cnocbui@xxxxxxxxx writes:
<< What kind of quality does an endoscope have, and what kind of optics? Is
it
a narrow field-of-view macro lens, or a fisheye lens? >>
The Oly flexible endoscopes have a huge bundle of glass fibres. The fibre
must be perfectly aligned at each end so the light coming in comes out at the
same relative spot at the other end. Yet the fibres must not be glued
together all the way down otherwise it cannot flex and bend. I believe optics
are added at both ends. I don't know too much about the optical details but I
suggest you do a search on the IBM patent server for endoscope and Olympus
and you should get lots of design details. The end of the endoscope is
steerable using external knobs that pull fibres (probably Kevlar) attached
off centre near the tip. This causes the tip to bend like a finger joint with
ligaments. Multiple fibres allow more complex steering motion than a human
finger. In solid endoscopes the design is like a periscope with optics at
each end and a side looking mirror or prism that looks at an angle to the
axis of the scope. The illumination then comes at an angle from a section of
the endoscope that sticks forward beyond the optics entry. For solid ENT
endoscopes the device can be really thin something like 1-1.5mm and looks
straight ahead. Many fibre scopes are quite large (6mm+) to accomodate lumens
for biopsy tools, fluid flushing, fibres for illumination etc. The optical
quality of a fibre scope is not that good because of the discrete fibre
nature of the image. Looking through my solid endoscope it looks a bit like a
fish eye. By definition the space is very limited so it probably has to have
a reasonably wide angle of view. The extreme close position gives huge
perspective "distortion" so I don't know how much of the effect is because of
fish eye optics or just the close up viewpoint. In the US they have a science
program on television called NOVA. Some years back they had a film made by a
well known science photography group from Cambridge (England) who used
endoscopes for photographing bees entering flowers. The photography was from
the inside of the flower looking out as the bee landed and entered the flower
coming very close to the lens (scope tip) that must have been sticking into
the flower from the back. Unfortunately my scope is not small enough to get
inside a typical flower. Given the average age of this list some of the male
members at least must have had a close encounter with an Olympus endoscope in
their annual checkup!
Cheers,
Tim Hughes
>>Hi100@xxxxxxx<<
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