Common observation methods with optical microscopes
An optical microscope is an optical instrument that uses light as a light source to magnify and observe tiny structures invisible to the naked eye. The earliest microscope was made by an optician in 1604.
Over the past two decades, scientists have discovered that optical microscopes can be used to detect, track and image objects smaller than half the wavelength of conventional visible light, or a few hundred nanometers.
Since optical microscopes have not traditionally been used to study the nanoscale, they often lack calibration comparisons with standards to check that the results are correct to obtain accurate information at that scale. Microscopy can accurately and consistently indicate the same location of a single molecule or nanoparticle. However, at the same time, it can be highly inaccurate, and the location of an object identified by a microscope to within a billionth of a meter may actually be a millionth of a meter because there is no error.
Optical microscopes are common among laboratory instruments and can easily magnify different samples, from delicate biological samples to electrical and mechanical equipment. Likewise, light microscopes are becoming increasingly capable and affordable as they combine the lights and scientific versions of cameras found in smartphones.
Common observation methods with optical microscopes
Differential Interference (DIC) Observation Method
principle
The polarized light is decomposed into beams of equal intensity that are perpendicular to each other through a special prism. The beam passes through the object under inspection at two very close points (less than the resolution of the microscope), resulting in a slight difference in phase, making the image appear three-dimensional. Three-dimensional feeling.
Features
It can make the object being inspected produce a three-dimensional feeling and the observation effect is more intuitive. No special objective lens is required, and it works better with fluorescence observation. It can adjust the color changes of the background and objects to achieve the desired effect.
Dark field observation method
Darkfield is actually darkfield lighting. Its characteristics are different from bright field. It does not directly observe the illumination light, but observes the light reflected or diffracted by the object being inspected. Therefore, the field of view has a dark background, while the inspected object appears as a bright image.
The principle of dark field is based on the optical Tyndale phenomenon. When dust is directly passed through by strong light, the human eye cannot observe it. This is caused by the diffraction of strong light. If you shine light at it obliquely, the particles seem to increase in size due to the reflection of light, making them visible to the human eye. A special accessory required for dark field observation is a dark field condenser. Its characteristic is that it does not allow the light beam to pass through the object being inspected from bottom to top, but changes the path of the light so that it slants toward the object being inspected, so that the illumination light does not directly enter the objective lens, and uses the reflected or diffracted light on the surface of the object to be inspected to form Bright image. The resolution of dark field observation is much higher than that of bright field observation, reaching 0.02-0.004μm.
