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As camera technology develops, products have improved and people have an increasing demand for visual quality. To increase the field of view, many zooming modules have been designed, which has raised the cost of optic components, increased the amount of calculation required, and complicated image processing technology. To date, dashcam lenses are primarily a compensatory design that cannot autozoom. Developing technology with various focuses for use on different roads has become a critical topic for autopilot development. Possibilities include using a short focus on general roads and using a long focus for freeways. Dashcam lens design requires the ability to cover wide angles. The concept behind wide-angle zooming lenses is that when the focal length is the shortest, the widest monitoring range is achieved. To observe a point at a far distance, we can use optical zoom to increase the focal length, thereby enabling a view into the distance. At this time, the angular field of view is sacrificed. However, a reduction of the angular field of view leads to a reduction of distortion, which subsequently reduces the complexity of back-end image processing and leads to clearer images. The design in this study references the wide-angle lens patent US.20090080093 (Ning in Compact fisheye objective lens, U.S., Patent No. 20090080093, 2011) of Alex Ning, whose optical system consists of six spherical lenses. The angular field of view reached 170°. The total system length is 18 mm, and F/# is 3. The system focus is 1.652 mm. Four groups of liquid lenses were placed in this wide-angle lens. Altering the curvature and thickness of the liquid lenses changes the course of light and forms a new angular field of view. This system consists of three zoom settings, with fields of view being 170°, 160°, and 150°, respectively. The F/# was 2.4. The modulation transfer function at a spatial frequency of 1801 p/mm reached 6%, 0%, and 27%, respectively. F-Theta was controlled within ± 10%. The spot size was smaller than 4 μm, and the field curvature was smaller than ± 0.02 mm. The liquid lenses were successfully introduced into the wide-angle lens to achieve optical zoom without using a conventional mobile mechanical structure.

Consumers nowadays have a higher expectation on cameras beyond the function of taking photos or videos. In the early years, the applications of cameras with lenses were, however, very restricted. A new generation of super wide-angle lenses capture the user’s surroundings in full 360°, allowing the user’s friends or families to step inside our universe and experience it, live. However, for such wide angle lens coverage, the relative illumination of the lens must take the vector nature of the light into account. Consequently, the polarization of light becomes a critical parameter. Custom coatings are commonly spread on the lens surface to avoid light transmission polarization falloff. But for consumer applications, complex coating is not a practical solution because it raises cost. In this paper, we present how to take care of the polarization during the design and analysis of the lens design. Additionally, design tips are proposed to suppress the polarization impact.

Advances in Optical Astronomical Instrumentation 2019; Melbourne; Australia; 9 December 2019 through 12 December 2019; Code 157181.--Proceedings of SPIE - The International Society for Optical Engineering Volume 11203, 2020, Article number 112031M, Entire Visible Sky (EnVisS) is one of the payload proposed for the ESA selected F-Class mission Comet Interceptor. The main aim of the mission is the study of a dynamically new comet, or an interstellar object, entering the inner solar system. The EnVisS camera is designed to capture the entire sky in some visible wavelength bands while the spacecraft passes through the comet's tail environment. EnVisS optical head is composed of a fisheye lens with a field of view of 180° x 40° coupled with an imaging detector equipped with both band-pass and polarimetric filters. Very wide angle lens, as a fisheye, must be necessarily anamorphic, i. e. its focal length must change along the field of view, in order to fit a finite-size imaging detector. This anamorphic distortion is introduced by the optical designer, depending on the desired applications. Each possible distortion bring along different field of view mapping and this must be taken into account by the scientific/metrological user, because the plate scale is variable along the focal plane. To obtain useful scientific information from fisheye images (astrometry, flux calibration and brightness measurements), a precise determination of the mapping function has to be accurately determined. In this paper we describe the expected distortion map of the EnVisS camera. © 2020 SPIE.

