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We propose high-speed incoherent digital holography with a recording speed of 1,000 fps, which is designed for the three-dimensional (3D) motion-picture measurement of moving objects with high temporal resolution. We adopt single-shot phase-shifting incoherent digital holography, a high-speed polarization-imaging camera system, and a palm-sized self-interference interferometer designed for spatially and temporally incoherent light, to implement a high-speed phase-shifting incoherent digital holography system. High-speed four-dimensional (4D) (3D and time) measurement capability is experimentally demonstrated, using the constructed incoherent digital holography system set on a wagon and a daily-use white-color light-emitting diode.

I propose a multidimension-multiplexed imaging method with which multiple physical quantities of light are simultaneously obtained as interference fringe images. The varieties of light are distinguished by exploiting the proposed phase-encoding technique. Neither measurements of point spread functions in advance, nor iterative calculations to derive multidimensional information, nor a laser light source is required. Multidimensional imaging of an object and simultaneous three-dimensional image recording of self-luminous light and light transmitted from an object are experimentally demonstrated. A palm-sized interferometer based on the proposed holography is developed for the experiments to show its portability and physical-filter-free multidimensional imaging ability without an antivibration structure.

We propose single-path single-shot phase-shifting digital holographic microscopy (SSP-DHM) in which the quantitative phase information of an object wave is acquired without a laser light source. Multiple phase-shifted holograms are simultaneously obtained using a linear polarizer, a liquid crystal on a silicon spatial light modulator (LCoS-SLM), and a polarization-imaging camera. Complex amplitude imaging of a USAF1951 test target and phase imaging of transparent HeLa cells are performed to show its quantitative phase-imaging ability. We also conduct an experiment for the motion-picture imaging of transparent particles to highlight the single-shot imaging ability of SSP-DHM.

We review advancements in incoherent digital holography (IDH) with an image sensor and its applications to multidimensional microscopy and a palm-sized hologram recorder termed “holosensor”. There are two types of representative IDH technique: IDH with a structured illumination and a single photodetector termed optical scanning holography and self-interference IDH. The latter IDH is a technique to obtain an incoherent digital hologram by modulating an incoherent light wave between an object and an image sensor. Multidimensional information such as three-dimensional space and wavelengths is simultaneously recorded without changing optical filters by introducing interferometric techniques invented in laser holography. Applications to high-speed color-multiplexed holographic fluorescence microscopy, single-shot incoherent full-color holographic microscopy with white light, and a palm-sized multidimensional incoherent hologram recorder have been developed using multidimensional IDH systems. Schematics and experimental results obtained using IDH techniques, incoherent holographic microscopy systems, and compact IDH systems are introduced.

A palm-sized wavelength-multiplexed hologram recorder for a reflective 3-D object is presented. A color 3-D image is obtained using spatially incoherent color illumination light, wavelength-multiplexed incoherent holograms, and computational coherent superposition scheme.

Single-shot full-color holography with sunlight is presented. Single-shot phase-shifting incoherent and conoscopic holography, a minification system, and a color polarization-imaging camera are adopted for single-shot spatially incoherent full-color 3-D imaging of an outdoor scene.

A palm-sized single-path single-shot incoherent digital holography system is presented. Single-shot phase-shifting and self-interference incoherent holography with birefringent materials are adopted for incoherent 3-D imaging with a single exposure of a polarization-imaging camera.

We present phase-shifting interferometry techniques applied for multidimensional incoherent digital holography and toward ultimately low light-intensity sensing. Using incoherent holography with multiwavelength-multiplexed phaseshifting interferometry that is termed computational coherent superposition (CCS), full-color three-dimensional (3D) information of an incoherent object can be obtained from the recorded wavelength-multiplexed self-interference holograms. Furthermore, an optical setup of incoherent holography based on CCS is implemented as a palm-sized incoherent digital holographic sensing system, termed “Holosensor.” Using incoherent holography with single-shot phase-shifting holography, high-speed 3D motion-picture imaging has been demonstrated. Phase-shifting interferometry is also a powerful 3D sensing technique for ultimately low light-intensity conditions.

