An aluminum nitride substrate includes an aluminum nitride sintered body containing a rare earth oxide as a sintering additive component. The base has an inclined surface extends from the proximal extremity to the edge, and a generally horizontal surface extends from the edge to the distal extremity. A color photocopy machine which has a digital image output may be used to produce the original image file, and such a color photocopier, may also be used to produce the output hard copy printouts of processed image files. A rotary encoder with an extendable cable is used to measure scrub throughout the range of movement of the foot pedal.