Active imaging techniques have been, and will remain relevant as an integral part of the sensor network needed in mobile robotics navigation, most commonly with the use of LiDARs. For close range applications, time-of...
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ISBN:
(数字)9781510620629
ISBN:
(纸本)9781510620629
Active imaging techniques have been, and will remain relevant as an integral part of the sensor network needed in mobile robotics navigation, most commonly with the use of LiDARs. For close range applications, time-of-flight (TOF) cameras are an alternative to more expensive LiDARs. The Kinect v2 (Kinect for XboxOne) has been used frequently as a range imaging camera in machine vision research because of its low cost and good performance. For mobile robotics applications moving at low speed, a larger field of view than the original (70 degrees X 60 degrees) would be desirable to increase awareness of the surroundings, and also detect other moving objects in the trajectory. Our main goal is therefore to increase the Kinect v2 field of view while keeping its main feature of depth measurements. A simple but effective solution consists in using a conversion lens to increase the ray collection angle before the rays enter the IR camera. Depth measurements remain possible from each pixel using TOF with the Kinect v2 modulated signal, provided the field of illumination matches the field of view. A trade-off has to be made between accuracy of depth measurement, optical performance and field of view/illumination enhancement. Therefore, we modified a Kinect v2 to characterize its optical performances and evaluate its relevancy for applications requiring accurate knowledge of the 3D surroundings. A field of view improvement of the Kinect v2 and other similar TOF cameras could offer an alternative at minimal cost for depth measurements in machine vision, specifically in mobile robotics research where object detection and mapping tasks are frequently carried out.
The direct ophthalmoscope, a handheld device gives a highly magnified image of the retina. However, the sustainability of power source and cost are a limitation considering the usage demand. We compared a low-cost sol...
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ISBN:
(数字)9781510620629
ISBN:
(纸本)9781510620629
The direct ophthalmoscope, a handheld device gives a highly magnified image of the retina. However, the sustainability of power source and cost are a limitation considering the usage demand. We compared a low-cost solar-powered Arclight ophthalmoscope with a standard ophthalmoscope Heine K180 in terms of ease of examination, usage, field of view, color rendition and patient comfort. Two clinically trained optometrists examined 28 patients and graded the ease of retinal examination, ease of use and assessed cup-disc ratio, which is an important diagnostic parameter for glaucoma, patient comfort and length of examination (scale 1-4). The examiners had good agreement for all assessments. Of a total of 78 examinations, only 8(10.3%) did not result in cup-disc ratio measurement in the undilated pupil condition using both devices. Ease of use was scored higher for Arclight than Heine but this was not statistically significant. In conditions like large discs, the Arclight resulted in easier examinations due to its larger field of view. Color rendition was better with the Heine device. In undilated pupils, the patients often reported that there was significant glare with Heine, however, post-dilation, they reported more glare with Arclight compared to Heine (73% versus 55%). The performance of Arclight was comparable to that of Heine and can be considered a low-cost alternative to the standard direct ophthalmoscope especially in large-scale patient examinations in developing countries where cost might be a factor.
The proceedings contain 33 papers. The topics discussed include: correction of wavefront aberrations in focal and afocal TMAs;a thermal glass for infrared optics;caustic surfaces produced by a plane wavefront refracte...
ISBN:
(纸本)9781510620612
The proceedings contain 33 papers. The topics discussed include: correction of wavefront aberrations in focal and afocal TMAs;a thermal glass for infrared optics;caustic surfaces produced by a plane wavefront refracted through cemented doublet lenses;holographic progressive lenses;using effective medium theories to design tailored nanocomposite materials for optical systems;toward semantic loop closure in simultaneous localization and mapping systems;optic design and manufacturing issues of a high numerical broad band IR solid immersion microscope objective;opticaldesign and predicted performance of the WFIRST phase-B imaging optics assembly and wide field instrument;and novel designs for minimizing diffraction effects of large segmented mirror telescopes.
The basis of this work is a modification of the modern design of surgical binoculars based on substitution of mineral glasses with polymer lenses. Aberration analyses of the proposed systems is shown.
ISBN:
(纸本)9781510612082;9781510612075
The basis of this work is a modification of the modern design of surgical binoculars based on substitution of mineral glasses with polymer lenses. Aberration analyses of the proposed systems is shown.
The most widely used objectives for the space optics are mirror and catadioptric systems. We have considered several scheme types including the three-mirror schemes both of the Korsch-type and the systems without an i...
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ISBN:
(纸本)9781510612082;9781510612075
The most widely used objectives for the space optics are mirror and catadioptric systems. We have considered several scheme types including the three-mirror schemes both of the Korsch-type and the systems without an intermediate image and compare them from the point of view of packaging conditions, image quality and achievable characteristics. The two-mirror systems with lens correctors are also analyzed. The optical layout and parameters of several variants are presented and the image quality is shown.
