Nano-precision metrology of X-ray mirrors with laser speckle angular measurement

X-ray mirrors are widely used for synchrotron radiation, free-electron lasers, and astronomical telescopes. The short wavelength and grazing incidence impose strict limits on the permissible slope error. Advanced polishing techniques have already produced mirrors with slope errors below 50 nrad root mean square (rms), but existing metrology techniques struggle to measure them. Here, we describe a laser speckle angular measurement (SAM) approach to overcome such limitations. We also demonstrate that the angular precision of slope error measurements can be pushed down to 20nrad rms by utilizing an advanced sub-pixel tracking algorithm. Furthermore, SAM allows the measurement of mirrors in two dimensions with radii of curvature as low as a few hundred millimeters. Importantly, the instrument based on SAM is compact, low-cost, and easy to integrate with most other existing X-ray mirror metrology instruments, such as the long trace profiler (LTP) and nanometer optical metrology (NOM). The proposed nanometrology method represents an important milestone and potentially opens up new possibilities to develop next-generation super-polished X-ray mirrors, which will advance the development of X-ray nanoprobes, coherence preservation, and astronomical physics.

High precision circular plane system for angular measurement

The purpose of this project is to increase the measurement accuracy of the rotation angle and measurement speed. There is one rotatable circular plane with many holes in it, the initial location of this circular plane is stored in a CCD camera and is regarded as a stationary circular plane. When the rotatable circular plane is rotated, the intensity of the light across the holes of two circular planes is changed. This intensity will represent the position of the rotatable circular plane, so the position of that plane can be measured by calculating the intensities of light access between the two planes. In this project, several methods are proposed to increase the accuracy of measurement. To prevent a non- concentricity problem between two circular planes, only one circular plane is used in this system. To reduce the dfficulties in the fabrication process, holes will be used instead of using traditional slits. To increase the reading and calculation speed, an FPGA will be used in this system. For improving sampling accuracy, a Kalman filter is used. Overall, this system can reach an accuracy of 2:2176* 10-5 degree with all angles.

High precision circular plane system for angular measurement

The purpose of this project is to increase the measurement accuracy of the rotation angle and measurement speed. There is one rotatable circular plane with many holes in it, the initial location of this circular plane is stored in a CCD camera and is regarded as a stationary circular plane. When the rotatable circular plane is rotated, the intensity of the light across the holes of two circular planes is changed. This intensity will represent the position of the rotatable circular plane, so the position of that plane can be measured by calculating the intensities of light access between the two planes. In this project, several methods are proposed to increase the accuracy of measurement. To prevent a non- concentricity problem between two circular planes, only one circular plane is used in this system. To reduce the dfficulties in the fabrication process, holes will be used instead of using traditional slits. To increase the reading and calculation speed, an FPGA will be used in this system. For improving sampling accuracy, a Kalman filter is used. Overall, this system can reach an accuracy of 2:2176* 10-5 degree with all angles.

Artificial intelligence-based cephalometric landmark annotation and measurements according to Arnett’s analysis: can we trust a bot to do that?

Objective: To assess the reliability of CEFBOT, an artificial intelligence (AI)-based cephalometry software, for cephalometric landmark annotation and linear and angular measurement according to Arnett’s analysis. Methods: Thirty lateral cephalometric radiographs acquired with a Carestream CS 9000 3D unit (Carestream Health Inc., Rochester/NY) were used in this study. The 66 landmarks and the ten selected linear and angular measurements of Arnett’s analysis were identified on each radiograph by a trained human examiner (control) and by CEFBOT (RadioMemory Ltd., Belo Horizonte, Brazil). For both methods, landmark annotations and measurements were duplicated with an interval of 15 days between measurements and the intraclass correlation coefficient (ICC) was calculated to determine reliability. The numerical values obtained with the two methods were compared by a t-test for independent variables. Results: CEFBOT was able to perform all but one of the ten measurements. ICC values > 0.94 were found for the remaining eight measurements, while the Frankfurt horizontal plane - true horizontal line (THL) angular measurement showed the lowest reproducibility (human, ICC = 0.876; CEFBOT, ICC = 0.768). Measurements performed by the human examiner and by CEFBOT were not statistically different. Conclusion: Within the limitations of our methodology, we concluded that the AI contained in the CEFBOT software can be considered a promising tool for enhancing the capacities of human Radiologists.