WO1999000343A1

WO1999000343A1 - Laser-ignitable ignition composition and initiator devices and assemblies comprising the same

Info

Publication number: WO1999000343A1
Application number: PCT/US1998/012583
Authority: WO
Inventors: David W. Ewick; Steven L. Olson; Gus Bateas; Scot P. Riley; Daniel A. Toro
Original assignee: The Ensign-Bickford Company
Priority date: 1997-06-30
Filing date: 1998-06-16
Publication date: 1999-01-07
Also published as: AU8148098A

Abstract

A laser-ignitable ignition composition (24, 24a) contains a mixture of explosive material particles and light-absorbing particles wherein the explosive material particles have an average size of less than 4 microns, e.g., an average size of about 1 to 2 microns. The explosive material particles may have a particle size distribution in which about 90 percent of the particles have a diameter less than 2 1/2 times the average particle size. The explosive material particles may be BNCP. The light-absorbing particles may constitute more than about 3 percent by weight of the combined weight of the BNCP and the light-absorbing particles, e.g., about 5 percent by weight. The light-absorbing particles may comprise carbon black. The ignition composition is used in a laser-activated initiator assembly (10) having a casing (10a) having an input end, an output end and a signal train chamber opening to the input end. A header (12) is coupled to the casing to dispose the signal-emitting end of an optical fiber in the chamber. The ignition composition is disposed in the chamber in signal transfer proximity to the signal-emitting end of the optical fiber. The casing (10a) contains an output charge (22) that is sensitive to ignition of the ignition composition.

Description

LASER-IGNITABLE IGNITION COMPOSITION AND INITIATOR DEVICES AND ASSEMBLIES COMPRISING THE SAME

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to laser-ignitable ignition compositions and to laser-activated initiator devices including the same.

Related Art

U.S. Patent 3,724,383, issued on April 3, 1973 to J.A. Gallaghan et al and U.S. Patent 5,179,247, issued on January 12, 1993 to J.D. Hawley, each discloses devices utilizing an optic fiber to transmit energy from a laser in order to initiate an explosive material. U.S. Patent 4,898,095 to Tasaki et al, issued on February 6, 1990, discloses a laser-initiated detonator and teaches that the ignition composition may comprise a secondary explosive that may contain 0.5 to 10% by weight of a light-absorbing material such as carbon black (see column 3, lines 13-28). The carbon black used in an example had a particle size of 30 microns (see column 8, line 55). A paper by E.A. Spomer of Pacific Scientific and TJ. Blachowski of the Indian Head, Maryland Naval Surface Warfare Center, entitled Preliminary Screening Results For An Optical Detonator Utilizing BNCP as the Principle [sic] Energetic Material was published in connection with the 32nd AIAA/ASME/SAE/ASEE Joint Propulsion Conference at Lake Buena Vista, Florida, July 1-3, 1996. This paper dis- closes a detonator which accepts a laser energy input pulse and impinges it upon a mixture of the explosive coordination compound tetraammine-cis-bis (5-nitro-2H- tetrazolato-N ) cobalt (III) perchlorate, below and in the claims referred to as "BNCP", with 3% carbon black which acts as an optical absorber to transform the optical energy into thermal energy. The deflagration-to-detonation transition occurs in the ignition charge and the adjacent BNCP transition charge to the end tip high explosive which, in the illustrated case, is HNS. The particle size of the BNCP particles is not disclosed in this paper and is therefore assumed that it is the standard coarse particle size of about 15 microns diameter.

