Patent attributes
An overlay measuring apparatus includes a light source which generates visible light with a plurality of wavelengths, an optical module which selects visible light with a single wavelength from the visible light generated by the light source, makes the visible light with a single wavelength incident on a plurality of overlay patterns, and uses visible light reflected from the plurality of overlay patterns to project the overlay patterns with a predetermined color, an imaging unit which acquires images of the plurality of overlay patterns according to individual wavelengths of the visible light and acquires corresponding image signals, and a control unit which outputs a control signal to the optical module so that the optical module can project the overlay pattern with a specific color using information associated with the individual wavelengths of the visible light that is used to project the overlay pattern image selected by a selection unit.
