H. Richter

  • Citations Per Year
Learn More
The aim of this study is to characterise the properties of juvenile and mature heartwood of black locust (Robinia pseudoacacia L.). Content, composition and the subcellular distribution of heartwood extractives were studied in 14 old-growth trees from forest sites in Germany and Hungary as well as in 16 younger trees of four clone types. Heartwood(More)
Radiation coupling efficiency and directive properties of integrated lens antennas with log-spiral, log-periodic, and double-slot planar feeds coupled to a hot-electron bolometer were experimentally studied at frequencies from 1 to 6 THz and compared with simulations based on the method of moments and physical-optics ray tracing. For all studied antennas,(More)
and microbolometer array R. Eichholz, H. Richter, S. G. Pavlov, M. Wienold, L. Schrottke, R. Hey, H. T. Grahn, and H.-W. Hübers Institute of Planetary Research, German Aerospace Center (DLR), Rutherfordstr. 2, 12489 Berlin, Germany Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5–7, 10117 Berlin, Germany Institut für Optik und Atomare Physik,(More)
T h e line profiles of the overlapping hel ium lines 447.1 nm and 492.2 nm have been investigated in an improved plasma source of high purity at electron densities of 1 x 10 m 3 and 3 x 10' m~ . The plasma parameters NE, TE and T0 were de te rmined carefully by independent diagnostics, which enables a critical comparison with existing theories (BCS II and M(More)
As part of a study for a second generation heterodyne spectrometer on SOFIA we are developing a 2.5-THz frontend which is implemented in a pulse-tube cooler . It consists of a quantum-cascade laser as local oscillator and a phononcooled NbN hot electron bolometric mixer. Frequency stabilization to below 300 kHz full width at half maximum is achieved by(More)
Helmut Gottwald was born in Cosel/Upper Silesia on 5 November 1918 and died in Reinbek near Hamburg on 7 October 2008 after a prolonged illness, shortly before celebrating his 90th birthday, and 25 years after retiring from official duties. Surviving World War II, Helmut Gottwald first worked as an apprenticed carpenter from 1945 to 1947 and then studied at(More)
We report on the development of a compact local oscillator (LO) for operation on board of SOFIA, namely for GREAT, the German Receiver for Astronomy at Terahertz Frequencies. The LO combines a quantum-cascade laser (QCL) with a compact, low-input-power Stirling cooler. The output power is sufficient for pumping a hot-electron bolometer mixer. Frequency(More)
We report of a easy-to-use terahertz radiation source, which combines a QCL operating at 3.1 THz with a compact, low-input-power Stirling cooler. The QCL, which is based on a two-miniband design, has been developed for high output powers and low electrical pump power. The whole system weighs less than 15 kg including cooler, power supplies etc. The peak(More)
THz quantum-cascade lase rs (QCLs) are v ery attractive for applications such as a local oscillator in a heterodyne spectrometer. First, their emission is narrow in frequency (less than 20 k Hz), which allows for very high spectral resolution. Second, QCLs exhibit high output pow ers up to s everal tens of mW, suffic ient for pumping lar geformat mixer(More)
This work presents a programmable read-out chip for a miniaturized multi-parameter in vivo biosensor implant. The chip stimulates the measurement electrodes and reads out the generated analog signals in order to carry out temperature, pH and oxygen measurements. The design process aims at the optimization of the chip programmability and energy efficiency so(More)
  • 1