Described herein are systems and methods for mounting optical sensors in a physiological monitoring device worn by a user to sense, measure, communicate, and/or display physiological information. The monitoring devices may be embodied as, for example, a fitness band, a bracelet, a watch, or some other wearable device such as an activity tracker, a health, wellness, or sleep monitor, or an athletic training device. The device may comprise one or more light sources and optical detectors. Optical lenses may be mounted in a face of the device for partially receiving or containing the light sources and optical detectors. The devices and methods described herein may optically isolate the light source(s) from the optical detector(s) to ensure the accurate and reliable detection and measurement of physiological information.
