • Optical Design II
  • Optical Design III
  • Posters Session
Front Matter: Volume 7428
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Front Matter: Volume 7428
This PDF file contains the front matter associated with SPIE Proceedings Volume 7428, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.
Plenary Session
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Optical design dependence on technology development
Specific developments in optical technology over the past thirty years including refractive materials, thin film coatings and surface profiles will be discussed. A large variety of optical designs which depend on some of these developments will be described. The optical design examples presented will cover the infrared, visible, ultraviolet and combinations of these wavebands. A novel multi-waveband optical system that utilizes many of these developments will be illustrated in several possible configurations to meet different application requirements. A summary of the technologies employed in all of the optical design examples will indicate whether or not there may be trends in optical technology development. The optical design examples will be taken from issued Patents or published Patent applications and hence their optical prescriptions will be available for detailed analysis.
Invited Session: Joint Session with Conference 7429
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The fascinating early history of optics! Archaeological optics 2009: our knowledge of the early history of lenses, mirrors, and artificial eyes!
The early history of optics and vision science (older term: physiological optics) is indeed fascinating. The earliest known true lenses have been found in "eyes" of Egyptian statues which contain superb, complex, and well-polished eye-lens units. The oldest ones known are dated circa 2575 BCE = BC, Dynasty IV, Old Kingdom. These eye-lens units induce a fascinating and powerful visual illusion, but they are just too good to have been the first lenses, or even the first lenses of this design! So saying, no earlier dateable lenses have been found in Egypt or elsewhere. Recently, at the Boston Museum of Fine Arts, the writer noted a previously undetected lens in this series (a first in the Western Hemisphere). Oddly, dateable simpler magnifying lenses and burning glasses seem to have appeared later in time (?)! Manufactured mirrors are quite a bit older, dating from circa 6000 BCE in atal Hyk, located in south-central modern-day Turkey. Using these ancient mirrors, the image quality obtained is remarkable! Recently discovered ancient artificial eyes, located, in situ, in exhumed corpses, have been dated circa 3000 BCE (one discovered in Iran) and 5000 BCE (one found in Spain). On the 3000 BCE artificial eye, there are drawn light rays (the writer believes these to be the oldest known depiction of light rays!) spreading out from (or passing into) the iris/ pupil border! Added interesting aspects associated with the early development of light-rays are considered. Thus, early optics can be readily traced back to the Neolithic era (the new stone age), and in some cases before that time period. We have deep roots indeed!
Practical design considerations for modern photographic optics
In the 1950s, cameras and lenses didn't communicate. Optical bench tests were sufficient to characterize lens performance completely. Today, optics are only one small factor in the much larger electro-optical systems which are today's cameras. Bench performance alone isn't enough. For a lens to be useful it must work in concert with modern cameras' focus, exposure and data systems. This paper explores these numerous issues and their influences on lens design. Outside-the-barrel ergonomic and systems issues are covered in SPIE paper 7428-19.
Display systems and registration methods for mixed reality applications
Mixed reality technologies have been studied for many years, which now can be applied in many aspects of our daily life. Generally, appropriate display devices and registration methods are the key factors for the successful application of the mixed reality system. In the past decade, various types of display systems have been developed at Beijing Institute of Technology, and many of them have been successfully employed in different mixed reality applications. In this paper, we give a brief introduction to the various display systems and their corresponding tracking approach developed and realized at Beijing Institute of Technology for mixed reality applications. These technologies include an interactive projection system based on motion detection, a fixed-position viewing system, an ultra-light wide-angle head-mounted display system and a volumetric 3D display system.
Modeling and Optimization
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Efficient design process for the evaluation and control of flare in opto-mechanical systems
Even the best optical designs can be ruined by unwanted light: flare in the form of ghost images and veiling glare. The analysis of stray light in an opto-mechanical system is a step in the design process that is often limited to ghost image analysis by the optical designer. In many large design groups, stray light analysis is traditionally performed by optical engineers with very specialized analysis tools that are difficult to master. However, recent improvements in software packages are now offering tools that allow less experienced designers access to tool sets that can perform flare and veiling glare analysis for a substantial subset of optical design problems. This paper outlines an effective and efficient design process for determining the types and magnitudes of stray light in an optical system and demonstrates its use on an injection molded plastic lens assembly. We describe a capability that locates all of the optical paths and their relative magnitudes through an optical system and separates them into one of three categories: image path, ghost paths, or veiling glare. We then describe how to leverage this information to determine the most effective removal method for the "worst offenders".
