Optically recorded analog holograms can reconstruct photorealistic three-dimensional (3D) images without the need for specialized eyewear. Computer-generated holograms (CGHs) are created by simulating the holographic recording process digitally rather than capturing them optically. Large-scale 3D still-image reconstruction with wide-viewing-zone can be achieved by mapping the amplitude or phase profiles of CGHs onto diffractive optical elements (DOEs), which modulate in-plane wavefront distribution using wavelength-scale surface structures. However, DOEs exhibit limited wavelength selectivity, interacting with a broad spectral range beyond their design wavelength. This results in reduced overall transmittance and typically requires three separate CGHs for full-color reconstruction. In this work, we present an "invisible holographic window," a transparent, surface-relief CGH patterned directly on glass via laser grayscale lithography. By encoding the real component of the interference pattern and reducing the phase-modulation range, the surface-relief structure transitions from deeply wrapped, jagged phase profiles to shallower and smoother sinusoidal phase profiles, which is associated with improved optical transmittance. Furthermore, a spatial-frequency-domain band-division multiplexing strategy is applied to support crosstalk-free, full-color 3D image reconstruction from a single transparent CGH, albeit with a viewing angle reduction. This platform generates photorealistic full-color 3D still-images in real space, offering new possibilities for transparent augmented-reality display interfaces such as those integrated into storefront windows, office glass partitions, and museum display cases. Our findings pave the way for advanced holographic display technologies and promise to accelerate research in the field.

An integral 3-D technique provides a 3-D spatial image viewable from varying positions without the use of special light sources or viewing glasses. Therefore, this technique shows promise for diverse applications in various fields, including 3-D television broadcasting, advertising, and medical diagnostics. However, there are problems in capturing and displaying large amounts of information in realizing practical integral imaging devices. This paper overviews integral 3-D capturing methods and analyzes integral 3-D imaging technology at its capturing and displaying stages. To overcome the resolution problem, it also introduces our recent work for capturing high-resolution integral imaging information. The introduced device consists of a multiple-lens array and a complementary metal-oxide-semiconductor image sensor with a circuit patterned using multiple exposures. This device can capture depth-controlled spatial information by introducing additional optics. Two types of optics for depth control are applied to the capturing device: one functions as a convex lens to control and compress a relatively large object space and the other functions as an afocal lens array that controls a relatively small object space without any distortion in the depthwise direction. Experimental results of spatial information capturing and 3-D image displays confirm that the method produces 3-D images having an appropriate motion parallax. The presented method is scalable; thus, this technique offers possibilities for developing advanced high-resolution integral 3-D imaging devices.

Software development is knowledge-intensive as well as collaborative work carried out by several persons. In this type of education, project-based exercises are conducted in order to acquire skills. Object-oriented software development has recently emerged as the primary branch of learning. However, it is difficult for novice students to develop software using the object-oriented paradigm. This paper proposes a method of education and a learning environment for object-oriented software engineering based on the cognitive apprenticeship model.