In-situ high-precision surface topographic and Raman mapping by divided-aperture differential confocal Raman microscopy

Confocal Raman microscopy (CRM) is extensively employed in several fields owing to providing molecular fingerprint information without destroying and labelling samples. Most materials are heterogeneous; therefore, it is important to not only identify the chemical composition of samples, but also acquire high-precision surface topographic information. However, conventional CRM cannot accurately obtain the surface topographies of samples, which restricts the further application. We propose divided-aperture differential confocal Raman microscopy (DADCRM), which combines divided-aperture differential confocal microscopy with CRM. We use the reflected light to achieve accurate focus tracking, which is combined with Raman scattering to perform high-precision surface topographic imaging and Raman mapping simultaneously. The axial focusing ability of the proposed DADCRM system is estimated at 2 nm, which provides inherent anti-drift capability. The abilities of DADCRM to suppress background noise interference and improve stability are also demonstrated. We present in-situ Raman mapping and high-precision surface topographic imaging using DADCRM. These results provide new perspectives for both conventional CRM and CRM-based imaging in various fields.