Confocal is a high-resolution optical surface measurement technique that determines surface height by selectively detecting light from the focal plane while rejecting out-of-focus contributions. This is achieved using a confocal aperture, which improves axial resolution and contrast, enabling accurate three-dimensional measurements of surface topography with high lateral resolution.
HOW DOES CONFOCAL WORK?
Confocal microscopy works according to the following steps:
Illumination and detection alignment: The illumination and detection paths are optically aligned so that predominantly light originating from the focal plane contributes to the detected signal.
Monochromatic illumination: The sample is illuminated by a focused light source (laser or LED), providing well-defined spatial coherence for precise discrimination of focus.
Confocal aperture filtering: Reflected light passes through a confocal aperture, which blocks out-of-focus light and enhances axial resolution and contrast.
Axial scanning: The system scans the sample along the Z axis, recording the intensity response at each focal position.
Focus evaluation: For each lateral position, the surface height is determined by identifying the axial position corresponding to the peak intensity response.
3D reconstruction: The height data from all lateral positions are combined to reconstruct a high-fidelity three-dimensional surface topography.
APPLICATIONS
Confocal microscopy is applied in a wide range of fields, including:
Quality control in manufacturing: Ensuring product reliability by detecting fine topographic features and monitoring surface finish.
Engineering applications: Precise measurement of components and surfaces in mechanical and industrial engineering.
Microelectronics: Surface inspection and characterization of semiconductor[DP14.1] microstructures and patterned surfaces.
