Linear chirped slope profile for spatial calibration in slope measuring deflectometry

Area of Science:

• Optics and Photonics
• Metrology
• Materials Science

Background:

• Slope measuring deflectometry is crucial for characterizing X-ray optics used in synchrotron and free electron laser beamlines.
• Accurate determination of the modulation transfer function (MTF), which defines spatial resolution, remains a challenge for these instruments.
• Existing MTF calibration methods using 1D chirped profiles have limitations regarding amplitude variation with spatial frequency.

Purpose of the Study:

• To develop and validate a new approach for MTF characterization of slope measuring instruments.
• To design novel test surfaces with 2D-chirped topography optimized for MTF analysis.
• To address the amplitude-frequency drawback of existing 1D chirped test surfaces.

Main Methods:

• Design and fabrication of novel test surfaces featuring linear chirped slope profiles (LCSPs) with 2D topography.
• Development of a method for MTF characterization using these LCSP test samples.
• Experimental application of the developed test samples to measure the spatial resolution of the BESSY-NOM instrument.

Main Results:

• The proposed 2D-chirped test surfaces (LCSPs) effectively overcome the amplitude-frequency limitations of 1D chirped profiles.
• Successful fabrication of the LCSP test samples was achieved.
• Initial measurements demonstrated the capability of the test samples for spatial resolution assessment of slope measuring instruments.

Conclusions:

• The developed 2D-chirped test surfaces offer a superior method for MTF characterization of slope measuring instruments.
• This advancement enables more accurate assessment of spatial resolution in X-ray optics.
• The LCSP test samples provide a robust tool for optimizing instrument performance in advanced photon science facilities.