An opto-electronic measuring unit for a colour measuring device, in particular a hand-held colour measuring device for measuring monitors, projectors, projection surfaces, and ambient light, having an optical arrangement (L 1, B, D) for receiving measurement light originating from a measurement object, and having a sensor arrangement (L 2, F 1, F 2, F 3, S 1, S 2, S 3, 20, 21), to which measurement light is applied, which sensor arrangement converts the measurement light into corresponding electrical measurement signals and processes these measurement signals into digital measurement data that characterise the colour of the measurement object, wherein the measuring unit, having an optical axis, comprises a convex input lens (L 1) with a comparatively large diameter (d 1), an aperture for restricting the angle of incidence to +/- 2°-10°, a sensor lens (L 2), and at least three photoelectric sensors (S 1, S 2, S 3), which are sensitised to different spectral sensitivities by means of colour filters (F 1, F 2, F 3), wherein the aperture is essentially positioned in the focal plane of the input lens (L 1), wherein the filters (F 1, F 2, F 3) and the sensors (S 1, S 2, S 3) are arranged near the optical axis and parallel measurement light is essentially applied to them, and wherein the filters (F 1, F 2, F 3) and the sensors (S 1, S 2, S 3) are configured such that the electrical measurement signals generated by the sensors (S 1, S 2, S 3) essentially represent the tristimulus colour values XYZ according to CIE, or a linear combination of these tristimulus colour values XYZ; characterised in that: the measuring unit further comprises an optical diffusor, which has a depolarising effect, wherein the optical diffusor is arranged in the optical path in immediate proximity of the aperture and essentially in the focal plane of the sensor lens (L 2), wherein the diffusor is designed such that the electrical measurement signals generated by the sensors (S 1, S 2, S 3) essentially represent the tristimulus colour values XYZ according to CIE, or a linear combination of these tristimulus colour values XYZ; the sensors (S 1, S 2, S 3) are arranged at a distance (s) from the sensor lens (L 2), which distance essentially corresponds to the focal length (f 2) of the sensor lens (L 2); the measuring unit further comprising: a lens barrel being sectioned into three sections having the aforementioned optical components; measurement electronics, which control the sensors (S 1, S 2, S 3); a printed circuit board on which the measurement electronics are arranged; and a communication interface on the printed circuit board; wherein the measurement electronics provide the measurement signals from the sensors (S 1, S 2, S 3) in digital form to the communication interface, wherein the sensors (S 1, S 2, S 3) are mounted on the printed circuit board and are electrically connected to the measurement electronics; and wherein the printed circuit board is fixed to one end of the lens barrel. the measuring unit further comprises an optical diffusor, which has a depolarising effect, wherein the optical diffusor is arranged in the optical path in immediate proximity of the aperture and essentially in the focal plane of the sensor lens (L 2), wherein the diffusor is designed such that the electrical measurement signals generated by the sensors (S 1, S 2, S 3) essentially represent the tristimulus colour values XYZ according to CIE, or a linear combination of these tristimulus colour values XYZ; the sensors (S 1, S 2, S 3) are arranged at a distance (s) from the sensor lens (L 2), which distance essentially corresponds to the focal length (f 2) of the sensor lens (L 2); the measuring unit further comprising: a lens barrel being sectioned into three sections having the aforementioned optical components; measurement electronics, which control the sensors (S 1, S 2, S 3); a printed circuit board on which the measurement electronics are arranged; and a communication interface on the printed circuit board; a lens barrel being sectioned into three sections having the aforementioned optical components; measurement electronics, which control the sensors (S 1, S 2, S 3); a printed circuit board on which the measurement electronics are arranged; and a communication interface on the printed circuit board; wherein the measurement electronics provide the measurement signals from the sensors (S 1, S 2, S 3) in digital form to the communication interface, wherein the sensors (S 1, S 2, S 3) are mounted on the printed circuit board and are electrically connected to the measurement electronics; and wherein the printed circuit board is fixed to one end of the lens barrel.