Hui-Ying Wu

Holographic Optical Elements and Application

Holographic optical element has a high diffraction efficiency and a narrow-band frequency characteristic, and it has a characteristic that is able to implement several features in a single flat device. It is widely applied in various fields. In this chapter, the principle and characteristics of the holographic optical elements are described in detail, and few typical holographic optical element-based applications, such as head-mounted display, lens array, and solar concentrator, are introduced. Finally, the futuristic research concepts for holographic optical element-based applications and contents are discussed.

Holographic Solar Energy Concentrator Using Angular Multiplexed and Iterative Recording Method

Holographic optical elements can be fabricated to concentrate the solar energy with no sun tracking system. Concentrated diffraction efficiency (CDE) for the holographic solar concentrator is suggested as a new efficiency calculation method. The exposure response of a monochromatic hologram recorded in photopolymer film is presented. The iterative exposure schedules at three different angles are chosen to optimize the uniformity of the CDE using angular multiplexed technique. The experimental results confirm that the angular multiplexing method and newly proposed iterative recording scheduling are appropriate for fabricating the holographic solar concentrator.

Development of holographic solar concentrator using holographic optical elements

In this paper, we present the development of holographic solar concentrator using holographic optical elements (HOE). The transmission HOE was evaluated by measuring the optical efficiencies of holographic gratings recorded at 532 nm wavelengths. We experimentally confirmed that holographic solar concentrator can condense the wide angle light to a single point through HOE.

Holographic projection head mounted display with transparent volume hologram

The diffraction holographic images from various volume holograms for holographic projection head mounted display systems are investigated. We experimentally confirmed that holographic three-dimensional images are presented to eye through transparent volume hologram.

Real object-based 360-degree integral-floating display using multiple depth camera

A novel 360-degree integral-floating display based on the real object is proposed. The general procedure of the display system is similar with conventional 360-degree integral-floating displays. Unlike previously presented 360-degree displays, the proposed system displays the 3D image generated from the real object in 360-degree viewing zone. In order to display real object in 360-degree viewing zone, multiple depth camera have been utilized to acquire the depth information around the object. Then, the 3D point cloud representations of the real object are reconstructed according to the acquired depth information. By using a special point cloud registration method, the multiple virtual 3D point cloud representations captured by each depth camera are combined as single synthetic 3D point cloud model, and the elemental image arrays are generated for the newly synthesized 3D point cloud model from the given anamorphic optic system’s angular step. The theory has been verified experimentally, and it shows that the proposed 360-degree integral-floating display can be an excellent way to display real object in the 360-degree viewing zone.

Development of full color holographic optical element recorded on aspherical substrate with photopolymer

Holographic optical element (HOE) have classically been designed using grating theory, logically so, since an HOE is a grating produced on film by two interfering beams of coherent light. This paper describes the development of full color HOE recorded on aspherical substrate using a photopolymer. The reflection HOE was evaluated by measuring the diffraction efficiencies of holographic volume gratings recorded individually at 633 nm, 532 nm, and 473nm wavelengths. The spectral characterization of the HOE, recorded using a combined single beam, and recorded using sequential beam, was carried out. Practical methods for fabrication of high efficiency aspheric HOE by single layer photopolymer were developed.