レーザスポット走査型干渉計の開発

—小型レンズ金型の形状計測—

抄録

Small lenses are one of the most important elements in digital devices such as mobile phones with cameras. In order to minimize the machining error of aspheric lens molds with high form accuracy, on-machine measurement of the lens mold shape is important. However, they require large field of view of mm order in diameter, robustness against vibrational noises from environment, short tact time, and compact body for on-machine measurements. We developed a Fizeau-type interferometer with wide field of view. The interferometer has small laser spot of 2.5μm in diameter, which scans over the 10mm x 8mm of observation area. With the use of transparent reference plates set over the concave of the lens mold, fringe patterns of lens mold with about 1.5mm in diameter was successfully observed in 80 seconds. This interferometer is also designed in a compact size.