System and method for illuminating and imaging a surface for an optical navigation system

An optical navigation system comprising:

• a narrow spectral band light source to produce speckle in light reflected from a surface;
• an array of photosensitive elements;
• an optic system comprising:
• a unitary optic component including an illumination lens and at least one prism surface to project a collimated beam of light from the light source onto the surface and an imaging lens to image a portion of the illuminated surface to the array of photosensitive elements;
• and
• an aperture component that self-aligns with the unitary optic component during assembly of the optic system, the aperture component including an aperture sized and located between the imaging lens and the array of photosensitive elements to produce a predetermined average speckle size, the aperture is located at the focal point of the imaging lens to provide telecentric imaging that is telecentric in object space;
• and
• signal processing circuitry to combine signals from the array of photosensitive elements to generate a signal providing information on displacement of the optical navigation system relative to the surface.