the plate 26 the bars must be aligned in such a way that in the next processing step the second layer system which in the x cube production is the red reflection system 7 is deposited exactly perpendicular on the surface to be processed this is greatly simplified by the fact that all surfaces of the bar or bars 24 are perpendicular and practically plan parallel to each other and because they are extremely flat for example as indicated at 25 preferably several bars 24 can be wrought together in order to compensate any angular error resulting from the sawing process as mentioned and as shown on the left also individual bars 24 can be lapped or polished if the sawing process is sufficiently accurate lapping and polishing are given as examples of joint mechanical machining as shown with u2207 u2207 u2207 the opposite lateral surface of plate 26 or of the individual bar 24 can now be dual lapped or dual polished as shown in fig4 f and as a very important step of this invention one of the polished surfaces of the plate 26 or the individual bar 24 in the first case for all bars 24 involved are jointly repolished and subsequently coated in the x cube production a red reflection layer system 7 is deposited at this point as shown in fig4 f in this way the first layer system 5 and the cementing film are full surface coated with 7 after repolishing preferably a relatively cold coating process is used preferably a plasma and or ion assisted coating process preferably a sufficiently cold pvd process preferably sputtering or pecvd process but in particular a cold coating process with substrate temperatures not exceeding 150 degrees c preferably not exceeding 80 degrees c.