US3744874A

US3744874A - Fire fighting apparatus

Info

Publication number: US3744874A
Application number: US00079082A
Authority: US
Inventors: D Mccarthy; Albert J D
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-10-08
Filing date: 1970-10-08
Publication date: 1973-07-10
Anticipated expiration: 1990-07-10

Abstract

Fire fighting apparatus, to enable fire fighters to see through smoke, includes a mask or goggles which fit over the eyes. The goggles are optically connected, preferably by fiber-optics, to a laser device. The laser device includes a laser, an electronic circuit to pulse the laser at a high frequency, and a beam splitting optical mechanism which couples the laser beam to the fiber-optical bundle.

Description

sac-96.25 512 Umted State: r w I 1 11 1 3,744,874 McCarthy et al. July 10, 1973 [54] FIRE FIGHTING APPARATUS 3,096,767 7/ I963 Gresser ct al 350/236 X 3,216,778 11/1965 Davies Cl al 350/96 11 x [761 lnvemmsl L-Mccarhymos Avenue 3,183,347 5/1965 COClhO 350/272 x Brooklyn, 11210; 11mph 3.294.002 12/1966 Vitkine 95/115 DAlbert, 10 Patricia Road. Patchogue N'Y' Primary Examiner-David H. Rubin [22] Filed: Oct. 8, 1970 Attorney-Eliot S. Gerber pp 57 ABSTRACT 52 us. c1. 350/96 B, 128/142 Fire fighting PP able fire fighters see 511 lm. Cl. c0211 5/16 hmugh smke, includes a mask or goggles which fit [58] Field of Search 350/96 B, 235-237; the eyesgoggles are OPically connected,

331/945 preferably by fiber-optics, to a laser device. The laser device includes a laser, an electronic circuit to pulse [56] References Cited the laser at a high frequency, and a beam splitting opti- UNITED STATES PATENTS cal mechanism which couples the laser beam to the fiher-optical bundle.

504,984 4/1970 Bush 350/96 B X 3,380,358 4/1968 Neumann 95/! 1.5 3 Claims, 3 Drawing Figures wet/5L PAIENIEU JUL 1 0 I973 JOSEPH D'ALBERT 1M ATTORNEY Y .H mm mm C EM vL m N E D mm \\Nm x In "55% on VIN .358583 $93 mm f m 5 km nm on 102368 4 5& N u\|.\ 2 E561 1 FIRE FIGHTING APPARATUS BACKGROUND OF THE INVENTION One of the greatest problems in fighting fires is that of smoke. At the present time the adverse effects of smoke on breathing are combatted by an oxygen breathing apparatus similar to that employed by scuba divers, one of the best known of these being the Scott Pack, named after its manufacturer. These devices consist of a mask which fits over the fire fighters face and which is connected by a tube to an oxygen supplying bottle which he carries on his back. Using such a breathing apparatus he may enter a smoke-filled room and breathe up to minutes using the oxygen supply on his back. However, the breathing apparatus does not help with the second major adverse effect of smoke, namely, that of decreased vision. For example, when a fire fighter enters a smoke-filled room, he may be unable to see dangerous objects such as stairwells, which could lead to his death or injury. Similarly, he is often unable to see persons within the room who need to be evacuated, he cannot see the doors, and he cannot see the fire. In certain situations, for example, in submarines and other closed environments, it is essential that the fire (which is usually the source of the smoke) be rapidly located. If it is not, it cannot be extinguished and the smoke may continue to billow up, endangering the lives within the submarine.

The smoke problem, as it relates to decreased vision, has become increasingly serious due to the many occasions in which fires occur in industrial buildings or locations having machinery. In these instances the fires often produce a thick and oily smoke which decreases vision considerably more than a white smoke produced from a wood-burning fire. For example, a black, heavy and thick smoke may be produced by the burning of oil, rags or plastic or rubber compounds. In these situations, for example, in a fire in an industrial plant, it may be almost impossible to see within the plant, so that the fire must be fought from outside blindly. This may be extremely dangerous when the fire fighter is not aware of dangerous conditions within the plant and may consequently use the wrong material, for example, he may use water when he should be using foam.