Paraxial ghost image analysis
This paper develops a methodology to model ghost images that are formed by two reflections between the surfaces of a multi-element lens system in the paraxial regime. An algorithm is presented to generate the ghost layouts from the nominal layout. For each possible ghost layout, paraxial ray tracing is performed to determine the ghost Gaussian cardinal points, the size of the ghost image at the nominal image plane, the location and diameter of the ghost entrance and exit pupils, and the location and diameter for the ghost entrance and exit windows. The paraxial ghost irradiance point spread function is obtained by adding up the irradiance contributions for all ghosts. Ghost simulation results for a simple lens system are provided. This approach provides a quick way to analyze ghost images in the paraxial regime.
Finding order in the design landscape of simple optical systems
P. van Grol, F. Bociort, M. van Turnhout
Contrary to the frequent tacit assumption that the local minima of a merit function are points scattered more or less randomly over the design landscape, we have found that, at least for simple imaging systems (doublets with three and triplets with five variables) all design shapes we have observed thus far form a strictly ordered set of points, the "fundamental network". The design shapes obtained for practical specifications with global optimization algorithms are a subset of the set of local minima in the fundamental network and are organized in a way that can be understood on the basis of the fundamental network.
Photometrically corrected holographic lens
J. G. Suarez-Romero, R. Salas-Zuñiga
Optical detectors for illumination measurements have the known photopic response V(λ), which is implemented with the help of colored glass filters attached to silicon detectors. In the case of high precision photometry the filter of each detector is hand prepared and the spectral response measured until it is matched to the function V(λ). This method takes a long time and the precision is limited. In this work we propose an optical method to implement holographic lens with predefined spectral selection, this method permits to make the optical design of the hologram when the spectral response of the silicon detector is known.
Optical Design I
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Design and optimization of a collimating optical system for high divergence LED light sources
This paper presents the design of an efficient collimating optical system for an extended light source, namely a highbrightness high divergence light emitting diode (LED), sized 1x1mm, and viewing angle of 130°. The design lies in a catadioptric rotationally symmetrical system, which modeling and optimization has been done by specific optical design software, ZEMAX®, and its development was based on geometrical principles. The device consists of two optical systems, one for the rays emerging from the source with low numerical apertures (NA<0.26) and another one for those emerging with NA>0.26. The system for rays with low NA consists of an aspherical lens system which parameters are optimized by means of standard criterion for collimation. The system for high NA rays is a combination of a hyperbolic and a parabolic mirror, being the first one the only surface shared by both system (refractive near-axis, reflective offaxis). The result of this work is a system that reaches a collection efficiency of 80% of the LED emitted light. Moreover, the beam collimation quality has been analyzed obtaining a residual divergence of less than 2°. Thus, the results achieved by the proposed optical system improve those obtained with several commercially available devices and other previously proposed systems.
Design method of secondary optical element for LED applications
Light Emitting Diode, LED, has many advantages in many lighting applications, such as general illumination, street light, and auto lamp. In general, each application needs to do secondary optical design for its specific request. A secondary optical element can be separated into refractive and reflective part. In this paper, we present a design procedure of secondary optical design with intensity distribution of LED and sequential ray tracing. The method suits the both designs of refractive and reflective parts. In the first process, we integrate the series function of intensity distribution in spherical coordinate with a range of solid angle. In the second process, we calculate the redistribution parameters of luminous flux by the geometric parameters of LED, element, and detector. In the final process, we use ray tracing method to design the optical element by aspheric surface. The surface of the refractive part in secondary optical element could be Fresnel surface for reducing the thickness of element. For proving the design procedure, we design a secondary optical element of LED by this method with an illumination request.
Optical Design II
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Active alignment of vertebrate cone and rod photoreceptor waveguides: might this serve as a useful fiber-optics model?
Some years ago, the speaker demonstrated that vertebrate retinal photoreceptors are fiber optics elements and waveguides, and he succeeded in defining many of their properties. For a summary of much of this research, please see the reference to Enoch and Tobey listed below (Reference 4). Included are studies of photo-receptor alignments and maintenance of receptor alignments across the retina in normal and abnormal human eyes. With very rare exceptions, rod and cone photoreceptors across the retina align remarkably and precisely with the center-of-the-exit-pupil-of-the-optics-ofthe- eye throughout the lifetime of the individual! And within a modest period of time (a day or a bit more), it proved possible to alter that photoreceptor alignment by physically displacing the pupillary aperture; and with recentration of the eye pupil, these alignments recovered their original state. Here, the author asks, "Might advantage be gained by developing alignment sensitive, photoactivated, waveguide/fiber optic units? That is, might comparable mechanisms be adapted in a useful manner to non-biological fiber-optics applications? Since such characteristic responses have been clearly of great value for biological species; might similar designs serve other important roles?"
