Ray-Tracing Considering Form Errors on the Fabrication Process Using Local Interpolation for Aspheric Lens Surface

Minute vibration of grinding wheel greatly restricts machining accuracy of axisymmetric aspheric surface in precision grinding. This paper is dedicated to analysis micro-topography of grinding surface under grinding wheel vibration. The relative motion track of wheel to ideal lens surface and the interference of them are involved to study the effects of grinding wheel vibration on surface quality. For different operation parameters, the processed surface presents various micro-topography, and the restriction extent of vibration to surface quality is also different. Vibration waveform in the region near lens center is smoothed greatly by the interference of wheel and the processed surface. Therefore, surface quality gets some improvement from edge to center for axisymmetric aspheric lens. Experiment results verified the validity of the theoretical analysis.

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Linewidth measurement using the low voltage SEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100144681 ◽

1986 ◽

Vol 44 ◽

pp. 652-653

Author(s):

M.G. Rosenfield

Keyword(s):

Electron Microscope ◽

Scanning Electron Microscope ◽

Integrated Circuits ◽

Secondary Electron ◽

Low Voltage ◽

Fabrication Process ◽

Critical Dimensions ◽

Linewidth Measurement ◽

Threshold Technique ◽

Scanning Electron

Minimum feature sizes in experimental integrated circuits are approaching 0.5 μm and below. During the fabrication process it is usually necessary to be able to non-destructively measure the critical dimensions in resist and after the various process steps. This can be accomplished using the low voltage SEM. Submicron linewidth measurement is typically done by manually measuring the SEM micrographs. Since it is desirable to make as many measurements as possible in the shortest period of time, it is important that this technique be automated.Linewidth measurement using the scanning electron microscope is not well understood. The basic intent is to measure the size of a structure from the secondary electron signal generated by that structure. Thus, it is important to understand how the actual dimension of the line being measured relates to the secondary electron signal. Since different features generate different signals, the same method of relating linewidth to signal cannot be used. For example, the peak to peak method may be used to accurately measure the linewidth of an isolated resist line; but, a threshold technique may be required for an isolated space in resist.

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Octree Ray Tracing Method for Complicated Reactor Geometry

SNA + MC 2013 - Joint International Conference on Supercomputing in Nuclear Applications + Monte Carlo ◽

10.1051/snamc/201405206 ◽

2014 ◽

Author(s):

Oxana Yu. Poveshchenko ◽

Jasmina L. Vujic

Keyword(s):

Ray Tracing ◽

Ray Tracing Method ◽

Reactor Geometry ◽

Tracing Method

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