To address the challenges of low manual efficiency and surface damage risks in contact-based measurement for precision optical slits and pinhole lenses, this paper proposes an interpolation-Zernike collaborative subpixel detection method. By enhancing edge resolution through bicubic interpolation, reducing discrete sampling errors via reconstructed orthogonal basis templates, and correcting subpixel offsets with an asymmetric Gaussian model, the method improves antiinterference capabilities through dynamic thresholding and small connected-domain denoising. Simulation and experimental results demonstrate that the improved algorithm achieves a maximum detection error of 0.098 7 pixel (1.401 5 μm) for slit width and stabilizes pinhole diameter errors within 0.12 pixel (1.704 μm), representing a 62.3% accuracy improvement over traditional Zernike moment methods. Under pixel-aligned conditions, the method achieves nanoscale resolution of 0.000 2 pixel (2.84 nm), surpassing conventional micron-level limitations. The algorithm exhibits a linear positive correlation between accuracy and camera resolution, meets industrial detection standards within 3 μm under the experimental conditions, and demonstrates potential for nanometer-scale applications. This work provides an innovative solution for high-efficiency, non-destructive inspection of optical components.