A very wide angle lens with a field of view of 360°x180° - a fisheye lens - has been designed to be used in a space environment. As a case study, the lens is assumed to be mounted on a spinning probe passing through a comet’s tail. The lens, rotating with the probe passing through the comet coma, may map the entire sky as viewed from the interior tail, providing unprecedented data on the spatial distribution of plasma and dust. Considering the foreseen space applications for the lens, radiation hardened glass has been taken into account for the design. A key feature of the lens is the “angular scale” uniformity (F-theta) of the sky distribution map projected on the focal plane allowing to obtain a reliable whole sky reconstruction. Care has also been taken to obtain an almost telecentric design, in order to permit filters placed on the focal plane to work properly. A telecentric fisheye operating with a pixel-limited resolution in the waveband from 500 nm up to 770 nm and with an F-theta distortion is presented in this paper.

Here a refractometer with the liquid prism is proposed. It has a simple structure, low cost and a large measurable refractive index range. When the vertex angle of liquid prism is 30°, the measurable refractive index range is up to 1.00-3.86, while the common refractometers have only the measurable range of 1.30-1.70. The optical system of this refractometer is design, where the angle of field is 80° and the total length is 110mm. A linear array CCD is used as the image receiver. The design results show that MTF is 0.35 in the tangential surface and 0.55 in the sagittal surface at the Nyquist frequency of 70lp/mm and the full field. The MTF values of other fields are more than 0.6, and the maximum distortion is 0.37%.

In the present paper we consider quantitative estimation of the tolerances widening in optical systems with curved detectors. The gain in image quality allows to loosen the margins for manufacturing and assembling errors. On another hand, the requirements for the detector shape and positioning become more tight. We demonstrate both of the effects on example of two optical designs. The first one is a rotationally-symmetrical lens with focal length of 25 mm, f-ratio of 3.5 and field of view equal to 72°, working in the visible domain. The second design is a three-mirror anastigmat telescope with focal length of 250 mm, f-ratio of 2.0 and field of view equal to 4°x4°. In both of the cases use of curved detectors allow to increase the image quality and substantially decrease the requirements for manufacturing precision.

Very wide angle lenses have a field of view greater than one hundred degrees. The paradigm of ultra wide angle lens is widely recognized as the fisheye, which is characterized by a field of view covering a hemispherical field. Recently, due to the availability of low-cost digital sensors, panoramic omnidirectional lenses are also becoming popular. These lenses permit us to capture a panoramic field, i.e. with many tens of degrees above and below the horizon, at the cost of obscuring a region close to the optical axis. We describe here a very wide angle lens which merges the fisheye and the omnidirectional lenses capabilities. The total field of view of the hyper hemispheric lens results in 360 degrees in azimuth angle and up to 270 degrees in zenithal angle, then much more than a hemisphere: we call it "hyper hemispheric lens".

Using progressive design method, we designed and built a wide field of view (FOV) catadioptric lens for LWIR earth sensors in the 14 to 16 μm range. The prototype lens is compatible with 640×480 uncooled FPA and 25 microns pixel pitch. Its full field of view is 170° and F number is 0.86. The f-theta distortion is less than 1%. Besides, the system works well during a temperature range of -40°C~+60°C.

Lenses for staring-array point-source detection sensors must maintain good signal-to-noise ratio (SNR) over fields of view often exceeding 100 degrees. Such lenses typically have f-θ distortion to provide constant solid angle sampling in object space. While the relative illumination calculation is often used to describe flux transfer from a Lambertian extended object for imaging applications, maximizing SNR for point-source detection depends primarily on maximizing collected irradiance at the entrance pupil, the shape of which can vary dramatically over field. We illustrate this field-dependent SNR calculation with an example lens and outline the calculations needed to derive a simple aberration-based expression for the field dependence of point-source SNR.

The earth sensors on the satellites measure the attitude by observing the discontinuity between earth radiance and cold space background. As IR detector technology advances, the earth sensor has evolved from traditional scanning sensor to static sensors with uncooled infrared FPA. In order to obtain high pointing accuracy of the earth center and avoid the influence of the cloud layer, the optical system should have the following characteristics such as: excellent f-theta linearity, high MTF at corresponding frequency, and high transmittance in the 14 to 16 μm range. In addition, this earth sensor is intended to be used on a LEO satellite, so the optical system must cover a wide FOV larger than 130°, and be as light and compact as possible. This paper contains the full design process of a wide-angle lens used for LWIR earth sensors from paraxial power allocation calculation to optimization of lens. The lens has a relative large image circle of 13mm, which is compatible with a 640×480 25μm uncooled FPA, and its full FOV is 180°. Its focal length is 4.177 and F number is 0.8. The f-theta distortion is less than 0.25%. By choosing chalcogenide glasses as lens material, the lens has a higher transmittance compare to Germanium lens. Also by analyzing the chromatic aberration of the lens, applying a DOE surface helps to improve the image quality, and pushes the modulated transfer function towards diffraction limitation.

Plenoptic imaging can be used to correct aberrations. However, current techniques are demanding on computing power and limit themselves to systems with small field of view. We present a simplified correction technique well adapted to wide-angle lens. We then present simulation and experimental results carried on a custom simple wide-angle lens.

The feature three-dimensional entrance pupil of a wide angle lens with the increase of field of views (FoVs) and pupil size is explored. Results show that the entrance pupil moves forward, displaces the optical axis, tilts and deforms as the FoVs and pupil size increases.

Low cost monochrome camera systems based on CMOS sensors and C-mount lenses have been successfully applied to a wide variety of metrology tasks. For high accuracy work such cameras are typically equipped with ring lights to image retro-reflective targets as high contrast image features. Whilst algorithms for target image measurement and lens modelling are highly advanced, including separate RGB channel lens distortion correction, target image circularity compensation and a wide variety of detection and centroiding approaches, less effort has been directed towards optimising physical target image quality by considering optical performance in narrow wavelength bands. This paper describes an initial investigation to assess the effect of wavelength on camera calibration parameters for two different camera bodies and the same ‘C-mount’ wide angle lens. Results demonstrate the expected strong influence on principal distance, radial and tangential distortion, and also highlight possible trends in principal point, orthogonality and affinity parameters which are close to the parameter estimation noise level from the strong convergent self-calibrating image networks.

The fisheye lens is a kind of ultra wide angle lens, which can produce a big super-wide-angle lens distortion. In order to cover a large scope of light, barrel distortion is artificially added to the optical system. However, in some cases this distortion is not allowed, then it requires calibrations of those distortions. Most of the traditional distortion calibration method uses target plane calibration to do it. This paper discusses the way of design fisheye lens, through which we can know the forming process of distortion clearly. Based on this paper, a simple and effective calibration method can be understood. Different from common camera calibration method, the proposed calibration method can avoid the error occurring in the process of calibrating test, that directly use the lens’ characteristic curve. Through multiple sets of experimental verifications, this method is effective and feasible.

This paper describes a wide angle fovea (WAF) telescope developed for supporting rangers to help the people floating on the sea because of serious Tsunami disaster. The WAF telescope is designed using a proposed Multiple-Stage WAF model which has a wide field of view (FOV) not to miss a moving target captured inside once and a high magnification in the central FOV to observe in detail, simultaneously. This design concept has been inspired from a smart function of the actual human eye. In other words, the authors have given an optical telescope multiple functions of both wide-angle surveillance and detailed observation in order to improve its availability. Specification of the prototype has been determined paying attention to this point of view. The produced prototype has achieved a handy size by using two aspherical surfaces in the whole lens compound system.

Wide-angle lenses can be generally classified into two structures: a transmitted fish-eye structure and a catadioptric structure with a panoramic annular lens (PAL). Compared with the former, the latter exhibits better imaging capability for a super-large field of view. However, the PAL causes this type of optical system to lose its imaging ability in a small field of view in front of the lens. In this study, a novel extremely wide-angle lens is designed by combining the fish-eye and catadioptric structures. The designed lens integrates the transmissive and catadioptric structures and can simultaneously observe two fields of view. The two fields of view of the lens complement each other and completely eliminate the central observation blind area of ordinary catadioptric wide-angle lens. The forward field of view of the lens is 360°×(0°-56°), and the annular field of view is 360°×(55°-115°). The total field of view of the optical system reaches 230° when only spherical lenses are used for all the optical elements. The optical model shows that the imaging quality of the extremely wide-angle lens is good, which proves the advantages of the new optical system in a large field of view.

