Radiant energy – Photocells; circuits and apparatus – With circuit for evaluating a web – strand – strip – or sheet
Reexamination Certificate
1998-09-11
2001-06-19
Lee, John R. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
With circuit for evaluating a web, strand, strip, or sheet
C356S370000, C250S559290
Reexamination Certificate
active
06249007
ABSTRACT:
BACKGROUND OF THE INVENTIONS TECHNICAL FIELD
The present invention relates to a non-contact measuring apparatus, and more particularly, but not exclusively, to a non-contact measuring apparatus for determining the profile or cross-section of an object. For example, the apparatus can determine the internal cross section of an underground pipe, such as a sewage pipe, or any other hollow object.
DESCRIPTION OF THE RELATED ART
In many industries the measurement of cross-sections is necessary for a variety of purposes such as monitoring the deformation of a structure, assessing the condition of a structure, measuring the thickness of a coating and construction of three-dimensional computer aided design (CAD) models.
One method conventionally employed for such purposes is single point optical triangulation. In such a system a laser beam is directed to the object and a sensor measures the position of the image of the beam formed by a lens. The position of the reflected laser beam on the sensor gives an indication of the distance of the object from the measuring apparatus. In one known arrangement the laser and the sensor are mounted for rotation so that the distance of the object can be measured at a plurality of locations in order to collect data indicating the profile or internal cross-section of the object.
One problem with such conventional apparatus is that, when the internal cross-section of a hollow object is measured, parts are moved within the environment of the inside of the hollow object. This renders the measuring apparatus unsuitable for use in explosive environments, or in situations where the object may contain fluid.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention, there is provided a non-contact distance measuring apparatus, comprising a casing, and distance measuring means located within the casing for measuring the distance between the distance measuring means and an object using electromagnetic radiation, the casing being substantially transparent to the electromagnetic radiation used by the distance measuring means.
Moving means for moving the distance measuring means relative to the casing to measure the distance of said object at a plurality of locations may be provided.
The casing allows distance measurements to be made at a plurality of locations without the need for any external moving parts. This may enable the apparatus to be used, for example, in a pipe full of fluid, or in a hazardous environment such as an explosive environment where movement of parts might cause ignition.
Preferably, the distance measuring means located within the casing comprises an optical triangulation device. Optical triangulation devices are well known to those skilled in the art
The distance measuring means may comprise an electromagnetic radiation source, radiation from which is directed to the object, and detection means for detecting radiation reflected from the object, the arrangement being such that the distance of the object from the distance measuring means can be determined by detection of the reflected radiation.
The radiation source may comprise a laser.
The detection means may be a charge coupled device (CCD) sensor, and may have an elongate sensitive surface and means for detecting the position on the elongate sensitive surface of the image of the reflected laser beam. The use of a CCD sensor may enable distance measurement to be performed very quickly. The speed may be determined by the number of pixel elements and the integration time of the sensor and can be in the range from substantially 500 Hz to 150 kHz. Preferably, the CCD sensor is calibrated prior to use.
The moving means may be arranged to rotate the distance measuring means within the casing. This provides a convenient way of measuring the distance between the measuring means and the object at a plurality of locations in order that data representative of the profile or cross-section of the object may be acquired.
Conveniently, the casing is provided with means for moving the casing relative to the object. Such a feature may enable cross-sections to be determined at a plurality of locations of the object, thus providing information about the object in three-dimensions. The means for moving the casing relative to the object may comprise wheels driven by an electric motor. The electric motor is conveniently controlled remotely by an operator. This allows the apparatus to perform measurements inside objects which are too small to accommodate a person.
A CCD camera may be mounted in fixed relationship with the casing for providing images of the object to an operator. This may allow the operator to ascertain the position of the apparatus so that the measurement of, for example, a cross-section can be made at the appropriate place.
According to another aspect of the present invention there is provided a hollow body, such as a pipe, cross-section measuring device comprising a movable optical triangulation probe for measuring the distance of the hollow body or pipe at a plurality of locations to determine the profile or cross-section thereof.
The probe may be rotated relative to the hollow body of the pipe to determine the cross-section thereof at a first position, and the probe may also be translatable relative to the hollow body or pipe to determine another cross-section thereof at a second position.
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Clarke Timothy Alan
Gooch Richard Michael
Hatch Clive
Ockleston Grant Andrew
Lee John R.
McDermott & Will & Emery
Thames Water Utilities Limited
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