Evaluation of a high-speed multispectral light source for stroboscopic diu000berential imaging for endocardial examination of Daphnia magna

摘要

In the eld of medicine and biology there are fast repetitive movements at the microscopic level which inuencethe overall dynamics and behavior of the system. In order to present details of these fast movements whichare above the temporal resolution limit of the human eye, a new stroboscopic multispectral imaging systemwas developed. The Daphnia magna, which is a good test organism due to its transparent shell, served as atest animal to evaluate this new imaging system. The heart rate of the Daphnia magna is about 400 beatsper minute and thus the dynamics of the individual heart contractions of the animal can no longer be clearlydiu000berentiated using standard microscopy. These cardiac phases were visualized by stroboscopic illumination withpulse duration of 500 ns and with the aid of a microscope. The stroboscopic illumination was realized by a pulsedlight source consisting of four light emitting diods (LED). In general, the spectral range of the illumination isconfigurable using combinations of these LEDs, however, in this instance the wavelengths were selected with theknown absorption of haemoglobin at 410 nm, 470 nm, 680nm and 870 nm. Furthermore, it was also possible touse the four wavelength differences available to generate images of Daphnia magna utilizing the transmission andabsorption properties of biological tissue and its surrounding environment. In addition to a clear representationof the heart, the blood ow in the open cardiovascular system of the Daphnia magna was imaged byobserving the absorption of the macromolecule haemoglobin with different wavelengths.