The use of phase-shifting interferometry (PSI) in the ultra-low-light region would open the way for important applications, such as imaging of phototoxic substances and sensing of ultrafast phenomena. In the ultra-low-light region, the statistical nature of photons can be a dominant source of noise compared with other noise caused by experimental instruments. Here we theoretically derive the precision limit determined by the statistical nature of photons for simultaneously measuring the transmittance and phase of a sample with PSI. We show that the precision of PSI depends on the phase and transmittance themselves. We also show a trade-off relation between transmittance and phase. Then we compare PSI with sequential optimal measurements in which the transmittance and phase of a sample are separately measured for each corresponding optimal measurement. We also discuss the case where the input number of photons fluctuates with a Poisson distribution and show that the fluctuation affects both the transmittance and phase precision for PSI.

Fresnel incoherent correlation holography (FINCH) was a milestone in incoherent holography. In this roadmap, two pathways, namely the development of FINCH and applications of FINCH explored by many prominent research groups, are discussed. The current state-of-the-art FINCH technology, challenges, and future perspectives of FINCH technology as recognized by a diverse group of researchers contributing to different facets of research in FINCH have been presented.

We present multidimensional information sensing using incoherent digital holography with phase-shifting interferometry. Spatially incoherent light is recorded as an incoherent hologram by incoherent holography and three-dimensional, wavelength, and temporal information is obtained by applying various phase-shifting interferometry techniques such as the computational coherent superposition scheme.

We present color fluorescence imaging using an incoherent digital holographic technique in which holographic multiplexing of multiple wavelengths is exploited. Self-interference incoherent digital holography with a single-path in-line configuration and the computational coherent superposition scheme are adopted to obtain color holographic three-dimensional information of self-luminous objects with a monochrome image sensor and no mechanical scanning. We perform not only simultaneous color three-dimensional sensing of multiple self-luminous objects but also color fluorescence imaging of stained biological samples. Color fluorescence imaging with an improved point spread function is also demonstrated experimentally by adopting a Fresnel incoherent correlation holography system.

We propose a phase-shifting interferometry technique using only two in-line phase-shifted self-interference holograms. There is no requirement for additional recording or estimation in the measurement. The proposed technique adopts a mathematical model for self-interference digital holography. The effectiveness of the proposed technique is demonstrated by experiments on incoherent digital holographic microscopy and color-multiplexed fluorescence digital holography with computational coherent superposition. Two-color-multiplexed four-step phase-shifting incoherent digital holography is realized for the first time, to the best of our knowledge, using the proposed technique.

We present an incoherent two-color digital holography system to record holograms with 2,048 x 2,048 pixels at 72 fps for fluorescence-stained cell imaging. We utilize single-shot wavelength-multiplexed incoherent digital holography with computational coherent superposition.

We present an incoherent digital holography system with 102 fps for simultaneous, holographic, and microscopic motion-picture sensing of multiple fluorescence nanoparticles. We utilize single-path single-shot phase-shifting incoherent digital holography with a birefringent material array.

Phase-shifting interferometry selectively extracting wavelength information has been proposed since 2013, which is called computational coherent superposition (CCS) of multiple wavelengths. In this proceeding, we apply CCS to self-interference incoherent holography and construct single-path, mechanical-motion-free, wavelength-multiplexed, incoherent multicolor digital holographic microscopy systems. Also, we numerically investigate quantum fluctuation in phase-shifting interferometry for the sensing of weak light such as natural light and nonlinear light. After that, we briefly discuss the difference between the digital holography systems with CCS and phase-shifting interferometry with a Bayer color image sensor.

We numerically investigate the effect of quantum fluctuation in phase-shifting interferometry. Numerical results agree well with the theoretical ones and confirm the limit of measurement accuracy and a trade-off relationship between amplitude and phase.

