As the deposition of thin films does little, if anything, to improve the light scattering characteristics of a component but adds greatly to its cost, the current growing interest in improving the quality of substrates is understandable. Process control does, of course, require the use of adequate means for measuring the parameters which need to be controlled. This paper will compare and contrast the subjective methods employed in a number of standards with a variety of objective techniques developed in recent years, taking into account the requirements of both on and off-line inspection. Surface parameters to be discussed will include form, roughness, waviness, flaws and contamination, as all these have an adverse effect on the performance of the component to an extent depending on the application. The review will attempt to present a picture of current practice and suggest possible ways in which the process of surface inspection could be improved in future by the use of objective methods of measurement and standards, involving some photometry, rather than relying solely on visual assessment.