We already discussed the bistable behavior of a Fabry Perot resonator filled with molecular media as well as the characteristics of a spatial light modulator (SLM) based on the nonlinearity induced by excited state ab...
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ISBN:
(纸本)081941249X
We already discussed the bistable behavior of a Fabry Perot resonator filled with molecular media as well as the characteristics of a spatial light modulator (SLM) based on the nonlinearity induced by excited state absorption. In the present paper we present two practical configurations. First we analyze a cavity-less bistable element which removes some of the realization problems related to high finess cavity. In this configuration the nonlinear medium is located in one arm of an optical interferometer. The scheme provides the required amount of positive feedback by the bistable mechanism -- but without a cavity. We applied the nonlinear eikonal approximation, a method which takes care of the detailed propagation effects, and obtained conditions for bistability, as well as optimizing the design parameters such as the output mirror reflectivity, etc.
A method for computing the polychromatic MTF of hybrid refractive - diffractive elements is described taking into consideration the effects of not only the primary diffraction order but also the effects of additional ...
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ISBN:
(纸本)0819445347
A method for computing the polychromatic MTF of hybrid refractive - diffractive elements is described taking into consideration the effects of not only the primary diffraction order but also the effects of additional parasitic diffraction orders. The results of this approach are compared with the more conventional single order calculation and with actual measured performance. For certain markets and applications the cost of infrared lenses are critical in order to achieve customer expectations. Two possible methods of realising this requirement are the use of moulded optics or the use of multiple kinoform optics with no refractive power. Examples of such lenses are given along with discussion of the merits and limitations that each approach entails.
Interferometric measurements of real surfaces are combined with computed opticaldesign analyses. To accomplish this, a special software interface driver was developed to accept serial optical Path Difference (OPD) da...
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ISBN:
(纸本)0819402044
Interferometric measurements of real surfaces are combined with computed opticaldesign analyses. To accomplish this, a special software interface driver was developed to accept serial optical Path Difference (OPD) data from a Zygo Mark iii interferometer, apply standard algorithms, and convert the measured data into a CODE V readable file. Analysis was conducted on a large aperture developmental optical system containing a fold mirror of eggcrate construction. MTF performance of the entire system was computed as were the contributions of individual surfaces to overall optical quality. Diffraction effects due to the rib structure of the eggcrate mirror were apparent in this analysis, as were the effects of gravity and figure components of the wavefront. This hybrid analysis demonstrates the usefulness of coupling interferometry with an opticaldesign program in the analysis of complex optical systems.
optical systems are traditionally represented by a sequential series of `optical surfaces' that are ordered in the same manner experienced by light traveling from an object to an image point through the system. Th...
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ISBN:
(纸本)081941249X
optical systems are traditionally represented by a sequential series of `optical surfaces' that are ordered in the same manner experienced by light traveling from an object to an image point through the system. The actual system is composed of 3-D components which include these `active optical surfaces' as the external surface of the component. Modern simulation technology is based on solid modeling which provides a very close representation to the actual system and enables computer integrated manufacturing by being accurate and comprehensive enough for fabrication. The classical method to analyze an optical system is based on ray tracing, a technique based on geometrical optics where light propagation is assumed to be simulated by rays from the object to the image point. Each ray is represented by a linear vector traveling through the system to the evaluation plane by iterations. Each step calculates the propagation between two successive surfaces in a sequential order. The shift from `sequential surfaces' representation to `solid models,' which changes the classical method of ray tracing, but offers a variety of new analytical opportunities, is discussed.
In this paper, the design of a dual field-of-view optical system for 3-5 mum infra-red focal-plane arrays is described. Preliminary calculations are done to determine the first-order parameters of the narrow and the w...
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ISBN:
(纸本)0819445347
In this paper, the design of a dual field-of-view optical system for 3-5 mum infra-red focal-plane arrays is described. Preliminary calculations are done to determine the first-order parameters of the narrow and the wide-field modes. To achieve a switchable dual field-of-view system, two different optical configurations, one based on the axial motion of a lens group and the other based on a rotate-in motion of two separated lens groups, are studied and compared. Diffractive and conic surfaces are used to control the color and the monochromatic aberrations with less number of total lenses used. Paraxial and real-ray modelling of the Narcissus effect is described. It is shown that the rotate-in scheme achieves better optical performance in both the narrow and the wide-field modes. The axial-motion scheme suffers from poor lateral color in the wide-angle mode. The final opticaldesigns along with their aberrations curves and MTF plots are presented showing excellent performance.
Beam expander optical and structural characteristics can be utilized to desensitize line of sight (LOS) jitter. The overall LOS jitter for a given disturbance spectrum is largely dependent on the optical alignment sen...
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Helicopter mounted optical systems require compact packaging, good image performance (approaching the diffraction-limit), and must survive and operate in a rugged shock and thermal environment. The always-present requ...
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ISBN:
(纸本)0819445347
Helicopter mounted optical systems require compact packaging, good image performance (approaching the diffraction-limit), and must survive and operate in a rugged shock and thermal environment. The always-present requirement for low weight in an airborne sensor is paramount when considering the optical configuration. In addition, the usual list of optical requirements which must be satisfied within narrow tolerances, including field-of-view, vignetting, boresight, stray light rejection, and transmittance drive the opticaldesign. It must be determined early in the engineering process which internal optical alignment adjustment provisions must be included, which may be included, and which will have to be omitted, since adding alignment features often conflicts with the requirement for optical component stability during operation and of course adds weight. When the system is to be modular and mates with another optical system, a telescope designed by different contractor in this case, additional alignment requirements between the two systems must be specified and agreed upon. Final delivered cost is certainly critical and "touch labor" assembly time must be determined and controlled. A clear plan for the alignment and assembly steps must be devised before the opticaldesign can even begin to ensure that an arrangement of optical components amenable to adjustment is reached. The optical specification document should be written contemporaneously with the alignment plan to insure compatibility. The optics decisions that led to the success of this project are described and the final opticaldesign is presented. A description of some unique pupil alignment adjustments, never performed by us in the infrared, is described.
The major problems faced in spaceborne multielement optical systems used for high resolution imagery and remote sensing applications are the stability of optical and mechanical configurations under Shock, Vibration an...
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We present real-time measurements of the wave front distortion induced by a variable focal lens. This lens, called Varioptic, is made of a transparent cell filled with twin liquids. We submit a 4.5mm in diameter lens ...
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ISBN:
(纸本)0819445347
We present real-time measurements of the wave front distortion induced by a variable focal lens. This lens, called Varioptic, is made of a transparent cell filled with twin liquids. We submit a 4.5mm in diameter lens upon a 110V voltage step inducing a optical power shift of about 25 dioptries (m(-1)). Characteristic response time is shown to be of the order of a few 1/100s, the lens recovering its full quality after 5/100s. We present a scaling analysis of this response time versus lens size.
作者:
Kipman, Yair
185 Albany Street CambridgeMA02139 United States
This paper describes the optical hand-held scanner designed for use as an input device to the Kurzweil reading machine for the blind and visually-impaired. This device has numerous advantages over other scanners, chie...
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