The multi-focal imaging system is implemented with a spatial light modulator (SLM) placed at the Fourier plane of the system. The multiplexed grating pattern displayed on the SLM can modify the wavefront of the incoming light and compensate aberrations existing in the system. We demonstrate the multiplexed grating pattern displayed on the SLM can acquire 25 images in a short time sequence by acquiring 9 images at different depths simultaneously in each exposure. We compare and discuss the advantages and disadvantages between the digital micro-mirror device (DMD) with the liquid crystal spatial light modulator (LC-SLM) based on the theory and experimental results.
Imaging a volumetric sample in real time is required to directly observe biological anatomy and mechanisms. There are a variety of microscopic imaging systems, developed to achieve optical sectioning, such as confocal microscopy. However, the drawbacks of existing systems are long scanning time or strong laser power. To overcome such problems and to obtain high-speed optical sectioning images, we demonstrate HiLo structured illumination microscopy by the use of digital micro-mirror device (DMD) and the focal tunable lens (FTL). The proposed system is configured such that hybrid uniform and non-uniform pattern are projected onto DMD to reconstruct optical sectioning images. In addition, FTL is utilized to digitally change observation plane with constant magnification and resolution; thus, mechanical movement is eliminated. Furthermore, in vivo three-dimensional (3D) images of biological samples, including a live Canenorhabditis elegans, are experimentally demonstrated.
We report on the implementation of spiral phase contrast imaging at multiple planes using forked-shaped defocus grating. The dual function of grating helps in simultaneous generation of multiple edge enhanced images corresponding to different depths. Present method is simple, direct and is applicable to coherent and incoherent imaging system.
High-speed microscopy three-dimensional (3D) microscopy based on trans-illumination is implemented with an amplitude light modulator placed at the Fourier plane of the system. The phase of an incident wave-front is modified and encoded with a defocus parameter to divert the light onto different portion of an image plane depending on their diffraction order and depth positions. The design of the grating pattern for the light modulated is discussed through the simulation and the experiment. 3D imaging capability is demonstrated through the experiment.
Wide-field fluorescent imaging severely suffers low resolution and poor contrast from out-of-focus background to image biological samples. In order to enhance optical sectioning capability, Confocal approach has been developed to filter out-of-focus background using point-to-point detection through a spatial pinhole. Recently, active structured illumination in wide-field fashion has been developed to reduce the transversal scanning cost, but still requires scanning in axial direction. Here, we present a wide-field multi-focal fluorescence microscopy incorporating spatial-spectral volume holographic gratings (MVHGs) with 3D active structured illumination to obtain optically sectioned images without scanning is presented. In contrast to conventional holographic techniques, which in general can not obtain fluorescence images, our approach does not require the formation of a hologram during imaging and is compatible with fluorescence based methods of imaging. Our approach requires pair-wise multi-depth resolved images, one with 3D active illumination, and the other with standard uniform illumination. Our approach is configured such that 3D illuminated planes occur inside the specimen, and also serve as the structured modulation for multiple axial planes imaged by MVHGs and display laterally onto the camera. The system can also be combined with micro-objective and relay systems for endoscopic operation. We demonstrate the proposed system’s ability to simultaneously obtain wide-field, optically sectioned, and multi-depth resolved images of fluorescently labeled tissue structures.