Description
We present a correlative water window (WW) and visible light fluorescence microscope in an integrated lab-based setup [1]. The WW spectral range between the absorption edges of carbon and oxygen (280-530 eV) is particulary valuable for biological samples as it offers natural structural contrast due to the high absorption in carbon and high transmission in oxygen. Combining this with the functional contrast of fluorescence microscopy provides a holistic picture of the sample.
The wide-field zoneplate microscope is based on a laser plasma source, the gas puff target [2], while the fluorescence microscope operates in a wide-field epi configuration. By mounting the zoneplate and the fluorescence objective on a shared stage, it is possible to switch between the imaging modalities without alternation or moving of the sample.
With the WW microscope we achieve a resolution of 50nm half pitch, as demonstrated using a Siemens star test target. We present correlative imaging of different samples, ranging from simple test samples, such as fluorescent nanobeads, to biological specimens like cyanobacteria and critical-point dried NIH-3T3 and COS7 cells.
