Large-volume measurement method based on array chromatic confocal technique

Chromatic confocal measurement (CCM) is an extensive technique of confocal microscopy, where the inherent relation between the focused wavelength and the axial position enables depth sensing. Most CCM works by single-point, resulting in inevitable lateral scans for 3D measurement. To facilitate the process, a 3D measurement method was developed, characterized by combining depth obtained by chromatic confocal technique and lateral information obtained by DMD. To realize the field extension, an objective with hyper-chromatism and wide field was custom-designed to form a 16 × 16 × 5.2 mm 3 measurement range. Chromatism was decoded to depth by creating a spectral bar for each measurement point. As depth varied, the peak intensity was observed to shift linearly on a pixelized bar. An effective range of 10 × 10 × 3.35 mm 3 was obtained from calibration. To validate the 3D measurement ability, a planar mirror, a three-step height sample of a 10 × 8 mm 2 field of view (FOV) with 0.1 mm and 2.0 mm height and a letter “V” structure were tested. Current work proves the array-based chromatic confocal technique can be a promising 3D measurement approach of practical significance .