Optical Microscopy

OPTICAL MICROSCOPE

The optical microscope (µScope) of the SX-FIVE is equipped with a reflected light illuminator, and an optionally, a transmitted-polarized illumination system.  Pressing the ‘REFLECTED’ or ‘TRANSMITTED’ button will turn the chosen illuminator on.  The ‘LIGHT’ button also toggles the illuminator on and off.

Pressing the ‘POLARIZER’ button inserts or removes polarizers in the optical path.  For reflected light, there is a mechanically-coupled, rotatable polarizer-analyzer pair in the optical path.  For transmitted light, a lower polarizer and upper analyzer pair may be rotated together.  The angular offset between the two can be set using the ADJUST button.

The optical field of view

The Field of View (FOV) of the SX-FIVE optical microscope is defined by the length of the diagonal measurement of the optical image, and can be continuously changed between ~1750 µm (low magnification) to ~250 µm (high magnification), using the dedicated slider control. Although focus is retained at all magnifications, a default FOV of 500 µm is recommended to give good sensitivity for precise focusing.

The optical focus

The optical microscope built into the EPMA is a useful tool for locating areas of interest, or for correlating areas with previous optical microscopy work performed on the sample.  However, the microscope also serves a critical function for WDS X-ray analysis: optical focus ensures that the sample surface is on the X-ray Rowland Circle, along with the diffracting crystal and X-ray detector.  An error of few microns in Z position can greatly reduce the measured WDS X-ray intensity (precise Z position is less critical when using an inclined WDS spectrometer or an energy dispersive spectrometer, EDS).

The Z-axis adjustment can be performed manually, using the touch screen ‘Stage Z’ wheel or the slider and (+) and (-) buttons below the wheel for fine tuning.  Automatic Z-axis focusing is done by pressing the ‘AF’ button (FIGURE).  The user should check Z-focus before every analysis point to account for any variation in sample surface horizontality.

The joystick can also be used for setting Z-focus.

SAVE

SX-ETU can save the optical microscope image as a TIFF, BMP, JPEG or ImpDat file. ImpDat is a proprietary image format developed by CAMECA, containing additional information, such as XYZ position and instrument configuration.  The file can be viewed only with CAMECA software.
After file format selection, designate a filename and press the ‘SAVE’ button. The file will be automatically saved in the Images&Profiles folder within the previously-defined path (Project/Sample) and automatically opened in the SX-Results program.

MOZAIC

A new function implemented in SX-ETU allows acquisition of mosaic images using the optical microscope. Maximum X/Y range cannot exceed 1 mm x 2 mm (FIGURE). 

Outside of those dimensions opens up Mosaic program

After image size selection, the user is asked to define a filename and press the ‘SAVE’ button. The output file will be automatically saved in the previously-defined Project/Sample path and automatically opened in the ’SX-Results program.