Simulation of Electro-optic Crystal Conical Interference Based on the Virtual Lab Fusion

In recent years, due to the rapid development of range-gated lidar imaging technology, electro-optical modulation devices of crystals that can realize high-speed time-slicing have become the focus of research. The modulator acts as a "shutter" in the gating system, and controls the on-off of the optical path by loading a voltage on the crystal. However, due to the small aperture of the crystal, the imaging field of the commonly used electro-optical Q-switched electro-optical shutter is too small, and it is more practical to use the conoscopic interference phenomenon of the crystal to study the imaging characteristics of the shutter. Traditionally, Matlab software is used for simulation, but this software has problems such as too complicated setting of biaxial crystal orientation, high simulation difficulty, complicated simulation system model steps, inconvenient parameter switching, and difficulty in rapid simulation. The Virtual Lab Fusion software used in the simulation in this paper improves the above problems to a great extent. Virtual Lab Fusion is a high-speed optical simulation platform developed by German Light Trans with the concept of field tracing.As the world's only high-speed physical optics simulation software developed based on the concept of field tracing, Virtual Lab Fusion has the following features: 1. It can quickly switch between ray tracing and light field tracing; 2. It has a rich light source library, medium The library, the detector library, can perform system modeling arbitrarily and quickly; 3. The parameter setting during simulation realizes data visualization, which can carry out rapid simulation, which is more conducive to speeding up research progress. In this paper, Virtual Lab Fusion is used to simulate the conoscopic interference of crystals.The system is modeled by selecting appropriate optical components. By adjusting the angle between the transmission axis of the polarizer and the analyzer, the crystal orientation, and the incident angle of the incident light, the influence of these factors on the conoscopic interference phenomenon is studied. theoretical support. In the latest Virtual Lab Fusion 2021.1 version, biaxial crystals can also be modeled in the optical system, and there are multiple ways to define the crystal coordinate system, which greatly reduces the simulation difficulty of biaxial crystals. The simulation results show that: 1. Changing the direction of the transmission axis of the two polarizers can provide theoretical support for the study of the imaging characteristics of the crystal-based electro-optic shutter to a certain extent. 2. The crystal orientation has a great influence on the simulation results. 3. The increase of the incident light angle increases the isochromatic lines of the interference pattern. The imaging distortion caused by the interference of the crystal cone can be eliminated by controlling the incident angle of the light. However, the problem of the small field of view of electro-optical switch imaging still exists in practical applications, and further research is required.