Lens-array Holographic Optical Element Research Articles

Dual-side see-through integral imaging 3D display system based on lens array holographic optical element

We propose a dual-side see-through integral imaging 3D display based on a lens array holographic optical element (LAHOE). The display system consists of two projectors and a LAHOE. The LAHOE is fabricated according to the theory of reflective volume holograms. An interference pattern is formed by a plane-wave beam and a spherical-wave array beam, and the interference pattern is recorded into a photopolymer material. Thus, the LAHOE is formed. When a reference beam is projected into the LAHOE, the wavefront of a convex micro-lens array is reconstructed. When a phase conjugation reference beam is projected into the LAHOE, the wavefront of a concave micro-lens array is reconstructed. So, the LAHOE possesses the optical properties of a convex micro-lens array and a concave micro-lens array. The proposed display is developed using integral imaging principle and it realizes dual-side see-through integral imaging 3D display.

Aerial Projection 3D Display Based on Integral Imaging

We proposed an aerial projection 3D display based on integral imaging. It is composed of a projector, a lens-array holographic optical element (HOE), and two parabolic mirrors. The lens-array HOE is a diffraction grating and is made by the volume holography technique. The lens-array HOE can be produced on a thin glass plate, and it has the optical properties of a lens array when the Bragg condition is satisfied. When the display beams of the element image array (EIA) are projected on the lens-array HOE, 3D images can be reconstructed. The two parabolic mirrors can project 3D images into the air. The Bragg-unmatched light simply passes through the lens-array HOE. Therefore, the aerial projection 3D images appear to be imaged in the air without any medium. In the experiment, a BenQ projector was used for the projection of 3D images, with a resolution of 1600 × 1200. The diameter and the height of each parabolic mirror are 150 mm and 25 mm, respectively. The inner diameter of the parabolic mirror is 40 mm. The 3D images were projected in the air, and the experimental results prove the correctness of our display system.

See-through 2D/3D compatible integral imaging display system using lens-array holographic optical element and polymer dispersed liquid crystal

A see-through 2D/3D compatible integral imaging display system including two projectors and a projection screen is proposed. The projection screen consists of a lens-array holographic optical element (LAHOE) and polymer dispersed liquid crystal (PDCL) film. The projection screen can operate at two different modes: the see-through and scattering display mode. With voltage, the projection screen works in the see-through display mode, 3D image for Bragg matched image can be presented, and 2D image can also be presented. Without voltage, the projection screen works in the scattering display mode, the 2D and 3D images can be presented. The prototype of the 2D/3D compatible integral imaging display system is developed. Experimental results confirm the feasibility of the proposed system.

Dual-View Integral Imaging 3D Display Based on Multiplexed Lens-Array Holographic Optical Element

We propose a dual-view integral imaging 3D display based on a multiplexed lens-array holographic optical element (MHOE). A MHOE is a volume holographic optical element obtained by multiplexing technology, which can be used for dual-view integral imaging 3D display due to the angle selectivity of the volume HOE. In the fabrication of the MHOE, two spherical wavefront arrays with different incident angles are recorded using photopolymer material. In the reconstruction, two projectors are used to project the elemental image arrays (EIA) with corresponding angles for two viewing zones. We have developed a prototype of the dual-view integral imaging display. The experimental results demonstrate the correctness of the theory.

14.3: See‐through 2D/3D Compatible Display Based on Integral Imaging

A see‐through 2D/3D compatible display based on integral imaging is proposed. It consists of a lens‐array holographic optical element (LAHOE) film, a polymer dispersed liquid crystal (PDLC) film and two projectors. The see‐through projection screen is composed of the LAHOE film and the PDLC film. The PDLC film is tightly behind the LAHOE film. With applied voltage, the projection screen works in the transparent display mode. 3D image for Bragg matched image can be presented, and 2D image can also be presented.

P‐82: Viewing‐Angle Enhanced 3D Display Based on Lens Array Holographic Optical element

A viewing‐angle enhanced 3D display based on lens array holographic optical element (LAHOE) is proposed. A reflection‐type flat LAHOE is recorded. The LAHOE works as a virtual curved lens array. The effective viewing angle of the prototype is about 42°, and it does not have crosstalk and flipped images.

35‐2: 3D/2D Switchable Display System Based on Integral Imaging

A 3D/2D switchable display system based on integral imaging is proposed by using a projection screen and a projector. The projection screen consists of a lens array holographic optical element (LAHOE) and a polymer dispersed liquid crystal (PDLC) film. The experimental results prove the feasibility of the proposed system.

High-resolution augmented reality 3D display with use of a lenticular lens array holographic optical element.

An augmented reality (AR) three-dimensional (3D) display based on one-dimensional integral imaging (1DII), by using a lenticular lens array holographic optical element (LLA-HOE), is proposed. The 3D image of the 1DII has higher vertical resolution compared with the image of conventional integral imaging whose resolution is sharply reduced for providing quasi-continuous viewpoints in both the horizontal and vertical directions. The proposed 3D display consists of a projector and an LLA-HOE and is compact. As an image combiner, the LLA-HOE can diffract Bragg-matched light rays that have the same wavelength and incident angle as the original reference wave; it can also function as a lenticular lens array to reconstruct a 3D image but transmit other light rays emitted from the surroundings. In the experiment, an LLA-HOE of 80 mm×80 mm size is recorded, and a combination of a high-resolution 3D virtual image and a real 3D object is presented by the proposed AR 3D display.

