The AU-UV beam line on ASTRID2
Specifications of the AU-UV beam line
In order to utilise the new 3rd generation light source, ASTRID2, the beam line has undergone only minor changes. The geometry of the old UV1 beam line, with a source to first mirror distance of 1700 mm, was such that it could not be directly attached to the new storage ring, as a radiation wall had to be accommodated. Therefore a pair of 1:1 focussing “pre-optics” mirrors were installed to image the source to an intermediate focus (IF), which acts as a source for the existing beam line without further alteration.
A sketch of the AU-UV beam line, which is located on a bending magnet source, is shown below:
A schematic diagram showing the optical layout of the AU-UV beam line on ASTRID2.
The beamline consists of the following optical elements:
- A toridal/plane mirror pair (TM1/PM) deflecting the beam down and creating an intermediate focus point (IF).
- A toroidal mirror (TM2) deflecting the beam towards the grating.
- Entrance slit (ENS)
- A toroidal grating to disperse the synchrotron radiation (G).
- A moveable exit slit (EXS)
There are two gratings available in the UV beam line.
- The high energy grating (HEG) is a 2000 grooves/mm laminar type and is optimized for high resolution in the wavelength range of 100-350 nm.
- The low energy grating (LEG) is a 1000 grooves/mm laminar type which gives higher flux than the HEG and operates in the wavelength range of 160 to 700 nm
The entrance and exit slits are of fixed but selectable sizes in order to choose between different photon bandwidths. In order to maintain the correct focus at the exit slit as the grating rotates, it is necessary to translate the exit slit. This translation is mechanically linked to the experimental platform upon which the experiments are mounted. The range of this movement is about 65 mm over the full wavelength range.
| Optic | Major radius | Minor radius | Active area | Wavelength range |
|---|---|---|---|---|
| TM1 | 6.051 m | 0.4597 m | 120 mm x 50 mm | |
| PM | n/a | n/a | 120 mm x 50 mm | |
| TM2 | 3.947 m | 0.3657 m | 120 mm x 50 mm | |
| LEG 1000 lines/mm | 1.0 m | 0.7755 m | 40 mm x 40 mm | 700 to 200 nm |
| HEG 2000 lines/mm | 1.0 m | 0.7755 m | 40 mm x 40 mm | 350 to 100 nm |
| Slit | Available sizes | |||||
|---|---|---|---|---|---|---|
| Entrance Slit | None | 50 μm | 100 μm | 200 μm | 500 μm | |
| Exit Slit | None | 100 μm | 200 μm | 500 μm | 1000 μm | |
Resolution of the AU-UV beam line
The calculated resolution for the AU-UV beam line HEG with slits of 0.1 mm.
The calculated resolution for the AU-UV beam line LEG with a slits of 0.1 mm.
Last Modified 24 June 2015