Point symmetric design approach to a wide-field wide-wavelength cat's eye retro-reflector anastigmat
A point symmetric design approach for creating a practical cat's eye retro-reflector (CERR) anastigmat lens with a wide field of regard (FOR), uniform reflectance and wide wavelength range is described. An anastigmat design is presented that demonstrates the performance capability of the design approach. The lens design is diffraction limited in double pass at F/3, has a "working distance" between lens and reflector, wide wavelength range of operation, and uniform reflectivity over a 120 deg FOR. An anastigmat fabricated from the design is presented; however, the design approach is generally useful for any application requiring a high performance retro-reflector. The design uses only spherical surfaces, thereby avoiding the fabrication expense of aspheric surfaces.
Fast catadioptric optics with large field of view
N. Blanchard, M. Doucet, N. Desnoyers, et al.
High resolution is in demand for the new applications based on the use of infrared technology. For observation task, high resolution provides more information either under the form of better resolving power or larger field-of-view. Various solutions can be envisioned to achieve high resolution imaging. In this paper, a combination of high resolution detector and microscanning system is proposed. This strategy results in higher resolution and reduced aliasing. A catadioptric configuration is preferred when a microscan is required to increase the spatial sampling frequency. Among the catadioptric configurations, the Schmidt-Cassegrain has wide angle capability due to its aspherical entrance window. However, when the system is used in harsh environment, this compensator window may have to be replaced often. In this case, a flat window would be preferred because it can be removed or easily replaced at reasonable cost. The reduction of the aberrations to an acceptable level without compensator window requires that the mirrors of the telescope be aspherized. In this paper, we present a modified Cassegrain telescope with two aspherical mirrors and one field lens. Due to the large obscuration of the secondary mirror, the effective F/1.05 necessitates a larger working F-number of 0.75. The spectral band ranges from 7.0 to 14.0 microns and the focal length is 50mm. The system is designed for the ULIS UL04171 microbolometer detector with 640 x 480 pixels and 25 microns pixel pitch. With this sensor, the total field of view of the system is 22.6 degrees, which is very large for a catadioptric system. A microscan increases the system maximal spatial sampling frequency from 20 to 40 cycles per millimeter. Despite of the compactness, there is enough room between the field lens and the detector to insert a shutter. A baffle extending ahead of the device is needed in this large field of view design to avoid undesired rays reaching the detector.
Optical Design III
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Thinking outside the barrel: what really matters in modern photographic lens design
Because optical performance has increased so far with modern design software and aspherical manufacturing processes, optical performance is now the least important factor in modern photographic lens design. Far more important are ergonomic (usability) and systems-integration factors which determine a lens' acceptance by photographers, and ultimately, its commercial success. Common SLR cameras tend to have the most advanced systems and features, so they tend to be the focus of this paper simply because they offer the most to discuss. Inside-the-barrel optics and other design considerations have been covered in SPIE paper 7428-3.
Posters Session
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Calculation of optical forces on a dielectric bead in a geometrically aberrated trap
Micron-sized particles can be trapped by means of a highly focused beam; light is concentrated in a tiny spot using a high numerical aperture objective. In this communication we describe a numerical tool we have developed for obtaining the force exerted by a beam on a spherical dielectric particle in realistic conditions. The system (a water immersion microscope objective) is simulated using an optical system design software that provides the required information to feed the application. The calculation of the force is carried out using the ray-optics (Mie) approach.
An optical switch of natural light guiding system based on cubic structure with fresnel surface
Recently, many researches focus on illumination with sunlight for saving energy and healthy lighting. A Natural Light Guiding System has collecting, transmitting, and lighting parts. In most systems, the paths on transmitting part are fixed so the collected sunlight of the Natural Light Guiding System can not be free managed and is sometime wasted. In this paper, we design an optical switch to change the path of the collected sunlight on the transmitting sunlight. The switch is cubic structure that includes a 45 degree mirror for reflecting sunlight. According to the structure of the optical switch, we can rotate the switch to manage the path of the collected sunlight. When the path is parallel with the mirror, the sunlight will pass through the switch; and when the included angle between the path and mirror is 45 degree, we can change the path of light. For coupling the exit beam into lightpipe, we design the surfaces of cubic structure to be aspheric surface with Fresnel surface. Finally, we simulate the efficiency of the optical switch when the path is changed by the mirror.
