JP3434518B2 - Ultraviolet irradiation and inspection system and fluorescent dye leak detection method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a method for leak detection, and in particular it fluoresces when illuminated with light of a certain wavelength, commonly referred to as "black light", such as typical ultraviolet light. It relates to leak detection using dyes.

Prior Art Ultraviolet light sources are commonly used for sterilization, exploration, document inspection, dental work hardening and leak detection and the like.

The fluorescent dye is typically mixed with a lubricating oil that is mixed with the liquid in the device being tested, such as the cooling means of an air conditioning system.

If there is a leak, the dye in the leak will fluoresce when exposed to UV light, and the leak will easily become visible.

Such dyes, when excited by shorter wavelength ultraviolet light, fluoresce or emit light in a specific visible wavelength band.

In order to make such leak detection easy and reliable, especially in a bright environment, it is necessary to use a powerful light source that emits light at an appropriate wavelength and does not emit visible light. . If visible light is reflected from the surface being inspected, the fluorescent light will be obscured.

Today, usable light sources do not have sufficient intensity, emit a considerable amount of visible light, and have insufficient contrast between fluorescence emission and visible light reflection for reliable inspection. there were.

Further, in an attempt to absorb and remove visible light with a filter lens, the problem of overheating also occurs.

Such overheating causes cracking and shortening of the life of the lens,
In particular, when water drops hit the lens, the shattered glass causes an accident to the user.

In an attempt to create a more powerful light source, a reflector is typically provided that focuses and directs the ultraviolet wavelength light emitted from the quartz envelope lamp. Conventional reflectors are typically rough molded and also have a destructive interference configuration with a protective coating such as silicon oxide.
The efficiency was low due to the interference setup).

It is an object of the present invention to provide a system of enhanced intensity UV irradiation for fluorescence leak detection which allows easier and more reliable inspection of the fluorescence emitted by the dye.

Another object of the present invention is to provide a UV source that emits an intense UV beam that is directed through the glass filter to remove visible wavelengths without the glass filter heating up.

DISCLOSURE OF THE INVENTION The above objects and other objects that will be apparent from the following specification and claims are to achieve maximum contrast for the fluorescence emitted from the dye when it is combined with an ultraviolet lamp, leaks, and is irradiated. , An improved parabolic refl combined with a viewing eyeglass that filters certain visible wavelengths.
ector) and a system having a filter.

The improved reflector has an accurately formed parabolic (pa
rabolic shape). A two-layer coating is applied to the reflecting surface and having different refraction. These coatings are
As the reflected light is closer to the incident light in phase, the offset phase shift
t) to minimize the interference between the incident light beam and the reflected ultraviolet beam. This maximizes the intensity of the reflected UV beam by minimizing the destructive interference between the incident and reflected light beams, which would otherwise occur. The UV source is preferably a quartz envelope tungsten halogen lamp located at the focal point of a reflective parabola.

The UV beam from the reflector is then selectively reflected, rather than absorbed, to minimize heat generation in the filter, such as occurs in a conventional light absorbing filter used for visible light removal. Law (process of s
elective reflectance) is passed through an optical filter to selectively remove visible light from the reflected light beam.

A combination of coating layers is applied to the borosilicate glass disk to achieve this. Successive layers of high and low refraction coatings are used to create selective reflectivity in the wavelength range from 475 nm to 700 nm above the UV wavelength and below the IR wavelength band.

Infrared light is passed through the filter to reduce heating of the enclosed space behind the filter.

The final element of the system is a pair of filtering viewing eyeglasses that allow the illuminated light to increase the fluorescence contrast and visibility of the illuminated dye to the examiner's eyes. In order to block the lower part by the wavelength of the fluorescent light in the wavelength, the wavelength just below the wavelength of the fluorescent light is absorbed.

As a result of the above synthesis, a practical beam is used to create a strong beam of ultraviolet light containing minimal visible light. The fluorescent light is thus strong and is not masked by the incident visible light reflected from the illumination beam.

DESCRIPTION OF THE FIGURES FIG. 1 is a diagram showing the main components of a system according to the invention.

FIG. 2 is an enlarged partial sectional view of a parabolic reflector component.

