Patent ID: 7176476

Claim:
In a device for acquiring latent image information contained in a phosphor layer, said device comprising, in combination: (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 the phosphor layer and the detector, which is substantially transparent in the first wavelength range (W 1 ) of the emission light and substantially non-transparent in the second wavelength range (W 2 ) of the excitation light, the improvement wherein the filter device is substantially non-transparent in at least a third wavelength range (W 3 ) that is located at longer wavelengths than the second wavelength range (W 2 ) of the excitation light, wherein the filter device comprises at least two filter elements, wherein at least a first one of the filter elements is substantially transparent in the first wavelength range (W 1 ) of the emission light and is substantially non-transparent in the second wavelength range (W 2 ) of the excitation light; wherein at least a second one of the filter elements is substantially transparent in the first wavelength range (W 1 ) of the emission light and is substantially non-transparent in the third wavelength range (W 3 ), which is located at longer wavelengths than the second wavelength range (W 2 ) of the excitation light; wherein at least one of the filter elements includes a first reflection layer that is substantially non-transparent for light in a fourth wavelength range (W 4 ), which is located between the second wavelength range (W 2 ) and the third wavelength range (W 3 ) and which partially overlaps the second wavelength range (W 2 ); and wherein at least one of the filter elements includes a second reflection layer that is substantially non-transparent for light in a fifth wavelength range (W 5 ), which is located at longer wavelengths than the second wavelength range (W 2 ) and which partially overlaps with both the third wavelength range (W 3 ) and the fourth wavelength range (W 4 ), whereby the filter elements and their reflection layers are substantially non-transparent to light in the wavelength ranges W 2 and W 3 as well as the wavelength range therebetween.