Patent Number: 
Section: description

With respect to the embodiment illustrated in FIG. 1 divergent X-radiation of an X-ray source 1 is directed upon a concave surface formed as an elliptical or parabolic form having a reflecting surface for the X-radiation used which is a multilayer system in this case. The X-radiation is reflected therefrom and continuously directed upon the convex parabolic reflecting surface of the reflecting element wherein the X-radiation reflected from the reflecting element 3 is simultaneously compressed and aligned in parallel. The parallel X-radiation thus focussed then can be employed for the different methods of X-ray analysis in which cross sections of X-radiation being in the range of smaller than 200 xcexcm are readily achievable. On the reflecting surface of the reflecting element 3 a multilayer system can also be available in which the layer thicknesses of the individual layers are locally taken into consideration in accordance with the different angles of incidence of the X-radiation. In this case the parallel reflected X-radiation is not only allowed to comprise a higher intensity but additionally it will also be provided in a monochromatic manner. With the embodiment of an arrangement according to the invention illustrated in FIG. 2 X-radiation having a smaller divergence and without divergence, respectively, is directed in a parallel form upon the concave, parabolic reflecting surface of a focussing element 2. The X-radiation is appropriately reflected from this surface and is simultaneously focussed and directed upon the surface of the reflecting element 3. From the illustration it is clearly recognizable that the beam cross section b of the X-radiation reflected in parallel from the reflecting element 3 is considerably smaller than the beam cross section b of the originally employed parallel X-radiation. Therefrom it results that with a sufficiently high reflectivity of (2) and (3) the photon flux density in the X-radiation reflected from the reflecting element 3 has been increased compared with the original parallel radiation. Advantageously, the reflecting element is again provided with a multilayer system on the reflecting surface wherein the period thickness d of the individual layers meet the BRAGG relationship xcex=2deff sin "THgr" (deff being the effective period thickness considering the dispersion). Since the focussed X-radiation predetermines different angles of incidence "THgr"i upon the reflecting surface of the reflecting element 3, consequently it is also required to employ an appropriate gradient multilayer system which comprises a different period thickness di depending on the respective angles of incidence with the appropriate wavelength of X-radiation. Ways of forming such a multilayer system are mentioned in the unpublished document DE 199 32 275 on which disclosure on this matter shall be fallen back in a complete scope. Both in the FIG. 1 and FIG. 2 it is illustrated that the respective reflecting surfaces of the focussing element 2 and the reflecting element 3 are formed and the two elements 2 and 3 are arranged to each other such that their focal points F coincide with each other. In the embodiments according to the FIG. 1 and FIG. 2 the reflecting surface of the focussing element 2 has a parabolic form (FIG. 2) however, it is allowed to employ an elliptical contour (FIG. 1) as well. In the embodiment according to the FIG. 2 in which parallel and almost parallel output X-radiation, respectively, is used, assuming that XA, XE  greater than  greater than  p/2, in particular the equation applies:                               b                      b            xe2x80x2                          =                                                            Y                E                            -                              Y                A                                                                    Y                E                xe2x80x2                            -                              Y                A                xe2x80x2                                              =                                                                      √                  2                                ⁢                                  px                  E                                            -                                                √                  2                                ⁢                                  px                  A                                                                                                      √                  2                                ⁢                                  p                  xe2x80x2                                ⁢                                  x                  E                  xe2x80x2                                            -                                                √                  2                                ⁢                                  p                  xe2x80x2                                ⁢                                  x                  A                  xe2x80x2                                                                                        (        1        )             wherein the parabolic equations Y=2px  and Yxe2x80x2=2pxe2x80x2x  respectively, have been based. Using the ray equation and the parabolic equation this can be simplified as                               b                      b            xe2x80x2                          =                  p                      p            xe2x80x2                                              (        2        )             wherein p and pxe2x80x2 are the respective parabolic parameters of the focussing element 2 and the reflecting element 3. It follows therefrom that an increase of the photon flux density can be achieved every time that the ratio of the beam cross sections multiplied by the product of the mean reflectivities of the focussing element 2 R(2) and reflecting element 3 R(3) becomes R(2)*R(3)*b/bxe2x80x2 greater than 1.