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This work presents a novel microscopic profilometry using diffraction image correlation, which is appropriate for in-situ automated optical inspection (AOI). In contrast to the traditional confocal microscopy, the developed technique replaces the detector pinhole by observing and matching the diffraction patterns. Thus accurate surface depth detection can be achieved by eliminating time-consuming vertical scanning operation. The development is the first attempt in optics to use image correlation between the pre-calibrated database of diffraction images and the measured one of the detecting object surface. The feasibility of the method has been theoretically verified by scalar diffraction theory, then verified by experimental testing. Also, a depth response curve with the physical meaning of similarity is introduced and interpreted. Meanwhile, multi-point lateral scanning in one field of view (FOV) is achieved by quickly switching micromirrors on the digital micromirror device (DMD), thus the quasi full-field 3-D reconstruction can be acquired by combining tens of captured images. Verified experimentally, a 3-D reconstruction with sub-micrometer vertical resolution can be realized, with a tunable lateral resolution.

A full-field microprofilometry involving innovative image correlation was developed for profile measurement without vertical scanning. High-speed optical inspection has become critical for confirming precise dimensions in semiconductor fabrication such as microbumping in 3D stacked ICs and precision manufacturing. A digital micromirror device (DMD) is designed to serve as a point-light-source array in a quasiconfocal optical configuration and perform lateral scanning to minimize signal crosstalk between neighboring testing points. More importantly, multiple diffractive images are detected and measured with a prebuilt depth-correlated database to extract the height information of a tested surface. A 100-nm repeatability can be realized in the absence of a detector pinhole and without vertical scanning, thus achieving high-speed submicrometer-scale surface profilometry.

An 8 Gbps automatic gain control (AGC) loop for PAM receiver is proposed. Incorporating digital intensive gain control scheme, the dynamic range of the variable gain amplifier is 22 dB with a resolution of 0.9 dB/step. The locking time of the AGC loop is less than 200 ns and independent of input amplitude. Fabricated in a 0.18 μm CMOS technology, the chip size is 0.62 mm × 0.62 mm. The total power dissipation is 84 mW from a 1.8 V supply.

This paper presents the design of a 3.125 Gbps monolithic CMOS optical receiver, integrating a photo detector, a transimpedance amplifier, and a post limiting amplifier on a single chip. The optical receiver is capable of delivering 420 inVpp to 50 Omega output load after optical to electrical conversion. High speed operation is achieved by utilizing spatial modulated light (SiVIL) detector and adaptive analog equalizer. Implemented in a 0.18 mum CMOS technology, the total power dissipation is 175 mW. The chip size is 0.7 mm2.