Method for Energy Calibration of a Plane Grating Monochromator

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The invention describes a method for energy calibration of a plane grating monochromator (PGM), a device used to select specific wavelengths of X-rays, often in synchrotron beamlines. The method uses a system of precise angle encoders on both the plane mirror and the plane grating, in conjunction with an ionization chamber and a detector. By systematically measuring photoionization extrema (peaks and valleys) in a known calibration gas and correlating these to precise angular positions, the method allows for highly accurate and repeatable calibration of the monochromator's energy scale, regardless of the initial absolute angle settings.

Use CasesContent extracted from patent full text and abstract with AI.

• Synchrotron radiation facilities for accurate X-ray spectroscopy and diffraction studies.
• Calibration routines for research laboratories using monochromators in soft X-ray or extreme ultraviolet (EUV) applications.
• In-situ, automated energy calibration of monochromator systems used in materials science or chemical analysis.
• Periodic recalibration of beamlines to account for encoder drift or hardware servicing.

BenefitsContent extracted from patent full text and abstract with AI.

• Provides a fast, accurate, and reproducible method of calibrating a monochromator's energy scale.
• Enables calibration without needing to know or reset absolute angular positions, increasing operational flexibility.
• Significantly reduces or eliminates errors introduced by encoder scale inaccuracies or hardware changes.
• Allows for in-situ calibration during beamline operation, minimizing instrument downtime.
• Improves reliability of scientific results dependent on precise energy determination in spectroscopy or crystallography.

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Patent Abstract

The invention relates to a method of energy calibration for a plane grating monochromator (PGM) which comprises a plane grating and a plane mirror, both of which are equipped with a drive with an angle decoder with an absolute scale. The method comprises the following steps: 1. providing the PGM and collimated x-ray radiation and an ionization chamber in the beam path downstream of the PGM, and a detector for detecting radiation arising in the ionization chamber. 2. searching for a first extremal value (EW) of the photoionization spectrum of the gas in the ionization chamber by varying the overall deflection angle 2θ at the PGM and the diffraction angle β of the plane grating and by determining, either by calculation on the basis of the energy of the first EW or by geodesy, an associated deflection angle θ of the plane mirror and calculating the associated angle value β of the plane grating and by assigning the angle values to the current graduation marks of the decoders as a starting point. Subsequently, in a step 3., (i) rotating the plane grating or the plane mirror until a second EW of the ionization spectrum adjacent to the first EW is reached and (ii) rotating the respective other one, in relation to (i), of plane mirror and plane grating back to the first EW of the ionization spectrum and, in the process, (iii) respectively forming pairs of the graduation marks of the decoders for each partial step (i) and (ii) of the rotations from the read initial graduation mark and the graduation mark when the respective next homed-in on EW is reached, and respectively assigning associated nominal angle differences between the energies of the two EWs of the ionization spectrum to the pairs of graduation marks. 4. repeating step 3. at least twice.