In this paper, a primary lens of concentrator photovoltaic (CPV) system is designed by using freeform optics. The designed lens is constructed based on a basic idea of a combination of Fresnel lens and freeform optics...
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ISBN:
(数字)9781510629028
ISBN:
(纸本)9781510629028
In this paper, a primary lens of concentrator photovoltaic (CPV) system is designed by using freeform optics. The designed lens is constructed based on a basic idea of a combination of Fresnel lens and freeform optics, in which the lens is divided into an array of sub-lenses, which are designed using the conservation of optical path length and the edge ray theorem to get uniform irradiance distribution over the receiver. In this design, every sub-lens is designed to guide the direct sunlight over the receiver with uniform irradiance so that the whole of the primary lens will converge uniformly the direct sunlight over the receiver. The structure of the lens is designed firstly by using Matlab program for every sublens. The Matlab data of the designed lens structure is then used to build the three-dimensional (3D) lens in LightTools (TM) software. The ray tracing technique in LightTools (TM) software is used to find out the optimum structure of the freeform lens. Furthermore, the simulation is performed to estimate the efficiency of the lens as a concentrator of a CPV system by using the light source with the sunlight spectrum. The designed lens can achieve high geometrical concentration ratio and uniform irradiance distribution over the receiver. The simulation results show that the lens can easily reach a high concentration ratio (494 times) with uniform irradiance distribution and good optical efficiency (86%).
The design of four mirrors anti-astigmatism astronomical telescope is carried out for low earth orbit satellite. By integrating with Cassagrain and Schwartzschild configurations, the telescope is design. It contains f...
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ISBN:
(数字)9781510629028
ISBN:
(纸本)9781510629028
The design of four mirrors anti-astigmatism astronomical telescope is carried out for low earth orbit satellite. By integrating with Cassagrain and Schwartzschild configurations, the telescope is design. It contains four mirrors with conic surface, to form an aberration free. The system contains two parts: first part is the Cassagrain type telescope for pick up the ground object to the stop position, and the second part is Schwartzschild configurations as relay optics, which is to relay the image to high resolution CCD sensor to provide 0.5 ground space distance image. The system is symmetric with aberration free within a one cubic size fitted for small satellite. The optic mechanical is simple easy to assemble for optical calibration, while the body is rigid in space.
A head-mounted display (HMD) requires a large field of view (FOV) and a large exit pupil diameter while maintaining a compact structure. In this paper, we show a head-mounted display design comprising two freeform mir...
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ISBN:
(数字)9781510629028
ISBN:
(纸本)9781510629028
A head-mounted display (HMD) requires a large field of view (FOV) and a large exit pupil diameter while maintaining a compact structure. In this paper, we show a head-mounted display design comprising two freeform mirrors covering a 28 degrees full field-of-view with an eye relief of 15mm. The simplified partial differential equation (PDE) method is applied in the design of a two-mirror HMD system. Then the data points on the unknown freeform mirrors are calculated using the rays from multiple fields and are used to construct the freeform mirrors in the HMD system, which is taken as a starting point. This simplified partial differential equation method makes calculations easier. The anamorphic surface and the XY polynomial freeform surface are used in the two freeform mirrors for improving the image quality, respectively. The optimization strategy is also described in detail. The final HMD system operates at F/3.75 with 8mm exit pupil diameter achieving good imaging performance.
To compensate the spherical aberration of the eye using the conic constant of the first surface of a contact lens for different refractive errors. Refractive errors were simulated by modifying only the first curvature...
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ISBN:
(数字)9781510629028
ISBN:
(纸本)9781510629028
To compensate the spherical aberration of the eye using the conic constant of the first surface of a contact lens for different refractive errors. Refractive errors were simulated by modifying only the first curvature of the cornea. For every refractive error was calculating Zernike polynomials using Optics Software for Layout and Optimization (OSLO) EDU edition with and without contact lens. To calculate the conic constant of the contact lens we use the Seidel sums for thin lenses from the longitudinal spherical aberration as it proposes V. Mahajan. The value of Zernike spherical aberration coefficient for the eye with farsightedness (+ 5.00 D) + spherical contact lens was 0.142691 mu m. The conic constant value to compensate the spherical aberration was -0.222995 and the value of Zernike spherical aberration coefficient of the eye + aspherical contact lens was 0.004354 mu m. The value of Zernike spherical aberration coefficient for the eye with myopia (- 5.00 D) + spherical contact lens was 0.144505 mu m. The conic constant value to compensate the spherical aberration was -0.101424 and the value of Zernike spherical aberration coefficient of the eye + aspherical contact lens was 0.072820 mu m. The proposed method allows us to design contact lenses that compensate for the spherical aberration of the eye from the Zernike polynomials. Although the design of contact lenses is to third order, we obtain a smaller spherical aberration than the chromatic aberration on the axis without use optimization routine.
The current trend for higher resolution and sensitivity for Astronomy and Earth Observation space missions is leading to larger entrance apertures for future optical payloads, often requiring challenging and ultra-sta...
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ISBN:
(数字)9781510629264
ISBN:
(纸本)9781510629257;9781510629264
The current trend for higher resolution and sensitivity for Astronomy and Earth Observation space missions is leading to larger entrance apertures for future optical payloads, often requiring challenging and ultra-stable optical performances driving the instrument design and implementation. The level of complexity for such large systems requires a multidisciplinary approach and technological developments in cross-sectorial areas such as optics, structures, pointing accuracy, control, mechanisms. We present here a range of ESA R&D developments related to future large ultra-stable optical instrument architectures, providing perspectives on the identification of enabling technologies in view of current and future optical missions as well as and a wayforward to maturity for implementation within potential future missions.
State of the art laser-based refractive surgery instruments require precise optical beam steering and focusing capabilities to actively control an operational laser beam during eye surgery. As part of an industrial co...
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ISBN:
(纸本)9781510624931
State of the art laser-based refractive surgery instruments require precise optical beam steering and focusing capabilities to actively control an operational laser beam during eye surgery. As part of an industrial collaboration, Celera Motion and SwissOptic AG worked on a novel design approach to realize a compact, actively controlled lens moving mechanism for beam focusing. This system incorporates a closed loop voice coil driven air bearing that integrates a focusing lens of 10 mm in diameter in a low module footprint. The application driven design approach, modularity, and scalability of the solution will be presented together with results of the practical system evaluation. Thereby, the achieved optical alignment accuracy of the moving lens of only a few microns along a moving range of up to 80 mm in combination with a lateral movement bandwidth up to 100 Hz indicate best agreement with the design requirements for the driving unit. Since the developed driving mechanism offers high system performance for additional applications, the authors will give further application examples and show scalability approaches for various lens diameters and moving ranges for customized z-scan units in opticalsystems. As part of future developments, design modifications for applications with higher bandwidth requirements and reduced module footprint with lower weight will be discussed.
Fundus cameras are the current clinical standard for capturing retinal images, which are used to diagnose a variety of sight-threatening conditions. Traditional fundus cameras are not easily transported, making them u...
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ISBN:
(数字)9781510629028
ISBN:
(纸本)9781510629028
Fundus cameras are the current clinical standard for capturing retinal images, which are used to diagnose a variety of sight-threatening conditions. Traditional fundus cameras are not easily transported, making them unsuitable for field use. In addition, traditional fundus cameras are expensive. Due to this, a variety of technologies have been developed such as the D-EYE Digital Ophthalmoscope (D-EYE Srl, Padova, Italy) which is compatible with various cellphone cameras. This paper reports on the comparison of the image quality of the Nidek RS-330 OCT Retina Scan Duo (Nidek, Tokyo, Japan) and the D-EYE paired with an iPhone 6 (Apple, Cupertino, USA). Twenty-one participants were enrolled in the study of whom 14 underwent nonmydriatic and mydriatic imaging with the D-EYE and the Nidek. Seven participants underwent nonmydriatic imaging with the D-EYE and the Nidek. The images were co-registered and cropped so that the region of interest was equal in both the D-EYE and Nidek images, as the D-EYE had a smaller field of view. Using the Nidek image as the reference, objective full-reference image quality analysis was performed. Metrics such as structural similarity index and peak signal noise ratio were obtained. It was found that the image quality of the D-EYE is limited by the attached iPhone camera, and is lower when compared to the Nidek. Quantification of the differences between the D-EYE and Nidek allows for targeted development of smartphone camera attachments that can help to bridge the current gap in image quality.
