The combined test specimen standard provides a 3 in 1 method for testing the performance of the TEM. The combined test specimen consists of graphitised carbon particles on a holey carbon which are shadowed with gold. Combines astigmatism test using perforated carbon film with resolution tests using graphitised carbon black and fine gold particles. The evaporated gold forms small polycrystalline islands in which lattice fringes can be resolved. The combined test specimen can also be used for contamination measurements by noting the carbon depositing rate within the holes of the gold film. Mounted on a 300 mesh copper TEM grid.