Binocular Revolving head: 4 objectives. Magnification: 40-2000x Built-in dark field condenser
Country:
PRC, under control of Levenhuk Ltd. (USA)
The biological microscope Levenhuk 850B is ideal for biochemical, pathologo-anatomic, cytologic, hematologic, urologic, dermatologic, biologic, and general clinical research in laboratories of any medical institution. It allows examinations using both bright field and dark field methods.
It also features a binocular rotatable nosepiece. Angle 30 degrees, rotatable 360 degrees. Revolving head allows positioning of four objectives. The microscope features the classical Koehler illumination system, with field and aperture diaphragm adjustment.
The focusing mechanism features integrated coarse and fine adjustment screws. Focus accuracy is achieved due to the vertical move of the stage relative to the fixed objective with use of focusing handles. Bi-coordinate stage can move in horizontal and vertical directions. The stage dimensions are 140x155 mm. Focusing mechanism and stage move smoothly, without jerks or backlash. Increment is 25mm for coarse focusing and 0.002 mm for fine focusing.
Microscope illumination system includes a halogen lamp 6V/20W, with smooth brightness adjustment.
The microscope is equipped with build-in dark field condenser which works while Abbe condensor is at full length upwards. To run it, you need to rotate the illumination ring counterclockwise until you get the desired result. When turning it clockwise, you will return to the bright field. The method of dark field in the transmitted light is used to get images of transparent objects which are invisible when using the bright field method. This method is widely spread e.g. in hemoscanning, a unique method of blood examination.
About dark field method:
When the light is coming out of the condenser, the main part of light rays have not changed their direction while coming through the transparent specimen, so they form a beam in the shape of a hollow cone and do not reach the objective (located inside of this cone).
The observed image is formed in the microscope with help of just small part of rays which have been dispersed into the cone by the specimen micro particles and then passed through the objective. As a result, bright images of the specimen structure elements whose refractive index differs from the environment are visible in the field of view against the dark background. For large particles, only brighter edges dispersing the light rays are visible.
Specifications
Magnification
40-2000x
Nosepiece
Binocular
Eyepieces
paired, wide field
PLAN WF 10x, PLAN WF 20x
Revolving head
4 objectives
Objectives
4x, 10x, 40x; 100x PLAN
Optical coating
Fully coated
Stage
Coordinate moving stage 140x155 mm
Condenser
Abbe N.A. 1.25 with premium iris diaphragm
dark field condenser
Focus
Fine - 0.002 mm
Coarse - 25 mm
Illumination
Halogen lamp 6V/20W, with smooth brightness adjustment
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