A new non contact optical surface characterisation techique called focus variation is used by the infinite focus microscope (IFM) to build true colour 3D images of surfaces and microscopic structures
Confocal microscopy and interfermometric systems are extremely powerful surface characterisation systems which can resolve nanometric features.
However there has up to now been an unfulfilled gap in the portfolio of non-contact, optical surface characterisation instrumentation available.
Say you want to build and measure a 3D image of a surface in true colour? Confocal and interferometers as techniques produce images in either monochromatic or pseudo colour.
Not ideal when you'd like to spot corrosion or discolouration due to laser machining for example.
Also surfaces and microscopic structures with high aspect ratio's (deep narrow troughs) and steep flanks (near vertical sides) can be difficult to image with confocal or interferometer systems.
Now a new non contact optical surface characterisation techique called focus variation addresses all these issues and others.
The infinite focus microscope (IFM) from Alicona of Austria uses this new technique to build true colour 3D images of surfaces and microscopic structures.
Very deep troughs can be imaged as can the flanks or sides of those structures almost up to 90deg in the vertical.
Surfaces with different materials and varying reflectivity are also no problem.
The instrument can still gather data and build images in traditionally difficult applications such as this.
Focus variation and the Infinite Focus (IFM) are ideal for applications that require characterisation of surfaces with significant variations in height across the area being studied.
Also ideal are surfaces with structures with steep sides.
For example fracture analysis or imaging Mems, microsystems and the results of laser machining are perfect.
Also if you require images in true colour the IFM is unique in allowing you to develop and measure 3D images of surfaces in true colour.
Once you have the image you can measure profile, areas and volume of surface features such as pitting and voids.
You can also measure roughness.
ACK Solutions represents Alicona in the Irish market place through Optimax in the UK.
It has developed a guide to the IFM and the focus variation technique which it says it would be happy to distribute.
The guide introduces the newly ISO recognised optical technique called focus variation and discusses the following topics:.
How the technique works.
How the technique fits into the portfolio of optical surface characterisation techniques.
Advantages and limitations of current surface characterisation techniques.
Advantages and limitations of the focus variation technique.
Characterising the surface - measuring profile, area, volume and roughness.
Application examples in the guide will demonstrate the following advantages of the Focus Variation technique:.
Large depth of focus - in mm range if required.
Advantages of imaging in true colour - spotting oxidisation and surface blemishes.
Imaging and measuring samples with deep valleys and steep vertical sides.
Imaging surfaces with widely varying reflective properties.
