Fig. 1. Schematic of graphene-based refractive index microscopy system

Fig. 2. Analysis of principle and microscopic images. (a) Schematic of the principle of probe beam scanning to measure the refractive index of the cell; (b)microscopic image of cell refractive index obtained in experiment; (c) experimentally obtained bright-field micrograph of the cell

Fig. 3. Fusion model FusionCNN

Fig. 4. The framework of FusionCNN algorithm

Fig. 5. Refractive index micrographs and bright-field images of three cells. (a)--(c) Refractive index micrographs of cell; (d)--(f) the corresponding cells bright-field images

Fig. 6. Experimental results of fusion of refractive index micrographs and corresponding bright-field images of three groups of cells using GTF (gradient transfer fusion) method, WL (wavelet transform-based fusion) method, and FusionCNN (CNN algorithm-based fusion) method, respectively. (a)--(c) Original refractive index micrographs; (d)--(f) fusion results obtained using FusionCNN method; (g)--(i) fusion results obtained using GTF method; (j)--(l) fusion results obtained using WL method

Fig. 7. Fusion of high spatial resolution bright-field image or low spatial resolution bright-field image with refractive index microscopic image. (a) Fusion using 700 pixel×700 pixel bright-field image and 100 pixel×100 pixel refractive index microscopic image; (b) fusion of 100 pixel×100 pixel bright-field image and 100 pixel×100 pixel refractive index microscopic image

Table 1. Objective evaluation indicators^[21]

Table 2. Fusion performance comparison of different methods