95mm plan apochromat objective，400-1064nm
Objective guide
1. Objective lens description
The objective lens is an important part of the microscope, which can magnify and present the image of the sample, make the details and structure of the sample more clearly visible, and is widely used in scientific experimental instruments such as microscopes.
2. Classification of objective lenses
Infinity conjugate objectives are suitable for applications that require advanced optical performance and large working distances, while finite conjugate objectives are suitable for applications with compact designs and simplified optical paths.
Infinity conjugate objectives:
In an infinity conjugate objective system, the posterior focus of the objective is located at infinity. The objective is marked with the infinity symbol (∞), and the light is refracted from the sample and passes through the objective, which then forms a parallel beam. This parallel beam can be further focused and processed by subsequent optical systems, such as eyepieces and detectors. This configuration keeps the objective focal length long, reducing distortion and aberrations during light transmission, while also providing a larger working distance. Infinity conjugate objectives are widely used in advanced microscopy systems such as inverted microscopes, fluorescence microscopes, and confocal microscopes.
Finite conjugate objectives:
Unlike infinity conjugate objectives, in finite conjugate objective systems, the posterior focus of the objective is located at a certain distance. The objective lens is usually marked with a fixed length of millimeters (160, 170, 210, etc.), i.e. the length of the mechanical barrel. In this configuration, the beam formed at the back focus of the objective lens is non-parallel and needs to be adjusted and focused through the eyepiece to form an observable image. Finite conjugate objectives typically have a short working distance and are suitable for simpler microscope systems or applications that require a compact design.
According to the degree of correction of chromatic aberration, it is divided into general achromatic objective, plan achromatic objective, semi-apochromatic objective and apochromatic objective.
General Achromatic Objective: The most common objective, usually marked with the word "Ach".
Plan Achromatic Objective: Generally marked with the word "PLAN", this objective has a flat field of view, which is very suitable for micrography and comfortable observation.
Semi-apochromatic objective: generally marked with the word "FL", it can correct the chromatic aberration and spherical aberration of red and blue, and can be used for fluorescence observation.
Apochromatic Objectives: Labeled with the word "APO" and corrected for chromatic aberration at red, blue, and yellow wavelengths, they are commonly used for microscopy and microphotography, and their performance is limited only by the laws of physics. Due to their excellent correction and extremely high numerical aperture, they have the highest resolution, color purity, contrast, and image straightness for microscopy and microphotography.
3. Objective lens parameters
Magnification: The magnification of an objective lens refers to the ability of the objective lens itself to magnify an object several times. Common magnifications for objective lenses are 2X, 5X, 10X, 20X, and 50X.
Numerical Aperture (NA): The numerical aperture of the objective lens is used to measure the reception angle of the objective lens, which is expressed as NA. It determines the resolution, depth of field, and brightness of the image. The larger the NA, the higher the resolution and the smaller the depth of field. It is expressed by the formula: NA=nsinθ. where n is the refractive index of the working medium of the lens, and for air, n = 1.0, θ is the half-angle of the largest light cone that can enter or leave the lens.
Working Distance (WD): The distance between the surface of the sample and the front of the objective when the light is focused. That is, the vertical distance between the lowest surface of the lens and the observed sample.
Resolution: The minimum distance between points or lines that can be distinguished as separate entities. The higher the resolution, the smaller the value, and the more detailed parts of the object can be observed; When used as a focus, it is possible to focus to a smaller light spot.
Parfocal distance: This is the distance from the shoulder to the top of the sample (for objectives that do not use a coverslip) or to the top of the coverslip. When working with multiple objectives in a single spindle, it is useful if all parfocal distances are the same, as there is little to no refocus when switching objectives. Objective lenses are usually available in 95mm parfocal, 45mm parfocal, 60mm parfocal, etc.
Focal length: A general property of an objective lens, which refers to the distance between the principal point and the focal point, usually denoted by f. For infinity-corrected optical systems, the magnification is determined by the ratio of the focal length of the tube lens to the focal length of the objective. For example, if the focal length of the lens is 200mm and the magnification of the objective lens is 20x, the focal length of the objective lens is f=200mm/20x=10mm.
Field Number and True Field of View (FOV): The number of fields of view is usually for the eyepiece, and the number of fields of the eyepiece is determined by the diameter of the field diaphragm of the eyepiece in mm. The FOV is the actual area that can be observed in the sample and is determined by the number of fields of view of the eyepiece and the magnification of the objective. FOV (mm) = number of fields of view / objective magnification
Depth of field: The distance from the very front to the back of the precise focal plane within the acceptable range of image clarity.
Mechanical barrel length: refers to the length of the microscope tube between the opening of the lens tube (where the objective lens is mounted) and the upper edge of the observation tube, and the objective lens is installed at the opening of the lens tube. Finite conjugate objectives are marked with a fixed length of millimeters (160, 170, 210, etc.) and infinity corrected objectives are marked with an infinity symbol (∞).
Objective Identification:
Ach: Achromatic correction
Fluor: Apochromatic correction
APO: Apochromatic aberration correction
Plan/PL: Flat field correction
L: Long working distance
W/Water: Immersion
Oil: Oil immersion
B: Brightfield
BD: Light and dark field
M: Metallographic
4. Objective lens application
Live-cell imaging: Imaging vesicles, organelles, etc., using objective lenses is important to understand the state of cells, including dynamic processes such as mitosis and embryonic development.
Industrial applications: Objective lenses can be used in industrial applications to show small details such as inspection, rework and assembly of parts, steel quality assessment, and more.
Metallurgy: Objective lenses can be used to study the microstructure of various metal materials, so as to optimize the smelting and processing of metal materials. In addition, the objective lens can be used to observe and analyze defects in metallic materials.
Material analysis: Objective lenses can be used to imaging, measuring, and analyzing a variety of materials, providing an important basis for the optimal design and manufacture of materials, such as metal alloys, semiconductors, glass, etc.
Earth Sciences: Objectives can be used to study ores, rocks, soils, sediments, and other components of the Earth's crust, oceans, and atmosphere.
Restoration of works of art: Objective lenses can be used to analyze, restore, and protect works of art, helping restorers, archaeologists, and more.
Public Prosecutor's Forensics: Through the objective lens, it is possible to study clues such as hair, fingerprints, etc., which may become strong evidence, and reveal forgeries in suspicious documents.
Education and academic research: Objective lenses are commonly used tools in education and academic research for teaching and research activities, such as teaching laboratories, research experiments, etc.
