We report on a concept of a benchtop microscope for routine applications. This concept system transfers key features of a high-end laser scanning microscope to a dedicated confocal fluorescence imaging system with appropriate footprint and reduced systems complexity. The optical beam path is specifically designed for the purposes of confocal imaging leading to a short beam path length that fulfills the footprint requirements. The system allows an optical 3D scanning through the sample of up to 100 depths of focus without moving the sample. The scanning unit consists of a 2D MEMS scanning mirror spanning and a deformable mirror forming 3 virtual scanning axes. For a compact integration of the detection beam path, a confocal detector with an actuated MEMS pinhole was developed to adjust the optical sectioning. The selected light sources are directly modulated lasers operating at wavelengths that are frequently used for fluorescence imaging in life science applications. To provide a simple interface to almost any user’s hardware such as laptops or tablets, the systems architecture for real time control and data acquisition is based on a FPGA.
Induced aberrations in general are higher-order aberrations caused by ray perturbations of lower order, picked up surface by surface in the preceding optical system. ,  Therefore, induced aberration coefficients are to some extent depending on the cumulative preexisting aberrations in the system. In the case of color aberrations, induced influences are already observable in the paraxial regime, since even paraxial rays are affected by dispersion. Hence, in every optical system small perturbations in ray heights and ray angles for paraxial rays of different wavelengths are present. These ray perturbations generate induced color aberration effects of higher-order. Here, the different orders refer to the paraxial ray dependency on dispersion. The linear or 1<sup>st</sup>-order terms result in the well-known Seidel contributions of axial and lateral color, where any interaction of dispersion between different lenses is neglected. Starting at 2<sup>nd</sup>-order terms, induced color effects are present. ,  In this contribution, at first an introduction on the basic idea of induced color aberration is given. Following this, a surface resolved analytical description for axial and lateral color, distinguishing between induced and intrinsic parts, will be derived and discussed on a descriptive design example. Here especially the reversibility of raytrace direction is considered.
The design and optimization process of an optical system contains several first order steps. The definition of the appropriate lens type and the fixation of the raytrace direction are some of them. The latter can be understood as a hidden assumption rather than an aware design step. This is usually followed by the determination of the paraxial lens layout calculated for the primary wavelength. It is obvious, that for this primary wavelength the paraxial calculations are independent of raytrace direction. Today, most of the lens designs are specified not to work only for one wavelength, but in a certain wavelength range. Considering such rays of other wavelengths, one can observe that depending on the direction there will already occur differences in the first order chromatic aberrations and additionally in the chromatic variation of the third-order aberrations. The reason for this effect are induced aberrations emerging from one surface to the following surfaces by perturbed ray heights and ray angles. It can be shown, that the total amount of surface-resolved first order chromatic aberrations and the chromatic variation of the five primary aberrations can be split into an intrinsic part and an induced part. The intrinsic part is independent of the raytrace direction whereas the induced part is not.
Secondary color strongly depends on appropriate glass choice during optical design. The specific impact of individual lenses to the overall correction can be revealed by a lens-resolved analysis of secondary color. In this paper, thick-lens contributions to secondary axial and lateral color are presented, utilizing a suitable definition for secondary color when residual primary color is present. Several design examples illustrate the systematic impact of glass choice on the overall color correction.
We present numerical solutions for low order hexagonal whispering gallery modes to simulate the resonant behaviour of single zinc oxide (ZnO) nanopillars. Experimental resonance spectra of such nanocavities, determined by polarization-resolved micro-photoluminescence spectroscopy, are well described by the results of our numerics. The spectral analysis yields the particular birefringence of every investigated nanopillar, consistent with current literature values for ZnO bulk material. Hence, the whispering gallery effect has been utilized to detect optical constants of individual nanostructures.