Infra-Red Beam Extraction Port

General description :

A slotted, non-cooled, mirror has been implemented for the extraction of synchrotron light from the downstream dipole in Cell 23 to feed an Infra-Red spectrometer and microscope in a new laboratory. The slot lets the energetic part of the synchrotron light go through and is kept vertically centred on the heart of the X-Ray beam in a slow feed-back loop.

The concept of a slotted mirror was adopted for reasons of maximum flux extraction and minimum wavefront distortion to preserve the high brightness quality of the source. Although 22% of the lightflux (l=10um) is lost through the 5mm high slot of the mirror, at 3.2m from dipole entrance, the extracted light is free of any distortion.

The slotted mirror has now been in continuous service since January 2004, and has not given rise to any interference with the machine operation or with the local machine vacuum quality. It not only avoids the mirror surface deformation from X-Ray heatload, but also allows a simple, compact and straightforward design that functions reliably without additional water-cooling or vacuum pumps.

In the commissioning stages, the flexible vertical mirror positioning also allowed the measurement of the dipole light characteristics, the assessment of thermal heatload deformation to the aluminium mirror, and the verification of the quality of stability and optical wavefront transmission.

References & links of relevant papers and presentations :