Multiwavelength Digital Holography for Metrology: Low-Coherent Noise Sensor Configuration and Its Application

Mitutoyo Research Center Europe B.V., De Rijn 18, 5684 PJ Best, The Netherlands.

Published online: 22 September 2025

Abstract

The demand for 100% inspection is increasing due to rising quality requirements in manufacturing. Multiwavelength Digital Holography (MDH) has emerged as a promising sensing technology capable of achieving both high throughput and high resolution. However, despite its potential, MDH has not yet been widely adopted in commercial metrology applications. One of the key challenges in MDH system design is minimizing noise in the laser-illuminated optical imaging system. Due to the high coherence of laser light, digital holography systems are particularly sensitive to particle contamination and internal reflections within optical components. We address this challenge by introducing a phase randomizing mirror (PRM) that controls coherent length by dynamically modulating the spatial profile of the illumination. Compared to conventional mechanical modulation methods, the PRM operates at significantly higher frequencies, enabling shorter exposure times. This results in a system that is not only high-throughput but also more resilient to environmental vibrations. In this presentation, we will discuss the impact of the PRM on our newly developed phase-shifting digital holography system and demonstrate its application in real-world inspection scenarios.