1：Experimental Design and Method Selection:

The study uses a microscopic imaging system to acquire speckle patterns in the deep Fresnel region, based on Kirchhoff approximation for theoretical derivation. The method involves moving the observation plane along the optical axis to capture patterns at different distances.

2：Sample Selection and Data Sources:

Ground glass samples (No. 1, No. 2, No. 3) are prepared by grinding holographic plates with silicon carbide powders. Surface morphology is measured using an atomic force microscope (AFM) for comparison.

3：List of Experimental Equipment and Materials:

Equipment includes a laser source (wavelength 532 nm), spatial filter, lenses (L1 and L2), microscope objective (Nikon, Dry, 100×, N.A. 0.9, WD 1 mm), 3D piezo nanometer stage (PI E516), CCD camera (Roper, Cascade 1k), and white light source for alignment.

4：9, WD 1 mm), 3D piezo nanometer stage (PI E516), CCD camera (Roper, Cascade 1k), and white light source for alignment. Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: The surface sample is illuminated with a laser beam, and speckle patterns are recorded by the CCD at various deviating distances (up to 30 μm) from the object plane. Measurements are taken at five different transversal positions for each sample to ensure accuracy, and intensities are averaged.

5：Data Analysis Methods:

The longitudinal correlation function is calculated from the speckle patterns. Fourier transform of this function is computed, and linear fitting in the log-log scale of the large spectrum region is used to extract the roughness exponent.