BACKGROUND: current multispectral photoacoustic instruments must use large and separate combinational structures to obtain various biological tissue information for multispectral ranges. OBJECTIVE: The optical aberrat...
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BACKGROUND: current multispectral photoacoustic instruments must use large and separate combinational structures to obtain various biological tissue information for multispectral ranges. OBJECTIVE: The optical aberration generated from the multispectral photoacoustic systems may reduce the image quality of biological tissue because the improper structures for combining light of different wavelength cannot produce good optical ray convergence points. To prevent this, complex combined structures need to be considered at the design level for multispectral photoacoustic systems. METHODS: In place of an optical refracted lens system, reflective mirrors could be designed for opticalsystems. To verify our proposed idea, we assessed optical distortion performance using red, green, and blue light, and combined optical light sources to compare their chromatic aberration characteristics. RESULTS: The high optical performance is realized regardless of the wavelength for a light source combined with multiple wavelengths, because our optical system was designed with only a reflective surface. CONCLUSIONS: The designed optical system using a reflective mirror can provide multispectral optical sources (such as infrared, visible, and ultraviolet optical lights) with only one light ray path, without any chromatic aberrations.
CMOS technologies have swiftly ameliorated across the past few years. To meet the demand of high performance applications like compact disc players, high definition television (HDTV), radar, medical imaging etc., this...
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ISBN:
(纸本)9781728120683
CMOS technologies have swiftly ameliorated across the past few years. To meet the demand of high performance applications like compact disc players, high definition television (HDTV), radar, medical imaging etc., this employs info conversion system for processing at later stages. Accuracy is highly desirable in many functional systems like optical communication, military surveillance etc. In optical communication system, transimpedance amplifier (TIA) is the fundamental part of optical receiver which is required to convert the low level current signal from the photodiode to an operable output voltage for further processing. Here in this paper, we propose a CMOS TIA using class-AB flipped voltage follower having less output resistance. Simulation results of the proposed circuit in 0.18 mu m technology depicts that the bandwidth and the transimpedance gain obtained are increased by 3.3 times and 1.03 times respectively.
Retinal examination using direct ophthalmoscope is preferred over other techniques for screening purposes because of its portability and high magnification, despite its power sustainability and cost issues. With incre...
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ISBN:
(数字)9781510629028
ISBN:
(纸本)9781510629028
Retinal examination using direct ophthalmoscope is preferred over other techniques for screening purposes because of its portability and high magnification, despite its power sustainability and cost issues. With increasing number of low-cost sustainable devices available in the market, it is important to assess the efficacy of the devices. We compared three devices - Arclight ophthalmoscope, a D-Eye attached to iPhone 6, and conventional ophthalmoscope Heine K180 - in terms of ease of examination, usage, field of view, color rendition, patient comfort, length of examination, and closeness to the eye. Two trained optometrists examined 26 undilated eyes and graded the ease of retinal examination, ease of use and assessed vertical cup:disc ratio (VCDR). Patients reported their comfort level in terms of glare produced by the light source, length of examination and closeness to the eye. The examiners had a good agreement for all assessments. Of 26 eyes, VCDR assessment was not possible in 10/ 26 (38.4%) of the examinations, in (3/26, 11.5%) examinations with Arclight, in 0/26 examinations with D-Eye. Ease of use score was higher for Arclight and D-Eye than Heine. D-Eye had a relatively larger field of view than other 2 devices. Heine ranked first in color rendition. The luminance level of the high-beam setting of Arclight was more than twice that of Heine and D-Eye. Despite that, the patients reported experiencing uncomfortable glare in Heine (14/26, 53.8%), significant glare with Arclight (16/26, 61.5%) and some/no glare with D-Eye. The examination time was shorter when using D-Eye. Overall, D-Eye scored better in most of the evaluation items followed by Arclight.
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