An interference microscope based on a wavelength-to-depth encoding technique is analyzed. The wavelength-to-depth encoding is achieved with a diffractive lens and a wavelength-tunable laser. The theoretical depth resolution is consistent with the experimental result. The technique offers a comparable depth resolution as traditional depth scanning. With the rapid advances in microfabrication and wavelength- tunable lasers, the system is promising for fast, noncontact, and high- resolution three-dimensional imaging.