Infinite. 100X. Plan Achromatic Objective. Objective Parfocal Distance: 45mm. Objective for Focal Length: 180mm. Objective Working Distance: 2.1mm. N.A. 0.80. MT0512 Series Microscope.
|The objective (lens) is the first set of optical systems that image the object being observed, and is also the most important imaging component in the microscope.|
Depending on the application, objective is usually classified into the following categories:
Phase Contrast Objective
Dark/Bright Field Objective
Monocular Video Microscope Objective
Infinity-Corrected Long Working Distance Objective
Telecentric Objective Lens
Some objectives are mounted directly on the microscope body, some separate from the body and are installed when needed.
Different types of microscope objectives are generally not interchangeable. However, when ofthe same type and parameter design the same or similar, the objectives of different models and manufacturers are interchangeable, provided that attention shouldbe paid to the change in magnification, working distance, field of view and image quality.
Usually, on the objective outer casing, there are signs of the following parameters:
Objective Magnification: for example 10X, 40X
Numerical Aperture (N.A.): for example, /1.30
Objective Immersion Media: Oil represents oil, W represents water, and Glyc represents glycerin
Mechanical Tube Length and Objective Cover Glass Thickness: the two parameters are usually written together and separated by /. The finite mechanical is usually 160, 195, etc., and infinite is represented by "∞"; objective cover glass thickness (thickness / mm) is expressed after/, for example /0.17; for specimen that does not use objective cover glass, it is represented by 0, for example, "/0"; for those that do not use objective cover glass or the objective cover glass thickness is smaller than 0.17, it is represented by "/-".
Phase Contrast Objective: represented by PH, for example, PH2, the digit after PH represents the associated ring diaphragm.
Polarizing Objective: represented by POL.
Plan Objective: represented by PLAN or PL
Achromatic: generally, achromatic objective does not require identification
Apochromatic: represented by APO
Long Working Distance: represented by L
There are also objectives that are unique in magnification and medium, and their difference is indicated by color circle.
For objectives that do not have mark, it is necessary to refer to the microscope body for judgment, or refer to the product manual.
Usually, the objective has very fine mounting threads. When there is a need to install the objective /objective frame, be careful to install it. Align the nosepiece installation position, keep it completely “flat”. When it is blocked, remove it and reinstall it. Do not force it in.
Note: although between different manufacturers, some objectives can be used universally, they may still bring magnification error and image quality degradation.
|Microscopes and components have two types of optical path design structures.|
One type is finite optical structural design, in which light passing through the objective lens is directed at the intermediate image plane (located in the front focal plane of the eyepiece) and converges at that point. The finite structure is an integrated design, with a compact structure, and it is a kind of economical microscope.
Another type is infinite optical structural design, in which the light between the tube lens after passing the objective lens becomes "parallel light". Within this distance, various kinds of optical components necessary such as beam splitters or optical filters call be added, and at the same time, this kind of design has better imaging results. As the design is modular, it is also called modular microscope. The modular structure facilitates the addition of different imaging and lighting accessories in the middle of the system as required.
The main components of infinite and finite, especially objective lens, are usually not interchangeable for use, and even if they can be imaged, the image quality will also have some defects.
The separative two-objective lens structure of the dual-light path of stereo microscope (SZ/FS microscope) is also known as Greenough.
Parallel optical microscope uses a parallel structure (PZ microscope), which is different from the separative two-object lens structure, and because its objective lens is one and the same, it is therefore also known as the CMO common main objective.
|The finite objective is the lateral magnification of the primary image formed by the objective at a prescribed distance.|
Infinite objective is the lateral magnification of the real image produced by the combination of the objective and the tube lens.
Infinite objective magnification = tube lens focal length (mm) / objective focal length (mm)
Lateral magnification of the image, that is, the ratio of the size of the image to the size of the object.
The larger the magnification of the objective, the higher the resolution, the smaller the corresponding field of view, and the shorter the working distance.
|In the case of polychromatic light imaging, the aberration caused by the light of different wavelengths becomes chromatic aberration. Achromatic aberration is to correct the axial chromatic aberration to the two line spectra (C line, F line); apochromatic aberration is to correct the three line spectra (C line, D line, F line).|
The objective is designed according to the achromaticity and the flatness of the field of view. It can be divided into the following categories.
Achromatic objective: achromatic objective has corrected the chromatic aberration, spherical aberration, and comatic aberration. The chromatic portion of the achromatic objective has corrected only red and green, so when using achromatic objective, yellow-green filters are often used to reduce aberrations. The aberration of the achromatic objective in the center of the field of view is basically corrected, and as its structure is simple, the cost is low, it is commonly used in a microscope.
Semi-plan achromatic objective: in addition to meeting the requirements of achromatic objective, the curvature of field and astigmatism of the objective should also be properly corrected.
Plan achromatic objective: in addition to meeting the requirements of achromatic objectives, the curvature of field and astigmatism of the objective should also be well corrected. The plan objective provides a very good correction of the image plane curvature in the field of view of the objective, making the entire field of view smooth and easy to observe, especially in measurement it has achieved a more accurate effect.
Plan semi-apochromatic objective: in addition to meeting the requirements of plan achromatic objective, it is necessary to well correct the secondary spectrum of the objective (the axial chromatic aberration of the C line and the F line).
