onto the steel body of casing hanger 23 each gage 47 has a plurality of apertures 46 that are laser machined in a geometric pattern apertures 46 are spaced evenly apart from each other in a row and are preferably identically sized in this example apertures 46 extend axially along one side edge of gage 47 and horizontally along another side edge when tension is applied gage 47 stretches slightly changing the spacing between apertures 46 this change in spacing is detectable and provides an indication of the stress being applied and the strain occurring optionally each gage 47 may have one or two rows of apertures 48 that are spaced apart from each other different amounts and have different widths to define a bar code containing information in this example apertures 48 extend along the other axial side edge and other horizontal edge from apertures 46 optionally a central aperture 50 may be cut in the film of gage 47 but that is not necessary a reader 51 optically reads apertures 46 48 of gage 47 and provides direct measurement of strain and other information reader 51 has a lens a ring light source and strain measurement software reader 51 is located within a view port 49 that extends through the sidewall of casing head 13 preferably view port 49 is located on a radial line of the axis of casing head 13 a flange 53 bolts to the exterior of casing head 13 around view.