Bright Field (BF) Imaging:
• Select the objective lens To focus on the sample.
• Adjust the condenser lens To ensure the electron beam is converging onto the sample (you can use the condenser aperture for finer control).
• Set the objective aperture Wide open, allowing the unscattered (direct) electrons to pass through.
• Focus on the sample.
• Capture the BF image, Which uses the transmitted, unscattered electrons. These electrons create the image of the sample where contrast is typically based on the sample thickness and atomic number.

Switch to Dark Field mode:
• Using the selected area diffraction (SAD) aperture, select a diffraction spot corresponding to a particular crystallographic plane or feature you want to observe in the image.
• Center the diffraction spot in the diffraction plane by adjusting the selected area aperture.
• Use a smaller objective aperture to block out the transmitted (zero-order) electrons, and allow only the diffracted electrons (from a specific crystal plane or lattice) to pass through.

WBDF Imaging:
For WBDF imaging, the specimen was first tilted to achieve a near two-beam diffraction condition. A higher-order diffraction reflection (typically g+3g) was selected using the objective aperture. The electron beam was then tilted slightly away from the exact Bragg condition to establish the weak-beam condition. Under these conditions, contrast from strain fields associated with dislocations, stacking faults, and other lattice defects was enhanced. Images acquired using different diffraction vectors enabled application of the g·b invisibility criterion for defect characterization.

HRTEM Imaging:
For HRTEM analysis, the specimen was aligned along a suitable low-index zone axis identified from the selected-area diffraction pattern. Thin regions of the specimen were selected to minimize multiple scattering and improve lattice visibility. Fine adjustments of objective lens focus were performed near the optimum imaging condition to maximize lattice fringe contrast. High-resolution images were then acquired to resolve atomic planes, interfaces, and defect structures. Fourier transforms of the HRTEM images were used to verify crystallographic information and lattice spacings.