Hans-Juergen Dobschal

New solutions to realize complex optical systems by a combination of diffractive and refractive optical components

Diffractive optical elements (DOEs) have a great potential in the complete or partial substitution of refractive or reflective optical elements in imaging systems. The greater design flexibility compared to an all-refractive/reflective solution allows a more convenient realization of the optical systems and additionally opens up new possibilities for optimizing the performance or compactness. To demonstrate the opportunities of the hybrid optical concept we discuss different imaging systems for various applications. We present the lens design of a hybrid microscope objective which is especially applicable for wafer inspection technologies. Meeting the requirements for such a system used in the deep-UV regime (248 nm) is very challenging. The short wavelength limits the material selection and demands cement free optical groups. The additional requirement of an autofocus system, working at a wavelength in the near infrared region, is fulfilled by the special combination of two selected and adjusted DOEs. Furthermore, we discuss the opportunities of the hybrid concept c of a slit lamp used for ophthalmologic examinations. The DOEs are the basic elements of this hybrid concept. We demonstrate that holographic lithography is an appropriate technology to realize a wide variety of elements with different profile geometries. We address in particular the additional possibilities of an UV-laser system as an exposure tool. Additionally to the high spatial frequencies, the 266 nm exposure wavelength allows the use of novel photo resists with advantageous development behavior.

Single-Longitudinal-Mode (SLM) Generation at Power Diode Lasers by Using a Diffracto-Optical External Cavity

Environmental research at the atmosphere contains a lot of methods investigating the chemical nature of air pollutions and their distribution in the air. Laser spectroscopic methods and Lidar among these are able to solve some of that tasks. Laser analytical investigations make necessary tunable laser sources. For mobile operations at satellites or aeroplanes a lidarsystem has to be small, light, compact, robust and reliable. The improvement of such systems could be substantial by using laser diodes. In comparison with conventional types of lasers (CO2- or solid state lasers) laser diodes have the advantage of rather simple tunability and modulability.