Alexander Morozov

3D holographic printer: fast printing approach.

This article describes the general operation principles of devices for synthesized holographic images such as holographic printers. Special emphasis is placed on the printing speed. In addition, various methods to increase the printing process are described and compared.

Measurement of the optical characteristics of electrowetting prism array for three-dimensional display

Recently liquid-based optical devices are emerging as attractive components in three-dimensional (3D) display for its compact structure and fast response time. Among them an electrowetting prism array is one of the promising 3D devices. It steers a beam, which enables to provide corresponding perspectives to observer. For high quality autostereoscopic 3D displays the important factors are the beam steering angle and the beam profile, the optical characteristics. In this paper, we propose a method to measure the optical characteristics of the liquid prism and show experimental results on our prototype electrowetting prism array, which consists of prisms with 200um by 200um size. A modified 4-f system is adopted for the proposed method. It provides two kinds of information of the optical characteristics of the liquid prism at the image plane and at the Fourier plane. First, the proposed measurement setup magnifies the image of the liquid micro prism array so that we can observe the status of the each prism array directly with bare eye and align a mask easily for selecting a prism to be examined at the image plane. Secondly, the steering angle can be calculated by measuring the displacement of the beam at the Fourier plane, where the angular profiles that have important information on the oilwater interface is observed precisely. The principle of the proposed method will be explained, and the measured optical characteristics from experimental results on the liquid prism we fabricated will be provided, which proves the validity of the measurement method.

Slim coherent backlight unit for holographic display using full color holographic optical elements

The coherent backlight unit (BLU) using a holographic optical element (HOE) for full-color flat-panel holographic display is proposed. The HOE BLU consists of two reflection type HOEs that change the optical beam path and shape by diffraction. The illumination area of backlight is 150 mm x 90 mm and the thickness is 10 mm, which is slim compared to other conventional coherent backlight units for holographic display systems. This backlight unit exhibits a total efficiency of 8.0% at red (660 nm), 7.7% at green (532 nm), and 3.2% at blue (460 nm) using optimized recording conditions for each wavelength. As a result, we could get a bright full color hologram image.

A miniaturized near infrared spectrometer for non-invasive sensing of bio-markers as a wearable healthcare solution

A novel miniaturized near-infrared spectrometer readily mountable to wearable devices for continuous monitoring of individual’s key bio-markers was proposed. Spectrum is measured by sequential illuminations with LED’s, having independent spectrum profiles and a continuous detection of light radiations from the skin tissue with a single cell PD. Based on Tikhonov regularization with singular value decomposition, a spectrum resolution less than 10nm was reconstructed based on experimentally measured LED profiles. A prototype covering first overtone band (1500-1800nm) where bio-markers have pronounced absorption peaks was fabricated and verified of its performance. Reconstructed spectrum shows that the novel concept of miniaturized spectrometer is valid.

Ultra-slim coherent backlight unit for mobile holographic display

We propose slim coherent backlight unit for a mobile holographic display. This backlight unit consists of glass substrate for waveguide and two surface gratings produced by two-beam interference. The area of backlight illumination is 150 by 85 mm, and the thickness is 0.7 mm, which is thin compared to other conventional coherent backlight units. This backlight unit exhibits a total efficiency of 0.1%, preserving the collimation and a uniformity of 80% over the whole area. The proposed slim coherent backlight can be applied to a mobile holographic display.

Integrated Hologram Optical Head for Holographic Printer

We propose a compact holographic printer using RGB waveguide integrated optics. Our research reduces overall prototype size by 20 times, the number of optical components by 2 times, and improves the efficiency by 3 times.

Beam reshaping for rectangular area illumination

In many optical devices a task often arises to illuminate a rectangular-shaped area. With LEDs used as light sources, this task implies reshaping of the beam from a square Lambertian emitting surface to obtain a rectangular uniformly illuminated area ofappropriate dimensions and positioned above or decentered relative to the light source. We describe a new type ofrefractive lens developed for this purpose and the single-pass synthesis algorithm for its shape requiring no optimization step.