This paper presents a simple method to estimate center of distortion and correct radial distortion from fish-eye lens. If the center of image is not locate that of lens in a straight line, the disadvantage of FOV model is low accurate because of correcting distortion without estimated centre of distortion. We propose a method accurately estimating Distortion center using FOV model and 2D pattern from wide angle lens. Our method determines the center of distortion in least error between straight lines and curves with FOV model. The results of experimental measurements on synthetic and real data are presented.

Wavefront coding (WFC) is a hybrid technology designed to increase depth of field of conventional optics. The goal of our research is to apply this technology to the short-focus and ultra-wide-angle lens which suffers from the aberration related with large field of view (FOV) such as coma and astigmatism. WFC can also be used to compensate for other aberration which is sensitive to the FOV. Ultra-wide-angle lens has a little depth of focus because it has small F number and short-focus. We design a hybrid lens combing WFC with the ultra-wide-angle lens. The full FOV and relative aperture of the final design are up to170° and 1/1.8 respectively. The focal length is 2 mm. We adopt the cubic phase mask (CPM) in the design. The conventional design will have a wide variation of the point spread function (PSF) across the FOV and it is very sensitive with the variation of the FOV. The new design we obtain the PSF is nearly invariant over the whole FOV. But the result of the design also shows the little difference between the horizontal and vertical length of the PSF. We analyze that the CPM is non-symmetric phase mask and the FOV is so large, which will generate variation in the final image quality. For that reason, we apply a new method to avoid that happened. We try to make the rays incident on the CPM with small angle and decrease the deformation of the PSF. The experimental result shows the new method to optimize the CPM is fit for the ultra-wide-angle lens. The research above will be a helpful instruction to design the ultra-wide-angle lens with WFC.

An ultra-wide angle lens design with relative illumination analysis is presented. The half field angle of 80°, the relative illumination of the image plane will be reduced. It is necessary to increase the image numerical aperture ratio for X and Y direction, and decrease the angle between the chief ray and optical axis in the image space. However the ultra-wide angle lens induces great barrel distortion causing image extrusion. Therefore, we use F-theta distortion to replace optical distortion. Seven lenses and two pieces of flat glass are used for a sensor 1/6” sensor with 2.1 million pixels. The final result for the lens is a half viewing angle of 80°, F/2.4, a focal length 1.1 mm, a length of 22.37 mm, F-theta distortion of less than 2%, and relative illumination greater than 83%.

After comparing different structures of wide-angle projecting lenses,a wide-angle lens for 162.6 cm(64 in) rear projection laser display is designed.The focal length of the system is 7.38 mm,the wavelength used in the design is F,d,C and the full field of view reaches 100°.The technical indii of the projection lens are summarized as follows: DMD(Digital Micromirror Device) is used in the light digital processing,90% MTF is greater than 0.6 at the Nyquist frequency;the barrel distortion of the system is smaller than 1.4%,and 90% of the energy in the point target is focused in a pixel dimension.Furthermore,a right angle prism is used to fold the optical path to decrease the length of the lens,so that the whole optical length of the system is 259 mm after outspreading the right angle prism.The vignetting factor of the wide angle is negative,which enhances the image illumination after projection.Moreover,an aspheric surface with the small size,zero conic constant and the maximum eight order coefficient is used to promise the feasibility of the mounting.Analytical results show that the design can decrease the production costs of the projecting system and promote the technological industrialization.