A paper by R.G. Jungst, F.J. Salas, R.D. Watkins and L. Kovacic, all of Sandia National Laboratories, Albuquerque, New Mexico, entitled Development of Diode La- ser-Ignited Pyrotechnic and Explosive Components was published in conjunction with the proceedings of the Fifteenth International Pyrotechnics Seminar, July 9-13, 1990. This paper discloses that high-power semiconductor diode lasers were used to initiate both a pyrotechnic comprising a mixture of titanium (Ti) and potassium perchlorate (KClO₄), and the DDT explosive CP. The article notes that while diode lasers avail- able at the time of the article could not directly initiate explosives, a detonation output is obtainable from a diode laser source by means of the defiagration-to-detonation transition process. The DDT explosive CP was used in particle sizes of 15 microns and 4-6 microns, and was mixed with carbon black at 1, 5 and 10% carbon black by weight of the mixture. Other dopant materials evaluated for use with CP included LR- 132 (a laser dye from the Eastman Kodak Company which absorbs near the 800 nanometer wavelength in solution) and KTNBC, described as an energetic compound which absorbs strongly at 800 nanometers wavelength. Tests were conducted with physical blends and also coprecipitation of the LR-132 with CP. The coprecipitation was said to produce a smaller CP mean particle size (4 to 6 microns) than standard production material (15 microns), and some of the physical blends were repeated with the 4 to 6 micron particles to determine whether particle size had any effect on the apparent ignition threshold. No significant improvement in results was reported for the smaller particles of CP (see page 559). The test results are stated to show that most of the reduction in laser energy firing threshold from doping occurred at concentrations of the dopant below 1% (the low threshold graphed for 1.4% carbon black being deemed "nonrepresentative") with a general trend slowly downward with increases in dopant levels, and it is concluded that "higher dopant levels can still make modest improvements in threshold. Eventually, inert dopants would be expected to dilute the energetic nature of CP, causing the thresholds to rise again." However, Figure 6 (page 559) shows that carbon black causes the firing threshold to rise at levels over 1% in admixture with CP. A paper entitled BNCP Prototype Detonator Studies Using a Semiconductor Bridge Initiator was published on July 25, 1996 by D.W. Fyfe and J.W. Fronabarger of Pacific Scientific Energy Dynamics Division, Goodyear, Arizona, and R.W. Bickes, Jr. of Sandia National Laboratories, Albuquerque, New Mexico in conjunction with proceedings of the 20th International Pyrotechnics Seminar, Colorado Springs, Colorado (July 25-29, 1996). The paper discloses the development of semiconductor bridge (SCB) detonators utilizing BNCP. BNCP is disclosed as being related to pen- taammine (5-cyano-2H-tetrazolato-N ) cobalt (III) perchlorate, below referred to as "CP". The paper discloses the use of 25 micron and 15 micron BNCP and demon- strates that BNCP undergoes deflagration-to-detonation transition ("DDT") in shorter distances than CP under similar confinement, and that BNCP requires less confinement than CP to provide DDT performance. The 15 micron BNCP was said to be somewhat more sensitive to BNCP initiation than 25 micron BNCP, but it has not been established in the prior art that a similar increase in sensitivity would be seen in a different initiation mechanism such as laser initiation. Two types of devices were tested, both utilizing a semiconductor bridge detonator, generally of the type disclosed in U.S. Patent 4,708,060, issued on November 24, 1987 to Bickes, Jr. et al.

SUMMARY OF THE INVENTION The present invention relates to a laser-ignitable ignition composition comprising a mixture of explosive material particles and light-absorbing particles wherein the explosive material particles have an average size of less than 4 microns. In a particular embodiment, the explosive material particles may have an average size of about 1 to 2 microns. Typically, the explosive material particles may have a particle size^'dis- tribution in which about 90 percent of the particles have a size less than 2 1/2 times the average particle size.

According to one aspect of the invention, the explosive material particles comprise BNCP, and the light-absorbing particles may comprise more than about 3 percent by weight of the combined weight of the explosive material particles and the light-absorbing particles.

The light-absorbing particles may comprise carbon black, which may comprise about 5 percent by weight of a mixture with the BNCP. The invention also pertains to ignition compositions comprising a mixture of BNCP particles having an average size of less than 10 microns, preferably, less than 4 microns, e.g., 1 to 2 microns, and light-absorbing particles. The BNCP particles may have a size distribution such that at least 90%) of the BNCP particles have a size smaller than 2 1/2 times the average size.

The invention also provides a laser-activated initiation device comprising a casing having an input end, an output end and a signal train chamber to the input end thereof. A laser-ignitable ignition composition as described above is disposed within the signal train chamber at the input end of the chamber. There is an output charge disposed within the signal train chamber in signal transfer proximity to the ignition charge so when ignited, the ignition charge in rum initiates the output charge. The output charge may comprise a pyrotechnic material, in which case the assembly is a squib. Alternatively, the output charge may comprise an explosive base charge and a DDT charge, in which case the assembly acts as a detonator. The invention further relates to a laser-activated initiator assembly comprising an optical header comprising an optical device having a signal-emitting end, such as an optical fiber, coupled to an initiation device as described above, for disposing the signal-emitting end so that it can emit a laser signal onto the laser-ignitable ignition composition in the signal train chamber of the device, to ignite the laser-ignitable composition.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic cross-sectional view of a laser-activated initiator assembly comprising a detonator comprising an ignition composition in accordance with a particular embodiment of the present invention; and Figure 2 is a schematic cross-sectional view of a laser-activated initiator assembly comprising a squib comprising an ignition composition in accordance with another particular embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS THEREOF

