In the fields of semiconductor manufacturing, aerospace, precision instruments, etc., the high true vacancy stage serves as the core motion execution component, and its motion accuracy directly determines the reliability of experiments and production. The particularity of high vacuum environment (low pressure, no lubrication, high temperature stability requirements) makes it difficult to apply conventional displacement table calibration methods, so it is crucial to establish a scientific and efficient accuracy calibration system.
The calibration of the motion accuracy of the high true vacancy moving platform needs to focus on core indicators, mainly including positioning accuracy, repeat positioning accuracy, reverse clearance, and motion straightness. Positioning accuracy refers to the deviation between the actual motion position and the commanded position, and is the core parameter for measuring the performance of the displacement table; The accuracy of repeated positioning reflects the consistency of multiple movements to the same position, which directly affects the repeatability of experimental data; The reverse clearance is the empty stroke error when switching the direction of motion, which can easily lead to positioning lag; The straightness of the motion ensures that the displacement table runs smoothly along the preset trajectory, avoiding attitude deviation.
Among the commonly used calibration methods, laser interferometer calibration method is the mainstream in the industry. This method utilizes the high coherence of laser and calculates the actual displacement by measuring the optical path difference of the laser before and after movement on the displacement table, achieving nanometer level accuracy detection. In high vacuum environments, it is necessary to use a vacuum adapted laser interferometer equipped with sealed optical components to avoid the influence of vacuum on laser transmission, and to correct errors caused by environmental temperature fluctuations through temperature compensation algorithms. During the calibration process, it is necessary to move the displacement table point by point according to the preset step size, record the measured deviation at each position, and finally generate the accuracy error curve.
The calibration method for capacitive displacement sensors is suitable for short stroke high true displacement platforms. The principle is to convert the displacement amount by detecting the capacitance change between the displacement table and the sensor plate, which has the advantages of fast response speed and strong resistance to electromagnetic interference. Before calibration, the sensor needs to be calibrated in a vacuum environment to eliminate the influence of vacuum medium on capacitance detection, while ensuring that the sensor installation surface is perpendicular to the direction of displacement table movement to reduce installation errors. This method is easy to operate and suitable for rapid calibration on site, but the measurement range is relatively limited and is usually used for displacement tables with a stroke less than 100mm.
In addition, the atomic force microscope assisted calibration method can achieve ultra-high precision verification. By utilizing the nanoscale positioning capability of atomic force microscopy as a standard reference and comparing the motion trajectory of displacement stages, it is suitable for cutting-edge research that requires high accuracy.
During the calibration process, attention should be paid to environmental control to ensure that the temperature fluctuation inside the vacuum chamber is less than ± 0.1 ℃ and to avoid airflow interference; At the same time, regular traceability verification of calibration equipment is carried out to ensure the accuracy of measurement standards. By scientifically selecting calibration methods and strictly controlling experimental conditions, the motion accuracy of the high true vacancy stage can be effectively guaranteed, providing reliable support for manufacturing and scientific research work.