MICROSPECTROSCOPY AND MICROSPECTROPHOTOMETRY 



243 



2. THE OBJECT IS ILLUMINATED IN MONOCHROMATIC LIGHT 



The arrangement is schematized in Fig, 10.1. The monochromator 

 is set ahead of the microscope and adjusted so that the image of the 

 outgoing-sUt F' is formed in the condenser C (reflecting objective). 

 The condenser C is adjusted so as to image 4 in the specimen P. 



w 



Fig. 10.1. Diagram of a basic system for microspecrophotometry (monochromator 



before the microscope). 



Next the reflecting objective O^ of the microscope forms the image P' 

 of P in the photographic plate E. The layout is like the one shown 

 in Fig. 9.14. Thus is obtained a photograph, in monochromatic light, 

 of the specimen. Once this photograph is microdensitometer-analysed, 

 the absorption obtaining at several points of the specimen at this 

 wave-length, may be compared with a point located in a vacant area 

 of the specimen. Measurements may be carried out with the neutral 

 wedge W against the photographic plate E in a suitably uniform 

 imageless area of the field. Both the wedge and E are illuminated 

 simultaneously by the same wave-length. 



The layout, shown in Fig. 10.2, in which the beam illuminating W 

 docs not pass through the microscope, may also be used. The semi- 



