Patent ID: 7071484

Claim:
In a device for acquiring latent image information contained in a phosphor layer, said device comprising: (a) a light source for irradiating the phosphor layer with excitation light that is suitable for exciting emission light in the phosphor layer, said emission light having a first wavelength range (W 1 ) and said excitation light having a second wavelength range (W 2 ); (b) a detector for detecting the emission light that has been excited in the phosphor layer; and (c) a filter device, arranged between at least one of the (1) phosphor layer and the detector and (2) the phosphor layer and the light source, the improvement wherein the filter device comprises at least three absorption filter elements, which are joined to one another, and wherein at least two of the filter elements that are joined to one another exhibit differing coefficients of thermal expansion, the filter elements that are joined to one another being arranged such that: (i) at least two filter element pairs are each obtained from two filter elements with differing thermal expansion coefficients, wherein at least one second filter element with a second thermal expansion coefficient is arranged between at least two first filter elements, each with a first thermal expansion coefficient; and (ii) bending forces, which occur at temperature changes in the individual filter element pairs, work against each other and tend to cancel each other out; and wherein the thicknesses of the first filter elements are all the same order of magnitude.