Miniaturized Two-Photon Microscopy System for Extreme Shock and Vibration Environment

Two-photon fluorescence microscopy, based on the principles of two-photon excited fluorescence and second harmonic generation, enables real-time non-invasive in vivo imaging of skin and cells, providing a means to assess human health status. In this paper, a miniaturized two-photon imaging system is designed and fabricated to withstand extreme vibration and shock environments. The mechanical stability of the optical and structural components of the miniaturized probe is evaluated under random vibration and shock vibration tests using finite element simulation methods and ray tracing techniques. During the environmental testing, the maximum stress on the probe is 11.5 MPa, which is well below the threshold for structural failure. The largest structural displacement occurs at the collimator, where random vibrations produce an offset of 10.9 μm. This offset is analyzed by using geometric optics and point spread functions. Under the maximum collimator offset, the theoretical resolution, as calculated by the point spread function, shifted from 463.28 nm to 463.48 nm. Additionally, a lateral offset of 127 nm is observed at the center position, which does not significantly impact the imaging performance. Finally, environmental and imaging performance tests are conducted. The system’s measured resolution after the environmental tests is 530 nm, consistent with its resolution prior to testing. Imaging tests are also performed on the skin’s stratum corneum, granular layer, spinous layer, and basal cell layer, revealing clear cellular structural information. These results confirm the device’s potential for applications in extreme shock and vibration environments.