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Optical system of surgical operating microscope

Aug. 06, 2021

Surgical operating microscope technology enables doctors to observe fine tissues more clearly. With the operating microscope, doctors discover various lesions and complete various microsurgery operations. Operating microscopes integrate optics, precision machinery and electronic control technology. They are used in neurosurgery, ENT, dentistry, ophthalmology and other fields.

The microscope part is the core structure of the surgical microscope. Its optical path system includes an observation system and an illumination system.

Observation Optical System

The operating microscope is a three-dimensional microscope system. The stereo microscope is designed according to the principle of human stereo vision. Two separate light paths image the object to the left and right eyes of the human. The images are processed by the brain to produce a complete stereo impression. In order to ensure a good stereoscopic effect, the left and right eyes must observe the object at slightly different angles. During the operation, the assistant's cooperation is often needed, so the observation system is often designed as a double binocular form for simultaneous use by the doctor and the assistant.

The observation system in an operating microscope mainly includes a objective lens, a zoom system, a conversion system and an eyepiece system.

Objective Lens (Cemented Lens)

Most surgical microscopes commenly use a main objective lens. The object surface is located on the focal plane of the main objective lens to form an infinity optical system. The focal length of the main objective lens determines the working distance of the operating microscope. According to the requirements of different microsurgery, the focal length of the main objective lens is generally between 150mm-400mm. The small objective lens mainly images the infinity target provided by the main objective lens and the zoom system onto its focal plane for magnification and observation by eyepieces.

Zoom system (Lens Group)

During the operation, it is often necessary to change the magnification of the surgical microscope. Therefore, the zoom system is added. There are two basic forms of the microscope zoom system: step-by-step zoom and continuous zoom.

Revolving Image System (Plane Mirror and Prisms)

This system mainly realizes the inverted image and changes the direction of the light path, which is convenient for observation and operation.

Eyepiece System (Cemented Lens and Plano Convex Lens)

The magnification of the operating microscope using binocular observation tube is generally 10 times, 12.5 times, 15 times and 20 times. For the eyepiece system, it is very important to adjust the interpupillary distance and diopter. The eyepiece requires a high eye point to facilitate observation by the wearer.

Energy Analysis of Microscope Optical System

The optical system has a loss of light energy. The connection between the stereo assistant microscope and the main knife microscope is realized through a beam splitter, which means the energy of the main system must be reduced. In order to observe effectively, the optical elements in the entire optical system will be coated with anti-reflection coating or aluminum reflective coating. For example, optical lenses are coated with antireflection coating, optical mirrors are coated with aluminum reflective coating.

Illumination Optical System

Illumination Optical System are divided into internal lighting and external lighting. Among them, the internal lighting uses double convex lenses and other convex lenses to gather light beams. The external lighting filters the infrared light through a optical filter.

CLZ Precision Optics Co., Ltd provides high-precision optical components for operating microscopes, including biconvex lenses, plano convex lenses, cemented lenses, mirrors and prisms. They could be coated with antireflection coatings and aluminum reflective coatings.