| Normal Incidence Monochromator, Off Plane Eagle for synchrotron beamline applications
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McPherson Normal Incidence Monochromator (NIM) as built for the Chemical Dynamics research team at the Lawrence Berkeley National Lab Advanced Light Source (ALS). At ALS it is called 'beamline 9.0.2.' It is a very productive beamline and has been the instrument used for a great deal of experimental work. McPherson provided this 6.65-meter focal length off-plane monochromator complete. It includes precision slits that may be rotated about the optical axis and real-time, laser interferometic feedback of grating rotation and focus position. The grating translates over a distance greater than 1-meter to maintain focus at a selected wavelength.
Researchers at the Lawrence Berkeley National Lab Advanced Light Source (ALS) added two 3-meter focal length Normal Incidence Monochromators to this beamline. This provides additional end stations for diverse research and more flux albeit at lower resolutions. The McPherson 6.65-meter Eagle is also used at Stanford Synchrotron Radiation Laboratory (SSRL).
Current McPherson ultra high vacuum (UHV) instruments are baked and RGA tested prior to shipment. Unique proven McPherson designs separate support members for chambers and precision grating mechanism. This for reduced sensitivity to vibration and thermal environmental factors. Scan grating angle by computer control and use rotary or laser tilt encoders for absolute feedback. Index gratings under vacuum, manually or by motor control. We have a variety of beam line instruments and accessories available.
| Monochromator resolution - A photoionization scan of Ne with the 6.65-m monochromator on Endstation 2 showing a resolution of 72,000.This resolution has now been improved to 120,000 with the use of a 4800-line/mm grating.Data courtesy of P.A.Heimann (ALS)et al.[Proc.SPIE 2856, 90 (1996)]. |
 Interior view of the McPherson 6.65-m Off Plane Eagle Monochromator during fabrication and test. |
 Interior view of the Laser interferometer corner cube arrangement. A high resolution and in vacuum interferometer provides feedback as to grating tilt (wavelength) and translation position (focus.) This extremely precise feedback allows unprecedented positioning of the optical element relative to the slit assemblies. |
An additional PDF format description of the McPherson Off-Plane Eagle is available here.