Integral imaging-based 2D/3D convertible display system by using holographic optical element and polymer dispersed liquid crystal.

An integral imaging-based 2D/3D convertible display system is proposed by using a lens-array holographic optical element (LAHOE), a polymer dispersed liquid crystal (PDLC) film, and a projector. The LAHOE is closely attached to the PDLC film to constitute a projection screen. The LAHOE is used to realize integral imaging 3D display. When the PDLC film with an applied voltage is in the transparent state, the projector projects a Bragg matched 3D image, and the display system works in 3D mode. When the PDLC film without an applied voltage is in the scattering state, the projector projects a 2D image, and the display system works in 2D mode. A prototype of the integral imaging-based 2D/3D convertible display is developed, and it provides 2D/3D convertible images properly.

P-86: Multi-view-zone 3D Display System Based on Integral Imaging

We propose a multi-view-zone 3D display system based on integral imaging. This system comprises multiplexed lens-array holographic optical element (MLAHOE) and two projectors. The MLAHOE is used as a projection screen, which is used to record the wavefront of two sets of lens-arrays on the holographic plate by two point light sources, respectively. The beam with element image array (EIA) information is used instead of the point light source, which satisfies the Bragg condition. The left and right viewing zones are respectively reconstructed by the MLAHOE, and different 3D images are reconstructed in the left and right viewing zones, respectively.

Color waveguide transparent screen using lens array holographic optical element

A color transparent screen was designed in this paper, a planar glass was used as a waveguide structure and the lens array holographic optical element (HOE) was used as a display unit. The lens array HOE was exposed by two coherent beams. One was the reference wave which directly illuminated on the holographic material and the other was modulated by the micro lens array. The lens array HOE can display the images with see-through abilities. Unlike the conventional lens array HOE, a planar glass was adopted as the waveguide in the experiment. The projecting light was totally internal-reflected in the planar glass to eliminate the undesired zero-order diffracted light. By using waveguide, it also brings advantage of compact structure. Colorful display can be realized in our system as the holographic materials were capable for multi-wavelength display. In this paper, a color transparent screen utilizing the lens array HOE and waveguide were designed. Experiment results showed a circular display area on the transparent screen. The diameter of the area is 20 mm and it achieved the pixel resolution of 100μm. This simple and effective method could be an alternative in the augment reality (AR) applications, such as transparent phone and television.

Recent progress in see-through three-dimensional displays using holographic optical elements [Invited

The principles and characteristics of see-through 3D displays are presented. We especially focus on the integral-imaging display system using a holographic optical element (IDHOE), which is able to display 3D images and satisfy the see-through property at the same time. The technique has the advantage of the high transparency and capability of displaying autostereoscopic 3D images. We have analyzed optical properties of IDHOE for both recording and displaying stages. Furthermore, various studies of new applications and system improvements for IDHOE are introduced. Thanks to the characteristics of holographic volume grating, it is possible to implement a full-color lens-array holographic optical element and conjugated reconstruction as well as 2D/3D convertible IDHOE. Studies on the improvements of viewing characteristics including a viewing angle, fill factor, and resolution are also presented. Lastly, essential issues and their possible solutions are discussed as future work.

See-through integral imaging display using a resolution and fill factor-enhanced lens-array holographic optical element.

We report on the development of a high-resolution see-through integral imaging system with a resolution and fill factor-enhanced lens-array holographic optical element (HOE). We propose a procedure for fabricating of a lens pitch controllable lens-array HOE. By controlling the recording plane and performing repetitive recordings process, the lens pitch of the lens-array HOE could be substantially reduced, with a high fill factor and the same numerical aperture compared to the reference lens-array. We demonstrated the feasibility by fabricating a lens-array HOE with a 500 micrometer pitch. Since the pixel pitch of the projected image can be easily controlled in projection type integral imaging, the small lens pitch enhances the quality of the displayed 3D image very effectively. The enhancement of visibility of the 3D images is verified in experimental results.

Solution for pseudoscopic problem in integral imaging using phase-conjugated reconstruction of lens-array holographic optical elements.

We propose an optical pseudoscopic to orthoscopic conversion method for integral imaging using a lens-array holographic optical element (LAHOE), which solves the pseudoscopic problem. The LAHOE reconstructs an array of diverging spherical waves when a probe wave with the phase-conjugated condition is imposed on it, while an array of converging spherical waves is reconstructed in ordinary reconstruction. For given pseudoscopic elemental images, the array of the diverging spherical waves integrates the orthoscopic three-dimensional images without a distortion. The principle of the proposed method is verified by the experiments of displaying the integral imaging on the LAHOE using computer generated and optically acquired elemental images.

Full-color lens-array holographic optical element for three-dimensional optical see-through augmented reality

A novel system of optical see-through augmented reality (AR) is proposed by making use of a holographic optical element (HOE) with full-color and lens-array functions. The full-color lens-array HOE provides see-through property with three-dimensional (3D) virtual images, for it functions as a conventional lens array only for Bragg-matched lights. An HOE recording setup was built, and it recorded a 30 mm × 60 mm sized full-color lens-array HOE by using the techniques of spatial multiplexing for large-area recording and wavelength multiplexing for full-color imaging. The experimental results confirm that the suggested full-color lens-array HOE can provide the full-color 3D virtual images in the optical see-through AR system.