Why is the inverted microscope "inverted"?
The composition of an inverted microscope is the same as that of an ordinary microscope, except that the objective lens and the illumination system are inverted, the object is located in front of the objective lens, and the distance from the objective lens is greater than the focal length of the objective lens, but less than twice the focal length of the objective lens. After passing through the objective lens, an inverted enlarged real image is formed. What our eyes see through the eyepiece is not the object itself, but the image that has been magnified once by the objective lens.
Because the materials observed by the inverted microscope are generally cultured cells, the transparency is great and the structural contrast is not obvious, so the inverted microscope is often equipped with a phase contrast objective, which actually constitutes an inverted phase contrast microscope.
On the inverted microscope, various types of consumables, such as Petri dishes and perforated plates, are often used, and the thickness of the bottom is different, which will change the light passing through. At this time, it is necessary to use the objective lens with the function of correction ring, and its middle part is equipped with a ring-shaped adjustment ring. When the adjustment ring is rotated, the distance between lens groups in the objective lens can be adjusted, so as to correct the aberration caused by the nonstandard thickness of the cover glass (Petri dish) (conventional Petri dish is 1.2mm and cover glass is 0.17mm). The correct use method is: adjust the calibration ring to the standard value of 1.2mm and focus the sample. Adjust the calibration ring half a square to the right, and then focus on the sample. If the image effect becomes better, adjust it to the right and focus again, otherwise adjust it to the left.
Inverted biomicroscope realizes dual-channel function. A newly added infinite optical path enables you to introduce additional light sources to realize technologies such as FRAP, photoactivation, laser ablation, laser tweezers or optogenetics.
Inverted microscope was born to adapt to the microscopic observation of tissue culture, cell culture in vitro, plankton, environmental protection and food inspection in biology, medicine and other fields. Due to the special restrictions of these samples, the tested objects are all placed in Petri dishes (or culture bottles), so the working distance between the objective lens and the condenser of the inverted microscope is very long, and the tested objects in the Petri dishes can be directly observed and studied microscopically. Therefore, the positions of the objective lens, condenser and light source are reversed, hence the name "inversion".
