Optical arrangement for recording a variable light absorbance in objects also having a variable optical thickness

Claim 1

In an optical arrangement for measuring along a certain coordinate axis (x) the light absorbance at a certain wave length ( lambda ) of an object in which not only the absorbance, but also the optical thickness varies along said coordinate, comprising a light source, a holder for said object, means for monochromatizing the radiation from said light source, a lightsensitive device having a specific active area for receiving from said light source radiation that has passed through said object and said monochromatizing means, a slit which is narrow in the x direction and which limits the angular extension in said x direction of that radiation to subtend a first angle which hits the active area of the light-sensitive device, and means for relative motion in the x direction between said object and said slit, the improvement which comprises means for varying the position of the light-sensitive device with respect to said slit for exposing the entire length of said active area in the x direction to said radiation during measurements of said object in the x direction the light source having a constant radiation intensity in the x direction over a length subtending a second angle from the slit which is always greater than a third angle subtended by the active area of the light-sensitive device from said slit, said third angle always being no greater than said first angle.