Scatterometer basing on a STAR GEM idea for optical measurements of microlenses

摘要

It is important to measure both reflectance (R ) and transmittance (T ) with the same accuracy. But many commercial accessories are exchanged by themselves or a sample is replaced on the other position in one accessory, when the reflection measurement is changed from the transmission measurement, so that it is impossible to measure reflectance and transmittance with the same accuracy. Accordingly the absorptance (A=1-R-T ) of the sample is not a sufficient index to evaluate the optical properties. A new scatterometer, which overcomes the defect, has been developed in AIST. It consists mainly of two ellipsoidal mirrors and a new detection system, which is composed of a hemispherical lens, a fiber optic taper and a CCD camera. These mirrors are a belt-shape and a quarter ellipsoidal mirrors with two focal points and are combined such that each focal point is a common focal point, on which the sample is placed. A rotating mirror is set on a remaining focal point of the belt-shape mirror. Each arrangement, where the rotating mirror looks at the upper or lower arm of the belt-shape mirror, is for the transmission or reflection measurement, respectively. The center of the hemispherical lens in the detection system is set on a remaining focal point of the quarter mirror, the incident plane of the fiber optic taper coincides with the image plane of the hemispherical lens and the outgoing plane of the fiber optic taper is in contact with the CCD camera. A clear image can be obtained using this detection system. The absolute values of the reflectance and transmittance and the light distributions of the reflection and transmission of the micro-ball-lenses, whose radii were 0.75, 1, 2.5 and 4.8mm, were measured. The systematic errors of our scatterometer are briefly discussed.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.