Glasses-free 2D/3D switchable display using an integrated single light-guide plate (LGP) with a trapezoidal light-extraction (TLE) film

A 10.1-inch 2D/3D switchable display using an integrated single light-guide plate (LGP) with a trapezoidal lightextraction (TLE) film was designed and fabricated. The integrated single LGP was composed of inverted trapezoidal line structures made by attaching a TLE film on its top surface and cylindrical lens structures on its bottom surface. The top surface of the TLE film was also bonded to the bottom surface of an LCD panel to maintain a 3D image quality, which can be seriously deteriorated by the gap variations between the LCD panel and the LGP. The inverted trapezoidal line structures act as slit apertures of parallax barriers for 3D mode. Light beams from LED light sources placed along the left and right edges of the LGP bounce between the top and bottom surfaces of the LGP, and when they collide with the inclined surfaces of the inverted trapezoidal structures, they are emitted toward the LCD panel. Light beams from LED light sources arranged on the top and bottom edges of the LGP are emitted to the lower surface while colliding with the cylindrical lens structures, and are reflected to the front surface by a reflective film for 2D mode. By applying the integrated single LGP with a TLE film, we constructed a 2D/3D switchable display prototype with a 10.1-inch tablet panel of WUXGA resolution (1,200×1,920). Consequently, we showed light-field 3D and 2D display images without interference artifacts between both modes, and also achieved luminance uniformity of over 80%. This display easily generates both 2D and 3D images without increasing the thickness and power consumption of the display device.

High collimated coherent illumination for reconstruction of digitally calculated holograms: design and experimental realization

Future commercialization of glasses-free holographic real 3D displays requires not only appropriate image quality but also slim design of backlight unit and whole display device to match market needs. While a lot of research aimed to solve computational issues of forming Computer Generated Holograms for 3D Holographic displays, less focus on development of backlight units suitable for 3D holographic display applications with form-factor of conventional 2D display systems. Thereby, we report coherent backlight unit for 3D holographic display with thickness comparable to commercially available 2D displays (cell phones, tablets, laptops, etc.). Coherent backlight unit forms uniform, high-collimated and effective illumination of spatial light modulator. Realization of such backlight unit is possible due to holographic optical elements, based on volume gratings, constructing coherent collimated beam to illuminate display plane. Design, recording and measurement of 5.5 inch coherent backlight unit based on two holographic optical elements are presented in this paper.

Glasses-free 2D-3D switchable display using an integrated single light guide plate

To commercialize glasses-free 3D display more widely, the display device should also be able to express 2D images without image quality degradation. Moreover, the thickness of display panel including backlight unit (BLU), and the power consumption should not be increased too much, especially for mobile applications. In this paper, we present a 10.1-inch 2D-3D switchable display using an integrated single light guide plate (LGP) without increasing the thickness and power consumption. The integrated single LGP with a wedge shape is composed of prismatic line patterns on its top surface and straight bump patterns on its bottom surface. The prismatic line patterns, which are composed of micro prisms having the light aperture on one side, act as slit apertures of parallax barriers for 3D mode. The linear bump patterns arranged along the vertical direction scatter the light uniformly together with the reflective film disposed under the LGP for 2D mode. LED light sources are arranged as edge-lit in the left and right sides of the LGP for 2D mode, and on the top edge of the LGP with the wider thickness for 3D mode. Display modes can be simply switched by turning on and off the LED light sources, alternatively. Applying the integrated single LGP, we realized a 2D-3D switchable display prototype with a 10.1-inch tablet panel of WQXGA resolution (2,560 × 1,600), and showed the light-field 3D display with 27-ray mapping and 2D display. Consequently, we acquired brightness uniformity over 70% for 2D and 3D modes.