Page 19 - Chip Scale Review_January February_2022-digital

Figure 2: WSI system concept: scanning interferometry for large FOV, high speed, and multi-reflectance surface 3D measurement.
the small size of the bumps and the scanning method. In our system, hundreds of acquired images. A light
requirement for a fast measurement the beam splitter (B/S) is lighter source with narrow enough bandwidth
speed, a high numerical aperture than the optical reference mirror, so is used to expand coherence length.
(NA) imaging lens was developed so we decided to use the B/S moving Therefore, scanning is possible for
that a large FOV can be measured method in order to achieve high-speed a few hundred um range. A light-
with high resolution. scanning. Reference mirror scanning emitting diode (LED) is used as the
A WSI system is descr ibed i n is also an option when we use cube B/ light source projected by a Koehler
Figure 3. A piezo actuator, which can S. A general-purpose computing on illumination system. The LED power
move the range of a few nanometers graphics processing units (GPGPU) is 24W with a center wavelength of
to a few microns, is applied as the method was implemented to process 628nm and a 30nm bandwidth.

Figure 3: WSI system specification and setup.

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