Quantization noise characterization in spot displacement measurement: CCD surpasses bucket and quadrant detectors in precision and dynamic range

Spot displacement measurement technique (SDMT) is widely used in precision measurement, and its performance directly determines the measurement limits of various physical quantities. Quantization noise introduced by the analog-to-digital converter (ADC) is unsuppressable by signal amplification and thus becomes the dominant noise source in certain scenarios. In this paper, we address this situation by modeling spot displacement measurement based on bucket detector (BD), quadrant detector (QD), and charge-coupled device (CCD), and systematically analyze their displacement resolution (<i>r</i>_Δ) and linear dynamic range (LDR) under the constraint of quantization noise. The results demonstrate that the CCD scheme significantly outperforms the previous two approaches in terms of precision and dynamic range, and is particularly well-suited for precise measurement of low-frequency signals.