12 



V. E. COSSLETT AND P. DUNCUMB 



Fig. 5. White pearlitic cast-iron. Oj + 0, ' 

 magnification: 1000. 



14'', 02= 12', with correcting lens, M^l M.,= 3. Exposure time: 3 seconds. Direct 



blement constante. Elle presente une sensibilite au 

 relief comparable a celle des methodes optiques in- 

 terferentielles ou par contraste de phase, tout en 

 ayant une limite de resolution dix fois meilleure en- 

 viron, dans les conditions actuelles. Ces caracteristi- 

 ques essentielles, fixeront, sans aucun doute. le 

 domaine propre d'utilisation de la microscopic eiec- 

 tronique par reflexion dans Tobservation directe des 

 surfaces. 



BiBLIOGRAPHlE 



1. VON BoRRiES, B.,Z. Physik 116, 370 (1940). 



2. Pert, Ch., Compt. rend. acad. sci. 248, 333 (1954). 



3. Pert, Ch. et Marty, B., Compt. rend. acad. scl. 241. 1454 



(1955) 



4. Pert, Ch., Marty, B. et Laporte, R., Comptes rendus du 



colloqiie CNRS a Toulouse, Avril 1955. 



5. RusKA, E., Z. Pliysik 83, 492 (1933). 



A Scanning Microscope with either Electron or X-Ray Recording 



V. E. CossLETT and P. Duncumb 



Cavendish Laboratory, Cambridge 



1 HE purpose of the scanning microscope is to form 

 an image of a surface either by electron scattering 

 or by x-ray emission, and to analyse the elements 

 in a selected volume of about one cubic micron in 

 the surface by the characteristic x-ray lines emitted. 

 A block diagram of the apparatus is shown in 



lenses into a small spot on the specimen, using a 

 similar technique to the x-ray projection microscope 

 (4, 6), and is scanned over the specimen by the deflec- 

 tion coils. These coils are similar to those used by 

 McMullan and Smith in their scanning electron 

 microscope (5, 7), and give the beam a double deflec- 



fig. 1. The electron beam is focussed by two magnetic tion balanced so that the beam always goes through 



