Configurations for a photonics assembly design and methods for mitigating coherent noise thereof are disclosed. The photonics assembly may include a set of light sources, an optical subsystem that may include a set of optical elements, and a diffusing element. The light emitted by the set of light sources may be different wavelengths and the light may be de-cohered by a phase shifter before being received by the set of optical elements. The diffusing element may be moveable and may be capable of repeating the same positions or set of positions for each beam of light emitted by the set of light sources. By combining the coherent noise mitigation techniques of the moveable diffusing element and the de-cohered light, the photonics system may provide an illumination profile with a specific spatial profile and angular profile on the sample that allows reliable measurement of the sample and coherent noise mitigation.