1, числове діафрагма (Н.А.)
The числове діафрагма (N.A.) is обчислення використання наступне рівняння.
N. A.=n × Sinx
N=refractive index of the medium between the sample and the objective lens (air: n=1, oil: n=1.515)
X: The кут сформований by the оптичний вісь і the refracted light far from the center of the objective lens.
Коли спостереження під a мікроскоп, if you want to growth the NA value, the aperture angle cannot be increased. the solution is to growth the refractive index n value of the medium. Based on this principle, water immersed objective lenses and oil immersed objective lenses are duced. Since the refractive index n of the medium is greater than one, the NA value can be be greater than than one one.
The maximum numerical aperture value is 1.4, which has reached its theortical and technical limit. At present, bromonaphthalene with a high refractive index is used as a medium, and the refractive index of bromonaphthalene is 1.66, so the NA value can be greater than 1.4.
It must be pointed out here that in order to fully utilize the numerical aperture of the objective lens, the NA value of the condenser lens should be equal to or slightly greater than the NA value of the objective lens during observation,
Числовий діафрагма is closely related to other technical parameters, as it almost determines and affects other technical parameters. It is пропорційний to resolution, пропорційний to збільшення, and inversely proportional to focal depth. As the NA value increases, the field of view width and working distance will відповідно зменшення.
2, Роздільна здатність
Resolution, also known as "discrimination rate" or "resolution". It is other important technical parameter for measuring the performance of microscopes.
The resolution of the microscope is expressed by the formula: d=l/NA
In the formula, d is the minimum resolution distance; L is the wavelength of the light; NA is the numerical aperture of the objective lens. The resolution of a visible objective is determined by two factors: the NA value of the objective and the wavelength of the light source. the the value, the shorter the wavelength of the light, the shorter the wavelength of the illumination light, the smaller the d value, і вище роздільна здатність роздільна здатність.
To improve resolution, тобто reduce the d value, the follow measures can be taken
1. Зменшити довжина хвилі l значення і використання a коротка довжина хвилі світло джерело.
2. Збільшення the n value of the medium and increase the NA value (NA=nsinu/2).
3. Збільшення діафрагма кут.
4. Збільшення контраст між світлим і темним.
3, збільшення швидкість
Збільшення є збільшення 2c який посилається до відношення of the розмір of the final image seen by the human eye to the size of the original object after being magnified by the the objective lens and then by the eyepiece. it is the product of the magnification of the objective lens and the eyepiece.
Magnification is also an important parameter of a microscope, but one cannot blindly believe that higher magnification is better. When selecting, the numerical aperture of the objective lens should be considered first.
4, фокус глибина
Focal depth is the the abbreviation for focal depth, which means that when using a microscope, when the focus is aligned with an object, not only can the points located on the plane of the point be clearly seen, but also within a certain thickness above and below the plane. the товщина of this clear part is called focal depth.
Ви можете бачити цілий шар з об'єкт буття тестований, тоді якщо the focal depth is small, you can only see a thin layer of the object being tested. the focal depth is related to other technical parameters as follow:
1. The глибина of фокус is обернено пропорційний to the total збільшення і цифровий діафрагма of the objective lens.
2. Велика глибина з фокус і зменшення роздільна здатність.
Due to the large depth of field of the low-power objective, it causes difficulties when making photos with the low-power objective. A detailed introduction will be secure during micrography. V Field of view діаметр
Hen observing a microscope, the bright prototype range seen is called the field of view, and its size is determined by the field of view aperture in the eyepiece.
The diameter of the field of view, also known as the width of the field of view, refers to the factual range of the object being inspected that can be accommodated within a circular field of view seen under a microscope. The larger the diameter of the field of view, the easier it is is to observe.
From the formula, it can be seen that:
1. діаметр of the field of view is пропорційний to the number of fields of view.
2. Збільшення збільшення of the objective lens reduces the field of view діаметр. Тому, if the full view of the object being tested can be seen under a low-power lens, and replaced with a high-power objective, only a small part of the object being tested can be seen.
6, Робота відстань
The work distance, також known as object object distance, refers to the distance between the surface of the front lens of the objective lens and the object being tested. During microscopic examination, the object being examined should be between one and two times the focal length of the objective lens. Тому, it and focal length are two concepts, and what is commonly referred to as is actually adjusting the the working Відстань.
Коли цифрова діафрагма of the objective lens is fixed, the shorter the working the the larger the aperture кут.
A висока потужність об'єктив з a великий числовий діафрагма has a малий робочий відстань.
7, Погано покриття
The optical system of the microscope also includes a cover glass. Due to the non-standard thickness of the cover glass, the optical path of light entering the air through the cover glass undergoes a change in refraction, resulting in a difference in coverage. the generation of poor coverage impacts the sound quality of the microscope.
Відповідно до міжнародних регламентів, the standard thickness of cover glass is 0.17mm,
The allowable range is {{0}16-0}.18mm, and the difference in this thickness range has been calculated in the manufacturing of the objective lens. the label on the objective shell is indeed 0.17, indicating that the товщина of the cover glass required for the objective lens.
