Multi-image position detection

The exact measurement of positions is of fundamental importance in a multitude of image-sensor based optical measurement systems. We propose a new method for enhancing the accuracy of image-sensor based optical measurement systems by using a computer-generated hologram in front of the imaging system. Thereby, the measurement spot is replicated to a predefined pattern. Given enough light to correctly expose the sensor, the position detection accuracy can be considerably improved compared to the conventional one-spot approach. For the evaluation of the spot position we used center-of-gravity based averaging. We present simulated as well as experimental results showing an improvement by a factor of 3.6 to a positioning accuracy of better than three thousandths of a pixel for a standard industrial CCD sensor.