9366524 B2 abstract one embodiment relates to a device that senses alignment and height of a work piece the device may include both an alignment sensor and a height sensor the alignment sensor generates a first illumination beam that illuminates an alignment mark on the work piece so as to create a first reflected beam and determines the alignment of the work piece using the first reflected beam the height sensor generates a second illumination beam that is directed to a surface of the work piece at an oblique angle so as to form a second illumination spot and images the second illumination spot to determine the height of the work piece other embodiments aspects and features are also disclosed application_number US 201414481076 A description accurate and precise alignment of a work piece is often highly desirable or necessary in manufacturing and other processes in an exemplary application the work piece may be a semiconductor wafer on which integrated circuits are being manufactured in this context the alignment sensor may be an optical sensor that may use imaging diffraction or optical interference to determine the relative position of a mark on the wafer fig1 a is an optical ray diagram showing an.