The LEXT microscope utilises low wavelength optical technology with a 408nm laser in combination with confocal scanning making it one of the most powerful laser-scanning microscopes on the market today.
By developing a special optical system, which minimises the aberrations associated with short wavelength and maximises the transmission at 408nm, Olympus achieved improved image quality and signal response.
Unlike other systems on the market, which requires skilled handling, LEXT increases usability and measuring speed by a unique operation and display concept. LEXT has a 2-channel live image display with the possibility to show both - a conventional coloured microscope image and a confocal image -in parallel on the screen.
The LEXT microscope makes focusing on the specimen surface and finding the desired position similar to a conventional microscope. After the scan area has been defined by focusing on the top and on the bottom surface of the specimen the scan process is running automatically.
The resolution power is improved by the confocal scanning technique. With this technique the specimen surface is scanned point by point. At the detector side (photomultiplier) a special confocal pinhole blocks all rays that are reflected from out of focus planes.
The photomultiplier measures the signal intensity at each point by gathering 3D information of the inspected surface. This confocal system produces intensity maps, which can be reconstructed to a 3-dimensional image.
The XY scanner utilised in the LEXT - a micro-electro mechanical system (MEMS) developed by Olympus - makes the scanning process faster and results more reproducible compared to conventional scanner technologies as the moving mass is much lower.
To allow the scan of specimens with different reflection characteristics, such as the substrate surface and copper-wiring surface of a printed substrate LEXT is equipped with an enhanced mode by which these kinds of specimen can be captured clearly. The same feature can detect slanted samples, which are difficult to reflect laser, which are problematic for conventional 3D measuring equipment.
Once the 3D data had been acquired numerous measurement functions are available to analyse the shape of the surface. Height, distance, angle and volume can be easily extracted and documented.
The optional motorised scanning stage enables automated image acquisition and measuring on several points of the specimen. A macro recorder can easily store image acquisition and measuring procedures. The stage navigator allows the programming of predefined grids or individual point settings so that LEXT can be efficiently used for statistic process control.
The LEXT also includes enhancements to the 3D colour images generated Defects of colour filters or metal corrosion that can not be shown by monochrome observation are displayed by LEXT in clear 3D colour images, enabling much more comprehensive analysis than is possible by SEM (Scanning Electron Microscopy).
LEXT achieves this by the parallel scan of height information (confocal system/ photomultiplier) and colour information (microscope system/CCD). Through a special algorithm both information can be overlaid precisely.
Differential Interference Contrast (DIC) is a common microscope technique used to resolve extremely small surface indentations. By utilising DIC in combination with the LEXT 408nm laser and the precise Z-scan brilliant 3D images can be acquired which are beyond the capabilities of conventional laser microscopes.
With these observation and measuring possibilities LEXT is giving metrology a new dimension - for more efficient processes, for products with higher reliability, for a better understanding of surfaces and new findings that helps engineers to develop new materials with better properties.