Optical navigation with specular reflection blocking

An apparatus for filtering light for optical navigation, the apparatus comprising:

• a lens configured to focus a specular portion of the light to a focus region;
• a mask at approximately the focus region, wherein the mask is configured to filter out substantially all of the specular portion of the light and pass at least some of a scattered portion of the light outside of the focus region, wherein the mask is located within 1 mm of the focus region, and wherein the focus region is located on a plane at which the cross section of the specular portion of the reflected light is minimal;
• and
• an image sensor to generate a navigation signal based on the scattered portion of the light that passes outside of the focus region and is incident on the image sensor.

A method for optical navigation, the method comprising:

• generating light at a light source;
• directing the light to a navigation surface;
• focusing a specular reflected portion of the light at a focus region;
• filtering out the specular reflected portion of the light at approximately the focus region and passing a scattered portion of the light to an image sensor, wherein the scattered portion of the light is outside of the focus region, wherein the focus region is located on a plane at which the cross section of the specular portion of the reflected light is minimal and the filtering occurs within 1 mm of the focus region;
• detecting the scattered portion of the light at the image sensor;
• and
• generating a navigation signal based on the scattered portion of the light.