US Patent 7322118 Non-contact electronic level

A non-contact electronic level has a light source, a vial having a bubble and positioned to be irradiated by light from the light source, and a photo sensor located at a position corresponding to the bubble at a fixed distance from the vial. The photo sensor captures an image of the bubble after the vial is irradiated by the light source. An image processing unit is electrically coupled to the photo sensor and converts the image of the bubble into an electronic level signal by comparing the centroid of the image of the bubble with a predetermined point.