What is the optimal measurement distance and measurement area per element for integral and 3 element color sensors?
The nearer the measurement object, the better the measured values will be without any additional optic. But you always need a homogeneous lighting level with great intensity for the measurement area.You need additional optics at a distance of >1 cm. The illuminating intensity is the problem above that distance. You need a lot of energy, because the intensity of illumination at the measurement area decreases quadratically with the distance to the sensor. In this case an additional optic lens is absolutely necessary, due to the light dispersion. The dimension and form of the measurement area is defined by the optic in front of the sensor. You get good values by measuring round areas with a diameter of ca. 5-7 mm. If you have greater measurement areas you will get problems due to the increasing rate of light beams with an angle of incidence about 10°. Generally the optical lens results from the calculation of object size, distance and sensor area. You have to consider also the light source, measurement frequency and the sensor signal amplification.
The nearer the measurement object, the better the measured values will be without any additional optic. But you always need a homogeneous lighting level with great intensity for the measurement area.You need additional optics at a distance of >1 cm. The illuminating intensity is the problem above that distance. You need a lot of energy, because the intensity of illumination at the measurement area decreases quadratically with the distance to the sensor. In this case an additional optic lens is absolutely necessary, due to the light dispersion. The dimension and form of the measurement area is defined by the optic in front of the sensor. You get good values by measuring round areas with a diameter of ca. 5-7 mm. If you have greater measurement areas you will get problems due to the increasing rate of light beams with an angle of incidence about 10°. Generally the optical lens results from the calculation of object size, distance and sensor area. You have to consider also the light source, measurement frequency and the sensor signal amplification.