How an image is created from optical components

Endoscopes make it possible to look inside the body without performing major invasive procedures. But how does an endoscope work? René Zünd explains which optical components are necessary and what tasks they fulfil.

A so-called optical transmission system is needed to bring the image from the endoscope's tip to the surgeon's eye. This starts with an objective lens, of which there are two variants: Lenses with fixed focal lengths depict a structure located at a certain distance into one image plane. In an endoscope, the image plane can can represent an intermediate image or sensor plane.

Objective lenses with variable focal lengths depict structures that are located at different distances into one image plane. In this case, the image plane in an endoscope is usually the sensor directly .

The intermediate image of the lens is transferred several times into different intermediate images via so-called reversal systems (2) to bridge the distance to the eye. Subsequently, an ocular (3) is required. These map the intermediate image to infinity, either observed directly by the eye or transferred via another lens to a sensor and thus to a digital monitor.

Optional components are angle optics,which can change the viewing angle of the endoscope through prisms . For example, structures can be observed from the side or at an angle, not just at a 0° degree angle directly in front of the lens. Prisms are also used when the handpiece of the endoscope is angled to allow surgeons to work more ergonomically .

FWOZ manufactures all these optical components as well as assemblies. Rod lenses are produced the most in quantities since several are needed for one endoscope . In contrast, at most, two lenses are required at the distal end, one at the proximal end, and one ocular. Therefore, these parts are produced in smaller numbers.

Currently, FWOZ is excited about their novel focusing lens that allows structures to be in focus at a constant back focal length (distance between the lens and the image plane). With this enormously small product, we expect to open up new application fields of Surgical Robotics and Endoscopy.


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Our optical components are particular, individualized parts that always belong to a larger product. For example, we develop and produce a lens for an endoscope, which is installed in an assembly. But how does that cooperation work?

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Over 20 years of experience

Gut gelaunt und professionell sind drei unserer langjährigsten Mitarbeiterinnen täglich bei Feinwerkoptik Zünd anzutreffen. Sofia Santos und Filippina Prestagiacomo sind seit 27 Jahren bei uns dabei, Sanela seit 24 Jahren.