A tensile tester is used for detecting the amount of elongation in a stationary specimen marked with at least a pair of fluorescent coating bench marks comprising at least two pairs of projector-optic arrangements spaced along the length of and in the elongation direction of said specimen, each pair of projector-optic arrangements comprising an ultraviolet lamp projector means for irradiating ultraviolet light onto the respective one of said bench marks and optic means including a detector means for detecting luminescent light rays reflected from the respective one of said ultraviolet light irradiated bench marks on said specimen caused by irradiation from said projector means, said detecting means measuring the amount of incident light from said bench mark;
Support metans for independently supporting each of said projector-optic arrangement for movement back and forth along the length of at least a portion of said specimen adjacent a respective one of said bench marks;Drive means for independently driving said projector-optic arrangement along said portion of said specimen.
Elongation detector means for each said projector-optic arrangements for transmitting respective displacement signals indicative of the amount of movement of said projector-optic arrangements; and difference determining means responsive to both of said elongation detector means for determining and indicating the spacing between said bench marks.
Article from : Qinsun Instrument Co.,LTD