Embodiments In the following detailed description, certain technical terms are used for the sake of clarity, and US Pat.
Particular embodiments are described based on the requirements of 2), but are not to be so limited or construed, and the present invention is intended to be in the form of many forms and modifications within the scope of the claims. It should be understood that changes can be made.

The system according to the invention uses a mobile UV source, different from a flashlight, and also a parabolic shap.
e) A parabolically shaped reflect installed in a housing 12 (only a portion of which is shown in cross section) in which a lamp 14 located at approximately the focal point is installed.
or) have 10.

The lamp 14 is a high color temperature Xenon lamp.
p,> 3500K), and those which emit substantially long ultraviolet rays are preferred. The envelope is made of quartz, which has its own high transparency to such long-wave ultraviolet light.

The lamp 14 is also relatively compact so that it can be located at the parabolic focus of the reflector.

As a suitable bulb, part number FCR64625HLX from Osram Sylvania can be used as part.

The parabolic reflector is a precision electoroformed nickel on a precisely formed stainless steel mandrel.
of nickel).

A 0.187 inch focus allows the lamp 14 to be roughly positioned at the focus of the parabola, such as maximizing beam density.

The lamp 14 is powered by a suitable power supply means 16, which can also consist of a transformer that lowers 110 volts (vac) (or 220 volts) to 12 volts.

A 12 volt DC power supply means can also be used, such as an auto battery. The lamp 14 draws 100 watts of power because it requires a high power source, which is substantially larger than that required by typical flashlights. Preferably, in order to minimize the lighting time of the lamp 14, the switch of blinking of the lamp 14 is normally off spring biased s.
A witcn) relay is used.

The reflecting surface 18 of the parabolic reflector 12 has a two-layer coating (coatin).
g) and is designed to eliminate destructive interference due to refraction at the interface of each media through which light passes while being reflected from the reflective surface 18. Refraction of short wavelength ultraviolet rays causes destructive interference of reflected ultraviolet rays and also reduces the intensity.
It usually causes a phase difference between the incident light and the reflected light.

Surface 18 is coated with one layer of aluminum and one layer of silicon dioxide. The interfaces between silicon dioxide and air and silicon dioxide and aluminum cause opposite double refraction, and
This offsets each other so as to eliminate possible destructive interferences that would otherwise occur.

The first coating 18A is an aluminum layer, while the second coating 18B is
Is a silicon dioxide layer (see FIG. 2). The layer thickness of silicon dioxide must be homogeneous and precisely constructed in order to achieve the objective, and the thickness is "quarter stack".
k) ”determined by the principle.

The index of refraction at each interface, that is, the index of refraction at each interface between silicon dioxide and air and between silicon dioxide and aluminum, determines the effective phase change of the reflected light. Layer thickness 0.057 micron (mic
ron) aluminum and silicon dioxide with a layer thickness of 0.066 microns have been successfully used for this purpose. The silicon dioxide-air interface has a forward phase change of about 13 degrees (dgree) (for
The silicon dioxide-aluminum interface causes a lagging phase shift of about 13 degrees, which offsets the ward phase shift.

Heretofore, silicon dioxide coatings have been used merely to protect the substrate from scratches and oxidation, however, to achieve enhanced reflection of UV wavelengths, even at a uniform thickness or at a suitable thickness. There was no

A coated parabolic reflector suitable for this application is available from American Galvano, Inc. of California, USA.
Galvano) (312 N.Cota St., Unit 1, Corona, Californi
a 91720) can be used.

Glass disk filter 20
Is another component of the system of the present invention installed to receive the ultraviolet beam emanating from the lamp 12 and parabolic surface 18.

Filter 20 is designed to reduce the visible light component of the ultraviolet light received from lamp 14 and reflector 10.

Although such filters have been used in the past,
However, it has been designed to absorb visible light and prevent its passage. This leads to overheating of the lens when using a high intensity light source, and a partial point of the glass poses an increased risk of cracking or breaking if it comes into contact with a drop of water due to quenching.

In accordance with the inventive concept, a coating is provided that reflects visible light rather than absorbs it and greatly reduces the heat of lens 20.

As the filter 20 itself, borosilicate glass (bo
Rosilicate glass is preferred, commercially available "Pyrex" ™, and it has a very low coefficient of thermal expansion to minimize cracking from thermal shock.