In one broad aspect, the present invention provides a laser-ignitable ignition composition useful in initiation devices such as detonators and squibs. The ignition composition of the present invention is more easily and, therefore, more reliably ignit- able than prior art compositions, as will be discussed further below.

Typically, a laser-ignitable ignition composition comprises a mixture of particles of an explosive material with particles of a light-absorbing material. To state a minimum, the light-absorbing mixture generally comprises at least about 0.5 weight percent of the mixture. The light-absorbing material absorbs light energy obtained from a laser and converts it to thermal energy that it releases to initiate the explosive material. The ignition compositions of the present invention are distinguished from those taught in the prior art in several ways, including the particle size of the explo- sive material, the specific choice of explosive material, and the quantity of light- absorbing material in the mixture.

One aspect of this invention relates to the discovery that at least one explosive material (BNCP) is significantly more sensitive to laser initiation when it is provided in the form of particles having an average size of less than 10 microns, e.g., particles having a 1 to 2 micron average size. In addition, it was found, contrary to teachings in the art, that ignition sensitivity did increase with proportions of light-absorbing material above 1%> by weight of the ignition composition. Without wishing to be bound by any particular theory, it is believed that this increased sensitivity is due to the relatively high surface area of small-sized particles, which provides more opportunity for heat transfer from the light-absorbing material in the ignition composition. It is further believed that the increase in surface area of the explosive material allows for substantial reduction in threshold firing energy with proportions of light-absorbing materials in excess of 1% by weight of the ignition composition, whereas such proportions of light-absorbing materials yielded little or no improvement in mixtures comprising explosive materials of larger particle size. Accordingly, the invention is believed to relate broadly to laser-ignitable ignition compositions comprising explosive materials in the form of particles smaller than those previously used in the art, e.g., particles having an average size of less than 4 microns.

The stated particle sizes of explosive materials discussed herein refer to the average particle diameter of the identified material as determined by scanning electron microscope analysis. The explosive material from which the limitations of the present invention were deduced had an average particle size of about 1 to 2 microns and was obtained by ball milling larger sized particles having a size distribution of about from 10 to 300 microns. Thus, the particle size distribution of explosive materials used for the present invention correspond to those typically obtained by ball milling larger particles. In a particular sample according to the present invention, BNCP particles having an average particle size of 2 microns had a particle size distribution such that more than 90 percent of the particles had a size of not more than 5 microns (i.e., 2 1/2 times the average). A majority of the particles had sizes less than 2 microns (i.e., the median size was less than the average size).

Laser-ignitable ignition compositions that comprise secondary explosive ma- terials typically comprise a light-absorbing material because most secondary explosive materials are not sufficiently efficient in absorbing laser light to make laser initiation practical. The light-absorbing material absorbs the laser light and converts it to thermal energy that can initiate the explosive material. At least one reactive light- absorbing material is known (see the discussion of light-absorbing KTNBC in the Jungst et al paper mentioned above), but more typically, the light-absorbing material is relatively inert. A typical material for light-absorbing particles for use in a laser- ignitable composition is carbon black, but other light-absorbing materials are known, e.g., graphite, laser dyes, etc. Particles of any conventional laser light-absorbing material known in the art, or combinations thereof, may be used in a composition accord- ing to the present invention. The term light-absorbing particles is intended to encompass all such materials if no specific materials are mentioned.

