Raman microscopy is a high resolution imaging technique that has become widely used for the characterization of materials in terms of their chemical composition. Through the selection of optimized microscope components it is possible to approach the theoretical limit in spectral and spatial resolution. In this way information on sample properties can be obtained on the micro- and even nano-scale.
Confocal Raman Microscopes
Confocal Raman microscopy combines chemical sample characterization with the imaging capabilities of an optical microscope. Thereby, a spatial resolution down to 200 nm can be achieved. In a confocal microscope, only light from the focal plane is detected while out of focus light is rejected, thus providing depth resolution and a strongly reduced background signal. Images are recorded point by point and line by line while scanning the sample through the excitation focus. With this technique, the specimen can be analyzed in steps along the optical axis and even a depth profile or 3D image can be generated.The Resolution
The spectral and spatial microscope resolutions are important factors for the quality of the acquired measurements. The spectral resolution of a confocal Raman microscope is mainly defined by the individual components of the spectroscopic system. The focal lengths, the grating, the pinhole, the pixel size of the CCD camera, and the imaging quality of the spectrometer all contribute to optimization.
Furthermore, the depth resolution is an important characteristic of a confocal system. The instrument design and also the pinhole and the sample illumination influence the depth resolution. With the usage of proper microscope components a depth resolution below 750 nm can be achieved.
High Resolution and Ultrafast 3D Image Acquisition
The spectral and spatial resolution of a confocal Raman microscope setup can be optimized by the usage of optimized optical and mechanical microscope components. In this way high-resolution depth scans and 3D Raman images can be generated and information about the chemical sample composition can be obtained.
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