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Scanning electron microscope and image signal processing method

  • US 8,362,426 B2
  • Filed: 09/14/2006
  • Issued: 01/29/2013
  • Est. Priority Date: 09/14/2005
  • Status: Active Grant
First Claim
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1. A scanning electron microscope comprising:

  • a secondary electron detector for detecting secondary electrons discharged from the surface of a specimen when a primary electron beam is irradiated on the specimen surface, generating an observation image signal on the basis of an amount of detected secondary electrons and outputting the observation image signal; and

    an image signal processor for generating a display image of said specimen surface on the basis of the observation image signal delivered out of said secondary electron detector and displaying the display image, wherein said image signal processor includes;

    dynamic range reference value setting means for setting dynamic range reference values;

    storage means for storing the observation image signal from the secondary electron detector with respect to a reference luminous intensity peak generation specimen which is configured to provide peaks at positions corresponding to a minimum luminous intensity and a maximum luminous intensity on a histogram expressing frequency luminous intensity, the reference luminous intensity peak generation specimen having alternately arranged black and white stripes;

    dynamic range adjustment means for adjusting a dynamic range of said observation image signal on the basis of said dynamic range reference values set by the dynamic range reference value setting means, and outputting the thus adjusted observation image signal as an observation image signal after adjustment;

    display image generation means for determining luminous intensity levels of individual pixels of an image to be displayed on the basis of the observation image signal after adjustment outputted from said dynamic range adjustment means to generate a display image;

    histogram generation means for generating a histogram of luminous intensity levels of the individual pixels of said generated display image and extracting from the thus generated histogram a value at which the frequency corresponding to a luminous intensity level is maximized as a luminous intensity peak value; and

    histogram display means for displaying said extracted luminous intensity peak which becomes a reference of a luminous peak and a histogram to be generated.

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