There have been no successful efforts to enable fire fighters to see through smoke. The use of goggles, while it decreases eye irritation, does not aid in seeing through the smoke. The use of a Scott Pack or other breathing apparatus enables the fire fighter to keep low to the ground where the smoke is less thick but again does not directly aid his vision.

SUMMARY OF THE INVENTION The present invention relates to fire fighting apparatus and more particularly to such apparatus which will enable the fire fighter to see through smoke. The apparatus of the invention includes a mask or goggles which fit over the fire fighters eyes. These goggles may be built in as an integral unit with the mask which he uses as a breathing apparatus. The goggles are optically coupled to a laser-electronics instrument, such optical coupling preferably occurring by means of two bundles of flexible fiber-optics, each bundle consisting of a large number of individual strands of flexible glass which are oriented exactly the same at both its faces. The lower ends of the fiber-optic bundles terminate in a box which is hand-held with a strap so that it may be let go of for life saving. The box contains a laser, an electronic circuit and a beam splitting optical mechanism. The laser and electronic circuit are connected to a source of power, preferably a battery pack, which is carried on the fire fighters back and which may be physically associated with the oxygen supply container as part of a single strapped-on unit. The laser is pulsed at a very high frequency, for example, I million Hz, to decrease the adverse effect of back-scatter from the smoke particles. The laser beam has within it an optical beam splitting mechanism, preferably a thin-film dielectrically coated optical quality glass beam splitter which enables the beam to pass through and which also enables the fiber-optic bundles to see within the beam.

It is the objective of the present invention to produce a fire fighting apparatus which will enable the fire fighter to see through smoke. The apparatus: (1) is sufficiently light in weight so that it may be carried by individual fire fighters; (2) is sufficiently economical in power consumption so that a fire fighter may spend at least 20 minutes within a smoke-filled environment without the recharging or replacement of the power source; (3) is sufficiently powerful so that it may penetrate dense smoke such as is produced by a diesel-oil fire; (4) presents a sufficiently wide beam so that objects and distance may be correctly and accurately perceived; (5) presents a sufficiently modulated beam so that back-scatter of the laser beam will not prevent vision or distort vision.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in FIG. 1, the apparatus includes a face mask 10 which is adapted to fit over the face of the fire fighter by means of the adjustable strap 13. The face mask has a breathing tube 14 whose end terminates within the mask near the mouth of the fire fighter. The breathing tube 14 leads to an oxygen supply 15, the breathing tube and oxygen supply being similar to a scuba divers breathing apparatus. A suitable breathing apparatus and oxygen supply is sold by the Scott Air Pack Company under the name Scott Air Pack. The air pack 15 is adapted to be carried on the back of the fire fighter by means of the strap 16 which fits over the fire fighters shoulder. A holding mechanism holds the air supply 15 together with the power supply 17 so that they may both be carried on the back of the fire fighter by means of strap 16.

The power supply 17 is connected by means of a power supply line 18 to the laser and circuit container 22. The laser and circuit container 22 is adapted to be hand-carried by a handle 23. The fire fighter may also loosely hold the laser and circuit control 22 by means of the strap 24.

The mask has a left eye piece 11 and a right eye piece 12. A left fiber-optic bundle 19 is connected to the left eye piece 11 and a right fiber-optic bundle 20 is connected to the right eye piece. The eyes of the fire fighter are consequently looking into the polished glass ends of the fiber-optic bundles. The two fiber-

optic bundles

19 and 20 are held together in a flexible enclosing tube 21 which leads both fiber-optic bundles into the laser and circuit container 22. Preferably the eye pieces are of the bi-focal type. The upper portion of each eye piece lens permits direct viewing. The bottom portion of each eye piece lens is the polished end of the optical fiber bundle and permits viewing through the laser beam, as shown in FIG. 3.

Fiber optics is a term describing the image pipe having a degree of flexibility, which is manufactured of thin cylindrical glass fibers of high optical quality. A single fiber, resembling a strand in a spider web, may

be from 5 to 100 microns in diameter, but preferably is about 25 microns in diameter. Light entering one end of the fiber is transmitted to the other end by total internal reflection, with the transmission of a 40-inch length being between 40 percent to 70 percent. This percentage of transmission is somewhat affected by wave length but is substantially flat in the wave length band from 0.400 microns to L4 microns.