Generally speaking, the compositions of the present invention are used in laser-activated initiation devices such as laser-activated detonators and squibs. The initiation device is secured to a source of laser light, typically, by coupling to a header secured on one end (the signal-emitting end) of an optical fiber that has at the other end (the signal-receiving end) a source of laser light. The initiation device comprises a casing that contains the ignition composition and that is dimensioned and configured to be coupled to the header to permit the ignition composition therein to receive the laser light. In addition to the ignition composition, the casing contains an output charge. In the case of a squib, the output charge generally comprises a pyrotechnic material such as, e.g., a mixture of titanium and potassium perchlorate; many others are known in the art. In detonators, the output charge generally comprises a secon- dary explosive base charge material. Since the ignition compositions of the present invention react initially to the laser light with a deflagration reaction, a detonator in accordance with the present invention generally comprises a DDT material so that the deflagration is transferred into a detonation signal to initiate the base charge material. The Applicants performed threshold firing tests on ignition compositions comprising using BNCP that had been ball milled to an average particle size of about 1 to 2 microns in admixture with carbon black in proportions of 1, 3 and 5 percent carbon black by weight of the mixtures, respectively. The tests were performed by assembling test detonators containing test ignition compositions and applying laser signals of various power levels to the ignition compositions therein. In this way, the threshold for igniting the mixtures using a 10 millisecond (ms) laser diode pulse of 800 nanometer wavelength was determined. The results were that the 99/1 mixture had an all-fire threshold of 247 milliWatt (mW); the 97/3 mixture had a 208 mW threshold and the 95/5 mixture had a 203 mW threshold. A 97/3 mixture with larger BNCP particles (average 10 microns) had a threshold of 250 mW. These data show that a major threshold reduction occurs between 1 and 3 percent carbon black and that a significant reduction is attained between 3 and 5 percent. This result is surprising in view of the teaching by Jungst et al (discussed above) that little effect would be seen above 1% and that carbon black provided no benefit over 1%>. In addition, despite Jungst et al's teaching that no shift in initiation threshold could be attributed to differences in particle size between CP charges, the Applicants' data show that there is a significant difference in initiation sensitivity between 10 micron and 1 to 2 micron average particle size for BNCP.

A detonator 10 comprising a laser-ignitable ignition composition in accor-^" dance with the present invention is shown as part of the laser- activated initiator assembly, comprising the detonator and a header to which it is coupled, shown in Figure 1. Detonator 10 is shown secured to an optical header 12 within which is secured an optical fiber 14 which has a laser signal-receiving end (not shown) and a laser signal- emitting end. Detonator 10 comprises a casing 10a that comprises a housing 16 and an output cup 18 welded thereto through seal 10b. Housing 16 has an internal bore 20 and cup 18 has an internal volume that communicates with, and thus extends, the internal bore 20 of housing 16 to constitute a casing bore, sometimes also referred to herein and in the claims as a signal train chamber. Detonator 10 contains an output charge 22 in the casing bore, e.g., partially in cup 18 and partially in internal bore 20 of housing 16. A portion of output charge 22 is secured within an output cup 18 that is secured to housing 16. Output charge 22 optionally comprises different materials for providing the DDT function and the detonation output function. The illustrated detonator comprises a DDT charge 22a in housing bore 20 that comprises loosely packed, DDT-grade BNCP and an output charge 22b that comprises a secondary explosive, e.g., hexanitrostilbene (HNS). Any suitable materials for providing the DDT and out- put signal functions may be used, and the DDT charge 22a may optionally comprise the same material as the output charge 22b. Casing 10a also contains a laser-ignitable ignition composition 24 according to the present invention, in the internal bore. For example, composition 24 may comprise ball-milled BNCP particles having an average size of 1 to 2 microns admixed with 5% carbon black by weight of the mixture. Housing 16 is equipped with coupling threads 16a so that the detonator can be coupled to a correspondingly threaded device to be initiated in response to the laser signal.

Optical header 12 and detonator 10 are interconnected via coupling means such as complementary housing threads 26 and header threads 28. Preferably, header 12 is also welded to housing 16 to provide a hermetic seal therebetween, thereby protecting ignition composition from contamination by unwanted environmental contaminants, e.g., moisture. Detonator 10 and header 12 are dimensioned and configured so that when header threads 28 engage housing threads 26, the signal-emitting end of optical fiber 14 will be positioned to emit a laser light into the signal train^' chamber of casing 10a onto ignition composition 24 from a laser signal introduced into the laser-receiving end (not shown) of optical fiber 14, i.e., in signal transfer relation to the ignition charge, preferably with the end of optical fiber 14 in contact with the ignition composition.

