Handheld Videoscope - Ø 8 mm x 2 m - 6 m, 2 ways articulation

The borescope must fit through the smallest hole required. When choosing a borescope diameter, consider more than clearing the sides of the hole. A slightly smaller scope may allow "wiggle room" so that you can see more by tilting the scope. The best thing is to try it. If you need to see into very small holes and relatively large ones, it is usually best to optimize for each, by using two borescopes. The Borescope IT's thinnest borescope can fit into a 0.11" (2.75mm) diameter hole.

Field-of-view may be very wide, wide, medium, or narrow. Think of it as a cone coming from the borescope tip, so that anything within the cone is visible. The field-of-view of the Borescope IT's thinest borescope is approximately 45°. Field-of-View should be dictated by the distance from the distal end of the borescope to the subject, for your application. The wider the field the lower the magnification, and vice versa. If you have plenty of space to move inside the cavity, but want to see both detailed close-ups and big picture views you might choose a 65° moderate wide angle. If the space is more confined but you still need to see most of it at one time, try a 70° extreme wide angle. On the other hand, if you can't get close enough to show the detail you need, a 45° telephoto might be required.

When a lens is focused on an object, there is some distance in front of the object and some behind which will also be acceptably sharp. This zone of sharpness which includes the subject is called the depth of field.

ROD LENS

Rod lens are extensively used in borescopes. But to get a better understanding of rod lens, one must have an idea of their exact role in terms of producing the image that the viewer sees at the eyepiece of the borescope.

As you probably know, borescopes are either rigid or flexible. The difference between rigid and flexible borescopes is in the construction. Most rigid scopes incorporate a convex glass lens system, in which the small glass lenses are separated by large air spaces. Basically, those individual lenses magnify the image and present it to the eye for viewing. A flexible borescope uses a coherent fiber bundle with thousands of individual fibers to relay the image from the objective to the eyepiece. Due to this technology, the image from a fiberscope is never as good as a rigid one with the same diameter. What’s more, the focus ability of a flexible borescope is greatly reduced.

In contrast, the rod lens telescope, invented by Professor Hopkins, utilizes comparatively longer rods of glass and smaller air spaces. The main advantages of the rod lens system are the greater light transmission, better image resolution, wider field of view and image magnification.

Currently, the small-diameter rigid endoscopes usually utilize the Hopkins rod-lens relay system because it offers much better aberrational correction and light throughput than the traditional form of relay system. However, there are disadvantages to that system as it does produce a significant amount of astigmatism and field curvature which may reduce the off-axis image quality appreciably. The rod-lens employed in the Hopkins system consists of a singlet field lens and a doublet aperture lens which are both cemented onto a cylindrical rod.

Rod Lenses are polished on the circumference and ground on both ends. Their optical performance is similar to a cylinder lens. Collimated light passing through the diameter of the rod will be focused into a line. All dimensions are in mm.

Other advantages of rod lenses are that they provide uniform ultraviolet curing of large areas and eliminate distortion and movement in optical applications, such as casting lenses and domes and positioning of fiber optic components.

Rod Lenses are generally used as light pipes. Its optical principle is similar to fiber optics where light can be transmitted from one end to the other with relatively small leakage. Rod Lenses can also be used as cylindrical Lenses. In certain application, Rod Lenses can also be used as homogenizers.

Before you can see anything in a dark cavity, you need some light on the subject. Prior to 1960, borescopes used hot and often dangerous incandescent lamps at the distal (working) end. Today, quality borescopes usually uses fiber optic illumination, where glass fibers carry light from an external light source through a flexible light guide, then through the borescope, to the distal end. Some inexpensive borescopes still use a bulb at the tip of the scope for illumination, which can lead to illumination, heating and contamination problems. All Borescope IT's rigid borescopes use fiber optic illumination in the scope body and can connect either directly with our out-of-competition Portable 4W LED Light Source or with stand-alone Xenon, Metal Halide or Halogen light sources through fiber optic light cable for brighter illumination.

Type of Insertion Probe can be rigid, semi-rigid or flexible (with or without articulated tip).