A large number of fibers are gathered together to form a bundle, for example, a suitable bundle would be 1 inch in diameter. The ends of the bundle are bonded together and an optical clear plastic is used to pot or glaze the ends of the fiber bundle. Each fiber is insulated with a glass coating having a lower refractive index than the refractive index of the fiber itself, the coating preventing light leaking from one fiber to another. The coating, called cladding, results in every fiber constituting a core which is completely enclosed in its own clad. For example, the core may have a refractive index of about 1.62 and the cladding a refractive index of about 1.52. The entire bundle of fibers is encased in a flexible plastic or aluminum tubing to prevent the crushing or severe bending of the fibers. Each fiber is located in a precise pattern identical at either end, forming an oriented or coherent" bundle. Each fiber transmits a tiny segment of the original image so that the image formed at the entrance face of the bundle is reproduced, as a mosaic, by the image at the exit face. Preferably, the cross-sectional shape of the bundle is rectangular, although other shapes may be used.

As shown in FIG; 2, the circuit includes the power supply 17, the power supply lines 18, 'a modulator circuit 26 and a laser 25. Preferably the laser is a laser which produces a coherent beam of light which is invisible at 9,050 A (IR) and is ofthe order of 5 KW peak wer.

The laser 25 (light amplification by stimulated emission of radiation) is a device which operates in the infrared (invisible) and optical regions by amplification of electromagnetic waves by stimulated emission of radiation. In one type of laser the pumping radiation, for example, from a lamp, is introduced to a group of unexcited atoms in a material, for example, a ruby rod (crystalline aluminum oxide) positioned between a reflecting end plate and an opposed partially reflecting end plate. A wave oriented along the axis between the in the valance band. The energy of recombination corresponds to the band gap and is radiated as optical or infrared light. A suitable semiconductor device uses gallium arsenide having a flat junction between the ntype and p-type materials. The reflecting and partially reflecting plates are the polished ends of the gallium arsenide crystal. The oscillator circuit 26 is a high frequency circuit which pulses, i.e., gates, an electrooptical shutter 34, at a predetermined high frequency, for example, 1 million Hz. A suitable oscillator may be constructed by selecting a high frequency piezoelectric crystal of the desired frequency which controls an oscillator circuit. The piezoelectric crystal can be chosen at the selected oscillator frequency or alternatively the I frequency of the piezoelectric crystal may be above or below the final oscillation frequency in which case the crystal oscillator would have to be either multiplied or divided by known electronic techniques. The output of the piezoelectric crystal oscillator is amplified, for example, by a transistor oscillator of Darlington configuration, and the amplified pulses used to gate or charge the electro-optical shutter.

The ultra-fast pulsing of the light beam is made possible by the shutter 34. Preferably the shutter is an electro-optical device such as a Kerr cell or a laser beam modulator such as the device sold by Lasermetrics lnc., New Jersey, under the name of electro-optic modulator, for example, a Pockells effect crystal. In a Kerr shutter a positive or negative birefringent liquid, such as carbon disulfate, is placed in a thin closed container having flat optically transparent and electrically conductive flat walls. The conductive walls form a condenser or alternatively a transparent condenser is placed in a glass cell of the same liquid. The light beam passes through the plates only when the plates are charged, the electric field causing a rotation of the plane of polarization.

The laser beam 30 goes to a double convex lens 35 which focuses it through a spatial filter 36 and to a collimating lens 37. The lens 35 enlarges the beam to the desired size. The laser beam 30 impinges on a beam splitting mechanism 27 which preferably is a beam splitter having a dichroic coating. The beam is split so that one part 31 goes straight through and a second part 32 is transmitted at a right angle. The straight part 31 goes to an optical shutter which is the high speed pulser.

The right angle beam 32 goes to a collecting lens 33 which is within the container 29. The collecting lens is a double convex lens one of whose sides is optically matched to the optically polished end of the fiber-optic bundle 19.

