Eckhard Langenbach

Focusing of diode lasers for high beam quality in high-power applications

We have designed a diode laser system that is capable of imaging more than 50 W to a spot of 0.4 mm with a numerical aperture NA equals 0.1. The theoretical limits of the efficiency and the beam quality of the system are discussed. For applications needing higher beam quality coupling optics for a longitudinally pumped Nd:YAG laser operated in the fundamental mode are presented.

Diffractive optics for compact space communication terminals

Abstract Free-space laser communication links with data rates between 10 and 500 Mbits s−1 are required to cover the large amount of communication needs between low-orbit satellites, geostationary satellites and ground stations. The objective of this paper is to demonstrate the potential of diffactive optical elements for the design of optical and optoelectronic systems for advanced laser communication terminals. Three different examples have been realized: a ring pattern generator, an athermalized and achromatic hybrid collimator system, and a hybrid beacon system.

High-power diode laser collimators

High power diode lasers are anisotropic light emitters with high aperture angles in the plane perpendicular to the semiconductor plane. The collimation of this radiation with different cylindrical collimator types is discussed. Special attention is paid to the usable numerical aperture, the offense against Abbes sine condition and production constraints.

Zoom lens with 'electronic' curves

A zoom lens with two independently driven lens groups is presented. In contrast to conventional zooms each lens has its own individual and temperature dependent zoom curves, which are determined with an interferometric test setup.