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Basic Concepts of Laser Imaging
Published in Helmut H. Telle, Ángel González Ureña, Laser Spectroscopy and Laser Imaging, 2018
Helmut H. Telle, Ángel González Ureña
If one thinks of an analog signal function as a 1D image (see Figure 17.7), it is rather straightforward to extrapolate to the 2D (and 3D) imaging scenario: the image data now vary in 2D or 3D, but the rest of the imaging and analysis procedures still apply. From the point of view of image resolution, this means that the “bandwidth” of an image must be somehow associated with its “sharpness,” and this is related to the highest spatial frequencies it contains. While in consumer photography, it is often problematic to apply an image analysis along the aforementioned criteria (even an out-of-focus or blurred image may still carry memorable impressions), in scientific imaging and microscopy, access to the proper imaging parameters is in most cases feasible. For example, at the very least, one knows (1) that the diffraction limits the maximum sharpness of the data that can be recorded and (2) that the “spatial frequency response” of a microscope can be defined by a suitable calibration sample [e.g., the “1951 USAF resolution test chart”—see Messina (2006); or the so-called “Siemens Star” target—see Thurman (2011)]. As a consequence of the above considerations, the convention is to adapt the relation between the imaging optics properties (ultimately governed by diffraction limit dAbbé) and the pixel size dpixel of the imaging array detector to obey
Design and implementation of CCD image-based DNA chip scanner with automatic focus calibration
Published in Systems Science & Control Engineering, 2019
The fluorescence emitted by the DNA chip was captured by the imaging lens and the CCD camera, so for a clear fluorescent image it was necessary to ensure high resolution of the imaging system. A 1951 USAF resolution test chart (Figure 13) can be used to measure the resolution level of a camera imaging system. The largest set of short lines on the chart that the imaging system can resolve is its resolution.