Complex sentence: The mission of SPIE is to serve scientists and engineers in industry, academia, and government working in a wide variety of fields that utilize some aspect of optics and photonics, the science and application of light.
Split into simpler sentences: The mission of SPIE is to serve scientists and engineers in industry, academia, and government. SPIE constituents work in a wide variety of fields that utilize some aspect of optics and photonics, the science and application of light.