Prism corner-cube

Fig. 5.17a,b. Two examples of possible ring resonators, using total reflection (a) with corner-cube prism reflectors and frustrated total reflection for output coupling (b) three-mirror arrangement with beam-combining prism... 

This interferometric dilatometer consists of a rather simple and small Michelson interferometer, in which the two arms are parallel, and of a 4He cryostat, in which the sample to be measured is hold. The sample is cooled to 4 K, and data are taken during the warm up of the cryostat. The optical path difference between the two arms depends on the sample length hence a variation of the sample length determines an interference signal. The Michelson interferometer consists of a He-Ne stabilized laser (A = 0.6328 xm), two cube corner prisms, a beam splitter, three mirrors and a silicon photodiode detector placed in the focal plane of a 25 mm focal length biconvex lens (see Fig. 13.1). 

The beams are backreflected by the cube corner prisms which are fixed, respectively, on the sample and on the sample holder. Since the cube corner prisms are able to make reflected beam exactly parallel to incident beam, this interferometer is tilt independent. The reflected beams get back to the beam splitter through the same path, but shifted by about 2 mm in the vertical direction. The beam splitter lets a part of the two beams go towards the photodiode sensor and lets the other part of beams reach the laser source (off axis, therefore giving no feedback effect). 

Figure 5.20. A truncated cube before (I) and after (II) a removal of the corners, and one of the prisms removed (ill). A cubic crystal (IV) with two triangular prisms removed which impinge on one another. A cubic crystal (V) with all the triangular prisms removed, and one of the hexagonal faces produced (VI) [87].

One half of the unit cell of the Sc2Re3Si4 structure with Zr5Si4 type derivative is shown on the left-hand side of fig. 46. The structure is characterized by pairs of M-centred trigonal prisms and T-centred cubes. All prisms are constructed of three R and three T atoms and all cubes of four R and four T atoms. Each group of four atoms at the cube corners and the T atom in the cube centre are on a diagonal cube plane. The crystal-chemical formula is... 

---