We introduce a new design technique by treating a two-group zoom lens system with a wide angle of view. First, the concept of the global optimization is introduced in the initial design stage, and from this, the global design technique is completed by analyzing and summarizing large quantities of modern design data. That is, we define the global structure function to achieve a new conceptual design technique for global optimization. And the function is put in a simple form by referring lots of patent data, manipulated with other algebraic equations, and solved finally such that we obtain the global solution region. The global solution region corresponds to the global optimization and suggests insightful systematized directions for the design of two-group zoom lens systems. These directions are attractive compared to global optimization.Keywords: Zoom lens, Wide angle lens, Global optimization, Local optimization, Global synthesisOCIS codes: (080.2740) Geometric optical design; (080.3620) Lens system design; (080.2468) First-order optics; (220.2740) Geometric optical design; (220.3620) Lens system design

Cornea, lens and eye models are analyzed and compared to experimental findings to assess properties and eventually unveil optical design principles involved in the structure and function of the optical system of the eye. Models and data often show good match but also some paradoxes. The optical design seems to correspond to a wide angle lens. Compared to conventional optical systems, the eye presents a poor optical quality on axis, but a relatively good quality off-axis, thus yielding higher homogeneity for a wide visual field. This seems the result of an intriguing combination of the symmetry design principle with a total lack of rotational symmetry, decentrations and misalignments of the optical surfaces.

The purpose of this work is to characterize the sky relative radiance and luminance distributions from the analysis of sky images acquired using a monochromatic CCD wide angle lens camera. The proposed methodology is based on the reduction of the number of the gray levels from the original image, in order to sharpen the different regions of the sky hemisphere, resulting in low level gray scale maps. In these maps each gray level is related to an intensity level and each pixel is associated to a sky direction. An experimental system that is able to simultaneously supply images from the sky and solar irradiance data was developed using a commercial CCD camera. The sky relative radiance and luminance distributions for different sky conditions were also determined. The resultant maps agree with observations of the main characteristics of sky radiance and luminance distributions.

This paper describes the development of an underwater camera system with a laser line source to measure seafloor features at millimeter scales. The quality of underwater photography is limited by the visibility of the water column. In real underwater environments, there are always suspended particles in the water column and light is scattered by these particles. As a result, photographic images taken under such conditions will be blurred. The stronger the light source is, the more severe the blurring will be. Therefore, it is difficult to discern the features of the intended target directly from the underwater images. To overcome this problem, a laser stripe can be projected onto the target and the profile of the target can be inferred from the displacement of the laser scan lines relative to a reference baseline. With a calibrated camera, the displacement expressed in pixels can be converted into the dimensions of the target in engineering units. To obtain a broader view in a closer distance, a wide-angle lens is usually used. As a result, the image taken with the wide-angle lens is nonlinear and is strongly distorted at the edges of the image. Calibration of a camera involves finding the optical and geometrical parameters of the camera and the environment in which it works. In this paper, a modified coordinate mapping calibration procedure is used. We divide the scope of the camera into several regions and build linear mappings between the world coordinate system and the pixels in the regions. We lay vertical and horizontal grid lines separated by 50 mm on an acrylic board that is aligned with the laser scanning sheet. These grid lines serve as longitude and latitude lines of a map. On the captured image, we curve-fit the grid points in pixel coordinates. A pair of interpolated longitude and latitude lines which pass through the target point are used to estimate the location of the point in the world coordinate system. We assess the accuracy of this procedure with test pieces (grooved blocks and seabed ripples) fabricated by a computer numerical control milling machine. Our measurements show that the error is less than 1.5 mm when the target is scanned from a distance of 1 m.

Modern lens designs for digital sensors, such as those required in medium volumes for cinematography, often require the use of one or two high departure aspheric surfaces. With departures from best fit sphere of up to a few millimeters, the use of such surfaces are accompanied by a number of consequences: high cost metrology, very tight opto-mechanical tolerances and image artifacts due to the sub-aperture grinding and polishing process. Previously we examined the use of multiple aspheric surfaces with very low departures from best fit sphere (BFS) and concluded that advantages may be gained in standard and telephoto lenses, but not in wide angle lens designs1. In this work we consider the potential benefits of low departure aspheric surfaces, as applied to wide angle lenses in particular. We review the number, placement, and nature of aspheric surfaces in some wide angle lens design examples, and look at the potential to redesign with an increased number of low departure aspheric surfaces that have the potential to be manufactured without the need for computer generated holograms (CGH’s). The use and limitations of modern interferometers capable of measuring aspheric surfaces without the use of CGH’s will be considered. In one example we examine the performance, manufacturing, and cost perspective, paying particular attention to testing and mechanical alignment tolerances.

