Structured-light illumination (SLI) means projecting a series of structured or striped patterns from a projector onto an object and then using a camera, placed at an angle from the projector, to record the target's 3-D shape. For multiplexing these structured patterns in time, traditional SLI systems require the target object to remain still during the scanning process. Thus, the technique of composite-pattern design was introduced as a means of combining multiple SLI patterns, using principles of frequency modulation, into a single pattern that can be continuously projected and from which 3-D surface can be reconstructed from a single image, thereby enabling the recording of 3-D video. But the associated process of modulation and demodulation is limited by the spatial bandwidth of the projector-camera pair, which introduces distortion near surface or albedo discontinuities. Therefore, this paper introduces a postprocessing step to refine the reconstructed depth surface. Simulated experiments show an 78% reduction in depth error.
Semiconductor device manufacturers have made technological advances in fabricating devices at 65nm and 45nm nodes. Technology is advancing towards 32nm node devices. Reticles at these device nodes are designed with tight critical dimension (CD) specifications and sub-resolution features. Inspection tools capable of detecting CD defects on the order of 20 nm are required to accommodate these device nodes. To meet this challenge, KLA-Tencor has developed a new "CD Detector" capability on the TeraScanHR reticle inspection tool that efficiently detects two-sided CD defects on reticles at the 45nm node and beyond. The CD Detector is available in both Die-to-Die (DD) and Die-to-Database (DB) inspection modes. This paper presents results of a CD Detector Beta evaluation on variety of advanced reticles in a production setting at Advanced Mask Technology Center (AMTC) in Germany. Inspection results will demonstrate improved sensitivity to two-sided CD defects and good inspectability, at inspection times similar to a standard HiRes inspection. Discussion will focus on enabling the highest sensitivity to CD defects at 72nm pixel inspections, which is suitable for advanced research and development studies, as well as improved sensitivity at 90nm pixel inspections for higher productivity.
Interacting with computer technology while wearing a space suit is difficult at best. We present a sensor that can interpret body gestures in 3-Dimensions. Having the depth dimension allows simple thresholding to isolate the hands as well as use their positioning and orientation as input controls to digital devices such as computers and/or robotic devices. Structured light pattern projection is a well known method of accurately extracting 3-Dimensional information of a scene. Traditional structured light methods require several different patterns to recover the depth, without ambiguity and albedo sensitivity, and are corrupted by object motion during the projection/capture process. The authors have developed a methodology for combining multiple patterns into a single composite pattern by using 2-Dimensional spatial modulation techniques. A single composite pattern projection does not require synchronization with the camera so the data acquisition rate is only limited by the video rate. We have incorporated dynamic programming to greatly improve the resolution of the scan. Other applications include machine vision, remote controlled robotic interfacing in space, advanced cockpit controls and computer interfacing for the disabled. We will present performance analysis, experimental results and video examples.
Structured light pattern projection is a well known method of accurately extracting 3-Dimensional information of a scene. Traditional multi-frame structured light methods require several different patterns to recover the depth, without ambiguity and albedo sensitivity, and are corrupted by object motion during the projection/capture process. The authors have developed a methodology for combining multiple patterns into a single composite pattern by using spatial modulation techniques. A single composite pattern projection does not require synchronization with the camera so the data acquisition rate is only limited by the video rate and therefore suitable for high-speed depth measurement. However, the composite pattern is restrained by the spatial bandwidth directly related to the number of embedded patterns and the lateral resolution of the camera. Another problem is the processing requires image demodulation which is computational intensive. As part of a NASA Phase I STTR, we address the first limitation by analysis of the source of the error and post-processing the reconstruction data with dynamic programming approach. For the second problem we propose the use of a 4-f optical correlator, not as a correlator, but instead as an optical demodulator. Simulation results show reasonable depth reconstruction using our strategy for composite pattern after the post-processing.
Based on recent discoveries, we present a method to project a single structured pattern and then reconstruct the three-dimensional range from the distortions in the reflected and captured image. Traditional structured light methods require several different patterns to recover the depth, without ambiguity and albedo sensitivity, and are corrupted by object movement during the projection/capture process. Our method efficiently combines multiple patterns into a single composite pattern projection -- allowing for real-time implementations. Because structured light techniques require standard image capture and projection technology, unlike time of arrival techniques, they are relatively low cost. Attaining low cost 3D video acquisition would have a profound impact on most applications that are presently limited to 2D video imaging. Furthermore, it would enable many other applications. In particular, we are studying real time depth imagery for tracking hand motion and rotation as an interface to a virtual reality. Applications include remote controlled robotic interfacing in space, advanced cockpit controls and computer interfacing for the disabled.
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