Plan apochromatic objective: in addition to meeting the requirements of plan achromatic objective, it is necessary to very well correct the tertiary spectrum of the objective (the axial chromatic aberration of the C line, the D line and the F line) and spherochromatic aberration. The apochromatic aberration has corrected the chromatic aberration in the range of red, green and purple (basically the entire visible light), and there is basically no limitation on the imaging effect of the light source. Generally, the apochromatic aberration is used in a high magnification objective.
|Objective parfocal distance refers to the imaging distance between the objective shoulder and the uncovered object surface (referred to as the “object distance). It conforms to the microscope design, usually 45mm. |
The objective of different magnifications of the compound microscope has different lengths; when the distance between the objective shoulder and the object distance is the same, the focal length may not be adjusted when converting to objectives of different magnifications.
|Objective for focal length is a design parameter of the tube focal length of the microscope that the objective is suitable for.|
|The objective working distance is the vertical distance from the foremost surface end of the objective of the microscope to the object surface to be observed.|
Generally, the greater the magnification, the higher the resolution of the objective, and the smaller the working distance, the smaller the field of view. Conversely, the smaller the magnification, the lower the resolution of the objective, and the greater the working distance, and greater the field of view.
High-magnification objectives (such as 80X and 100X objectives) have a very short working distance. Be very careful when focusing for observation. Generally, it is after the objective is in position, the axial limit protection is locked, then the objective is moved away from the direction of the observed object.
The relatively greater working distance leaves a relatively large space between the objective and the object to be observed. It is suitable for under microscope operation, and it is also easier to use more illumination methods. The defect is that it may reduce the numerical aperture of the objective, thereby reducing the resolution.
|Numerical aperture, N.A. for short, is the product of the sinusoidal function value of the opening or solid angle of the beam reflected or refracted from the object into the mouth of the objective and the refractive index of the medium between the front lens of the objective and the object.|
Simply speaking, it is the magnitude of the luminous flux that can be brought in to the mouth of the objective adapter, the closer the objective to the specimen for observation, the greater the solid angle of the beam entering the mouth of the objective adapter, the greater the N.A. value, and the higher the resolution of the objective.
When the mouth of the objective adapter is unchanged and the working distance between the objective and the specimen is constant, the refractive index of the medium will be of certain meaning. For example, the refractive index of air is 1, water is 1.33, and cedar oil is 1.515, therefore, when using an aqueous medium or cedar oil, a greater N.A. value can be obtained, thereby improving the resolution of the objective.
N.A. = refractive index of the medium X sin solid angle of the beam of the object entering the front lens frame of the objective/ 2
Numerical aperture of the objective. Usually, there is a calculation method for the magnification of the microscope. That is, the magnification of the microscope cannot exceed 1000X of the objective. For example, the numerical aperture of a 100X objective is 1.25, when using a 10X eyepiece, the total magnification is 1000X, far below 1.25 X 1000 = 1250X, then the image seen in the eyepiece is relatively clear; if a 20X eyepiece is used, the total magnification will reach 2000X, much higher than 1250X, then eventhoughthe image actually seen by the 20X eyepiece is relatively large, the effect will be relatively poor.
|The thickness of the cover glass affects the parfocal distance of the objective. Usually, in the design of the focal length of the objective,the thickness of the cover glass should be considered, and the standard is 0.17mm.|
|The use of different media between the objective and the object to be observed is to change and improve the resolution. For example, the refractive index of air is 1, water is 1.33, and cedar oil is 1.515. Therefore, when using an aqueous medium or cedar oil, a greater N.A. value can be obtained, thereby increasing the resolution of the objective.|
Air medium is called dry objective, where oil is used as medium iscalled oil immersion objective, and water medium is called water immersion objective.
However, because of the working distance of the objective, when the working distance of the objective is too long, the use of liquid medium will be relatively more difficult, and it is generally used only on high magnification objective having a shorter working distance, such as objectives of 60X, 80X and 100X.
When using oil immersion objective, first add a drop of cedar oil (objective oil) on the cover glass, then adjust the focus (fine adjustment) knob, and carefully observe it from under the side of the objective of the microscope, until the oil immersion objective is immersed in the cedar oil and close to the cover glass of the specimen, then use the eyepiece to observe, and use the fine focus knob to lift the tube until the clear imageof the specimen is clearly seen.
The cedar oil should be added in an appropriate amount. After the oil immersion objective is used, it is necessary to use a piece of lens wiping tissue to dip xylene to wipe off the cedar oil, and then wipe dry the lens thoroughly with a lens wiping tissue.
|For microscopes of different manufacturers and different models, the thread size of their objectives may also be different. |
In general, the objective threads are available in two standard sizes, allowing similar objectives between different manufacturers to be used interchangeably.
One is the British system: RMS type objective thread: 4/5in X 1/36in,
One is metric: M25 X 0.75mm thread.
|After unpacking, carefully inspect the various random accessories and parts in the package to avoid omissions. In order to save space and ensure safety of components, some components will be placed outside the inner packaging box, so be careful of their inspection.|
For special packaging, it is generally after opening the box, all packaging boxes, protective foam, plastic bags should be kept for a period of time. If there is a problem during the return period, you can return or exchange the original. After the return period (usually 10-30 days, according to the manufacturer’s Instruction of Terms of Service), these packaging boxes may be disposed of if there is no problem.
|Packaging Type||Carton Packaging|
|Packaging Material||Corrugated Carton|
|Packaging Dimensions(1)||4.5x4.5x6.5cm (1.772x1.772x2.559″)|
|Ancillary Packaging Materials||Plastic|
|Gross Weight||0.12kg (0.26lbs)|
|Minimum Packaging Quantity||1pc|
|Transportation Carton||Carton Packaging|
|Transportation Carton Material||Corrugated Carton|
|Transportation Carton Dimensions(1)||15.2x15.2x15.2cm (6x6x6″)|
|Total Gross Weight of Transportation(kilogram)||0.26|
|Total Gross Weight of Transportation(pound)||0.56|