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Beamline Engineering Excellence

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Air Bearing DCM

• Very high radial stiffness of 270N/µm created by 10µm air film.
• Zero backlash & no mechanical hysteresis.
• No contact points, only a 10µm air film.
• For mechanical tables the rotational speed is limited by the high ratio gearbox; with a direct drive air bearing the speed is limited by the motor torque.
• High speed direct drive torque motor with variable Bragg speed greater than  20°/sec achievable.
• External Bragg encoder with Renishaw DSI ring encoder technology.
• Measured angular stability of 54 nrad.

The high Bragg speeds achievable are ideal for Quick EXAFS operation. The DCM can also be operated in step-scan mode with the distinct advantage of no wear or degradation over time.

IDT have installed air bearing monochromators on GSECARS, MR-CAT and 9-BM at the APS, and on SMI at NSLS-II.

* © Copyright Science and Technology Facilities Council 2011. Manufactured by Instrument Design Technology under licence from the Science and Technology Facilities Council​.

Sulphur Micro-XRF

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Sulphur Micro-XAFS

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Results from GSECARS using Air Bearing DCM:

54 nrad Measured Beamline Stability

Click to visit Stability page

Bragg Static Stability

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The many applications of an air bearing DCM (XAFS, pseudo channel-cut mode etc.) rely fundamentally on the stability of the Bragg drive in maintaining its position once commanded to sit at a particular energy. IDT have been able to directly measure the static stability of our Bragg rotation stage by sampling the closed loop encoder output directly over a 10s time frame as a function of Bragg angle, yielding an average static stability of 35 nrad across the angular range of the DCM.

Bragg Axis Static Stability

Measured Beamline Stability

The stability of the GSECARS ID-E beamline at the APS, featuring the IDT air-bearing DCM, has been measured to be 54 nrad.

See our monochromator stability page for more information.

IDT have developed an air bearing rotary stage, based upon a licenced goniometer* from STFC, as part of our program of continuous  development of cutting-edge monochromators

The combination of this air bearing goniometer with our proven ultra-stable crystal cage mechanics provides a world class platform for DCM operation and offers significant improvements over other mechanical goniometers, with a frictionless & ultra-smooth Bragg drive with no degradation or wear over time. Other features of the air-bearing goniometer include: