Common observation methods of optical microscope
Optical microscope is an optical instrument that uses light as light source to enlarge and observe tiny structures invisible to the naked eye. The earliest microscope was made by an optician in 1604.
In the past twenty years, scientists have found that optical microscopes can be used to detect, track and image objects, which are less than half the wavelength of traditional visible light, or hundreds of nanometers.
Because optical microscopes have not been used to study the nanometer scale traditionally, they usually lack calibration comparison with the standard to check whether the results are correct or not, so as to obtain accurate information at this scale. Microscopes can clearly and consistently indicate the same position of single molecules or nanoparticles. However, at the same time, it can be highly inaccurate. The position of the object identified by the microscope within the billionth meter may actually be one millionth meter, because there is no error.
Optical microscope is very common in laboratory instruments, which can easily enlarge different samples, from delicate biological samples to electrical and mechanical equipment. Similarly, optical microscopes are becoming more and more capable and economical because they combine the lights in smart phones with the scientific versions of cameras.
Common observation methods of optical microscope
Differential interferometry (DIC) observation method
principle
Polarized light is decomposed into beams perpendicular to each other and with equal intensity by a special prism, and the beams pass through the detected object at two very close points (less than the resolution of the microscope), so that the phase is slightly different, and the image presents a three-dimensional feeling.
characteristic
So that that observe effect of the three-dimensional sensation generated by the detect object is more intuitive. No special objective lens is needed, which is better matched with fluorescence observation and can adjust the color change of background and objects to achieve ideal results.
Dark field observation method
Dark field of vision is actually dark field lighting. Its characteristics are different from that of bright field of vision. It does not directly observe the illuminating light, but observes the light reflected or diffracted by the inspected object. Therefore, the field of view is a dark background, while the inspected object presents a bright image.
The principle of dark field of vision is based on the optical Tyndall phenomenon. Dust can't be observed by human eyes when strong light passes directly, which is caused by the diffraction of strong light. If the light is obliquely directed at it, the particles seem to increase in size and become visible to human eyes due to the reflection of light. The special accessory needed for dark field observation is the dark field condenser. Its characteristic is not to let the light beam pass through the inspected object from bottom to top, but to change the path of the light beam and make it obliquely incident on the inspected object, so that the illumination light does not directly enter the objective lens, and a bright image is formed by using the reflected or diffracted light on the surface of the inspected object. The resolution of dark field observation is much higher than that of bright field observation, reaching 0.02-0.004 μ m.
