This test specimen is made of a single crystal silicon of overall dimension 5mm x 5mm. It is marked with clearly visible squares of periodicity of 10µm. The dividing lines are about 1.9µm in width and are formed by electron beam lithography. A broader marking line is written every 500µm. This is a very useful additional feature for Light Microscopy. This is an excellent specimen for comparing magnification and assessing any distortion in