Relationships between lens performance and different sensor sizes in professional photographic still SLR cameras
Current photographic still cameras, in the professional SLR step, are available in two basic sensor sizes, 16x24mm and 24x36mm and both of them can be used with the same or similar range of focal length lenses. Lens aperture determines resolving power and diffraction effects and indeed, MTF function. In order to preserve an acceptable image quality level, it must be taken into account that a high lens resolving power at larger apertures can be replicated by the sensor as a false response or aliasing, while the size of the Airy disc must be related with photo receptors pitch. Provided that a standardized metric of image quality is the system MTF, this work compares different lenses resolving power as a function of aperture with the lens and system MTF; both aliasing and resolution affectations can be observed in the system MTF. Lens resolving power has been measured by visual inspection of the aerial image of an USAF1951 test target through a suitable microscope. The lens PSF and MTF has been measured by means of a Shack-Hartmann optical wave front sensor. The system MTF is measured by the slanted edge method. The different experimental procedures have been applied to two professional SLR cameras equipped with the same general use lens.
Auto-focus imaging systems with MEMS deformable mirrors
Miniaturization is the key point to design image system for portable devices. Motor-driven lens technique is the traditional way to achieve auto-focus and zoom functions. Nevertheless, systems with moving parts are difficult to downscale. A solution presented in this paper has more potential to downscale and maintain high optical performance simultaneously by combining reflective optics and MEMS deformable mirror. The system we designed with MEMS deformable mirror is a 2M pixel auto-focus image system which is only 5.4mm in thickness before packaging and 6.7mm in thickness after packaging.
Exact analytical design method for paraxial chromatic correction in axis-symmetrical optical systems
We derive and investigate an exact analytical paraxial longitudinal chromatic function for axis-symmetric optical systems. We prove the existence of two conjugate pairs of achromatic points in the object and image space of every centered optical system (in general they are two, but in some cases they can be missing or their number can be one or infinite-dimensional) and derive formulae for determination of their position in object and image spaces. On the base of this function we develop an exact analytical design method for paraxial chromatic correction in axis-symmetric optical systems. In addition we show some examples.
Exact analytical astigmatic function of aspherical surfaces
We derive an exact analytical image astigmatic function for aspherical and hyper-aspherical surfaces of arbitrary shape that describes correctly (without any approximations) image astigmatism for the whole object space and investigate this function for two general cases: in the presence and in the absence of object astigmatism. So we discover the boundary astigmatism correction ability of aspherical surfaces. We prove that in general there are two anastigmatic points on each chief ray in every aspherical surface. We find as well analytical expressions for anastigmatic and extreme points of the function and its vertical and horizontal asymptotes. As a result we prove that in the object and image space of every refracting aspherical surface at each stop position there are two pairs of anastigmatic surfaces one of them coincides with the refracting surface itself. In the object and image space of every reflecting aspherical surface at each stop position there is in general one anastigmatic surface which coincides with the reflecting surface itself. There are special cases when the whole space of the reflecting aspherical surface is anastigmatic.
Optical system module having zooming function and image quality of mega pixel for a cellular phone camera
Seong Jong Park, Jong Jin Lee, Chang Sub Chung
We designed and developed a cellular phone camera like HD digital still camera having zooming function. To design an optical system module having the auto-zooming and the image quality of 2M mega pixel using Code V, we considered 6 lenses which were four aspheric plastic lenses and two glass lenses. The specifications of designed optical system module for a cellular phone camera were the focal length of 4.29mm at wide position to 10.55mm at tele position, fnumber of 3.2 at wide position to 5.3 at tele position, and field of view of 27.4 degree at tele position to 65.8 degree at wide position. Its zoom ratio was 2.5. The values of modulation transfer function (MTF) at 200lp/mm of the designed optical system module were over 21% at zoom position. We applied the design results of optical system module to the fabrication of a cellular phone camera having the zoom ratio of 2.5 and the image quality of 2M mega pixel, and adopted the aspheric glass lens having higher abbe number to compensate chromatic aberration and the VCM (Voice Coil Motor) as sub-miniature motor. We fabricated the optical module system having zoom ratio of 2.5 and image quality of 2M mega pixel in order to apply to a HD cellular phone camera.
Optical design of a highly segmented wide field spectrograph
A lot of scientific interest around both seeing limited wide field imaging and wide field spectroscopy has been shown in the recent past. Technological difficulties have indeed been identified when proposing classical prime focus corrector for 8 meters class telescopes with Field of View bigger than one degree, because of the huge opto-mechanics and of the very large arrays of detectors required. A new concept, the Smart Fast Camera, has been recently proposed: the idea behind relays on splitting the huge Field of View in smaller portions, each of them re-imaging onto a reasonable size detector a part of the scientific Field of View. In this way, one could think to build a modular instrument, with most of the components identical for each module, with the exception of the field corrector, which is of course radial dependent. In this paper, a further development of this concept, allowing for spectroscopy, is presented, applied to an existing 8 meter class telescope, the Large Binocular Telescope. A preliminary study is traced out, with the aim to find a feasible optical design for such an instrument.