DIRECT WRITING OF HOLOGRAPHIC FRINGES Before we get to the main subject of this chapter, though, we should say something about the type of holographic imaging that results from direct fringe writing, which is one concept of the way holography should be going. It has now become possible to “write” holographic fringes directly into the recording medium, but we need rst to have both the computing ability to design the fringe structure and the facilities to etch the pattern. e former has until fairly recently been limited to simple structures such as geometrical patterns or alphanumerical characters, and the latter requires a writing instrument with a resolution equal to or better than the wavelength of light, such as an electron beam. is method is described in detail in Goncharsky and Goncharsky [3] and is nding favor for producing high-quality masters for embossed holography; but it is very expensive and time-consuming.