3
obsolete, except for operating inby the last open crosscut.
Because of the improvements and increased availability of
modern video borescopes, they have quickly become the
most widely used borescope for mine roof lithology identi-
fication in the United States.
Videoscope prices range widely based on features, reso-
lution, and manufacturer. The top tier videoscopes can cost
multiple tens of thousands of dollars, and provide features
such as removable batteries, faster processors, better screen
refresh rates, removable head prisms (for different viewing
angles), and have larger viewing screens. In addition to the
features, the materials used to manufacture them are of
better quality such as stainless-steel jacketed wires, quartz
prism head windows, and rotating head windows. These
types of videoscopes are less commonly used mostly due
to their cost, and most mines have instead turned to lower
cost videoscope alternatives.
VIDEOSCOPE FEATURES
When selecting a low-cost (under 300 dollars) videoscope
for mining applications such as lithology identification,
there are certain features, as described below, that will
enhance the overall experience and accuracy for the end
user. While some of these features may not be available in
the low-cost models, opting to have them at a potentially
increased cost may offer the end user a package tailored for
their specific needs.
• Adjustable LED light intensity – Proper lighting,
when viewing the borescope image, is extremely
important. Too bright of an intensity can cause an
overexposure that may whiteout the video screen.
This is especially the case when water is in the bore-
hole causing reflectance. Also, a low light intensity
may result in loss of critical details necessary to clas-
sify roof lithology. An adjustable light will aid in con-
trolling the amount of reflectance to avoid over and
under exposure.
• Microphone –The ability to record sound will help
with analyzing the data collected as the ability to
replay the lithology interpretation as it is being called
and the depths at each interval as they are occurring
adds value to the video. It should be noted that it is
a good practice to maintain a field notebook while
interpreting the lithology and depths at each change
in case an audio recording feature is not available,
the sound level is too low, or background noise is too
high to hear during video playback. The microphone
works best when located on the video screen unit and
not on the camera head.
• Length – The length of the borescope wire between
the video screen and the top of the camera window
required will depend on the length of the longest
roof bolts the mine uses for support. The length of
the roof bolts is dependent on many factors such
as lithology, geologic structures, and overburden. A
videoscope with the length of approximately 20 feet
should be sufficient for almost every coal mine in the
United States based on the maximum length of sup-
plemental cable bolts observed in field data collec-
tion visits. Some video borescopes can come in 50 ft
or longer and should be carefully considered. The
additional wire length can be cumbersome and affect
portability, especially in dark underground environ-
ments and other confined spaces.
• On-screen depth indicator – An on-screen depth
indicator is another feature that is very helpful when
examining lithology during video playback. If depth
is not displayed on the video, simple depth indica-
tors can be applied onto the poles used to insert the
videoscope into the roof borehole. As previously dis-
cussed in the microphone section, it is recommended
to keep a physical log to backup any video taken.
• Multiple cameras – Dual camera systems are typi-
cally configured in a forward (vertical) and right-
angle (side) view to catch both the borehole in a
360-degree and 90-degree bedding view. Some older
models will only have a vertical camera with a mag-
netic mirror to see at 90 degrees. The magnetic mir-
ror can detach and be easily lost during operation
and is not recommended. Some of the newer models
of video borescopes have a triple lens configuration
which includes a macro camera for clear images very
close to the rock within a borehole.
• Secure Digital (SD) card – Most video borescopes
utilize SD cards as the medium to store data. SD
cards can vary from storage capacity and writing
speeds. When recording video (and especially if the
borescope has a microphone) ensure that the SD
card storage size is adequate. Typically, recording
video will utilize a 16-GB SD card at the minimum.
Depending on resolution settings, audio/video capa-
bilities, and duration of data collection, operators
(operators vs operation/use of the unit) may require
a higher storage capacity.
• 1080 Progressive Scan recording – High definition
(HD) images are necessary to be able to see lithol-
ogy clearly for accurate identification. In HD, small
features can be seen such as sandstone grain size,
mica streaks, thin beds of coal, and micro cracks.
obsolete, except for operating inby the last open crosscut.