Header 12 may be secured onto optical fiber 14 in a manner that avoids plac- ing tensile strain on optical fiber 14. This may include securing header 12 onto a tension-bearing casing disposed about optical fiber 14. In addition, there may be strain- reducing members at the junction of header 12 and optical fiber 14 to prevent kinks and fractures in optical fiber 14 in the region near header 12, as is well-known in the art.

Typically, header 12 is formed from stainless steel and has a bore extending therethrough. The optical fiber is inserted through the bore of header 12 and may be secured therein by a suitable adhesive, e.g., an epoxy adhesive 12a. The output end of header 12 forms a cup or ferrule 12b at its output end that is received by detonator 10. Optical fiber 14 protrudes into ferrule 12b and is secured therein by depositing within the ferrule a pellet 30 comprising a malleable metal, e.g., aluminum. The pellet 30 has a fiber bore therethrough into which the protruding stub of optical fiber 14 may be passed. Once pellet 30 is in place within the header ferrule 12b, pellet 30 is pressed by mechanical means so that it deforms within the ferrule 12b. This action causes a hermetic seal to form between pellet 30 and the end of optical fiber 14 and between pellet 30 and header 12 and leaves pellet 30 exposed at the output end of header 12. Then, the end of fiber 14 is polished. By forming a seal in this way, the need for an adhesive or other sealant material such as epoxy to form a hermetic seal at the end of header 12 is obviated. The exclusion of such adhesive or other sealant is advantageous because these materials have, in prior art devices, been smeared across the end of the optical fiber during the polishing process, thus blocking part of the laser signal emitted from optical fiber 14 and diminishing the function of the device. In addition, the presence of adhesives or sealant materials such as epoxies at the interface with the ignition composition posed issues of chemical compatibility between them; such issues are avoided when those materials are omitted.

While some prior art header devices have made use of aluminum pellets to form a hermetic seal between a steel header and an optical fiber, never before has the aluminum pellet been positioned at the output end of the header so that it helps to enclose the ignition composition and, more significantly, the DDT composition, in a detonator casing. Instead, the pellet was placed deep within the header to establish a seal between the optical fiber and the header. The optical fiber was inserted through a separate steel cup-shaped ferrule that opened towards the DDT material. The stainless steel ferrule helped to provide the containment necessary for prior art DDT materials, e.g., HMX, to achieve the DDT function. Since BNCP is able to achieve DDT function with less confinement than other materials, the present invention provides, in one aspect, a novel header configuration in which the aluminum pellet provides a mating surface with the initiation device and may serve to contain the BNCP DDT charge. While it is possible to load the output charge of an initiation device into the casing before coupling the device to a header, the usual assembly procedure for a header-initiation device assembly involves coupling together the header and the casing before loading the reactive materials in the casing. For example, the assembly of Figure 1 is typically assembled by screwing header 12 into housing 16 via threads 26 and 28 so that the signal-emitting end of optical fiber 14 is open to bore 20 and aluminum pellet 30 bears against the shoulder formed by housing 16. Then, the ignition composition 24 is pressed into bore 20, typically at a compaction pressure of about 20,000 psi. After that, the DDT charge 22a is deposited into bore 20 at, e.g., 10,000 psi, and, optionally, part of the explosive base charge may be added thereto. In any case, bore 20 is filled with reactive material, and then cup 18, filled with a secondary explosive base charge, is welded onto housing 16. Aside from having an aluminum (or other malleable metal) pellet 30 positioned to confine the ignition and DDT charges, optical header 12 is a conventional structure and may be constructed in any suitable manner. Typically, a header for an optical fiber is designed to reduce tensile strain and kinking in the optical fiber by clamping onto a jacket 32 that encases the optical fiber and that can be flared about header 12. Jacket 32 may comprise a woven Kevlar™-type material. Then, a device such as a clamp sleeve 34 may secure jacket 32 to header 12. Should there be relative motion between header 12 and optical fiber 14, the resulting strain could be borne by jacket 32. Clamp sleeve 34 and optical header 12 may be dimensioned and configured so that clamp sleeve 34 can be disposed over jacket 32 and by moving clamp sleeve 34 axially, jacket 32 is secured onto header 12. Such motion may be achieved through the use of a retainer sleeve 38 dimensioned and configured to engage housing 16 when header 12 is in position within housing 16. Retainer sleeve 38 may engage housing 16 so that jacket 32 is appropriately clamped against housing 12.