Panoramic omnidirectional lenses have the typical draw-back effect to obscure the frontal view, producing the classic "donut-shape" image in the focal plane. We realized a panoramic lens in which the frontal field is make available to be imaged in the focal plane together with the panoramic field, producing a FoV of 360° in azimuth and 270° in elevation; it have then the capabilities of a fish eye plus those of a panoramic lens: we call it hyper-hemispheric lens. We built and test an all-spherical hyper-hemispheric lens. The all-spherical configuration suffer for the typical issues of all ultra wide angle lenses: there is a large distortion at high view angles. The fundamental origin of the optical problems resides on the fact that chief rays angles on the object side are not preserved passing through the optics preceding the aperture stop (fore-optics). This effect produce an image distortion on the focal plane, with the focal length changing along the elevation angles. Moreover, the entrance pupil is shifting at large angle, where the paraxial approximation is not more valid, and tracing the rays appropriately require some effort to the optical designer. It has to be noted here as the distortion is not a source-point-aberrations: it is present also in well corrected optical lenses. Image distortion may be partially corrected using aspheric surface. We describe here how we correct it for our original hyper-hemispheric lens by designing an aspheric surface within the optical train and optimized for a Single Photon Avalanche Diode (SPAD) array-based imaging applications.

Purpose: To describe an autoclavable wide-angle two-piece noncased contact lens system (two lenses: equatorial and wider-angle lens) for vitrectomy. Design: The inferior lens is made of an autoclavable plastic with a concave contact surface of 7.7 mm and the superior lens is a convex glass lens. The superior lens is mounted on the inferior one to make the lens assembly. Result: The equatorial lens has a power of +81 D and a field of view of 80–96°, while the wider-angle lens power is +151 D and the field 110–120°. The lens is kept on the cornea upon a drop of viscoelastic substance. An assistant holds it with a conventional lens holder. The lens is easy to sterilize by autoclaving and does not require expensive gas sterilization or potentially injurious chemical sterilization. Conclusion: This lens system provides a panoramic wide-angle view of the retina during vitreous surgery. The autoclaving makes this lens system cost-effective and fast to reuse.

In 2014, miniature camera modules are applied to a variety of applications such as webcam, mobile phone, automotive, endoscope, tablets, portable computers and many other products. Mobile phone cameras are probably one of the most challenging parts due to the need for smaller and smaller total track length (TTL) and optimized embedded image processing algorithms. As the technology is developing, higher resolution and higher image quality, new capabilities are required to fulfil the market needs. Consequently, the lens system becomes more complex and requires more optical elements and/or new optical elements. What is the limit? How small an injection molded lens can be? We will discuss those questions by comparing two wide angle lenses for consumer electronic market. The first lens is a 6.56 mm (TTL) panoramic (180° FOV) lens built in 2012. The second is a more recent (2014) panoramic lens (180° FOV) with a TTL of 3.80 mm for mobile phone camera. Both optics are panomorph lenses used with megapixel sensors. Between 2012 and 2014, the development in design and plastic injection molding allowed a reduction of the TTL by more than 40%. This TTL reduction has been achieved by pushing the lens design to the extreme (edge/central air and material thicknesses as well as lens shape). This was also possible due to a better control of the injection molding process and material (low birefringence, haze and thermal stability). These aspects will be presented and discussed. During the next few years, we don’t know if new material will come or new process but we will still need innovative people and industries to push again the limits.

In this paper a dielectric bifocal lens for a 60 GHz wide angle scanning antenna is presented. The lens is designed with the construction algorithm of Holt & Mayer. The construction algorithm is improved in a way that the bend of the lens towards the focal plane is no longer determined by trial and error but calculated numerically with a bisection method. Finally a zoned bifocal lens made of high density polyethylene (HDPE) is simulated and compared to a conventional plano-convex one of the same diameter.

