Radiant energy – Radiant energy generation and sources – With radiation modifying member
Reexamination Certificate
1999-10-29
2002-03-12
Anderson, Bruce (Department: 2881)
Radiant energy
Radiant energy generation and sources
With radiation modifying member
C250S50400H
Reexamination Certificate
active
06355935
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a light source and system for detecting leaks in fluid systems using light-emitting substances.
BACKGROUND OF THE INVENTION
Leak detection methods have been developed to analyze fluid systems (e.g., climate control systems such as heating, cooling, ventilating, and air conditioning systems, hydraulics, engine oil systems, automatic transmission systems, fuel systems, brake systems, or radiator coolant systems) using dyes. Some methods operate by adding emissive substances (e.g., fluorescent or phosphorescent dyes) to the refrigerants and/or lubricants of the fluid system. Suitable dyes include naphthalimide, perylene, thioxanthane, coumarin, or fluorescein, and derivatives thereof. Leaks can be detected by observing fluorescence of the dye at leak sites resulting from excitation of the dye with a light source having particular illumination characteristics (e.g., wavelength or intensity). Examples of leak detection methods are described in U.S. Pat. Nos. 5,357,782 and 5,421,192 which issued to Richard G. Henry on Oct. 25, 1994, and Jun. 6, 1995, respectively, both of which are assigned to the same assignee as the assignee of the present application. Similar fluorescence methods can be used in the non-destructive testing industry.
In the field of leak detection, crack detection, and related non-destructive testing, different dyes can be utilized which fluoresce at different wavelengths. Fluorescence is the emission of light at wavelengths greater than the wavelength of light emitted from the light source used to probe for leaks.
Suitable light sources for use in fluorescence detection emit light of wavelengths suitable to excite the dye and cause light emission. The visibility of the fluorescence from the dye can be increased when the leaks are illuminated with light having a wavelength between 300 and 700 nanometers. In general, the dyes fluoresce brightly when excited by light sources which emit light in the 300 to 500 nanometer range.
Typical light sources used in these types of applications include alternating current lamps operating on either 110 to 220 volts, such as the PAR 38, manufactured by Phillips. These lamps had power outputs in the 100 to 200 watt range and produced a substantial amount of light outside of the wavelength range desired to produce a good fluorescence signal. These lamps also tend to create a large amount of heat and required the use of a ballast which provided additional bulk and weight. Self-ballasted lamps were also developed that generally had relatively long warm-up periods and were very sensitive to voltage surges.
SUMMARY OF THE INVENTION
In general, the invention features a light source that is small, portable, and light weight. The light source produces a collimated beam of light. The light source produces a high output of light having a wavelength that can effectively excite emissive substances used in leak detection systems. The light source can have a parabolic reflector and can have a low-voltage lamp.
In one aspect, the invention features a light source for examination of a substance which emits light at a wavelength greater than a wavelength of light emitted from the light source when the substance is excited by the wavelength of light emitted from the light source. The light source includes a housing having a light outlet, a reflector located within the housing, a lamp positioned in the housing between the reflector and light outlet, and a filter positioned in the housing between the lamp and the light outlet. Accordingly, the wavelength of the light emitted from the light source through the light outlet is restricted to a predetermined range effective to enhance the detection of emission of light from a substance when the substance is excited by the wavelength of light emitted from the light source. The preferred lamp is a low-voltage lamp (e.g., a halogen lamp). The preferred reflector is a parabolic reflector.
The filter restricts the wavelengths of light emitted from the lamp and the light reflected by the reflector. The filter can be an absorption filter, dichroic filter, or other interference filter. The filter can be part of the glass that surrounds the element of the lamp.
The light source produces a light power density in the ultraviolet wavelength region of at least 0.1 mW/cm
2
at a distance of two feet from the light outlet or a light power density in the blue wavelength region of at least 0.75 mW/cm
2
at a distance of two feet from the light outlet.
The lamp is capable of being connected to a source of electrical power, such as a battery, battery pack, or transformer. The reflector can be a dichroic reflector. The reflector can have a faceted surface or a smooth surface. The reflector can substantially reflect a selected wavelength of the light emitted from the lamp. For example, the reflector can reflect light primarily in the blue wavelength range, in the ultraviolet wavelength range, or in the blue and ultraviolet wavelength ranges.
In another aspect, the invention features a system for detecting leaks in fluid systems. The system includes a substance capable of emitting an emission wavelength of light after being excited by an excitation wavelength of light, and the light source, which is capable of emitting the excitation wavelength of light.
In another aspect, the invention features a method of detecting a leak in a system containing a substance capable of emitting an emission wavelength of light after being excited by an excitation wavelength of light. The method includes the steps of providing a collimated beam of light at the excitation wavelength from a light source to a leak site, and detecting emission of light from the substance. The substance and the light source can be provided in a single package. The substance can be added to the system.
The substance can be an emissive leak detection dye, such as a naphthalimide, perylene, thioxanthine, coumarin, fluorescein, or other fluorescent or phosphorescent dye.
The system can include a filter lens for detecting the emission wavelength of light, where the emission wavelength of light emitted is enhanced by the utilization of filter lens by an observer of the emission wavelength. The filter lens can be incorporated in eyewear or a shield. The shield can be hand-held or mounted directly on the light source. When mounted on the light source, the observer can view the emission wavelength through the mounted filter lens.
The low-voltage lamp can be a high color temperature, low voltage bulb, such as, for example, a quartz halogen-xenon bulb. Small, direct current lamps of the halogen type, or similar lamps rich in gases such as xenon require no ballast, are small in dimension, are light weight, and are typically not subject to voltage surges or spiking. The low-voltage lamps provide portability.
The low-voltage lamp can be powered by batteries (e.g., 4.5V, 6V, 9V, or 12V batteries) or battery packs. The batteries or battery packs can be rechargeable. In other embodiments, the low-voltage lamp can be powered by a transformer.
Reflectors can be used to adjust the output wavelengths of light from the low-voltage lamp so that sufficient light power density (i.e., candle power density) reaches the emissive substance. The light source can include an essentially parabolic reflector. The parabolic shape of the reflector geometry can create a collimated beam consisting of parallel beams of light. The collimated beam can provide a relatively constant illumination intensity over the leak detection area.
The parabolic reflector has a three-dimensional paraboloid shape. A lengthwise cross-section of a parabolic reflector reveals a parabolic shape having a focal point or a focal region. In a parabolic reflector, light rays emanating from the focal point or region are reflected by the surface of the paraboloid in a direction essentially parallel (e.g., over the distance to the leak site) to the lengthwise axis of the reflector to form the collimated beam. Because the rays are parallel, they do not noticeably diverge or converge with d
Cavestri Richard C.
Kalley Terrence D.
Miniutti Robert L.
Anderson Bruce
Bright Solutions Inc.
Fish & Richardson P.C.
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