Fig 1.
a) The schematics of FPM setup. It consists of a conventional microscope, involving an objective, tube lens, a camera, and an LED matrix replacing the condenser for specimen illumination. b) Fourier spectrum of the sample at the objective’s back-focal plane. The circular subregion corresponds to the objective’s aperture size. It shifts with the shifting illumination angle. c) Shifting illumination angle is provided by illuminating LEDs at different locations on the matrix.
Fig 2.
The full FOV image of a blood smear slide with SBP of ~0.9 gigapixel by FPM using 2x 0.08 NA objective (center) and its magnified subregions (surrounding).
The red subregions are directly extracted from the full FOV image, and the corresponding blue subregions are taken by a 20x 0.5 NA objective. They both offer enough details from which we can discern the shapes and sizes of the WBCs and their nuclei. The blue circle in the middle of the center image represents the relative size of the FOV achieved by a 20x objective compared to that of FPM.
Table 1.
WBC counting performance on 20 different regions on a blood smear slide using the 3 respective methods.
Fig 3.
Several white blood cells from the imaged regions by a 20x conventional microscope (above) and FPM (below).
Different morphologies can be observed among these cells. The left-most cell has an eccentric, single-lobed nucleus, suggesting that it is a lymphocyte, while other cells display multi-lobed nuclei structure, suggesting that they are eosinophils, basophils, or neutrophils.
Fig 4.
WBC detection by the automatic counting algorithm.
The algorithm analyzes a section of the specimen image obtained by FPM (left), and outputs the image overlaid with red markings on the detected WBCs.