The wide-angle lenses, which apply four pieces of glass lenses with the angle of view 100 degree, the distortion controlled within 40%, and MTF in the angle of view above 40lp/mm

An integrated variable-focusing microlens chip with thermal actuator and sensor, which is capable of adjusting its focal length over a wide range, is reported. The packaged microlens chip consists of a flexible polymer lens, a thermal actuator, and a sensor. The focal length change is controlled by varying the voltage applied to the thermal actuator and without any mechanical moving parts. The focal length varies from 9.197 to 2.619 mm, which corresponds to the change of numerical aperture from 0.146 to 0.448. Potential applications include the camera phone, surveillance camera, disc recording systems, collimator, sensing systems, confocal imaging systems, and optical communication.

An axis-symmetrical optical laser triangulation system was developed by the authors to measure the inner geometry of long pipes used in the oil industry. It has a special optical configuration able to acquire shape information of the inner geometry of a section of a pipe from a single image frame. A collimated laser beam is pointed to the tip of a 45° conical mirror. The laser light is reflected in such a way that a radial light sheet is formed and intercepts the inner geometry and forms a bright laser line on a section of the inspected pipe. A camera acquires the image of the laser line through a wide angle lens. An odometer-based triggering system is used to shot the camera to acquire a set of equally spaced images at high speed while the device is moved along the pipe’s axis. Image processing is done in real-time (between images acquisitions) thanks to the use of parallel computing technology. The measured geometry is analyzed to identify corrosion damages. The measured geometry and results are graphically presented using virtual reality techniques and devices as 3D glasses and head-mounted displays. The paper describes the measurement principles, calibration strategies, laboratory evaluation of the developed device, as well as, a practical example of a corroded pipe used in an industrial gas production plant.

In photogrammetry applications, camera parameters must be as accurate as possible to avoid deviations in measurements from images. Errors increase if wide angle lens cameras are used. Moreover, the coupling between intrinsic and extrinsic camera parameters and the lens distortion model influences the result of the calibration process notably. This paper proposes a method for calibrating wide angle lens cameras, which takes into account the existing hard coupling. The proposed method obtains stable results, which do not depend on how the image lens distortion is corrected., This work was supported in part by the Universidad Politecnica de Valencia research funds (PAID 2010-2431 and PAID 10017), the Generalitat Valenciana (GV/2011/057) and the Spanish government and the European Community under Project DPI2010-20814-C02-02 (FEDER-CICYT) and Project DPI2010-20286 (CICYT). The associate editor coordinating the review of this paper and approving it for publication was Dr. Subhas C. Mukhopadhyay.

Almost every aspect concerning the design of modern panoramic lenses brings new challenges to optical designers. Examples of these include ray tracing programs having problems finding the entrance pupil which is moving through the field of view, production particularities due to the shape of the front lenses, ways of tolerancing these systems having strong distortion, particular setups required for their characterization and calibration, and algorithms to properly analyze and make use of the obtained images. To better understand these modern panoramic lenses, the Optical Engineering Research Laboratory at Laval University has been doing research on them during the past few years. The most significant results are being presented in this paper. Controlled distortion, as in commercial panomorph lenses (Immervision), is used to image a specific part of the object with more pixels than in a normal fisheye lens. This idea is even more useful when a zone of interest vary in time with dynamically adjustable distortion as in a panoramic locally magnifying imager. Another axis of research is the use of modern computational techniques such as wavefront coding in wide-angle imaging systems. The particularities of such techniques when the field of view is large or with anamorphic imagers are considered. Presentation of a novel circular test bench in our laboratories, required to calibrate and check the image quality of wide-angle imaging system, follows. Another presented setup uses a laser and diffractive optical elements to compactly calibrate wide-angle lenses. Then, a discussion of the uniqueness in tolerancing these lenses, especially the front elements due to the large ratio between lens diameter and entrance pupil diameter, is included. Lastly, particularities with polarization imaging and experiments of triangle orientation detection tests before and after unwrapping the distorted images are briefly discussed.