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Application Notes

Close Fitting Inner Diameter (ID) Inspection

If a view directly at the wall is desired, and the scope is a close fit in the bore, the focus and illumination must be optimized for this condition. A direction of view between 110° and 70° can be used depending on the condition of the wall. The reason for choosing a direction will depend on what is trying to be seen, and the reflectivity of the wall.

Highly polished walls are very difficult to view. The polished surface reflects the light away so that almost no light gets reflected back into the scope. When looking at welds that have a flatter finish, the scope will be able to inspect the welded area, but the polished area will be difficult to inspect.

A straight ahead, or 0° direction of view can also be used to view the walls of a close fitting bore. Sometimes a very wide field of view is used to optimize the view of the wall and minimize the view down the center of the bore. The 0° direction can be used to view the entire ID at once without needing to scan the wall as in the side viewing scopes described above.

Intersecting Passages

If coaxial lighting is needed to view into a very small passage, a mirror tube may be needed. However, if the passage is large enough it can be illuminated using separate prisms. If intersecting passages are to be viewed, a mirror tube may be the best way to achieve the direction of view. A mirror tube is a close fitting tube that slips over the OD of the scope to position a mirror at the tip of the scope to reflect the image and illumination at 90°. While mirror tubes are very susceptible to dirt, they offer a coaxial lighting effect that helps to view deeply into a passage at right angles to the scope axis. When the passage is at an angle other than 90°, a mirror tube may not be the appropriate solution.

A flexible scope may be needed to enter the intersecting passage, and a tool of some kind can be used to help the scope around the bend. Normal practice has been to use articulating scopes for this, but they are not necessary. Standard Zibra Corp products will do a good job if they can be guided into the passages. They can also be customized for special requirements. Please contact Zibra Corp to discuss possible solutions.

Large Cavities with Multiple Object Distances

A large cavity usually requires a large amount of light. This simply requires the largest possible scope. If the scope can be rigid it will be a simple matter to focus at the required distances.

If the scope needs to be smaller due to access limitations, multiple access points should be investigated. Tools can be made to deliver a smaller scope to defined points within the cavity. Auxiliary lighting probes can be produced to help deliver light in addition to the light from the scope probe.

If a semi-rigid scope is desired for durability, a tip focusing scope can focus at multiple distances. Another advantage of a tip focus scope is the brightness can be better than an equivalent rigid scope. If the access is restricted only in one dimension, probes can be built to take advantage of the space available to maximize illumination. In the case of a slit access, the probe can be built with tubes placed adjacent to carry more lighting fibers and higher resolution image optics.

Orbital Welds in Piping

Welded sections of sanitary piping or other high purity piping requires a superflex scope that can make the sharp bends, look at the wall and rotate 360° to view entire welds. A straight ahead view with a wide field can be used, but the detail is not as good, and some of the weld can be shadowed depending on the shape of the weld bead. The multiscope® superflex scope has a range of centering tools that can be added to the tip to maintain alignment in the pipe and focus distance to the weld. These can inspect 1/4”Ø pipe to 4”Ø pipe.

Standard diameters are 2mm, 4mm, 6mm and 9mm. The 9mm diameter is built with sheathing that is stiffer than the 2mm, 4mm and 6mm diameters. This allows it to be pushed into larger piping.

Very Close Focus

Close focus requirements can be met with customized lenses. Our in-house lens design capability means that we can accommodate your requirements with a minimal lead time.

Fiber-based scopes are very sensitive to the focus of the tip lenses. The focus of the image at the tip of the scope cannot be changed once the scope is built, and it is not changed by refocusing the video or eye lenses. Rigid scopes use a more traditional relay system where the image from the tip lenses is passed through a series of focal points along the length of the probe, so a refocus of the rear lenses will change the working distance at the tip of the scope.

In a very close focus (0-3mm) application, the depth of focus is usually reduced so that controlling position of the probe becomes more important. Illumination can sometimes be difficult because a certain amount of space is required for the lighting to cross into the inspection area. Mirror tubes are sometimes used in close focus side viewing applications because the airspace between the tip of the scope, the mirror and the object allows the illumination to converge at the target area.

Zibra product part numbers for probes include the focus distance. We always take focus requirements into account when building scopes. See our page covering the part number descriptions for information on how to specify your focus requirement. Do not hesitate to e-mail or call if you have either special requirements or need to discuss the options for your particular needs. The close focus scopes do require extra thought in specification and usage.

Infrared Applications (IR)

Most cameras have filters that eliminate the IR for color balance reasons. When this filter is removed IR sensitivity is increased with some corresponding loss of color balance.

Most light sources generate plenty of IR, but it may be filtered out to prevent burning of fibers. Filter(s) may need to be removed. Illumination fiber in the borescope will be heat damaged if too much IR is present, or cooling of lightguide tip is not adequate.

