ABSTRACT
For an optical window material, the amount of transmitted light should be maximized. Although diamond’s total transmittance may be smaller than most optical window materials (e.g., quenched quartz, LiF, CsI), diamond has the highest mechanical strength of all materials; hence, it can be much thinner than other window materials. Diamond can be classified chemically based on its impurities contained. This classification is reflected in its optical properties, such as color. Because diamond’s carbon atoms are very small, they can be substituted only by very few other elements’ atoms, notably boron and nitrogen. Hence, the optical classification of diamond is primarily based on the type of dopants present in diamond. The strong mechanical strength, high thermal conductivity, and extreme radiation hardness have made diamond the undisputed first choice (exceeding boron nitride, silicon nitride, silicon carbide, and other ceramics) as the mask material.