This paper presents a refractive optical system consisting of two lens bodies with helical surface structures, which allows for tuning the optical refraction power by means of a mutual rotation of the lens bodies arou...
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ISBN:
(纸本)9781510612082;9781510612075
This paper presents a refractive optical system consisting of two lens bodies with helical surface structures, which allows for tuning the optical refraction power by means of a mutual rotation of the lens bodies around the optical axis. Thus, the refraction power can be tuned continuously in a certain range. The helical surfaces are shaped by changing the radius of curvature as a function of to the polar angle. Combination of such two surfaces results in an optics with refraction power being tunable by a mutual rotation. This optical system is multifocal with at least two sectors with different individually tunable refraction powers. To obtain a monofocal rotation optics, obscuration of one of the lens sectors is necessary. Conventional lens systems providing tunable refraction power do so by mutual axial or lateral shift of the lenses or the lens parts. Hence, additional space for lens movement is needed in the mechanical design. Since the rotational optics allows for adjustment of the refraction power by a mutual rotation of the lens parts, no displacement of lenses is needed and a more compact design is obtained.
We designed a compact middle-wave infrared (MWIR) lens with a large focal length ratio ( about 1.5:1), used in the 3.7 to 4.8 mu m range. The lens is consisted of a compact front group and a re-imaging group. Thanks t...
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ISBN:
(纸本)9781510612082;9781510612075
We designed a compact middle-wave infrared (MWIR) lens with a large focal length ratio ( about 1.5:1), used in the 3.7 to 4.8 mu m range. The lens is consisted of a compact front group and a re-imaging group. Thanks to the compact front group configuration, it is possible to install a filter wheel mechanism in such a tight space. The total track length of the lens is about 50mm, which includes a 2mm thick protective window and a cold shield of 12mm. The full field of view of the lens is about 3.6 degrees, and F number is less than 1.6, the image circle is about 4.6mm in diameter. The design performance of the lens reaches diffraction limitation, and doesn't change a lot during a temperature range of -40 degrees C+60 degrees C This essay proposed a stepwise design method of infrared optical system guided by the qualitative approach. The method fully utilize the powerful global optimization ability, with a little effort to write code snippet in opticaldesign software, frees optical engineer from tedious calculation of the original structure.
Conventional round spot quadrant detector trackers are inherently non-linear. This non-linearity requires multiple iterations to converge onto perfect alignment with the object tracked. We created a system that genera...
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ISBN:
(纸本)9781510612082;9781510612075
Conventional round spot quadrant detector trackers are inherently non-linear. This non-linearity requires multiple iterations to converge onto perfect alignment with the object tracked. We created a system that generates a square spot. The convolution of a square spot with a circle, generated by the quadrant detector, allows this spot to achieve perfect alignment in one iteration. This invention is thus essential to any system that requires speed and accuracy. In this paper, we introduce the theory behind the square spot as well as the design of our linear optical quadrant detector tracking technology.
The design of a secondary opticallens for light beam shaping using the transformation method is performed by transforming the light source energy distribution using the concepts of energy conservation and light energ...
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ISBN:
(纸本)9781510612082;9781510612075
The design of a secondary opticallens for light beam shaping using the transformation method is performed by transforming the light source energy distribution using the concepts of energy conservation and light energy mapping. Using these concepts creates a dependency relation between the output optical performance and the luminous intensity distribution of the light source. This relation leads to errors on the optical performance due to the fabrication misalignment between the light source and the secondary opticallens. On the other hand, in the illumination applications, the integration method has been proved to be an efficient method for achieving a high degree of homogenized luminous intensity distribution by integrating and superimposing the light source energy over the illuminated objects. In signal lighting applications, the luminous intensity distribution must meet the requirements regarding the brightness perception of users over the spatial angular distribution, not the illumination of objects. In this paper, the integration method is combined with the transformation method to design a refractive lens-array for signal lighting applications. The difference between the two methods is described, presenting the advantages of the combination process. design procedures are explained in detail including the lens-array modeling. The optical performance is investigated using an optical ray tracing. Finally, the influence of the misalignment between the light source and the refractive lens-array is measured.
The fluorescence of optical glasses is a property that needs to be taken into account in opticaldesigns for life science applications. Many optical glasses from SCHOTT show a very low intrinsic or auto-fluorescence. ...
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ISBN:
(纸本)9781510612082;9781510612075
The fluorescence of optical glasses is a property that needs to be taken into account in opticaldesigns for life science applications. Many optical glasses from SCHOTT show a very low intrinsic or auto-fluorescence. The fluorescence depends mainly on the applied excitation wavelength and the optical glass type. The fluorescence of optical glasses is usually defined as the quotient of the integral of the emission spectrum with the integral of the emission spectrum of a reference glass. This definition does not give any information about the actual quantum efficiency of the fluorescence. In this presentation recent data on the integral fluorescence of SCHOTT optical glasses are presented. Additionally, first measurements of the quantum efficiency of SCHOTT optical glasses are presented and compared to the standard method.
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