Kuang Lung Hunag has his expertise in Lens Design and Optical Engineering. He used to work in optical industry for many years. Currently he is a full time Faculty of Department of Materials and Energy Engineering, MingDao University, Changhua, Taiwan, ROC. He is also in charge of several projects related to lens design and optical engineering.
Statement of the Problem: Reduction lens has been used in many applications for a long time. However, as the requirement for space limitations is the key issues of design, the fundamental theory for thin lens layout becomes crucial. The compact micro-reduction lens has only 10 mm total axial length, and 3 mm back focal length. The reduction ratio (image/object) is -0.212 and has diffraction image performance. Methodology & Theoretical Orientation: The design evolved from Seidel aberration theory. In finding initial solution for compact structures and long back focal length, a thin lens layout with “+, -” and “-, +” structures have been investigated. Findings: A thin lens layout with “+, -” configuration has less BFL than that of the “-, +” structure’s. The axial glass length of the first lens can reduce air thickness for compact requirements and balance aberrations, which leading the high contrast performance of the reduction lens. Conclusion & Significance: The compact micro-reduction lens has designed based on Seidel aberration theories. An initial solution with “-, +” structure can balance the Petzval curvature aberration and have longer BFL for mechanical constraints. The image performance reaches diffraction limit under the -0.212 reduction ratio.
Jianhua Liu got his Master’s and Bachelor’s degree from Shanghai University of Science and Technology in 1992 and 1989, respectively. In 1995, he got his PhD from Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Science. His interested fields of research include laser spectroscopy of laser crystals, experimental studies on the interaction of short laser pulses with thin film materials, liquid crystal optics, and optical properties of optical planar waveguides.
Optical bandpass (OBP) filter is a kind of important device that has been widely used in many optical fields. OBP filters, with bandwidth in nanometer scale and sideband well depressed, usually are made of tens or even hundreds of this thin film pairs piling together. The transmission efficiency typically gets in a range of 50-90%, due mainly to the material imperfection and errors in the film deposition processing. In the past two decades, waveguide grating (WG) provided a new way of making narrow bandwidth optical bandpass filters due to the novel property of optical anomaly, i.e. 100% transmission efficiency and extremely narrow bandwidth in nano/picometer scale. However practically precise control of the profile in the constituent materials of the WG structure is not an easy task. Recently, we have proposed a new type of narrow bandwidth optical bandpass filter which is composed of only a few (minimally 3) layers of films that form a planar optical waveguide, and two coupling prisms cladding on both side of the POW. Light transmits from one prism to the other through the sandwiched POW under the condition of a two-step guided mode resonances (GMR), which makes the transmittance extremely sensitive to the structural configuration, wavelength, and the angle of incidence. We have obtained simulation results of single and/or multiple pass-bands in the visible spectrum with transmission efficiencies about 99% with practical material parameters. The most prominent feature of this kind of OBP filter is that bandwidths for most of the pass-bands are in picometer scale. Meanwhile sensing applicability has also been explored. Because of the simple structure and less number of layers, it could be easily implemented in terms of device fabrication.