1 
A NEW CAMERA OF EXTREMELY HIGH LUMINOSITY AND 
RESOLUTION BASED ON THE CONCENTRIC OPTICAL 
MIRROR SYSTEM 
by A. Bouwers and J. J. van der Sande. 
N.V. Optische Industrie „de Oude Delft”, 
Delft — Holland. 
In this paper a new camera of great luminosity and high resolution is 
described. It is based on the concentric optical mirror system, which has been a 
subject of our investigations for quite some time now x ). Successful applications 
have already been made to fluorography, microscopy, telephotography, telescopes 
and to infrared detection. 
Although originally the camera here described was not intended to be applied 
to photogrammetry we feel that in the future cameras of this type may perhaps 
find a successful application in this highly specialized field. 
Optical system. 
As shown in figure 1 the optical part of the camera consists of a concave 
mirror M and two corrector elements E x and E 2 , the latter being passed two times 
by the light rays viz. before 
and after reflection at the 
mirror M. All the optical 
surfaces, the film surface 
included, are concentric, C 
being the centre of curva 
ture. Near this centre C a 
diaphragm is placed. The 
flat surface of the doublet 
E x is used for achromatiz 
ing purposes and is not 
detrimental to the concen 
tricity of the system, as the 
refractive indices for yellow light of the two components are equal. Only the 
dispersions of the glasses differ. Elsewhere this special method of colour correct 
ion has already been described 1 ). 
Due to its concentricity the system is completely free from coma, astigmatism 
and distortion. The residual lateral spherical aberration for yellow light is within 
1/15,000 of the focal distance, and this is achieved at an aperture ratio 1 :1.4. The 
longitudinal and lateral chromatic aberrations are negligible and in fact the 
colour correction may be considered as aphochromatic in the visible part of the 
spectrum and the near infrared. 
As already stated the geometric relative aperture of the objective is //1.4 and 
the T-stop value amounts to //1.7 appr. Ud till now the camera has been con 
Fig. 1 
x ) Bouwers A. Achievements in Optics; Elsevier Publishing Co., New York — Amsterdam, 1946.