This study investigates the structure of an optical microscope and the three-dimensional (3D) image-processing algorithm for recovering 3D images from multiple camera images. The images were acquired using both the optical and fluorescence phase-contrast microscope lenses. The designed optical microscope has a Z-axis actuator with a resolution of 0.1 μm. Hundred still images are then obtained by moving in 0.1 μm increments of a total of 10 μm in the upward direction from the focus-completion position. To construct the 3D images, each image went through a five-step filtering process: Gaussian filter, Laplacian filter, Laplacian mask, MAX Index detector, and Median filter. To construct 3D images, 100 filtered photos are then stacked orderly. The experiments with hemoglobin images have confirmed that 3D images can be obtained effectively using this method. If future studies use fluorescence phase-contrast microscopes, cell counting and cell contour line extractions can be effectively analyzed.