What is the objective lens in the eyepiece and how to choose the eyepiece and objective?

The meaning of the title is ......Eyepieces and objective lenses are inherently ...... different

There are two main considerations when selecting objectives and eyepieces:

First, the matching of categories. That is, all plan objectives should be used in conjunction with special plan eyepieces.

Second, the reasonable matching of magnification. Under a certain magnification, the objective lens and eyepiece can be arbitrarily combined, but the premise of its combination is mainly to consider the effective magnification, which is an important rule for the correct use of the microscope. The effective magnification of the microscope is the numerical aperture of the objective lens used.

500 1000 times, i.e. the product of the magnification of the objective and eyepiece is equal to 500 1000 times the numerical aperture of the objective.

If you are using a 40x objective with a numerical aperture, you should choose a large size.

First, the effective total magnification is calculated according to the effective magnification, and then divided by 40, that is, the multiple of the eyepiece should be selected. The calculation process is: (.

In other words, an objective lens with a numerical aperture should be matched with an eyepiece of 8 16x in the range of effective magnification (500 1000x). If the eyepiece magnification is too low and the total magnification is too small, the resolution of the objective lens cannot be fully utilized, and the details that could have been recognized are crowded together because the total magnification is too small, and it is difficult to distinguish them.

However, the large multiple of the discharge circle obtained by the eyepiece higher than 16 times is called "empty magnification", and the resolution of the affected details is not improved in the slightest, but the clear depth is small, and it cannot clearly reflect the structure of different horizontal levels.

Differences: 1. Different definitions.

Eyepiece: A mirror head close to the human eye, marked with the words 16 or 10, indicating that the eyepiece is magnified by 16 times or 10 times.

Objective: A lens that is close to the object being observed, marked with words such as 10 or 40, indicating that the objective lens is magnified by 10x or 40x.

2. The characteristics are different.

Eyepiece features: no threads.

Objective features: threaded.

3. The relationship between length and magnification is different.

The longer the eyepiece, the smaller the magnification; The shorter the eyepiece, the greater the magnification.

The longer the objective, the greater the magnification; The shorter the objective, the smaller the magnification.

Differences

1. The definitions are different.

The eyepiece is a visual optical device used to observe the image formed by the optical system in front of it, and is a component of visual optical instruments such as telescopes and microscopes. The eyepiece is composed of two parts, the lens located at the upper end is called the eye lens, which plays a magnifying role, and the lower lens is called the converging lens or field lens, so that the brightness of the image is uniform.

An objective lens is a lens group that combines several lenses. The purpose of the combination is to overcome the imaging defects of individual lenses and improve the optical quality of the objective lenses. The magnification of the microscope mainly depends on the objective lens, the quality of the objective lens directly affects the quality of the microscope image, it is the main component that determines the resolution of the microscope and the clarity of the imaging, so the calibration of the objective lens is very important.

2. The characteristics are different.

The eyepiece is unthreaded, and the objective lens is threaded.

3. The relationship between length and magnification is different.

The longer the eyepiece, the smaller the magnification; The shorter the eyepiece, the greater the magnification.

The longer the objective, the greater the magnification; The shorter the objective, the smaller the magnification.

Differentiation methods

1. Distinguish from the structure of the two:

1. The structure of the eyepiece: The structure of the eyepiece is much simpler than that of the objective lens. The eyepiece is composed of two parts, and the lens located at the upper end is called the eyepiece lens, which plays a magnifying role; The lower lens is called a converging lens or a field lens, which makes the image brightness uniform.

In the middle of the upper and lower lenses or at the lower end of the lower lens, there is a light bar, where accessories such as micrometers, cross glasses, and pointers are installed.

2. The structure of the objective lens: the structure of the objective lens is complex, the production is precise, and it is usually composed of lens groups, and the lenses are separated from each other by a certain distance to reduce the difference. Each set of lenses is made of one or several lenses of different materials and different parameters glued together.

Objectives have many specific requirements, such as axial closure and parfocal.

2. Distinguish from the imaging characteristics of the two:

1. Imaging characteristics of the eyepiece: the eyepiece works in a narrow beam, but its inclination angle is large (field of view), when calculating the objective lens and the eyepiece, there is a big difference in eliminating aberration.

2. Imaging characteristics of the objective lens: The objective lens is the most complex and important part of the microscope, which works in a wide beam (large aperture), but the inclination angle between these beams and the optical axis is small (the field of view is small).