This is a mode of measurement that allows you to set multiple sensitivity levels for an area with a large reflectance variation to prevent data loss.

Shown below is a comparison of images capturing the same printed circuit board in HDR (high dynamic range) mode and in normal mode. In normal mode, the area of circuit board pattern is too dark because of low reflectance. In HDR mode, however, an image is captured with optimal sensitivity both at the metal surfaces where reflectance is high and at the circuit pattern where reflectance is low.

In this mode, you can divide the measurement range along the Z direction up to 6 sub-divisions and make a gain setting individually for each sub-division. This is useful when you perform measurement on a sample whose reflectance varies with height.

The image below is a trench structure with a high aspect ratio on a silicon wafer. The reflectance at the top of the structure is high, whereas the reflectance at the bottom of the trenches and slopes is low. It is difficult to conduct measurement with this kind of sample, but we succeeded by making an optimal gain setting for each sub-division of height.

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