GB1559665A - Fibre optic sealing device - Google Patents

Description

(54) FIBRE OPTIC SEALING DEVICE (71) I, LORIN ROLLINS STIEFF, of P.O. Box 263, Kensington, Maryland, 20795, United States of America, a citizen of the United States of America, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to a fibre optic sealing device and a security device incorporating such a sealing device. More particularly the invention relates to a tamper-resistant.

field-identifiable device which can be continuously monitored for integrity and identity.

Typically, prior art security seals have employed metal tapes or wires whose ends are joined by one-time-use clasps, interlocking metal or plastic cups or mouldable material carrying an inscribed serial number or other type of identifiable mark. Some types of seals have, in addition, randomly inscribed marks or randomly distributed particles which are photographed prior to use and are re-photographed after the seal has been removed and disassembled. Other seals are identified with the aid of ultrasonic scanners.

Although these types of seals are generally effective, they cannot withstand sustained attack, may be counterfeited, are usuallv not reusable, and cannot be continuously monitored.

Fibre optic seals with juxtaposed and twisted ends are described in US Patent 3.854,792. In devices described in that patent, half of the joined end is illuminated, producing a unique pattern of light on the other half.

One object of the present invention is to provide a tamper-resistant, fibre optic security sealing device which has a unique identity and optical integrity and which can be verified in the field without disassembly or the removal of the seal.

Another object of the invention is to provide a tamper-resistant sealing device which can be applied in a wide variety of hostile environments and which is capable of withstanding sustained attempts to defeat the seal.

A further object of the invention is to provide a sealing device which can be checked in the field by using either visually obtained microscopic data on the position and appearance of individual optic fibres or by using photomicrographic methods to record the fingerprint and decoded image of the line reticle formed by the random distribution of the optical fibres at the end of the bun Ale.

Still another object of the invention is to provide a tamper-resistant sealing device which can be continuously monitored for its optical integrity and identity over sustained periods during which the device will be unattended.

According to the present invention a fibre optic sealing device comprises a block having two intersecting passageways, the passageways having openings in spaced relationship on facial areas d the block and bundle holding means in each passageway of the block, each bundle holding means being arranged to hold a fibre optic bundle in its respective passageway.

The holding means may include mounting means for mounting a portion of a fibre optic bundle in an opening at the end of a passageway in the block.

The mounting means may comprise a collet having an inner bore for receiving a fibre optic bundle, having a first outer portion which engages the wall of the passagewav and a tanered second outer portion with a slit extending from the tapered second outer portion to the bore of the collet, and a collar having an outer portion adapted to fit within the passageway wall and a tapered inner opening for cooperating with the tapered second outer portion of the collet to compress the tapered portion of the collet onto a fibre optic bundle in the bore.

Spreading means is preferably mounted in the passageways near an interset;tion of the passageways in a block for spreading the indivirliial fibres in a fibre optic bundle. The spreading means may comprise an insert having an outer portion arranged to fit in one of the passageways, and having a distal end facing outward in the passageway and having a proximal end near an intersection of the passageways, each insert having a bore extending inward from its distal end and having a spreading channel extending inward from the bore, the channel being generally rectangular in cross section and having a transverse dimension less than a similar transverse diametrical dimension of the bore, whereby fibres in a bundle located in the bore and the channel are spread and fanned outward in the channel. The proxi mal end of a corresponding other insert.

The fibre optic sealing device may include a fibre optic bundle having a first end positioned in one of the passageways, a medial portion extending from the block and a second end remote from the block.

A portion of a first end of a fibre optic bundle may be positioned within an intersection of the passageways in a block, the fibres arranged to receive randomly crossed fibres in interstices between fibres. A terminus of the first end of the bundle is preferably tightly held in a facial opening at the end of a first passageway and a portion of a fibre optic bundle which emerges from an opening at the opposite end of the first passageway is tightly held in that opening.

The free end of the fibre optic bundle has an outer covering removed from a length of the bundle from a remote terminus of the bundle at least as far along the bundle asa distance from an intersection to an opening of a second passageway in the block.

Means may be provided in association with the sealing device for selectively controlling the light source for selected illumination of fibre optic termini at one end of a bundle. This means may comprise a reticle between a light source and fibre termini and means for moving the reticle.

The reticle mav have an opaque line diametrically positioned across an optical axis connecting a light source and a medial portion of fibre termini, the line being slightly wider than a fibre diameter. and a rotatable wheel on which the retical is positioned.

