Digital holographic microscopy
Digital holographic microscopy (DHM) captures a hologram with an electronic device such as a CMOS or CCD camera, and three-dimensional images from the captured hologram are reconstructed on a computer using diffraction calculation. In comparison to normal microscopy, the DHM can obtain simultaneously not only the amplitude of samples but also the phase; therefore, the DHM can perform three-dimensional measurement and high-accuracy thick measurement.
Real-time digital holographic microscopy
The DHM requires diffraction calculation to reconstruct images from captured holograms; unfortunately, it is difficult to perform the real-time reconstruction since the diffraction calculation is time-consuming even if using recent computers. We succeeded in developing real-time DHM system using a graphics processing unit[1].
Media1. CPU reconstruction
Media2. GPU reconstruction
Media3. GPU reconstruction(depth)
Our laboratory has been also developing useful numerical library for wave optics, which is referred to as CWO++ library. CWO++ is useful for not only DHM but also other wave optics applications (e.g., holographic display, holographic projection, designing optical elements and analyzing beam generation)[2].
http://cwolibrary.sourceforge.net/
Fig. 1 An example of CWO++ code.
Multiview digital holographic microscopy
The DHM requires diffraction calculation to reconstruct images from captured holograms; unfortunately, it is difficult to perform the real-time reconstruction since the diffraction calculation is time-consuming even if using recent computers. We succeeded in developing real-time DHM system using a graphics processing unit.
Media4. Multiview digital holographic microscopy
Giga-pixel digital holographic microscopy
We demonstrate a DHM using a consumer scanner in which we captured a hologram with 23,602✕18,023 pixels (0.43 gigapixels). The system using a consumer scanner has a simple structure, compared with synthetic aperture digital holography using a camera mounted on a two-dimensional moving stage.
Fig.2. Giga-pixel digital holographic microscopy
Media5. Giga-pixel digital holographic microscopy
GPU acceleration of compressive holography
Compressive holography is a holographic technique using compressive sensing that is an efficient signal acquisition and reconstruction framework exploiting signal sparsity. Compressive holography can introduce features that were not possible with conventional DHM,
but it requires high computational cost. Our aim is to accelerate compressive holography with GPU computing[3][4].
References
- Tomoyoshi Shimobaba, Yoshikuni Sato, Mai Takenouchi, Junya Miura and Tomoyoshi Ito, "Real-Time Digital Holographic Microscopy using the Graphic Processing Unit", Optics Express, Vol.16, No.16, pp. 11776-11781 (2008) [link]
- Tomoyoshi Shimobaba, Jiantong Weng, Takahiro Sakurai, Naohisa Okada, Takashi Nishitsuji, Naoki Takada, Atsushi Shiraki, Nobuyuki Masuda and Tomoyoshi Ito, "Computational wave optics library for C++: CWO++ library", Computer Physics Communications, 183, 1124-1, 138 (2012) [link]
- Yutaka Endo, Tomoyoshi Shimobaba, Takashi Kakue, and Tomoyoshi Ito, "GPU-accelerated compressive holography," Opt. Express 24, 8437–8445 (2016). [link]
- Yutaka Endo, Tomoyoshi Shimobaba, Takashi Kakue, and Tomoyoshi Ito, "GPU-Acceleration of Compressive Fresnel Holography," in Imaging and Applied Optics 2016, DW5I.7 (July, 2016). [link]