Optical navigation device

An optical navigation device, comprising:

• a casing movably located above a navigation surface;
• a circuit board disposed inside the casing;
• an illumination light source disposed on the circuit board and adapted to provide an illumination channel toward the navigation surface;
• and
• an optical receiver disposed adjacent to the illumination light source, an imaging channel of the optical receiver being substantially parallel to a planar normal vector of the navigation surface and further slantwise crossed by the illumination channel, and the optical receiver being adapted to acquire and identify features on the navigation surface within a crossed range formed between the imaging channel and the illumination channel for providing navigation information via diffuse reflection detection, wherein the crossed range is defined as a working depth of field of the optical navigation device.