Provided is a validation tool and a method for validating optical equipment that is used for measuring a plurality of characteristics of one or more tyre components during winding application of said tyre components around a tyre building drum, wherein a first tyre component of the one or more tyre components includes a first characteristic of the plurality of characteristics which, after measuring, is overlapped by the same or another tyre component of the one or more tyre components including a second characteristic of the plurality of characteristics, wherein the validation tool is provided with a first reference element that is arranged to represent the first characteristic and a second reference element that is arranged to represent the second characteristic, wherein the second reference element is offset with respect to the first reference element to at least partially expose the first reference element.