A precision edge detection system and sensor assembly is provided that uses a reflection technique to provide an energy efficient device that can be achieved using a relatively small form factor. There is provided an optical reflective sensor assembly that includes a light source, an optical element positioned to collimate and focus light from the light source to generate a focused beam, and at least one photodetector positioned adjacent the light source. The at least one photodetector is configured to detect light from the focused beam that has been reflected by an object positioned opposite the light source.