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Industrial borescopes generally fall into two categories: rigid borescopes and flexible borescopes, also known as fiberscopes. The type of borescope employed is contingent on the application. These devices are used in a number of industries to attain quality assurance, enabling inspection for manufacturing defects without necessitating part destruction. They also are used in equipment maintenance programs, eliminating the need for teardowns when checking for defects.
Rigid borescopes are selected for applications in which a straight path exists between the viewer and the object being viewed. A rigid borescope is made up of a tubular shell, eyepiece, optical lens, viewing head and light source. Typical borescopes are made in lengths from 4 inches to 150 feet and diameters generally range from 0.067 to 2.75 inches. Object magnification is usually from 3X to 4X, but powers up to 50X are available. The viewing head determines the direction of view and field of view. Viewing heads are commonly manufactured with right angle, circumference, bottoming, forward oblique and retrospective designs.
Flexible borescopes are used in applications in which there is not a straight path between the viewer and the object being viewed. A fiberscope is comprised of an image guide fiber bundle, an objective lens, protective sheath, eyepiece lens, focus and diopter rings, and remote controls for the top articulation; these components are connected to a light source via a fiber-optic cable. Fiberscopes are available in diameters from 0.071 to 0.512 inch and in lengths up to 30 feet, though quartz fiberscopes can reach as long as 300 feet.
Generally a sealed housing of flexible stainless steel conduit, allowing the fibers to bend around corners, protects the fiber-optic bundles. A controllable bending section is usually found at the tip of the fiberscope, to direct the scope during insertion and then scan an area after the device is in position. The objective lens can be focused to accommodate different viewing distances, and as with the rigid borescope, different viewing heads are available.
Two considerations that need to be taken into account when selecting the appropriate borescope are the object being inspected and the environment in which the device will be used. The inspected object decides the specifications of the borescope and the illumination requirements. Factors to be considered are object distance, size of defect, entry port size, size of object, reflectivity, depth of object and location of area to be examined. Most borescopes can operate in temperatures from -30 to 150 F, but specially designed devices can be made to withstand temperatures reaching 3,500 F. Borescopes can also be manufactured for use in pressures above ambient as well as in atmospheres exposed to radiation.
The following presents an offering of industrial borescopes available to quality professionals today.
The FreedomView LED fiberscope by Optim Inc. (www.optimnet.com) offers a design that represents the latest advances in light emitting diode (LED) technology. It delivers LED light output, mobility, flexibility and resolution.
In creating the fiberscope, the company’s goal was to design an instrument that addressed customers’ needs for greater mobility and more light. Both were achieved by integrating an LED lighting platform into the scope handle.
The distal tip articulation and light intensity controls are integrated into the handle. The shaft is constructed of rugged Tungsten braid and is fully immersible in gasoline, diesel fuel, water, jet fuels and other liquids. The unit is video and digital camera compatible and has a full line of accessories, including a digital camera/coupler kit that attaches to the eyepiece. Other accessories include an AC wall plug, DC car plug, guide tube and a right-angle side-viewing attachment. The scope is available in two diameters-6 and 4 millimeter-and four lengths-20, 40, 60 and 80 inches.
The scopes feature probe tubing constructed in stainless steel for extra durability. They are available with a standard 32-millimeter eyepiece, and accept the Flexbar c-mount coupler for video system usage. Fiberoptic lighting provides bright and even light, and the scopes have a wide-angle field of view for direct and lateral viewing. Extended lengths and custom models are available.
The portable VideoProbe can be used for applications such as on-wing turbine engine inspection in the aerospace sector and cylinder-head checking in automotive manufacture. It uses a handheld controller with an integrated joystick and high-resolution display, or a wireless remote control. Intuitive software control buttons and drop-down menus guide operators through the control functions and give step-by-step instruction for each component until the inspection is complete. Images can be tagged for future identification and to incorporate inspection comments, and the instrument’s software allows text and arrow overlays and custom logos.
The base unit has an aluminum chassis with impact-absorbing rubber bumpers and the handset is contained within a tough, polycarbonate housing. An attachable, integrated battery can run the unit for one or two hours. The Everest XLG3 provides twice the light output of earlier generation VideoProbe systems and the 360-degree all-way articulation ensures that this light reaches even the darkest of turbine recesses. When combined with the VideoProbe’s lenses, advanced digital signal processing and a 1:1 pixel ratio between camera and monitor, the result is sharp, high-quality images delivered directly to the extra-bright, high-resolution LCD screen.
The system is easy to operate; the operator points the insertion probe, clicks the power button and views the results. The V5 is self-contained, and lets recorded data be transferred directly to a computer to save or send as e-mail files. It features ITI’s patented Protecht over-torque protection system, which significantly cuts accidental breakage, repair costs and downtime. Its rugged tungsten probe jackets withstand harsh environments, and the durable case makes the V5 practically indestructible. The outer case has wheels and a retractable pull handle for easy transport from one site to another. The V5 uses either an external power source or its own integrated, rechargeable battery system. Custom computer designed optics, all-digital S-video signals and a high-resolution (10.4 inches) LCD monitor provide exceptional image quality and brightness. The V5 is a true, value-added system designed for remote viewing performance at most inspection sites without costly, unnecessary bells and whistles.
For viewing inside complex assemblies, the videoscope has a tight bending radius and a four-way, 150-degree articulated tip that allows manipulation around corners, through pipe bends and past blockages. The working portion of the scope is protected with polyurethane-impregnated tungsten braiding and is available in diameters of 6 or 8.4 millimeters, with lengths to 7.5 meters.
The VideoFlex hand-piece is made of all-metal constructions and has a 2-meter length umbilical cable. The operator can articulate the tip using ergonomically designed single-hand controls. The connections on the handheld unit include interchangeable light source connectors enabling compatibility with most brands of light sources, along with interfaces for auxiliary monitor connection, video output and 12 volt DC powering.
Advanced functions include video processor initialization, according to color temperature of light source used, and auto shutter activation. Accessories include a mini digital recorder with a 4-inch LCD monitor, interchangeable right-angle mirror heads and connectors for compatibility with other brands of light sources. Each scope comes with a 12 volt DC power supply and a rugged case, and a variety of light sources are available.
The system has a built-in recording unit for saving inspection images to removable compact flash card recording media. Inspection images can be saved in a JPEG format and transferred to a computer for use in reports, detailed target evaluation or shared through e-mail to off-site QA or engineering resources.