Fig. 4

Application of F-Mode to enhance visualization of structure in cultured biological cells. a Optical micrograph of CAKI-2 renal carcinoma cells grown on a UV fused silica substrate. Arrows indicate features which are accentuated in F-Mode images. b Frequency response of the 200 MHz transducer used to scan the sample. The vertical dashed lines with markers correspond to bands used to create F-Mode images. The difference in transducer sensitivity between the central frequency and each band exceeds 20 dB. c Label-free maximum amplitude projection image of the cells acquired with a 266 nm Nd:YAG laser. The strongest signal is from the cell nucleoli, with relatively homogeneous intensity throughout the remainder of the cell. The scale bar is 10 µm. d–f F-Mode images generated using the 90.5, 390.5, and 490.5 MHz frequency bands, respectively. In d, the cell appears uniform with prominent dark vesicles. In e, the periphery of both cells is accentuated, with a dark region in the center of the cells. Finally, in f only the nucleoli are apparent. The scale bar in c can be applied to all F-Mode images