Abstract
Digital holography (DH) with two wavelengths (TW) that are close to each other was applied to height measurement of solder bumps having spherical specular surfaces with diameters of ${\sim}{20}\;\unicode{x00B5}{\rm m}$ and heights of ${\sim}{20}\;\unicode{x00B5}{\rm m}$. We employed the parallel phase shifting method for instantaneous image capturing, and we improved the spatial resolution of our TW-DH system having two beams with different wavelengths that traveled in opposite directions in the interferometer. It gave 74-times higher repetition and 2.4-times higher spatial resolution than those in our previous DH system based on the Fourier transform method.
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