We present approaches for simultaneous, holographic, and microscopic multicolor motion-picture sensing of multiple natural light sources. We utilize single-shot incoherent digital holography with a polarization-imaging sensor, phase-shifting interferometry, and computational coherent superposition (CCS) as approaches.

We present a multiwavelength incoherent digital holographic microscope with wavelength-multiplexed phase-shifted holograms and halogen lamp. A multicolor holographic image is obtained from spatially incoherent white light, using neither mechanical scanning nor a color image sensor.

We present an incoherent color digital holographic microscope for single-shot multicolor three-dimensional imaging of microscopic specimens. The system does not require any spatial light modulator and light-use efficiency is improved due to no beam splitter.

We propose multiwavelength in-line phase-shifting digital holography with a monochrome image sensor, single reference arm, and no mechanical scanning. We use phase-shifting interferometry selectively extracting wavelength information as a method to obtain multiwavelength object waves separately from wavelength-multiplexed phase-shifted holograms. By exploiting a liquid crystal on silicon spatial light modulator with a wide phase-modulation range as an electrically driven phase shifter in this interferometry, we remove mechanically moving parts during phase shifting. Its effectiveness is experimentally demonstrated.

For incoherent and coherent digital holography, the parallel phase-shifting technique has been used to reduce the number of exposures required for the phase-shifting technique which eliminates zero-order diffraction and conjugates image components. Although the parallel phase-shifting technique can decrease the hologram recording time, the image interpolations require additional calculation time. In this study, we propose a technique that reduces the calculation time for image interpolations; this technique is based on the convolution theorem. We experimentally verified the proposed technique and compared it with the conventional technique. The proposed technique is more effective for more precise interpolation algorithms because the calculation time does not depend on the size of interpolation kernels.

Computational holography, encompassing computer-generated holograms and digital holography, utilizes diffraction calculations based on complex-valued operations and complex Fourier transforms. However, for some holographic applications, only real-valued holograms or real-valued diffracted results are required. This study proposes a real-valued diffraction calculation that does not require any complex-valued operation. Instead of complex-valued Fourier transforms, we employ a pure real-valued transform. Among the several real-valued transformations that have been proposed, we employ the Hartley transformation. However, our proposed method is not limited to this transformation, as other real-valued transformations can be utilized.

We propose a quantitative phase imaging technique with single-path phase-shifting digital holography using a light-emitting diode (LED). A reference wave is generated from an object wave in the Fourier plane using a single-path interferometer, based on self-reference digital holography. The object wave interferes with the reference wave, and the quantitative phase information of the object wave is recorded as a digital hologram. Quantitative phase images of objects are obtained by applying a phase-shifting interferometry technique. All the light diffracted from the objects can be utilized to generate a digital hologram. Its validity is experimentally demonstrated by constructing an optical system with a wide-field optical microscope.

We propose a palm-sized single-shot phase-shifting incoherent digital holography (SSPS-IDH) system in which three-dimensional (3D) information of spatially incoherent light is recorded as a self-interference hologram. To implement this single-shot 3D recording system, we adopt thin optical elements and no refractive lens. 3D information is obtained with a single-shot exposure of a polarization image sensor. More than 3,800-fold downsizing in volume can be achieved in comparison with a conventional incoherent digital holography (DH) system. An SSPS-IDH system is constructed, and its single-shot 3D sensing ability is experimentally demonstrated.

We propose a novel algorithm that does not require any Fourier transform to extract multiple object waves in a single image recorded with spatial frequency-division multiplexing. Smoothing is utilized to extract the desired object-wave information from a spatially multiplexed image. Numerical and experimental results show its validity and applicability for image and Fresnel digital holography. Our investigations clarify the speeding up of both the object-wave extractions and multiple object–image reconstructions quantitatively.

