Since CdS material has a direct and wide band-gap, it is very potential for fabricating photovoltaic devices. Due to its
wide band-gap, CdS film can be acted as a window material to combine with Cu(In, Ga)Se<sub>2</sub> film. To obtain a quite
uniform, easily scaling-up, and inexpensive sample, the CdS thin film with a thickness of 50 nm was deposited by using
chemical bath deposition (CBD) technique. Through varying annealing temperatures and holding times, the electrical
and optical properties of CdS film could be obviously improved. By Hall measurements, the carrier concentration of CdS
sample S8 annealed at 100°C with 20 min is the maximum and its surface resistivity is the minimum. Summarizing these
measuring data, we find that the concentration and the mobility of sample S8 are 2.4×10<sup>21</sup> cm<sup>-3</sup> and 20.5 cm<sup>2</sup>/v-s,
respectively, and it is very suitable for applying to Cu(In, Ga)Se<sub>2</sub>-based solar cell.
Light concentrator is a non-imaging optics whose design can seriously affect the performance of a concentrating
photovoltaic module. For effectively increasing the incoming light flux, a new combo system designed by the edge-ray
theorem was proposed for solar concentration optics. This system is composed of three zones of total internal reflection
(TIR) lens, Fresnel lens, and aspherical lens.
In this system, the TIR lens is responsible for large bending angle, while the Fresnel lens and aspherical lens are
responsible for small bending angle due to their suffering for total internal reflection at large bending angle. For the
requirement of compactness, the TIR lens is located at the outmost zone from optical axis of the lens aperture to shorten
the depth of the lens system. The aspherical lens is located at the central zone while the Fresnel zone is then aligned
On this design example, the size of solar cell is assumed to be a square with a length of 5.5 mm. The diameter of the lens
aperture is 120 mm and the depth of the lens is considered to be lain between 60 and 65 mm. Through design analysis,
the full acceptance angle is set at 1.0 degree. Design data shows that this new combo system can meet the requirements
of solar concentration optics under considerations and its optical efficiency of the whole system can approach to 81%.
Detection of signals in the THz frequency region is important for applications of THz waves in many areas, such as in
medical imaging, forbidden-combined sensing, weapon monitoring, and wireless communications. Cooling system
operating under very low temperature, for eliminating the unwanted background THz radiation that exists everywhere in
room temperature, sets an obstacle for applications of conventional THz signal detecting systems. We present a
combined cavity that can pick out the useful signal in high sensitivity, while the influence of the background THz
radiation can be neglected in the detection. The combined cavity consists of a point-defect photonic-crystal resonator
and a photonic-crystal WGR. The two resonators are coupled together through optical tunneling to form the combined
cavity. Under proper operating parameters, the two resonators are in simultaneous resonance, and the field intensity in
the point-defect resonator can be thousands of times of that of an incoming THz signal for a given frequency, so that the
sensitivity of detection can be very high. Since the background THz radiation is not in resonance with the cavity, the
influence of it to the detection of THz signals wanted can be neglected, and thus cooling systems can be omitted. Plane
wave expansion method is used to determine the resonance wavelengths and mode patterns of the cavity. Finite-difference-
time-domain method is used to find the quality factors and to simulate the resonance process. Parameter
optimization and the conditions for simultaneous resonance of the two cavities are studied.
This work presents a novel method for optical decrypted key production by screen printing technology. The key is
mainly used to decrypt encoded information hidden inside documents containing Moire patterns and integral
photographic 3D auto-stereoscopic images as a second-line security file. The proposed method can also be applied as an
anti-counterfeiting measure in artistic screening. Decryption is performed by matching the correct angle between the
decoding key and the document with a text or a simple geometric pattern. This study presents the theoretical analysis and
experimental results of the decoded key production by the best parameter combination of Moire pattern size and screen
printing elements. Experimental results reveal that the proposed method can be applied in anti-counterfeit document
design for the fast and low-cost production of decryption key.
Design a Fresnel lens for a concentrator to collect more sunlight onto the solar cell due to the efficiency and cost. Since 1970, the non-imaging concentrator was used for solar energy; most of them were reflecting mirrors. The non-imaging optical system provides large aperture and forgiving imaging requirements. The Fresnel lens used in non-imaging optical system was usually called non-imaging Fresnel lens. In this research, the Fresnel lenses were refracting optical elements but diffracting ones. According to the method of Ralf Leutz and Akio Suzuki <sub></sub>, using minimum deviation and minimum dispersion to design a non-imaging Fresnel lens, which obeys the edge ray principle. Use optical software TracePro to simulate the non-imaging Fresnel lens, and each pitch size was 0.3mm and 200mm focus distant. Discusses the losses of non-imaging Fresnel lens and find out the relation of efficiency and F-Number. The optical concentration ratio could reach 15X (2-D) and 230X (3-D).
Illumination system is an important component of projection display system, and decides the brightness and uniformity of the whole system. This paper will present a description of a simplification design and discuss the performance of LED illuminators with respect to light output, uniformity, and color performance.
The excitonic photoreflectance (PR) spectra of GaAs/A1GaAs multiple quantum wells, grown by the molecular beam
epitaxial (MBE) technique, were investigated at oblique and near-normal incident angle with different polarized probe lights.
The PR spectra have been measured at room temperature using He-Ne laser as a pumping beam in order to study the
variations of the spectral line shapes. The experimental results show that the usefulness of the electromodulation to
characterize the microstructure of the substrate may be enhanced if we take in account the polarization state of the probe light
which is incident at larger oblique angle. The PR spectra were fitted by a third order derivative functional line shape, thus
making it possible to determine the energy band gap, broadening parameters, amplitudes, and the phases of the spectral