Optical quality diamond material

Abstract

A CVD single crystal diamond material suitable for use in, or as, an optical device or element. It is suitable for use in a wide range of optical applications such as, for example, optical windows, laser windows, optical reflectors, optical refractors and gratings, and etalons. The CVD diamond material is produced by a CVD method in the presence of a controlled low level of nitrogen to control the development of crystal defects and thus achieve a diamond material having key characteristics for optical applications.

1 . (canceled) 
     
     
         2 . A CVD single crystal diamond material which shows at least one of the following characteristics, when measured at 20° C.:
 i) an ability to be processed to show a high surface polish with an R a  (arithmetic mean of the absolute deviation from the mean line through the profile) measured over a specified area of at least 1.3 mm×1.3 mm less than 2 nm; 
 ii) an ability to be processed to show a high flatness, with a flatness measured using 633 nm radiation and measured over a specified area of at least 1.3 mm×1.3 mm which is better than 10 fringes; 
 iii) an ability to be processed to show a high parallelism, with a parallelism measured over a specified area of at least 1.3 mm×1.3 mm which is better than 1 arc minute. 
 
     
     
         3 . A CVD single crystal diamond material according to  claim 2 , which can be processed to show a surface polish with an R a  less than 1 nm. 
     
     
         4 . A CVD single crystal diamond material according to  claim 3 , which can be processed to show a surface polish with an R a  less than 0.6 nm. 
     
     
         5 . A CVD single crystal diamond material according to  claim 2 , which can be processed to show a flatness better than 1 fringe. 
     
     
         6 . A CVD single crystal diamond material according to  claim 5 , which can be processed to show a flatness better than 0.3 fringes. 
     
     
         7 . A CVD single crystal diamond material according to  claim 2 , which can be processed to show a parallelism better than +/−30 arc seconds. 
     
     
         8 . A CVD single crystal diamond material according to  claim 7 , which can be processed to show a parallelism better than +/−15 arc seconds.