Infrared imaging: Synchrotrons vs. arrays, resolution vs. speed

At the ALS we have been testing out Thermo-Electron's newest infrared imaging system, the Continuum XL microscope. This microscope is equiped with a 32-element MCT (16 × 2) array which allows rapid infrared imaging with fixed step sizes. The microscope also has a conventional single element MCT-A, which can be swapped for an MCT-B, or InSb detectors. This microscope is installed on ALS Beamline 1.4.4 where the synchrotron source provides high brightness for the single element detectors. We present comparisons of the measured spatial resolutions available with each of these detector types for globar and synchrotron sources as a function of wavelength and optical configuration. We find that the synchrotron retains its superiority for ultimate spatial resolution and signal-to-noise, while the array detection system is fast and convenient for surveying larger regions of a sample. Therefore in practice we use the array system for initial infrared images which allow us to find the regions of interest where we 'zoom in' using the synchrotron source.