We propose a dual-wavelength phase-shifting digital holography technique with four wavelength-multiplexed holograms based on phase-division multiplexing utilizing the 2π ambiguity and zeroth-order diffraction-image suppression. Zeroth-order wave suppression is implemented by introducing the averaging method. Its effectiveness is experimentally shown and numerically and quantitatively investigated. The numerical investigation demonstrates the tolerance of the proposed technique against incoherent light noise and changes in the reference wave intensity. The image quality in the proposed technique depends on the intensity ratio between the object and reference waves but does not degrade with constant changes in intensity. In contrast, a previously reported four-step dual-wavelength phase-shifting technique was affected by the factors described above.

We propose a multicolor lensless three-dimensional image-sensing technique with a full space-bandwidth product of an image sensor, seven wavelength-multiplexed holograms, a single reference arm, and no mechanical movements. Its effectiveness is experimentally demonstrated.

We present a digital holography using high dynamic range (HDR) imaging to improve quality of the reconstructed image of digital holography. The technique extends the dynamic range of the digitally recorded hologram using multiple holograms recorded with different exposures. We numerically and experimentally demonstrated the technique based on an off-axis digital holography system. In the numerical simulation and experiment, the quality of the reconstructed images by the proposed technique is higher than that by the conventional digital holography without HDR imaging.

We propose a digital holographic microscope for the single-shot multicolor three-dimensional (3D) image sensing of specimens illuminated by spatially and temporally incoherent white light. The proposed microscope exploits self-interference, single-shot phase-shifting incoherent digital holography, a polarization-imaging color image sensor, and static polarization-sensitive optical elements to generate two object waves with different curvature radii. The microscope does not require any spatial light modulator or a beam splitter, and can be constructed with a compact single-path optical setup. The color holographic 3D motion picture recording of spatially and temporally incoherent white light at a speed of 10 fps order is experimentally demonstrated with the proposed microscope.

We propose a holographic technique by which multiwavelength three-dimensional spatial information is obtained with both a single-shot exposure of a monochrome image sensor and an in-line holographic multiplexing scheme. We develop a specially designed monochrome image sensor with a wavelength-dependent phase-modulation array, which is used to obtain the holographic information required for the proposed technique. The proposed technique is applicable for not only laser holography but also spatially and temporally incoherent holography. Its validity is experimentally demonstrated by constructing a color-multiplexed fluorescence digital holographic microscope and a multicolor incoherent digital holography system with a white-light source.

In this Letter, we propose spatially incoherent multiwavelength three-dimensional (3D) microscopy that exploits holographic multiplexing and is based on computational coherent superposition (CCS). The proposed microscopy generates spatially incoherent wavelength-multiplexed self-interference holograms with a multiband-pass filter and spatially and temporally incoherent light diffracted from specimens. Selective extractions of 3D spatial information at multiple wavelengths from the holograms are realized using the CCS scheme. We constructed fully mechanical-motion-free holographic multiwavelength 3D microscopy systems and conducted experiments to demonstrate the microscopy.

We propose multiwavelength-multiplexed phase-shifting incoherent color digital holography. In this technique, a monochrome image sensor records wavelength-multiplexed, phase-shifted, and incoherent holograms, and a phase-shifting interferometry technique selectively extracts object waves at multiple wavelengths from the several recorded holograms. Spatially incoherent light that contains multiple wavelengths illuminates objects, and multiwavelength-incoherent object waves are simultaneously obtained without using any wavelength filters. Its effectiveness is experimentally demonstrated for transparent and reflective objects.

The quality of reconstructed images in relation to the bit depth of holograms formed by wavelength-selective phase-shifting digital holography was investigated. Wavelength-selective phase-shifting digital holography is a technique to obtain multiwavelength three-dimensional (3D) images with a full space-bandwidth product of an image sensor from wavelength-multiplexed phase-shifted holograms and has been proposed since 2013. The bit resolution required to obtain a multiwavelength holographic image was quantitatively and experimentally evaluated, and the relationship between wavelength resolution and dynamic range of an image sensor was numerically simulated. The results indicate that two-bit resolution per wavelength is required to conduct color 3D imaging.