Fresnel Lens Array Research Articles

P-87: Optimization of Display Image in Fresnel Lens-based Floating Display System Using a Curved Screen

As an approach for a 3D real image display system without special glasses, a Fresnel lens-based 3D rear-projection display system is implemented. In this display system, the conventional 2D video image is projected into the air through some projection optics, a screen and a pair of Fresnel lens. As a result, it can form a floating video image having a real depth. In this paper we suggest the method to compensate the image distortion in floating display system. and we have measured the image depth and viewing angle of floating image about the various type of Fresnel lens array in floating display system using curved screen.

Low-temperature growth of Si-based organic–inorganic hybrid materials, Si–O–C and Si–N–C, by organic Cat-CVD

This paper describes the recent development of organic catalytic CVD (O-Cat-CVD), which is an extension of the conventional Cat-CVD technique to organic substances. O-Cat-CVD utilizes various types of metal organic (MO) compounds as Cat-CVD sources. Various functional organic–inorganic hybrid materials can be prepared on the basis of MO molecules. The growth and properties of Si-based organic–inorganic materials, Si–O–C and Si–N–C, are described with emphasis on the microscopic chemical-bonding structures depending on the source molecules. The application to a micro Fresnel lens array and selective oxidation mask of Si–O–C and Si–N–C are also demonstrated.

Micro Fresnel Lens Array를 이용한 Backlight Unit 설계

LCD Backlight에서 Micro Fresnel Lens Array (MFLA)가 결합된 도광판을 설계<TEX>${\cdot}$</TEX>분석하였다. MFLA가 적용된 도광판과 기존의 프리즘 형태의 도광판의 광학적 특성을 전산모의하여 비교한 결과를 나타내었다. MFLA를 이용한 도광판을 사용할 경우 기존의 LCD backlight 장치에서 필요로 했던 프리즘 필름을 대체할 수 있음을 보였다. A light-guide plate of an LCD backlight coupled with a microfresnel lens array (MFLA) is designed and analyzed. Computer simulated results of optical characteristics of our MFLA-type light-guided plate compared with the conventional prism-type one are presented. We show that the MFLA-type light-guide plate can replace well the conventional prism-type plate.

3D integral imaging using diffractive Fresnel lens arrays

We present experimental results with binary amplitude Fresnel lens arrays and binary phase Fresnel lens arrays used to implement integral imaging systems. Their optical performance is compared with high quality refractive microlens arrays and pinhole arrays in terms of image quality, color distortion and contrast. Additionally, we show the first experimental results of lens arrays with different focal lengths in integral imaging, and discuss their ability to simultaneously increase both the depth of focus and the field of view.

Study for wide-viewing integral photography using an aspheric Fresnel-lens array

Integral photography (IP) is one of the most attractive methods for autostereoscopic display. We experimentally study an IP system, adopting a commercial liquid-crystal display panel by testing several lens arrays that have different f numbers. The viewing angle in each case is calculated and measured. We show the limitation of the conventional lens array with respect to viewing angle, and suggest the method using an array of small-f-number aspheric Fresnel lenses to avoid aberration for wide viewing angles. The blur noise caused by the array is also discussed.

Three‐dimensional dynamic display system based on integral imaging

Three‐dimensional dynamic display system based on computer‐generated integral imaging is discussed and its feasibility is verified via some basic experiments. Integrated images observed from different viewing points are seen to have full parallax and the animated 3D image was implemented successfully. Moreover, using large size Fresnel lens array was found to helps widen viewing angle and to make the system more practical.

Exposure characteristics and three-dimensional profiling of SU8C resist using electron beam lithography

The properties of a new type of chemically amplified resist, SU8C, are evaluated for electron beam lithography. This resist is a modification of the ultraviolet sensitive negative epoxy SU8. Experimental results show that the sensitivity of SU8C is one of the highest among the different kinds of commercially available resists. At 50 keV energy exposure, the saturation dosage of SU8C is ∼3.8 μC/cm2 while that of PMMA is ∼500 μC/cm2. This implies that SU8C resist is suitable for large area exposure. The contrast γ can also be adjusted to near unity by adjusting the postannealing time, and this is essential for multilevel profiling. 16 level steps have been exposed in one electron beam exposure by changing the clock frequency in sequence, and a vertical profile resolution of 20 nm has been achieved. Lines as narrow as 100 nm have been produced, showing that the resist has high resolution down to the nanoscale. Hardness measurements have also been carried out, and SU8C is an order of magnitude harder than epoxy and PMMA. SU8C resist has high refractive index, high resolution, high sensitivity, and large hardness, making it suitable for microscale binary optics fabrication. To demonstrate the suitability of SU8C resist in microscale optical device fabrication, an array of Fresnel lenses has been designed and demonstrated.

Demonstration of Arrays of Sub-Micrometer Solid-State Fresnel Lenses for Electrons

AbstractWe demonstrate the focusing action of a compact solid state pixelated Fresnel phase (PFP) lens for electrons (700 nm in diameter), consisting of an array of holes (“pixelated”) directly drilled by a finely focused electron beam in a thin AlF3 thin film on carbon supporting film. The depths of holes, hence the phase of the exit electron wave is varied as a function of radius from the center of the pattern so that the wavelet from each hole can be in phase on axis at a designated focal point thus producing a lens. An array of two types of lenses, convergent and divergent, with nominal focal length of 1 mm for 200 keV electrons was produced. The estimated full-width-half-maximum of the focus is 8 nm. With improvement of the efficiency, these lenses may find applications in parallel electron-beam lithography, in X-ray optics and in light optics.

Wavefront analysis with high-accuracy inversion interferometer

A recently introduced wavefront analyzer, based on a Fresnel-lens array, is improved by incorporating phase-shifting procedures. The resulting compact and stable interferometer can measure wavefront distortions with extremely high accuracy. In our experiments, with no special efforts at environmental isolation, the instrumental noise level was under 0.02?.

Programmable coherent source arrays generated by spatial light modulators

Programmable coherent source arrays are generated by using addressable liquid-crystal spatial light modulators and two-dimensional arrays of Fresnel lenses. The modulators used are an optically addressed liquid-crystal light valve, a matrix-addressed pixelated display, and two devices that have individually addressable elements with specially designed patterned electrodes. One such device has a transparent electrode patterned as a Fresnel zone plate array; the other is a gate array used in a hybrid implementation with a Fresnel lens array etched on a glass substrate. The operation of devices that use binary-amplitude and binary-phase Fresnel lenses is described, identifying programmable features, resolution limits, and applications.

Electrically controlled polarization-independent liquid-crystal Fresnel lens arrays

We describe the properties and construction of a polarization-independent Fresnel lens array using nematic liquid crystals in which the diffraction efficiency of lenses can be electrically controlled. A novel structure is used such that the principal axis of the liquid crystals in two adjacent zones of each Fresnel lens are orthogonal. This makes the device polarization independent. We have characterized these lenses at different applied fields and input polarizations by diffracting an argon-ion beam into focus.