SPIE is making this freely available as an ebook. Click here to download the full PDF.Use of Smartphones in Optical Experimentation shows how smartphone-based optical labs can be designed and realized. The book presents demonstrations of fundamental geometric and physical optical principles, including the law of reflection, the law of refraction, image formation equations, dispersion, Beer's law, polarization, Fresnel's equations, optical rotation, diffraction, interference, and blackbody radiation. Many practical applications--how to design a monochromator and a spectrometer, use the Gaussian beam of a laser, measure the colors of LED lights, and estimate the temperature of an incandescent lamp or the Sun--are also included. The experimental designs provided in this book represent only a hint of the power of leveraging the technological capability of smartphones and other low-cost materials to create a physics lab. This book can be used as a guide for undergraduate students and instructors for a hands-on experience with optics, especially for an online optical lab; elementary and high school science teachers to develop smartphone-based labs for classroom demonstrations; and anyone who wants to explore fundamental STEM concepts by designing and performing experiments anywhere.