Because of the improvements and increased availability of
modern video borescopes, they have quickly become the
most widely used borescope for mine roof lithology identi-
fication in the United States.
Videoscope prices range widely based on features, reso-
lution, and manufacturer. The top tier videoscopes can cost
multiple tens of thousands of dollars, and provide features
such as removable batteries, faster processors, better screen
refresh rates, removable head prisms (for different viewing
angles), and have larger viewing screens. In addition to the
features, the materials used to manufacture them are of
better quality such as stainless-steel jacketed wires, quartz
prism head windows, and rotating head windows. These
types of videoscopes are less commonly used mostly due
to their cost, and most mines have instead turned to lower
cost videoscope alternatives.
VIDEOSCOPE FEATURES
When selecting a low-cost (under 300 dollars) videoscope
for mining applications such as lithology identification,
there are certain features, as described below, that will
enhance the overall experience and accuracy for the end
user. While some of these features may not be available in
the low-cost models, opting to have them at a potentially
increased cost may offer the end user a package tailored for
their specific needs.
• Adjustable LED light intensity – Proper lighting,
when viewing the borescope image, is extremely
important. Too bright of an intensity can cause an
overexposure that may whiteout the video screen.
This is especially the case when water is in the bore-
hole causing reflectance. Also, a low light intensity
may result in loss of critical details necessary to clas-
sify roof lithology. An adjustable light will aid in con-
trolling the amount of reflectance to avoid over and
under exposure.
• Microphone –The ability to record sound will help
with analyzing the data collected as the ability to
replay the lithology interpretation as it is being called
and the depths at each interval as they are occurring
adds value to the video. It should be noted that it is
a good practice to maintain a field notebook while
interpreting the lithology and depths at each change
in case an audio recording feature is not available,
the sound level is too low, or background noise is too
high to hear during video playback. The microphone
works best when located on the video screen unit and
not on the camera head.
• Length – The length of the borescope wire between
the video screen and the top of the camera window
required will depend on the length of the longest
roof bolts the mine uses for support. The length of
the roof bolts is dependent on many factors such
as lithology, geologic structures, and overburden. A
videoscope with the length of approximately 20 feet
should be sufficient for almost every coal mine in the
United States based on the maximum length of sup-
plemental cable bolts observed in field data collec-
tion visits. Some video borescopes can come in 50 ft
or longer and should be carefully considered. The
additional wire length can be cumbersome and affect
portability, especially in dark underground environ-
ments and other confined spaces.
• On-screen depth indicator – An on-screen depth
indicator is another feature that is very helpful when
examining lithology during video playback. If depth
is not displayed on the video, simple depth indica-
tors can be applied onto the poles used to insert the
videoscope into the roof borehole. As previously dis-
cussed in the microphone section, it is recommended
to keep a physical log to backup any video taken.
• Multiple cameras – Dual camera systems are typi-
cally configured in a forward (vertical) and right-
angle (side) view to catch both the borehole in a
360-degree and 90-degree bedding view. Some older
models will only have a vertical camera with a mag-
netic mirror to see at 90 degrees. The magnetic mir-
ror can detach and be easily lost during operation
and is not recommended. Some of the newer models
of video borescopes have a triple lens configuration
which includes a macro camera for clear images very
close to the rock within a borehole.
• Secure Digital (SD) card – Most video borescopes
utilize SD cards as the medium to store data. SD
cards can vary from storage capacity and writing
speeds. When recording video (and especially if the
borescope has a microphone) ensure that the SD
card storage size is adequate. Typically, recording
video will utilize a 16-GB SD card at the minimum.
Depending on resolution settings, audio/video capa-
bilities, and duration of data collection, operators
(operators vs operation/use of the unit) may require
a higher storage capacity.
• 1080 Progressive Scan recording – High definition
(HD) images are necessary to be able to see lithol-
ogy clearly for accurate identification. In HD, small
features can be seen such as sandstone grain size,
mica streaks, thin beds of coal, and micro cracks.