This study presents the methods for designing an expander lens for an MWIR zoom lens through the third-order aberration analysis and evaluating the optical zoom system. This expander lens is used to enlarge the focal lengths of an original main zoom lens two times, which unfortunately doubles the aperture size of the expander lens elements. Thus, this extended apertures significantly generate the aberrations of a zoom system. To solve the problem, an expander lens has been designed using the third-order aberration analysis numerically. Since an MWIR optical system uses a cooled detector, this zoom system should be designed to eliminate the narcissus effect. Using this design approach, we efficiently obtain an expander lens for an MWIR zoom system satisfying the current requirements.
This study presents a new method for selecting a pair of optical glass and housing material to achromatize and athermalize a lens system, by use of the factor of determination for material selection. To effectively obtain an optimum combination for materials, we newly propose the sequential material selection method by introducing the factor of determination for material selection, which depends on the level of contribution to correct these aberrations and the availability to be used as a suitable material. Even though there are many cases for material combinations, we can sequentially identify the best pair of glass and housing materials by checking the factor of determination. Using this design approach, we efficiently obtain an achromatic and athermal system through an optimum combination of materials, over the specified ranges in temperature and waveband.
This paper presents a new graphical method for selecting an optimum pair of optical glass and housing materials to simultaneously achromatize and athermalize a multilens system, by use of iterative method. To take into account the lens spacing and housing, we newly quantify the lens powers of the elements by weighting the ratio of the paraxial ray height at each element to them. In addition, we introduce the equivalent single lens and the expanded athermal glass map including a housing material. Even though there is no glass satisfying athermal and achromatic conditions, we can iteratively identify a pair of glass and housing materials by changing the power of equivalent lens.
By use of lens modules and diffractive optical elements, a new design approach is applied to the digital still camera lens system. The optimum initial design satisfying the specific requirements, and the real lens design obtained from the lens modules are presented. An initial design with a focal-length of 3.6931 mm is derived by assigning appropriate first-order quantities and third-order aberrations to each module along with the constraints required for the optimum solutions. In order to have a compact camera system, refractive and diffractive elements are used. This hybrid real lens, which is equivalent to the lens module, can be quickly obtained by matching the first- order quantities and the third-order aberrations of the module at a given conjugate. The constraints are the first- order quantities and third-order aberrations of the module obtained in the initial design. Compared to conventional design, this approach dramatically saves time and effort. The separately designed elements are then combined to establish an actual camera system. Finally, residual aberration balancing results in a lens which has enough performance over an f-number of 4.0 and is expected to fulfill all the requirements of a digital still camera lens.
By the lens module theory, an initial design containing the first and third order properties of the four-group video camera zoom system with zoom ratio of 14X, and its real lens design are presented. The optimum initial design with focal length range of 4.1139 to 55.6148mm is derived by assigning appropriate first order quantities and third order aberrations to each module along with the specific constraints required for optimization. In order to obtain the real lens system equivalent to each lens module, we have optimized each real lens group with the constraints composed of the first order quantities and all third order aberrations of module. In order words, a real lens for each group has been designed to match the first order quantities and third order aberrations at a given conjugates. Finally we have combined to establish an actual zoom system. The combination of the separately designed groups results in a system which satisfies the properties of the zoom system consisting of original lens modules.
This paper presents the procedures for an initial design containing the first and third order aberrations of a four-group, rear focus video camera zoom lens using lens modules, and the real lens design from an initial design. Lens modules in the zoom system can explicitly describe the first and third order properties of each group without detailed design. The optimum initial design with a zoom ratio of about 10X and a focal length range of 6 to 60 mm is derived by assigning appropriate first and third order aberrations to each module along with the specific constraints required for optimization. For a real lens design of each group, we set up the simultaneous equations for the first and third order aberrations, and the solutions result in the optical systems which satisfy the properties of original lens modules. As a result, the design of a zoom system using lens modules is broken down into the simple problem of designing the individual groups to satisfy sets of the first and third order properties, and quickly provides the optimum system.
A design of a four-mirror optical system for submicron lithography using a KrF excimer laser beam (λ = 248 nm) is presented. By thirdorder aberration theory, analytic solutions for a telecentric, flat-field, anastigmatic four-spherical-mirror system (reduction magnification 5 x ) are found. Aspherization is carried out to the spherical mirror surfaces in order to reduce the residual higher order aberrations and vignetting effect. We obtain a reflection system useful in submicron lithographic application.
A telecentric flat field and anastigmatic four mirror optical camera system is developed for lithographic application. We have Obtained initially the analytic solutions of the four spherical mirror system free from four Seidel aberrations with reduction magnification (5x). However the systems obtained after corrections have still sizable amount of residual aberrations and small field. To overcome these shortcomings aspherization of the three mirrors is performed and it is found that it gives more improved performances.
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