Laser Confocal Scanning Microscope
Laser confocal scanning microscope (laser confocal scanning microscope), using laser as scanning light source, fast scanning and imaging point by point, line by line, and surface by line, the scanning laser and fluorescence collection share an objective lens, and the objective lens scans the focal point of the laser light, which is also instantaneous imaging point of matter. Because the wavelength of the laser beam is short and the beam is very thin, the confocal laser scanning microscope has a high resolution, which is about 3 times that of the ordinary optical microscope. After the system is focused once, the scanning is limited to one plane of the sample. When the focusing depth is different, images of different depth levels of the sample can be obtained. These image information are stored in the computer. Through computer analysis and simulation, the three-dimensional structure of the cell sample can be displayed.
Why do you need a confocal microscope?
1. After the efforts and improvements of our great predecessors, the optical microscope has reached the point of perfection. In fact, ordinary microscopes can provide us with beautiful microscopic images simply and quickly. However, an event that brought revolutionary innovation to this nearly perfect microscope world happened, which is the invention of the "laser scanning confocal microscope". The feature of this new type of microscope is that it adopts an optical system that only extracts image information on the surface where the focus is concentrated, and restores the obtained information in the image memory while changing the focus, so that complete 3D information can be obtained. A stark image of intelligence. With this method, it is possible to easily obtain information about the surface shape that cannot be confirmed with a normal microscope. In addition, for ordinary optical microscopes, "increasing resolution" and "deepening depth of focus" are contradictory conditions, especially at high magnifications, this contradiction is more prominent, but in terms of confocal microscopes, this problem is easily solved.
2. Advantages of confocal optical system
Schematic diagram of laser confocal microscope
The confocal optical system performs point illumination on the sample, and the reflected light is also received by the point receptor. When the sample is placed in the focus position, almost all the reflected light can reach the photoreceptor, and when the sample is out of focus, the reflected light cannot reach the photoreceptor. That is to say, in the confocal optical system, only the image that coincides with the focal point will be output, and the light spots and useless scattered light will be shielded.
3. Why use laser?
In the confocal optical system, the sample is illuminated at a point, and the reflected light is also received by a point photoreceptor. Therefore, a point light source becomes necessary. Lasers are very point light sources. In most cases, laser light sources are used as light sources for confocal microscopes. In addition, the characteristics of monochromaticity, directionality and excellent beam shape of laser are also important reasons for its wide adoption.
4. Real-time observation based on high-speed scanning becomes possible
For laser scanning, the horizontal direction adopts the Acoustic Optical Deflector (AO element), and the vertical direction adopts the servo electronically controlled beam scanning mirror (Servo Galvano-mirror). Since the acousto-optical deflection unit has no mechanical vibration part, it can perform high-speed scanning and real-time observation on the monitor screen is possible. This high-speed imaging is a very important item that directly affects the speed of focusing and position retrieval.
