Persistent spectral hole burning used for spectrally high-resolved imaging of the sun


Persistent spectral hole burning (PSHB) makes it possible to store images of the sun spectrally and spatially in a single exposure step at very high resolution. The current system consists of a chlorin-doped polymer film (polyvinylbutyral), cooled to 2 K. It has a spectral resolution of 300 MHz (0.0004 nm) and may be used in the range of about 628 to 638 nm. Theoretically the spatial resolution is confined to molecular dimensions. In solar observations, however, it is determined by the optical setup and atmospheric conditions. The exposure is done by imaging the sun onto the sample (exposure energy: 6 mJ/cm$^2$ GHz). Afterwards the stored information is read out by scanning a tunable dye- laser across the spectal range of interest. The laser light is used to image the sample at each frequency point onto a cooled 12 bit CCD- camera. For acquisition, archiving, processing, and visualization of the huge amount of data (up to 10 GByte per experiment), a parallel processor system is used.