Disclosed are methods and apparatus for performing inspection or metrology of a semiconductor device. The apparatus includes a plurality of laser diode arrays that are configurable to provide an incident beam having different wavelength ranges. At least some of the laser diode arrays form two dimensional stacks that have different wavelength ranges from each other. The apparatus also includes optics for directing the incident beam towards the sample, a detector for generating an output signal or image based on an output beam emanating from the sample in response to the incident beam, and optics for directing the output beam towards the detector. The apparatus further includes a controller for configuring the laser diode arrays to provide the incident beam at the different wavelength ranges and detecting defects or characterizing a feature of the sample based on the output signal or image.