Design of solving circuit for 6-DOF heterodyne grating interferometry system

High-precision 6-DOF grating interferometers are crucial for applications such as photolithography, and the solving circuit is a key component of such systems. However, current data acquisition cards and other sampling devices on the market struggle to meet the simultaneous requirements of multiple channels, high speed, high precision, and high performance. To address this issue and enhance the sampling and processing capabilities of the solving circuit, this paper introduces a novel design specifically for 6-DOF heterodyne grating interferometry systems. The circuit supports simultaneous sampling across up to 20 channels and integrates analog signal conditioning circuits with a high-performance FPGA (Field-Programmable Gate Array). The analog signal conditioning part is responsible for filtering and amplifying the input signals to reduce noise interference and ensure that the signal strength is close to the optimal operating range of the ADC (Analog-to-Digital Converter). The selected ZYNQ-7035 FPGA provides substantial computational power, effectively handling data streams from multiple channels. Additionally, we conducted comprehensive tests on the solving circuit, including evaluating the gain characteristics of the analog signal conditioning circuit and the real-time response performance of the entire system. Finally, the proposed solution was validated on an actual grating interferometry setup. This research significantly improves the accuracy and overall performance of grating interferometry measurement technology.