the controller examines the reported location and decides whether or not to process said transparent article depending upon said location communicated to said controller this invention refers to establishing the correct processing side of a transparent article for machining purposes transparency in this case is defined principally as visual transparency to a human observer however transparency with respect to the laser processing or measuring beam is also possible an exemplary laser processing system for processing articles as described herein is the esi model mm5900 micro machining system manufactured by electro scientific industries inc portland oreg in a particular case the material is clear glass and the article is an essentially flat sheet with a band of black paint at the perimeter as shown in fig1 fig1 shows an article 10 with a coating 12 applied to the top surface of the article also in this case it is important that the orientation is known since the machining operation is not symmetric with respect to the top and bottom surfaces of the article in this embodiment a laser displacement sensor is used to detect the location of the article an exemplary laser displacement sensor is the acuity ar200 series sensor from schmitt industries portland oreg 97210 principles of operation of laser displacement sensors are well known and will not be discussed herein this sensor is selected so that the material to be located is transparent to the laser wavelength used the coating applied to the article is selected to be opaque or at least partially reflective to the laser wavelength used the laser sensor is directed to the article from a position above the article and perpendicular to the surface to.