A lateral differential confocal microscopy for accurate detection and localization of edge contours

•Using dual-axis confocal structure to avoid common path noise and additive disturbance in light source intensity and ambient lighting.•Considerations of offsets from the perspective of PSF.•Detailed theoretical analyses of offsets.•Improved accuracy and sensitivity.

Common path noise and disturbance in light source and ambient lighting affect detection accuracy of edge contours greatly in optical microscopy. In order to solve this problem, a lateral differential confocal microscopy is proposed based on principle of lateral difference and confocal microscopy. The approach proposed uses confocal dual-receiving light path arrangement and real-time heterodyne subtraction of two signals with lateral offsets by a differential detector to improve the system′s accuracy and detection sensitivity. Theoretical analyses have been presented. In addition, a simple prototype system has been built based on theoretical analyses. Related experiments have been performed under laboratory conditions. Different from former image processing methods, common path noise and additive disturbance in light source and ambient lighting are eliminated before they are recorded. Theoretical analyses and experimental results indicate a more accurate and sensitive result.