Applications of Light Microscopy
Optical microscopes are microscopes that use optical lenses to produce image magnification.
Light incident from an object is amplified by at least two optical systems (objectives and eyepieces). First, the objective lens produces a magnified real image, and the human eye observes the magnified real image through the eyepiece that acts as a magnifying glass. General optical microscopes have multiple interchangeable objectives, and the observer can change the magnification as needed.
These objectives are usually placed on a rotating objective disk. By rotating the objective disk, different eyepieces can easily be brought into the light path. The English name of the objective lens disk is Nosepiece, also translated as nosewheel.
Current optical microscope structures are very complex and sophisticated. For accurate imaging, the light path of a microscope must be carefully designed and controlled. However, the working principle of light microscopy is very simple.
The simplest objectives are made of high-resolution glass lenses with a very short focal length, about 160 mm. The resulting image is a real image that can be seen with the naked eye without looking through the eyepiece, and can also be imaged on paper. In most microscopes, the eyepiece consists of a double lens. One is in the eye, which produces a virtual image, allowing the naked eye to see the magnified image; the other is close to the objective to produce the real image.
Application: Optical microscopes are mainly used for micron-level tissue observation and measurement on smooth surfaces. Since visible light is used as the light source, not only the surface organization of the sample, but also the organization within a certain range below the surface can be observed, and the optical microscope is very sensitive and accurate for color recognition.
Optical microscopes can be divided into three categories: upright microscopes, inverted microscopes, and dissecting microscopes.
upright microscope
An upright microscope is a type of optical microscope. Under the observation of penetrating light, the light source reaches the sample from the bottom of the fuselage through the condenser, then passes through the objective lens above the sample, and then reaches the observer's eye or other imaging equipment through the mirror and lens. The space between the objective lens and the condenser lens of an upright microscope is small, which is suitable for objects observed by an upright microscope. It is usually thin enough to be clamped in a glass slide. The advantage of an upright microscope is its simplicity, so most microscopes fall into this category.
Inverted microscope
An inverted microscope is a type of microscope. Under light-transmission observation, the bright-field illumination light source and condenser come from above the fuselage. Light travels through the condenser to the sample and then passes through the objective below the sample. , and then to the observer's eye or imaging device. For fluorescence microscopy, the fluorescence excitation light source and objective lens are located on the bottom. Since the excitation light source can be a high-power large laser light source or an arc lamp, the inverted design stabilizes the structure of the microscope mirror. Inverted microscopes are often used to observe cells or tissues in culture, especially fluorescent biological samples.
dissecting microscope
Dissecting microscopes, also known as solid microscopes or stereo microscopes, are microscopes designed for different work requirements. When viewed with a dissecting microscope, the light entering the two eyes comes from a separate path, with a small angle between the two light paths, so the sample can take on a three-dimensional appearance when viewed. There are two types of optical path designs for dissecting microscopes: the Greenough concept and the telescope concept.
Dissecting microscopes are often used for surface observation of some solid samples, or for dissection, watchmaking, and inspection of small circuit boards.
