an optical keyboard includes a key assembly for alphanumeric data input ; a keyboard housing being an integrally formed rectangular block for surrounding the key assembly , the keyboard housing including a left frame member , a right frame member , a rear frame member , and a front frame member ; and at least one actuation sensing module disposed on a periphery of the keyboard housing , each of the at least one actuation sensing module including a light emitting member for emitting light directed to a predetermined space above the key assembly within the keyboard housing to create a sensing zone , and a photo sensor for sensing light emitted from the light emitting member .