ELK(II{( >N M K l{< >SC()I*Y 



upper ceiU 



Cower cotU 



defUcierf beam 



ntm.J eHected tea 

 Sf>ecimen. 



Fig. 1. Principle of reflection method. 



Fig. 2. JEM-5Y Electron microscope equipped 

 with reflection device. 



change the angle /3 to any angle between 0° 

 and 30°. The reflection specimen may be 

 tilted to any angle between 0° and 30° from 

 the lens axis, about an axis perpendicular to 

 the plane of incidence, and may be rotated 

 in its own surface plane, i.e., azimuthal 

 plane. It is helpful to change the azimuthal 

 angle for the reflection method, because 

 many observations from several directions 

 are needed to give a perfect interpretation of 

 the image obtained. The specimen-shifting 

 mechanism for the two horizontal directions 



is the same as that for general use of the 

 transmission type. 



In the reflection electron microscope, the 

 electrons striking the specimen surface at a 

 small angle arc scattered to the angle Q and 

 then the scattered electrons are imaged. 

 When the angle Q becomes larger, the inten- 

 sity of the image is much lower; when the 

 angle Q is smaller, the distortion of the 

 image is more marked. The relation between 

 the angle Q and the distortion of the image 

 is sho\vn in Fig. 3. In the present device, as 

 an angle Q larger than 20° is used, distortion 

 of the image can be considerably reduced. 

 Because of its large chromatic aberration, 

 however, the resolution of reflection is less 

 than that of transmission. 



On the other hand this method has two 

 features. The change of the specimen at high 

 temperature can be directly observed by us- 

 ing a specimen-heating device at the same 

 time. It is also possible to obtain the electron 

 diffraction pattern and microscopic image 

 from almost the same area of the specimen. 

 In the reflection method, however, it is diffi- 

 cult to obtain the diffraction pattern of the 



/2h 



O* 



30" C0° 



Observation an^ic 



10' 



Fig. 3. Relation between image distortion and 

 observation angle. 



260 



