We describe the optical design of a calibration unit for the off-axis laser guide stars at the Large Binocular Telescope's ARGOS facility. Artificial stars with the desired wavefront are created using a computer generated hologram.
Effective calibration procedures play an important role for the efficiency and performance of astronomical
instrumentation. We report on the calibration scheme for ARGOS, the Laser Guide Star (LGS) facility at the LBT. An
artificial light source is used to feign the real laser beacons and perform extensive testing of the system, independent of
the time of day and weather conditions, thereby greatly enhancing the time available for engineering. Fibre optics and
computer generated holograms (CGHs) are used to generate the necessary wavefront. We present the optomechanical
design, and discuss the expected accuracy, as well as tolerances in assembly and alignment.
When hemoglobin concentration in a beating heart muscle was determined before and after hemodilution by remission spectrometry and calculated on the basis of classical integration of the area between the hemoglobin spectrum and the dark current no meaningful changes in Hb concentration could be found. In a study performed in suspensions of scattering particles a first attempt was made to find a rational explanation for these observations.