Microscope Spectroscopy

Combining various types of stereo- or light microscopes with spectral analysis, expands the capacities to inspect structures and single particles close to the limits of optical resolution. With this technique, samples with longer working distance can be analyzed, even in three-dimensional view. Spectrometers on conventional light microscopes, using highly stabilized illumination units, work in bright field, polarization and fluorescence in the in deep UV and NIR range.

  • Measurement theory

    Microscope spectroscopy focuses on small measuring spots. The smaller the structure the more difficult is the precise positioning of the sample. Therefore, variable pinholes are implemented inside the microscope beam path in order to focus the light on small detection areas.

    Microscope and spectrometer are linked by an optical fiber, which is coupled to the microscope by a special optical collimation adapter. With this flexible fiber connection, components such as cuvettes, microplates, tray cells can be used with the same sensor.

    The exposition time of the sample has to be kept as short as possible to prevent damage on the microscope or fading to the sample. Therefore, a high efficient signal transmission and a spectrometer with best possible sensitivity must be chosen for these sophisticated configurations.

    • Precise alignment of the sample into the optical axis
    • Excellent optical signal transfer from the microscope to the spectrometer
    • Optimized size and position of the measurement pinhole (confocal effect)
    • Visualization of measuring aperture
    • Focus on the excitation light precisely to the detection point
  • Examples of use
    • Detecting structures on solid specimen with complex surface topography, e.g. on art objects (requires three-dimensional visualization and a precise positioning of very small detection areas)
    • Evaluating minerals or isotropic materials (requires polarized light to enhance contrast and to improve image quality)
    • Analyzing textile fibers (using deep UV to differentiate between natural and synthetic fibers)
    • Determination of layer thicknesses or quality control of wafers (achieved by expanded NIR light penetration inside a semitransparent material)
    • Forensic comparison of fibers (requires deep UV to differentiate between synthetic or natural fibers)
    • Color measurements on fibers, paints, papers, surfaces and wood
    • Proof of origin in documents and biological materials
    • Petrographic analyses and geological maturation studies
    • Optical properties of transparent coatings on glasses and reflectance of surfaces
    • Detection of layer thickness on semitransparent coatings
    • Determination of particle sizes and distributions in colloidal mixtures
    • Geological studies on coal and oil or maturity of sediments 
  • MCS 600 spectrometers systems

    MCS modules implemented inside the microscope controlling units are well suited for stereomicroscopic investigations:

    • Measurement of spectral range from 190 to 2,200 nm, achieved by a modular design, which combines different types of UV/VIS/NIR spectrometers into one system
    • Peltier cooled CCD spectrometers provide highest possible sensitivity, optimized to measure weak fluorescence signals, dark field results or UV and NIR measurements; large pixel size (24 x 24 ┬Ám) and vertical binning (> 50 pixels) results in high sensitivity; exceeds the active detection area of more than 28,000 square microns per 0.8 nm resolution