硬度块压痕直径和对角线一般是用读数显微镜和光学计测量的。测量时应注意不要使仪器的固定刻线和游动刻线与压痕边缘(或顶点)相切(如左图),要使两条刻线恰好通过压痕边缘(或顶点)(如右图)。这是因为读数显微镜和光学计在对零位时,两条刻是相重合而不是相切的,若以相切方式测量,零位就改变 Hardness block indentation diameter and diagonal are generally measured with a reading microscope and an optical meter. The measurement should be taken care not to make the instrument’s fixed and moving reticle tangent to the indentation edge (or vertex) (left), so that the two reticle passes just right of the indentation edge (or vertex) Figure). This is because the reading microscope and the optical meter in the zero, the two engraved coincide rather than tangent, if measured in tangent, zero change