Multi-point scanning dual-detection confocal microscopy for fast surface profiling

Abstract

We propose a multi-point scanning dual-detection confocal microscopy (MS-DDCM) for fast 3D volumetric measurements. The proposed MS-DDCM combines the multi-point scanning with a digital micro-mirror device and new height measurement method. In comparison with conventional confocal laser scanning microscopy, MS-DDCM can realize surface profiling without axial scanning. MS-DDCM also enables to achieve two-dimensional images rapidly due to multi-point scanning technique. The MS-DDCM reduces the 3D image acquisition time dramatically. MS-DDCM is composed of two CCDs, one collects the conjugate images and the other collects non-conjugate images, respectively. The ratio of the axial response curves measured by the two detectors provides the linear relationship between the height of the sample surface and the ratio of the intensity signals. Measured intensity is proportional to the reflectance of the sample surface. Whereas ratio of intensity is independent of the reflectance of the sample and intensity of light source. Therefore, MS-DDCM is able to accurately measure the height of samples with various reflectance characteristics. In addition, the conjugate image contains not only the light from the focal point but also the signals from side of focal point. By subtracting non-conjugate image from conjugate image, the resolution is enhanced.