This study presents a partially coherent illumination based (PCI-based) SIM apparatus for dual-modality (phase and fluorescent) microscopic imaging. The partially coherent illumination (PCI) is generated by placing a rotating diffuser on a monochromatic laser beam, which suppresses speckle noise in the dual-modality images and endows the apparatus with sound sectioning capability. With this system, label-free quantitative phase and super-resolved/sectioned fluorescent images can be obtained for the same sample. We have demonstrated the superiority of the system in phase imaging of transparent cells with high endogenous contrast and in a quantitative manner. In the meantime, we have also demonstrated fluorescent imaging of fluorescent beads, rat tail crosscut, wheat anther, and hibiscus pollen with super-resolution and optical sectioning. We envisage that the proposed method can be applied to many fields, including but not limited to biomedical, industrial, chemistry fields.

Quantitative phase microscopy (QPM) is a label-free imaging technique often employed for long-term, high-contrast imaging of live bio-samples. Yet, QPM is not specific to a certain subcellular organelle. As a remedy, fluorescence microscopy can visualize specific subcellular organelles once labeled with fluorescent markers. In this paper, a high-resolution phase/fluorescence dual-modality microscopic imaging method based on structured illumination is proposed. In the dual-modality microscopic system, periodic stripes are generated by a digital micromirror array (DMD), and are used as the common illumination for both modalities. For QPM imaging, the holograms of the sample under structured illuminations of different orientations and phase shifts are recorded, from which a quantitative phase image with resolution enhancement can be reconstructed via a synthetic aperture procedure. Furthermore, a numerical approach is proposed to compensate for the environmental disturbances that often challenge aperture synthesis of phase imaging. This method determines each time the phase distortions caused by environmental disturbances using the spectrum of the 0th order of the structured illumination and subtracts it from the phase distributions of the waves along the 0th, and the ±1st diffraction orders. Resolution enhancement of QPM imaging is realized by synthesizing the spectra of all the waves along different diffraction orders of the structured illuminations of different orientations. With phase images, 3D shapes, inner structures, or refractive index distributions of transparent and translucent samples can be obtained. For fluorescence imaging, intensity images (Morie patterns) of the sample under different structured illuminations are recorded. The spectra along different diffraction orders are separated by using a phase shifting reconstruction algorithm, and are shifted to their original positions, forming a synthesized spectrum that is much larger than the spectra of raw intensity images (NA-limited spectra). An inverse Fourier transform on the synthesized spectrum yields a super-resolution fluorescence image of the sample. With the the reconstructed fluorescence images, specific subcellular organelles labeled with fluorescent markers can be visualized. The combination of quantitative phase microscopy and fluorescence microscopy can obtain multidimensional information about the sample. In this dual-mode imaging system, the spatial resolutions of quantitative phase imaging and fluorescence imaging are 840 nm and 440 nm, respectively. The proposed dual-mode microscopy imaging technique has been demonstrated for imaging fluorescent beads, fly wings, spring/rice leaves, mouse tail transection, and fluorescence-stained SiHa cells. We envisage that this method can be further applied to many fields, such as biomedicine, industry, and chemistry.

This study presents a dual-modality microscopic imaging approach that combines quantitative phase microscopy and fluorescence microscopy based on structured illumination (SI) to provide structural and functional information for the same sample. As the first imaging modality, structured illumination digital holographic microscopy (SI-DHM) is implemented along the transmission beam path. SI-DHM acts as a label-free, noninvasive approach and provides high-contrast and quantitative phase images utilizing the refractive index contrast of the inner structures of samples against the background. As the second imaging modality, structured illumination (fluorescence) microscopy (SIM) is constructed along the reflection beam path. SIM utilizes fluorescent labeling and provides super-resolution images for specific functional structures of samples. We first experimentally demonstrated phase imaging of SI-DHM on rice leaves and fluorescence (SIM) imaging on mouse kidney sections. Then, we demonstrated dual-modality imaging of biological samples, using DHM to acquire the overall cell morphology and SIM to obtain specific functional structures. These results prove that the proposed technique is of great importance in biomedical studies, such as providing insight into cell physiology by visualizing and quantifying subcellular structures.

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