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US 9,006,655 B2Granted
Thermal imager with protective grid
AssigneeFluke Corporation
InventorsAlex S. Nikittin, Salvador Alvarez, Jr.
Life of this patent
Estimating the term…
Abstract
A protective enclosure for a thermal imager having a window and protective grid. The protective grid is designed in relation to the lens of the thermal imaging device such that the grid pattern geometry and size accommodate the thermal imaging device's pupil size.
Claims20
A protective enclosure for enclosing a thermal imaging device mounted in a predetermined location, the thermal imaging device having a pupil plane and a lens, the thermal imaging device to be used in a hazardous environment comprising:
- a housing having a proximal end and a distal end and a sidewall coupling the proximal end to the distal end, such that the sidewall surrounds the thermal imaging device when the thermal imaging device is in the predetermined location;
- a window assembly located near the distal end of the housing, the window assembly comprising:
- a window providing passage for infrared radiation to the thermal imaging device within the enclosure;
- and
- a protective grid comprising a first plurality of intersecting bars and a second plurality of intersecting bars, the protective grid located on one side of the window at the distal end of the housing wherein the protective grid is exposed on one side to the environment and is exposed on an opposite side to the window, the protective grid having a geometry constructed in relation to the thermal imaging device such that a ratio of blocked beam to adjacent unblocked beam projected on the pupil plane remains constant thereby providing a relatively uniform attenuation in the field of view of the thermal imaging device which may be compensated for with one transmissivity coefficient;
- wherein
- each of the first plurality of bars has a cross section with an elongate dimension defining a line extending therethrough, the bars oriented such that the lines extending through the elongate dimensions converge towards a first location within the housing, the first location being substantially coincident with the center of the lens of a thermal imaging camera when the thermal imaging camera is mounted in the predetermined location such that the protective grid provides relatively uniform attenuation from a field of view external to the enclosure to the first location within the housing;
- and
- each of the second plurality of bars is located near the periphery of the grid and has an elongate dimension oriented parallel to the elongate dimension of at least one adjacent bar, the at least one adjacent bar being in either the first plurality of bars or the second plurality of bars.
6 more elements
A method of constructing a protective grid to be used with a thermal imager in a hazardous environment, comprising:
- determining the imager's lens input pupil size and position relative to the grid;
- selecting a grid pattern geometry characterized by a pitch, p, and bar width, w, and size in relation to the input pupil size;
- and
- adjusting the grid geometry to maintain a substantially constant ratio of w to p in angular projection on the pupil plane.
1 more element
An industrial monitoring system, comprising:
- a protective enclosure for a thermal imaging device, the protective enclosure comprising:
- a housing;
- a window assembly located near the distal end of the housing, the window assembly comprising:
- a window providing passage for infrared radiation to the thermal imaging device within the enclosure;
- a thermal imaging device adapted to communicate with a remote image monitoring center of the system;
- and
- a protective grid located on one side of the window at the distal end of the housing wherein the protective grid is exposed on one side to the environment and is exposed on an opposite side to the window, the protective grid comprising a plurality of intersecting bars defining a hole pattern, wherein the hole pattern has a grid pitch, p, and each bar has a width, w, and configured such that (i) the pitch increases, (ii) the bar width decreases, or (iii) both, from the center of the grid to the peripheral;
- said thermal imaging device located inside said enclosure at a predetermined position in relation to said grid, such that the protective grid provides a relatively uniform attenuation in the field of view of the thermal imager which may be compensated for with one transmissivity coefficient.
5 more elements
Dependencies are inferred from the claim text.