What is a rigid borescope?
An endoscope having a rigid shaft, typically with a fixed direction of view. It is nearly always a purely optical endoscope (unlike a videoscope which has an integrated micro-camera).
How does a rigid borescope work?
Optically:
A distinction is made between pure lens and pure fibre-optical systems.
- A lens optical system is one in which an intermediate image of the object is generated by the objective lens in the tip. This intermediate image is projected through several lens systems inside the shaft, thus being transported to the eyepiece.
- In a fibre-optic system, the object is projected by an objective lens onto a thin bundle of glass fibres (frequently silicate fibres, each fibre diameter typically ranging from 4 µm to 10 µm and the number of fibres from approx. 3,000 to over 50,000!). This “image bundle” transports the image to the eyepiece.
The objective lens determines the field of view, i.e. the size of the area being viewed. In many cases, a prism for a predefined direction of view is arranged in front of the objective lens. In swivel prism borescopes, this prism is mechanically controllable, so the direction of view can be varied.
Cylindrical geometries can be inspected using panoramic prisms which show the entire cylinder periphery at a glance.
Mechanically:
Rigid borescopes do not require mechanically movable components except for the eyepiece focusing device, which is integrated in some cases, and for the angle adjustment device in swivel prism borescopes.
Illumination:
In rigid borescopes, light is usually transferred from an external light source via separate glass fibre bundles to the tip, where it emerges. Small light sources can be connected directly to the endoscope. Bigger and more powerful light sources are connected to the endoscope via a highly flexible light guide (“fibre-optic light cable”).
What are the features of WOLF rigid borescopes?
- Mechanical components of robust metal construction. In units with 5 mm and more in diameter, a triple tube-in-tube construction for maximum stability.
- insertion part not penetrable by water and most technical liquids, pressure-resistant up to 4 bar and heat-resistant up to approx. +140 °C.
- Computer-optimised, light-intense and colour-corrected lens system.
- High-quality multiple coating of all optical elements.
- Low-distortion wide-angle lens systems preventing the user from getting lost in close-ups.
- The biggest choice of swivel prism borescopes
- Swivel prism borescopes, partly with quick-zoom capability.
- New, completely revised thin borescopes with hightest brillance.
When should rigid borescopes be preferred to flexible endoscopes or videoscopes?
- Rigid borescopes usually provide images with significantly higher resolutions than flexible endoscopes and videoscopes.
- Rigid borescopes are usually much more light-intense than flexible endoscopes and videoscopes.
- Rigid borescopes are much more robust than flexible endoscopes and videoscopes.
- Rigid borescopes can be used in a wider temperature range.
- Most rigid borescopes are considerably less expensive.
- If damaged, rigid borescopes are much cheaper to repair than flexible endoscopes and videoscopes.
