Abstract: A frequency locker (100) for working with external light sources or frequency locked light sources (200, 300, 400) having integrated laser light sources (214, 414). The locker (100) provides multi-channel frequency tuning and stabilization with common components, particularly including common beam splitters (114, 118), an interferometer (128), and a processing circuit (138). The locked light source (200) integrates a light source (214) and single channel frequency tuning and stabilization capabilities. The locked light source (300) integrates multiple instances of the locked light source (200) within a single housing (312) to provide multi-channel capability. And the locked light source (400) provides multi-channel frequency tuning and stabilization with common components, particularly including a single beam splitter (420), an interferometer (426), and a processing circuit (434).