Radiation image information read-out apparatus

A radiation image read-out apparatus comprising a stimulating light beam projecting means which projects a line stimulating light beam onto a stimulable phosphor sheet, storing thereon radiation image information, to extend in a main scanning direction, a line sensor consisting of a plurality of photoelectric convertor elements which receive stimulated emission emitted from the portion exposed to the line stimulating beam to convert the amount of stimulated emission to an electric signal and are arranged in a row which extends along the line portion of the stimulable phosphor sheet exposed to the line stimulating beam, a condenser lens which is disposed along the line sensor to collect the stimulated emission on the light receiving face of the line sensor and a sub-scanning means which moves one of the line sensor and the stimulable phosphor sheet relatively to each other in a sub-scanning direction intersecting the main scanning direction, wherein the improvement comprises that the following formula (1) is satisfied, 1 ⁢ ( m ⁢ ⁢ m ) λ ⁢ ⁢ a ⁡ ( n ⁢ ⁢ m ) - λ ⁢ ⁢ b ⁡ ( n ⁢ ⁢ m ) ≤ Δ ⁢ ⁢ d ⁡ ( m ⁢ ⁢ m ) Δλ ⁡ ( n ⁢ ⁢ m ) ( 1 )

• wherein λa (nm) represents the center wavelength of the stimulating light, μb (nm) represents the center wavelength of the stimulated emission, Δλ (nm) represents the wavelength difference between the longest wavelength and the shortest wavelength of the incident light components on the condenser lens and Δd (mm) represents the distance of dispersion on the light receiving face of the incident light components on the condenser lens, the incident light components on the condenser lens including the stimulating light and the stimulated emission, and 1 (mm) corresponding to one millimeter.