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Direct
Video Imaging
Camera Dedicated Borescopes are
borescopes that focus their optical images directly onto video cameras
without use of auxiliary eyepieces, adapters, or magnifiers.
When borescopes were first
attached to video cameras, the very small borescope images (2mm to 4mm
diameter) had to be magnified several fold to fill the large 16mm diameter
format of 1" vidcon cameras. With these high 4X to 8X magnification
factors, came two major problems:
- High magnifications resulted in very dark
video images.
Magnification is inversely
proportional to image brightness.
- Existing image distortions in borescopes
were also magnified.
Magnification is directly
proportional to aberrations
Magnification was accomplished by
attaching a video adapter containing magnification lenses onto the
eyepiece of borescopes. The addition of this extra mechanical / optical
component often further distorted performance due to misalignment, while
the addition of extra lenses further reduced image brightness. (See Figure
1)

Figure 1. Typical Borescope With
Video Magnification Adapter
Beyond all of the optical and
mechanical problems associated with coupling borescopes to video cameras
was the major physical problem of the size and weight of video cameras.
Cameras overwhelmed small diameter borescopes and made handling very
difficult.
Here we had the classic problem
of existing technology (Visual Borescopes) attempting to adapt to a new
emerging technology (Digital Video). Overall the initial attempt to adapt
by using video adapters was a quick fix solution resulting in compromised
performance.
A major breakthrough came with
the development and miniaturization of solid state video cameras. First
came the 2/3" camera (11mm diameter) quickly followed by the ½" camera
(8mm diameter). Today we now have 1/3" cameras (5.5mm diameter) and ¼"
cameras (4mm diameter) with both 1/5" and 1/6" cameras in development
stages. (See Figure 2)

Figure 2. Evolution of Camera
Formats
Along with size reduction came
tremendous improvements in resolution and low light level sensitivity.
Cameras became smaller, better and less expensive. Because the camera
format has been reduced to practically match the borescope image size,
there was no further need of adapters with magnification lenses.
Borescopes could now deliver images directly to the camera without
increasing light losses or degradations due to eyepiece and adapter
interfacing. The time came to consider attaching cameras directly to
borescopes.
Other recent advancements in
electronics and digital information processing have helped make video
imaging the preferred method of borescope use. Images on a monitor can be
seen simultaneously by others, studied, enhanced, recorded, documented and
even transmitted. The cost to do so became reasonable.
Digital camera development made
it possible, customers requested it; now was the time for Camera Dedicated
Borescopes.
But first borescopes had to be
redesigned to take full advantages of these new opportunities. Since video
cameras are not as forgiving as the human eye, borescope optical systems
had to be improved in several areas to meet critical camera performance
requirements. The most difficult requirement was greater uniformity from
center of image to edge. Higher resolution to edge, brighter illumination
to edge, and most important, flatter fields center to edge.
The newest Camera Dedicated
Borescopes by ITI were developed to meet these new standards with better
clarity, better resolution, faster systems and increased uniformity.
Borescope images have never been better. (See Figure 3)

Figure 3. Camera Dedicated
Borescope
Fortunately, visual performance
is also improved as a result of the new camera dedicated design. A variety
of eyepieces are available, all of which quick – connect to the borescope
as readily as a video camera. The visual inspector benefits from camera
improved optics by "seeing" clearer, brighter images with far less
distortions than previously available.
Previously, borescopes were
primarily visual instruments with camera adapters required for video
presentation. Now borescopes have become highly corrected camera lenses
also optimized for visual use through use of detachable eyepieces.
Direct Video Imaging is now a
reality and the overall gain is total system performance
improvements.
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