Scopes built with fused quartz image fiber may lose image quality in the IR spectrum since the fiber is optimized for use in the visible light spectrum. Leached image bundles are recommended for IR use, or verification that fused quartz will perform well as applied is advised.

Fused quartz fiber being used in radioactive environments will degrade more slowly in the Infrared region.

Ultraviolet (UV) Illumination Applications

Typically this fiber has a lower acceptance angle and requires a narrow field of view in the image optics to match the illumination pattern. UV probes can be built for MilliscopeII® and Multiscope® with continuous lightguide specification(CL). This construction has a continuous illumination fiber bundle from the lightsource to the probe tip, maximizing UV throughput. If a detachable illumination bundle is desired, a Lumatech liquid lightguide can be used from the lightsource to the probe. Lumatech also produces a high quality UV lightsource.

Output measurements have been made on the following scopes:

4mmØx90° direction rigid probe ~4000 µW/cm² at 35mm.

1.7mmØ x90° direction rigid probe ~300µW/cm² at 10mm.

These tests were done using the Lumatech UV source and should serve as a guideline only.

High Magnification

Probes can be specified to create a microscope effect in the borescope. These can be used to inspect fine features in areas where a microscope cannot be used.

Fiberoptic connectors are an ideal application for this. The fiber surface can be inspected for dirt or polish flaws. The depth of focus is very limited, and some type of locating fixture is required. Magnifications of 100X-200X can be achieved. These can be built in rigid, flex or semi-rigid.

Sheathing Types

Rigid and semi-rigid scopes are almost always sheathed using 304 stainless steel tubing.

Flexible scopes have a wide range of sheathing options. Plastic sheathings include nylon 6, nylon 11, Teflon and polyimide. Reinforced sheathings can have nylon braid, stainless braid and tungsten braid on the outside or monocoil for crush resistance on the inside.

Illumination bundles are normally sheathed in squarelock stainless tubing with nylon or PVC extruded on the OD. MilliscopeII illumination bundles are normally sheathed in a heavy wall nylon tube.

High Temperature

We have experience building high temperature scopes for applications that require insertion through difficult paths and static use. Continuous bending shortens life, and sometimes causes unpredictable failures. All high temperature scopes work better the less they are cycled, and all will have some finite life. This varies by application, and can sometimes vary unpredictably.

The fiber bundles have chemical treatments applied that enhance flexibility, and depending on the manufacturer, these will bake off over time. If the scope is static, it is not usually a problem. These can be built up to approx 3M in length.

Rigid high temperature scopes have more choices. Cooling is easier to apply, and they can be built using fiberoptics without regard to bending issues. They can be built with conventional relay lens system for ultimate resolution, but if un-cooled, they must be built without any optical cement joints if working above ~400F. This will make the images more likely to be flawed by incoming debris from the operating environment.

Shaped / Shape Memory Probes

The shape is put into the tube using a heating process. The scope can be straightened with an outer sheath, and then deployed by retracting the sheath, or it can be used without the sheath. This type of scope is not advisable for general use where the shape memory properties are not needed because the tubing is more expensive and has a thicker wall which limits lighting possibilities. A scope of this type can replace a much more expensive and fragile articulating scope.

Conventional semi-rigid scopes can also be permanently bent into shapes specified by the customer. These scopes will remain bent and will not straighten or deflect like shape memory probes will.

Medical Applications

Zibra Corp builds medical instruments per customer specifications with rapid design to delivery times. We are an FDA registered manufacturer who can produce autoclavable micro endoscopes as well as other medical optical devices. As with our industrial products, we can offer optical design, mechanical design, prototyping, low and high volume production all under one roof. Our recent agreement with Biovision Technologies (www.biovisiontech.com) allows us to concentrate on design and prototyping medical products. Biovision can produce them in volume using their FDA and ISO certified facilities.

Video Equipment / Lightsources

Zibra Corp sells complete video systems to support our borescope customers. We recommend Imperx frame capture cards for use with laptop computers and Elmo cameras for multi- function capabilities. We recommend Elmo and TVS monitors. We can quote items from any of these manufacturers.

We have adapters for common digital cameras that allow for capture, zoom and display on standard monitors.

We have NTSC to VGA converters that allow camera output to be displayed on a computer monitor (computer disconnected). These are commercial items and can be also be found from other suppliers.

The Welch-Allyn 24W SOLARC® lighsource which is ideal for the small fiber bundles found in our scopes. This comes standard with an ACMI port. We add our own attenuator design to improve the low light cutoff through the scope. The lamp is a proprietary Welch-Allyn product and the power supply is an external transformer which is 120/240 AC input rated and 12v DC,4A output.

We also sell the Schott 150W ACE-1 halogen source for more general use. This comes with an aluminum adapter blank that can be modified to fit any size fiber bundle or adapter. The lamp is an EJA 12v, 150W and the power input is 120VAC.