Introduction to the classification and uses of various optical microscopes
1. binocular stereo microscope
Binocular stereomicroscope, also known as "physical microscope" or "anatomy mirror", is a visual instrument with an upright three-dimensional sense. It is widely used in slicing operations and microsurgery in the biological and medical fields; in industry it is used for observation, assembly, and inspection of tiny parts and integrated circuits. It has the following characteristics:
(1) Using a dual-channel light path, the left and right light beams in the binocular tube are not parallel, but have a certain angle - the stereoscopic viewing angle (generally 12 degrees - 15 degrees), providing a three-dimensional view for the left and right eyes. Image. It is essentially two single-tube microscopes placed side by side. The optical axes of the two tubes constitute the angle of view formed when people observe an object with binoculars, thereby forming a stereoscopic visual image in a three-dimensional space.
(2) The image is upright, making it easy to operate and dissect. This is because the prism under the eyepiece inverts the image.
(3) Although the magnification is not as good as that of a conventional microscope, its working distance is very long.
(4) The focal depth is large, making it easy to observe the entire layer of the object being inspected.
(5) Large field of view diameter.
The current optical structure of the stereoscope is: with a shared primary objective lens, the two light beams that image the object are separated by two sets of intermediate objective lenses - zoom lenses, and are combined into an integrated viewing angle and then imaged through their respective eyepieces. The magnification change is obtained by changing the distance between the intermediate lens groups, so it is also called a "continuous zoom stereomicroscope" (Zoom-stereomicroscope). With the requirements of the application, currently stereoscopes can be equipped with a wide range of optional accessories, such as fluorescence, photography, video, cold light sources, etc.
2. Metallurgical microscope
A metallographic microscope is a microscope specially used to observe the metallographic structure of opaque objects such as metals and minerals. These opaque objects cannot be observed in ordinary transmitted light microscopes, so the main difference between metallography and ordinary microscopes is that the former uses reflected light, while the latter uses transmitted light for illumination. In a metallographic microscope, the illumination beam is emitted from the direction of the objective lens to the surface of the object being observed, is reflected by the object surface, and then returns to the objective lens for imaging. This reflected lighting method is also widely used in the inspection of integrated circuit silicon wafers.
3. Fluorescence microscope
Fluorescence microscopy uses short-wavelength light to illuminate an object stained with fluorescein, causing it to be excited to produce long-wavelength fluorescence, which is then observed. Fluorescence microscopes are widely used in biology, medicine and other fields.
(1) Fluorescence microscopes are generally divided into two types: transmission and epi-illumination.
a. Transmission type: The excitation light comes from below the object to be inspected, and the condenser is a dark field condenser, so that the excitation light does not enter the objective lens, but the fluorescence enters the objective lens. It is bright at low magnification, but dark at high magnification. It is difficult to operate when immersed in oil and adjusted, especially the illumination range at low magnification is difficult to determine, but it can obtain a very dark background of the field of view. The transmission type is not suitable for non-transparent objects to be inspected.
b. Epi-illumination type: The transmission type is almost eliminated at present. Most of the new fluorescence microscopes are epi-illumination type. The light source comes from above the object to be inspected and has a spectroscope in the light path, so it is suitable for both transparent and opaque objects to be inspected. Since the objective lens functions as a condenser, it is not only easy to operate, but also can achieve uniform illumination of the entire field of view from low to high magnification.
