Jiří Novák

Method of zoom lens design

Optical systems with variable optical characteristics (zoom lenses) find broader applications in practice nowadays and methods for their design are constantly developed and improved. We describe a relatively simple method of the design of zoom lenses using the third-order aberration theory. It presents one of the possible approaches of obtaining the Seidel aberration coefficients of individual members of a zoom lens. The advantage of this method is that Seidel aberration coefficients of individual elements of a given optical system can be obtained simply by solving of a set of linear equations. By using these coefficients, one can determine residual aberrations of the optical system without detailed knowledge about the structure of its individual elements. Furthermore, we can determine construction parameters of the optical system, i.e., radii of curvature and thicknesses of individual elements of a given optical system. The proposed method makes it possible to determine which elements of the optical system can be designed as simple lenses and which elements must have a more complicated design, e.g., doublets or triplets.

Three-component double conjugate zoom lens system from tunable focus lenses.

A method for calculation of paraxial parameters of the double conjugate zoom lens is described. Such an optical system satisfies the requirement that the object, image, and pupil planes are fixed during the change of magnification. Formulas are derived for the calculation of parameters of a three-component double conjugate zoom lens system with tunable focus lenses, which enable us to calculate the optical power of individual optical components with respect to the transverse magnification. The main advantage of such an optical system is the possibility to achieve required zooming properties without any mechanical movement of individual components of the zoom lens.

Design of a double-sided telecentric zoom lens

A method is presented for the calculation of paraxial design parameters of a double-sided telecentric zoom lens with easy variation of the magnification range. The telecentric lens consists of a zoom lens with a fixed distance between focal points and a lens with a fixed focal length. The third-order aberration analysis is also performed, and spot diagrams are calculated for two f-number values.

Third-order aberration coefficients of a thick lens.

In this paper, formulas are described for the calculation of the third-order aberration (Seidel) coefficients for a thick lens in air. The explicit analytic dependence of individual aberration coefficients on a lens thickness is presented. Such formulas make it possible to analyze an influence of the lens thickness on lens aberration properties and the replacement of a thick lens optical system by a thin lens model.

Method for primary design of superachromats

This work deals with a method for primary optical design of superachromats, where chromatic aberration is corrected for several wavelengths. Equations for the calculation of optical power and curvature radii are described for aplanatic and nonaplanatic optical systems, which are composed of two or three thin lenses in contact. Results of the calculations are presented for chosen optical systems of superachromats with basic design parameters.

Theory of hyperchromats with linear longitudinal chromatic aberration

Optical lens systems have always chromatic aberration. Optical systems that are used for imaging in optical instruments, e.g. in binoculars, microscopes, cameras and projectors, have chromatic aberration corrected very well in order not to reduce imaging quality. In many cases, it is necessary to use optical systems with relatively large chromatic aberration. The optical systems that are characterized by a chromatic aberration of a predefined form are called hyperchromats. Our work describes a theory of hyperchromats with a linear dependence of longitudinal chromatic aberration on wavelength. The equations are derived for calculation of basic design parameters of these optical systems and several examples of calculations are shown. Mentioned optical systems can be used especially in 3D imaging systems and confocal microscopy.

Energy efficient network protocol architecture for narrowband power line communication networks

This paper presents newly researched and developed network layer protocol for narrowband power line communication (PLC) within the last mile of advanced metering management systems. This communication medium is known for its low data rates and issues with signal propagation and noise inherence. After the network properties are introduced and some of the published PLC routing papers are discussed, our network layer protocol concept is described with emphasis on the routing algorithm and route optimizations. The protocol is designed to optimize the energy efficiency of the PLC network. The next part of the paper briefly describes the network simulator and its model, which was used during the protocol development and debugging. Several networks with constant and dynamic channel parameters were simulated. The results are presented at the end of the paper. Final results proving energy efficiency and its positive influence on the network performance are presented in comparison to the minimum hop count metric.

Three-element zoom lens with fixed distance between focal points

This work deals with a theoretical analysis of zoom lenses with a fixed distance between focal points. Equations are derived for the primary (paraxial) design of the basic parameters of a three-element zoom lens. It is shown that the number of optical elements for such a lens must be larger than two.

Evaluation of centricity of optical elements by using a point spread function

Our work describes a technique for testing the centricity of optical systems by using the point spread function. It is shown that a specific position of an axial object point can be found for every optical element, where the spherical aberration is either zero or minimal. If we image such a point with an optical element, then its point spread function will be almost identical to the point spread function of the diffraction-limited optical system. This consequence can be used for testing the centricity of precisely fabricated optical elements, because we can simply detect asymmetry of the point spread function, which is caused by the decentricity of the tested optical element. One can also use this method for testing optical elements in connection with a cementing process. Moreover, a simple formula is also derived for calculation of the coefficient of third-order coma, which is caused by the decentricity of the optical surface due to a tilt of the surface with respect to the optical axis, and a simple method for detecting the asymmetry of the point spread function is proposed.

Dependence of depth of focus on spherical aberration of optical systems

This paper presents a theoretical analysis and computation of aberration coefficients of the third and fifth order of transverse spherical aberration of an optical system, which generates a ray bundle with a diameter of a geometric-optical circle of confusion smaller than a predetermined limit value. Equations were derived for the calculation of aberration coefficients of an optical system, which satisfy given conditions, and for the determination of the maximum possible depth of focus for given conditions.