CELL COUNTING.
Perhaps the most widely used in biology unit is an optical microscope, invented about 300 years ago the Dutchman Leeuwenhoek. With his help had been received the greatest amount of information on cell and single-celled organisms. And now he remains the most important accessory of any biological laboratory. Therefore, it is desirable, using electronics to expand its application.
One very common operation performed with a microscope, is recognition and counting of a particular cell type.
Counting cells under the supervision of a microscope, a person gets tired rather quickly. Therefore, at the expense of accuracy it is usually considered a relatively small number of cells. Need to find signs that could be used for automatic recognition and counting of microscopic objects.
From this point of view of great interest to use the phenomenon of photoluminescence. If the stain cells fluorochrome placed on the glass and then look at them in the fluorescent microscope, we can see how they glow green, red or any other color, usually some parts of the cells glow in different colors. Different colors - this is a different length of light waves. If you make a device that would distinguish the color, you can determine how many cells and what color is considered part of the glass.
Such a device is created. Brightness micro higher, the brighter the light source to excite their luminescence in the device so use a special mercury lamp. This lamp has brightness equal to or even exceeding the brightness of the sun. Through the diaphragm and filter light from the source strikes the beam splitter and reflected from it, with the lens focused on the drug analyzed, causing luminescence. Luminescence wavelength of light is always greater than the wavelength of incident light. Beam splitter is arranged so that, using this difference, it is easy to pass through a luminescent light and does not miss the exciting light. The same part of the exciting light, which still pass through a beam splitter filter is absorbed, while light from the luminescent particles passes through a filter with almost no losses. Coming out of the microscope objective and reflected by the mirror, the beam enters the input of the optical system. The optical system consists of a refractive prism and a series of mirrors. With this system, light luminescence depending on its wavelength is directed to the entrance of the photomultiplier. The microscope stage along with the analyzed preparation is replaced with a motor. Because of this the moment when the light from the luminescent cells in the diaphragm reaches the entrance of one of the photomultiplier tubes, it causes a pulse at its output. After amplification, the pulse enters the block corresponding to the registration counter. The number of pulses registered by the counter corresponds to the number of particles of luminescent single color. The described analyzer can be used when necessary to determine how many live and how many dead cells in the test preparation.