The theory of operation of the instrument is given below. The wave length of the laser beam is selected so that it penetrates the smoke the required distance. For example, the wave length is selectable by having two or more laser devices only one of which is used, depending upon the characteristics of the smoke. If one laser device is to be used, its wave length may be selected to penetrate the particle size most often found and most difficult to see through, for example, the black smoke characteristic of an oil fire.

The coherent laser beam enters the smoke and the following physical processes occur: (a) some of the light is absorbed by the smoke particles 38 (the dense medium); (b) some of the light is scattered (reflected) by the smoke particles 38. Much of the scattered light is directed, at l80, back to the laser, forming a backscattered" light; (0) some of the light is reflected by the object 39 and is used to view the object.

The major difficulty is that the noise, i.e., the backscattered light, may hinder reception of the signal, i.e., the light reflected from the object, see l-LC. van de Hulst Light Scattering by Small Particles, 1957. The harmful effect of back-scattering is dealt with by the selection of the proper wave length of the laser beam, as discussed above, and by the fast pulsing of the beam.

The high frequency pulsing of the laser beam has been described, in the above embodiment, by means of an electro-optical shutter which is distinct from the lamp, or other energy source, which provides the pumping of the laser. The laser will be pulsed" or pumped by an oscillatory source of energy to produce its coherent beam. The beam will then be pulsed by a shutter at a high frequency. However, modifications may be made in the present invention. For example, instead of a shutter, a modulator may vary the energy of the laser at a high frequency, i.e., the laser beam may vary at a sinusoidal fashion instead of in sequential quantum of light. As another alternative, the pumping frequency of the oscillator energizing the laser may be controlled so that the laser beam is in the form of sequential bursts (quanta) of light, in which event a subsequent shutter is not required.

As another possible change, other image transfer means may be substituted for the fiber bundles. Image intensifying means, such as the high voltage sniperscope, is preferably employed to enhance the clarity of the image, the intensifying means being part of the image transfer means.

For safety and health reasons, it is preferable for the eye not to directly view a coherent laser light beam. Attenuating filters will be interposed in the path of the laser beam directed to the eyepiece to avoid any such harmful effects. Suitable attenuating filters, constructed of chemically treated plastic sheets, to protect the eye from high energy density laser beams, are available from Glendale Optical Co. of Woodbury, N.Y.

We claim:

1. A portable instrument for viewing of objects through a particle laden atmosphere, comprising a face mask containing an eye piece, an optical image transfer means comprising a fiber bundle of oriented strands of glass fiber connected to said eye piece, said eye piece being a bi-focal device in which one portion permits direct viewing and the other portion is optically coupled to said image transfer means; a power source, a laser producing a coherent beam of light, said laser being connected to said power source, optical beam splitting means positioned in said laser beam to divide said laser beam into two differently directed light beams, means to optically couple said optical image transfer means to said beam splitting means to receive the portion of the laser beam reflected from the viewed object, and means to vary the intensity of said laser beam at a high frequency rate, said means to vary the intensity includ-- ing an electro-optical shutter and a high frequency oscillator, both being connected to said power supply and said oscillator gating said shutter.

2. An instrument as in claim 1 wherein the laser is a semiconductor laser.

3. An instrument as in claim 1 wherein said image splitting means is a beam splitter having a dichroic coating.

Claims

1. A portable instrument for viewing of objects through a particle laden atmosphere, comprising a face mask containing an eye piece, an optical image transfer means comprising a fiber bundle of oriented strands of glass fiber connected to said eye piece, said eye piece being a bi-focal device in which one portion permits direct viewing and the other portion is optically coupled to said image transfer means; a power source, a laser producing a coherent beam of light, said laser being connected to said power source, optical beam splitting means positioned in said laser beam to divide said laser beam into two differently directed light beams, means to optically couple said optical image transfer means to said beam splitting means to receive the portion of the laser beam reflected from the viewed object, and means to vary the intensity of said laser beam at a high frequency rate, said means to vary the intensity including an electro-optical shutter and a high frequency oscillator, both being connected to said power supply and said oscillator gating said shutter.

2. An instrument as in claim 1 wherein the laser is a semiconductor laser.