Structure and Components of a Confocal Microscope
Atomic force microscope is a scanning probe microscope developed based on the basic principles of scanning tunneling microscope. The emergence of atomic force microscopy undoubtedly played a driving role in the development of nanotechnology. Scanning probe microscopy, represented by atomic force microscopy, is a series of microscopes that use a small probe to scan the surface of a sample, providing high magnification observation. Atomic force microscopy scanning can provide surface state information of various types of samples. Compared with conventional microscopes, the advantage of atomic force microscopy is that it can observe the surface of samples at high magnification under atmospheric conditions, and can be used for almost all samples (with certain requirements for surface smoothness), without the need for other sample preparation treatments, to obtain three-dimensional morphology images of the sample surface. And it can perform roughness calculation, thickness, step width, block diagram or particle size analysis on the three-dimensional morphology image obtained from scanning.
Atomic force microscopy can detect many samples, provide data for surface research and production control or process development, which cannot be provided by conventional scanning surface roughness meters and electron microscopes.
1, Basic principles
Atomic force microscopy uses the interaction force (atomic force) between the surface of a sample and the tip of a fine probe to measure the surface morphology.
The probe tip is on a small flexible cantilever, and the interaction generated when the probe contacts the sample surface is detected in the form of cantilever deflection. The distance between the sample surface and the probe is less than 3-4nm, and the force detected between them is less than 10-8N. The light from the laser diode is focused on the back of the cantilever. When the cantilever bends under the action of force, the reflected light is deflected, and a position sensitive photodetector is used to deflect the angle. Then, the collected data is processed by a computer to obtain a three-dimensional image of the sample surface.
A complete cantilever probe is placed on the surface of the sample controlled by a piezoelectric scanner and scanned in three directions with a step width of 0.1 nm or less in horizontal accuracy. Generally, when scanning the sample surface in detail (XY axis), the Z-axis controlled by the displacement feedback of the cantilever remains fixed and unchanged. The Z-axis values that provide feedback on the scanning response are input into the computer for processing, resulting in an observation image (3D image) of the sample surface.