Fluorescent dyes typically used for leak detection have an excitation range of 320-475 nm UV wavelength. When excited by such ultraviolet rays, it emits fluorescence at 495 to 500 nm.

Thus, the transmission of excitation wavelengths from 320 nm to 475 nm can be maximized while reflecting the wavelengths from 475 nm to 700 nm.

Light above 700 nm belongs to the invisible infrared range, and
In particular, in order to avoid overheating of the reflector 10, it is allowed to pass through the filter 20 and out of the enclosed space.

A special coating is applied to reflect visible light of 475 nm or more and 700 nm or less in the filter 20.

"Quaterwave Stack (quarterw) developed by P. H. McRoad (PHMcCloud)
ave stack) using the principle of ave stack)
It can be stacked to allow transmission of wavelengths from nm to 475 nm and 700 nm to 1300 nm and to reflect only wavelengths from 475 nm to 700 nm.

This stack is formed from a coating on the inside surface of the filter and fill 20, which may be titanium oxide.

The glass and titanium oxide have a thickness required to reflect the wavelength in the above range.

Like magnesium fluoride,
Other coatings can be applied in various thicknesses,
It can also be applied to other borosilicate surfaces to remove the remaining transmitted visible light.

The general methodology creates a reflected light bandwidth above 475 nm and up to approximately 700 nm. The average of the wavelengths centered on such a bandwidth is 537.5 nm, thus necessitating the use of a reflection bandwidth of 225 nm.

Suitable reflecting-transmitting filter lenses for this purpose include:
ZC & R Coating for Optics (Z, C & R Coa
tings for Optics, Inc.) (1250 E.223rd.Street, Suite
111, Corson, California 90745) can be used.

The system also detects fluorescence wavelengths in the 495-500 nm range emitted by the illuminated dye in the leak liquid 28.
It includes the use of special viewing glasses 24 designed to absorb light wavelengths from 400 to 480 nm so that light emitted from the light source in the reflection range from 26 is not masked.

Such a narrow wavelength band blocking spectacle lens (narrow ban
d blocing eyeglass lens) is available from Noire medical (6155 Pont, Michigan, USA).
Items from iac Trail South Lyon, Michigan 48178) can be used.

Thus, a powerful UV illumination source is provided and the fluorescent light produced thereby is highly blocked based on the minimization of reflected visible light that is blocked by the filter 20 and absorbed by the eyepiece 24. It becomes visible.

This in turn makes leak detection inspections easier and more reliable, even in relatively brightly lit sites.

Continuation of the front page (56) Reference JP-A 61-158452 (JP, A) JP-A 6-307970 (JP, A) JP-A 61-93597 (JP, A) JP-A 62-97845 (JP , A) Actual development Sho 62-123273 (JP, U) Actual development Sho 62-123274 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) B01J 19 / 00-19 / 32 G01M 3/20

Claims (2)

(57) [Claims] 1. An optical system for irradiating an object with ultraviolet rays, comprising: a housing having an opening; and an ultraviolet, visible, and infrared wavelengths attached to the housing when a voltage is applied. A high power UV lamp with a much higher wattage than an ordinary flashlight, which produces a light beam containing; and an optical filter placed in the aperture to receive the light beam at the visible wavelength. While having a quarter wave stack coating that selectively reflects light while transmitting light in the ultraviolet and infrared wavelength ranges, directs light in the ultraviolet and infrared wavelengths from the opening, and light in the visible wavelength range. Causing a large proportion of the UV light in the light beam to be directed out of the housing through the aperture, Long-range light does not pass through the aperture, while infrared light wavelengths above about 700 nm have an optical filter that is directed out of the housing to minimize heating within the housing, and ultraviolet light. A parabolic reflector surrounding the high-power ultraviolet lamp with the lamp located substantially at the focal point for reflecting the ultraviolet light and directing the ultraviolet light to the optical filter, and the parabolic reflector is made of aluminum. It has a two-layer coating, including a first coating and a second coating of silicon dioxide, which two-layer coating removes destructive interference that diminishes the intensity of the reflected UV light, thus providing multiple layers in opposite directions. An optical system for irradiating an object with ultraviolet light, characterized by having a quarter-stack relationship that causes refraction. 2. The optical system of claim 1, wherein the first coating is 0.057 microns thick and the second coating is 0.066 microns thick.