Figure 2 shows a laser-activated initiation device comprising a squib 40 in ac- cordance with the present invention and an optical header 12 to which squib 40 is coupled. Squib 40 contains a laser-ignitable ignition composition 24a as described above. However, instead of an explosive output charge, squib 40 comprises a defla- gration output charge 42, which may comprise, e.g., a mixture of zirconium and potassium perchlorate. Deflagration output charge 42 may be secured in squib housing 16b by an elastomeric disk 44 and a petal disk 46 welded over housing 16b. Squib 40 is shown carrying an optional O-ring gasket 48 to facilitate a seal with a target device to be initiated by a laser signal. The construction of optical header 12 in squib 40, including the pellet 30, is the same as for the optical header 12 used with detonator 10, and so will not be described here.

While the invention has been described with reference to particular embodiments thereof, it will be understood upon a reading and understanding of the forego- ing that numerous variations and alterations of the described embodiments can be made by one of ordinary skill in the art given the foregoing teachings. For example, the casing of the initiation device may comprise a simple cylindrical shell rather than a housing that includes external threads. It is intended to include such variations and alterations within the scope of the appended claims.

Claims

THE CLAIMSWhat is claimed is:

1. A laser-ignitable ignition composition comprising a mixture of explosive material particles and light-absorbing particles wherein the explosive material particles have an average size of less than 4 microns.

2. The composition of claim 1 wherein the explosive material particles have an average size of about 1 to 2 microns.

3. The composition of claim 2 wherein the explosive material particles have a particle size distribution in which about 90 percent of the particles have a size of less than 2 1/2 times the average particle size.

4. The composition of any one of claim 1, claim 2 or claim 3 wherein the explosive material particles comprise BNCP and wherein the light-absorbing particles comprise more than about 3 percent by weight of the combined weight of the explosive material particles and the light-absorbing particles.

5. The composition of claim 4 wherein the light-absorbing particles comprise carbon black.

6. The composition of claim 5 wherein the light-absorbing particles comprise about 5 percent by weight of the combined weight of BNCP and the light-absorbing particles.

7. A laser-ignitable ignition composition comprising a mixture of explosive material particles comprising a mixture of BNCP particles and light-absorbing particles, the BNCP particles having an average size of less than 10 microns.

8. The composition of claim 7 wherein the BNCP particles have an average size of about 1 to 2 microns.

9. The composition of claim 8 wherein the BNCP particles have a particle size distribution in which about 90 percent of the particles have a size of less than 2 1/2 times the average particle size.

10. The composition of claim 7, claim 8 or claim 9 wherein the light-absorbing particles comprise carbon black.

11. A laser-activated initiation device comprising: a casing having an input end, an output end and a signal train chamber opening to the input end thereof; a laser-ignitable ignition charge in accordance with any one of claims 1, 2, 3, 7, 8 or 9 disposed within the signal train chamber; and an output charge disposed within the signal train chamber in signal transfer proximity to the ignition charge whereby ignition of the ignition charge in turn initiates the output charge.

12. The device of claim 11 wherein the explosive material particles comprise BNCP particles and wherein the light-absorbing particles comprise more than about 3 percent by weight of the combined weight of the BNCP particles and the light- absorbing particles.

13. The device of claim 12 wherein the light-absorbing particles comprise carbon black.

14. The device of claim 13 wherein the light- absorbing particles comprise about 5 percent by weight of the combined weight of BNCP particles and the light- absorbing particles.

15. A laser-activated initiator assembly comprising an optical header comprising an optical device having a signal-emitting end coupled to the device of claim 11 to dispose the signal-emitting end so that it can emit a laser signal onto the laser- ignitable ignition charge.

16. A laser-activated initiator assembly comprising an optical header comprising an optical device having a signal-emitting end coupled to the device of claim 12 to dispose the signal-emitting end so that it can emit a laser signal onto the laser- ignitable ignition charge.

17. A laser- activated initiator assembly comprising an optical header comprising an optical device having a signal-emitting end coupled to the device of claim 13 to dispose the signal-emitting end so that it can emit a laser signal onto the laser- ignitable ignition charge.

18. A laser-activated initiator assembly comprising an optical header comprising an optical device having a signal-emitting end coupled to the device of claim 14 to dispose the signal-emitting end so that it can emit a laser signal onto the laser- ignitable ignition charge.