A device for detecting analytes in samples, comprising: (a) n light source units (11, 12) generating light, said n light source units comprising at least a first light source unit and a second light source unit; (b) a reaction strip including (i) a test area illuminated with the light from a light source unit and including a material reacting to the analytes, (ii) a control area illuminated with the light from a light source unit (11, 12) and including a control material, and (iii) a background area illuminated with the light from a light source unit (11, 12), in which - the test area, the background area and the control area are arranged in this order along a first direction of the test strip, - the first light source unit is arranged in the first direction at a position between the test area and the background area to illuminate the test area and the background area with light from the first light source unit and - the second light source unit is arranged in the first direction at a position between the background area and the control area to illuminate the control area and the background area with light from the second light source unit, such that the test area and the control area share the background area; and (c) at least n + 1 light receiving units (21, 23, 24) arranged to one to one correspond to the test area, the control area, and the background area, respectively, for detecting light emitted from the test area, the control area, and the background area of the reaction strip, respectively. (a) n light source units (11, 12) generating light, said n light source units comprising at least a first light source unit and a second light source unit; (b) a reaction strip including (i) a test area illuminated with the light from a light source unit and including a material reacting to the analytes, (ii) a control area illuminated with the light from a light source unit (11, 12) and including a control material, and (iii) a background area illuminated with the light from a light source unit (11, 12), in which - the test area, the background area and the control area are arranged in this order along a first direction of the test strip, - the first light source unit is arranged in the first direction at a position between the test area and the background area to illuminate the test area and the background area with light from the first light source unit and - the second light source unit is arranged in the first direction at a position between the background area and the control area to illuminate the control area and the background area with light from the second light source unit, such that the test area and the control area share the background area; and (i) a test area illuminated with the light from a light source unit and including a material reacting to the analytes, (ii) a control area illuminated with the light from a light source unit (11, 12) and including a control material, and (iii) a background area illuminated with the light from a light source unit (11, 12), - the test area, the background area and the control area are arranged in this order along a first direction of the test strip, - the first light source unit is arranged in the first direction at a position between the test area and the background area to illuminate the test area and the background area with light from the first light source unit and - the second light source unit is arranged in the first direction at a position between the background area and the control area to illuminate the control area and the background area with light from the second light source unit, such that the test area and the control area share the background area; and (c) at least n + 1 light receiving units (21, 23, 24) arranged to one to one correspond to the test area, the control area, and the background area, respectively, for detecting light emitted from the test area, the control area, and the background area of the reaction strip, respectively.