Television microscope 



A very simple principle is the basis of the image be visible from all parts of the audi- 

 television microscope. In photomicrography torium. However, since the brightness of the 

 a real microscopic image is formed on the image decreases as the square of the mag- 

 photographic emulsion; here it is formed on nification, a corresponding increase in the 

 the receptive surface of the tube of a tele- intensity of illumination of the object is 

 vision camera. In other words, in compari- required to obtain sufficientl}' bright pro- 

 son with the customary manner of using a jected images. Even in lecture halls of aver- 

 television camera, the microscope takes the age size the limits of a permissible illumina- 

 place of a photographic objective as imaging tion load for the object are already reached 

 system. The advantages of such an arrange- with medium microscopic magnifications, 

 ment are due to the characteristics of the Nevertheless, one often encounters the er- 

 television installation and the principles roneous opinion that the determining limit 

 upon which it is based. Thus the application for microprojection is given by the efficiency 

 of electronic image transmission permits a of available light sources, 

 spatial separation of the object and the mi- One often encounters the false conception 

 croscope on one hand and the reproduction that it suffices, for protection of the object, 

 of the image on the other hand. This at the to filter out the invisible light, especially the 

 same time makes it possible to show the heat radiation. However, it is to be kept in 

 microscopic image to any number of ob- mind, at least in microprojection of biological 

 servers, also of such objects as are in rooms objects with transmitted light, that the 

 which for various reasons may not be entered illumination load on the object is decisive, 

 by the observers. This for example can be the A structurally determined absorption by the 

 case when microscopic images of infectious object is the presupposition for production 

 material are to be shown, or conversely, to of image contrast in the most commonly 

 avoid the danger of observers carrying in- employed bright-field illumination with 

 fection to tissue cultures. The television transmitted light. Independent of its wave- 

 microscope can also be advantageously used length, the total radiation absorbed by the 

 in the microscopic examination of radio- object is finally converted into heat. If now 

 active objects or objects subjected to radio- one compares the size of the receptive surface 

 activity. of a television camera tube having an effec- 



Application of the television microscope tive image diagonal of about 15 mm with 

 in the morphological branches of natural the diameter of the customary microprojec- 

 science and medicine have brought about a tion image of about 1-1.5 mm, and if one 

 substantial advance. It is generally recog- further considers that the illumination in- 

 nized that microprojection is a most valu- tensity required on the receptive surface for 

 able and almost indispensible aid in these operation of the camera tube is very low, 

 subjects. This is specially true today w^here then it is understandable that one arrives at 

 the number of instructors stands in a pro- requirements for illumination of the object 

 gressively less favorable ratio to the increas- which are not substantially greater than 

 ing number of students. The size of the those for direct subjective observation, 

 projection screen must be increased with the Herein lies the basis for the decided ad- 

 size of the lecture hall and the average dis- vantages of the television microscope. As a 

 tance of the observers from the screen in consequence of the slight illumination load 

 order that details of the microprojection on the object and the possibility of a large 



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