Micro thermal design of swing arm type small form factor optical pick-up system

Abstract

New multimedia information environment requires smaller optical data storage systems. However, one of the difficulties in the design of small form factor (SFF) optical pick-up is to emit the heat which is usually generated from laser diode (LD). The generated heat may reduce the optical performance of the system as well as the lifetime of LD. Therefore, it is important to include the thermal consideration in the development of SFF optical pick-up system for the high performance and longer lifetime of LD. It is also necessary to analyze the thermal characteristics of LD by the micro heat transfer analysis. In this study, micro heat transfer analysis was performed using the finite element method for the 28 × 11 × 2 mm3 super slim swing-arm type actuator of the optical pick-up in the Blu-ray disk (BD) format. Two different materials were used for a swing-arm; a double layer structure of polycarbonate/steel and a single layer structure of aluminum. The heat generated from LD (80 × 400 × 600 μm3) ranges from 100 to 250 mW. The maximum temperature at the LD is 78.9°C for the case of polycarbonate/steel swing-arm optical pick-up when the heat generation and the convection coefficient are 250 mW and 25 W/m2 K, respectively. On the other hand, it is 52.87°C for the case of aluminum swing-arm under the same conditions. The result of simulation indicates that the single layer structure of aluminum actuator is more suitable for the for the SFF optical pick-up in the viewpoint of heat release.