The fibre optic sealing device may include a fibre oDtic bundle with a p]uralitv of coextensive and coterminal optical fibres held other with portions of the fibre near one end of the bundle threaded between nortions of the fibres near the opposite end of the bundle in random arrangement, means to bold senaratelv first and second remote termini of the bundle of fibres, means for ir'trndiicing light into the first termini.

and means for observing light in the second termini. and means for predeterminately interrupting light in the first termini and means for recording locus - of fibre ends in the second termini showing characteristics of interrupted light An advantage of the invention is that the identity and optical integrity of the sealing device can be established in the field without removal or disassembly of the seal and also the device can be continuously monitored in the field for its optical integrity and identity, and, if desired, an encoded status report on the seal transmitted to headquarters.

Another advantage of this sealing device is that it is easily and quickly installed during field operations and that it is reusable and that it can be easily applied in a wide variety of situations.

It will be appreciated that the device can employ either commercially available or specially prepared glass or plastic fibre bundles, and a metal or plastic fibre locking assembly. This assembly holds the fibre bundle securely in place against accidental disassembly and includes mechanism for assuring complete mutual interpenetration of the fibres at each end of the bundle.

To make a seal, an appropriate length of fibre optic bundle material is cut; two tapered collars are placed on the fibre bundle neach each end, and approximately 1.25" of the protective plastic jacket is removed from each end of the bundle. One of the stripped ends of the fibre bundle is then fully inserted into one of two cylindrical holes in the bottom edge of the fibre sealing device and is secured by seating the tapered collar. The free end is then similarly inserted in the remaining cylindrical hole and secured.

The internal components of the fibre locking assembly block are designed to flatten the stripped fibre bundle ends into a fan shaped array of fibres so that the fibres from one end of the bundle may easily intersect and pass randomly in between the fanned fibres of the other end. The ends of the fibres above the intersection will now appear in the cylindrical holes at the top or exit edge of the assembly block. The fibres in the two fans are then recombined into two individual bundles by modified tapered collars analogous to those used to secure the jacketed fibre bundle at the base of the sealing device. These tapered collars hold the loose fibres firmly in place at the top edge of the seal. The identitity of the seal is established in the field by using a small, hand-held microscope and illuminator.

The completely assembled seal is placed in the indexing stage of the field microscope. One end of the fibre optic bundle is illuminated by light from a pen-sized flashlight through a 60 degree prism or mirror.

All of the fibre ends are illuminated by this reflected light with the exception of those fibres lying directly under a reticle contain inz at least one opaque line whose width is approximately equal or slightly larger than the diameter of the optic fibres used in the fibre bundle. This recticle may be rotated through an angle of 1180 degrees with its centre of rotation coinciding with the geo metric centre of the bundle. In this manner the light entering every fibre in the bundle may be controlled. A provision is made for measuring the angle of rotation of this reticle. The light transmitted through the fibres and emerging at the opposite end of the bundle is magnified and optically examined with the field microscope. The angular position and radial distance from the centre of the field of view of the microscope (i.e. the polar coordinates r, IB) of a selected, small set of individual fibres may be measured using the eyepiece reticle and recorded along with the seal's serial number.

This position data may be supplemented by additional observations on the size, colour, imperfections, and optical transmission properties of the individual fibres. Such data obtained on a small. well dispersed number of fibres (approximately 5) should be sufficient to uniquely identify a seal and should provide reasonable assurance that substitution or counterfeiting of a seal could not go undetected, Alternatively, a photomicrograph may be taken of the random pattern formed by the fibre ends in the field of view of the microscope using a Polaroid (R.T.M.) or film camera. The photographic procedure is recommended where the highest level of confidence is required and when it must be determined that a seal left unattended and unexamined for significant intervals of time has not be compromised.

The security of this type of fibre optic seal depends upon: (1) the unique fingerprint which is generated by the totally random pattern at the ends of the fibre optic bundle, (2) the unique scrambled or decoded image of the line reticle introduced at the illuminated end of the fibre bundle, (3) the ability to verify the optical continuity of every fibre in the bundle, (4) the necessity to completely destroy the fingerprint during disassembly, (5) the formidable problem which would be encountered in any effort to duplicate this unique fingerprint, and (6) the equally formidable problem of re-establishing the light transmitting capability of the individual fibres interrupted in the process of cutting the fibre bundle.

If there is a requirement to continuously monitor a fibre optic seal, the fibre locking assemblv block mav be inserted into a solid state monitoring device. The monitor contains a pulsed LED light source which is used to illuminate one end of the fibre bundle. a Dhoto-transistor circuit which detects the light transmitted through the fibre optic loop. and a microprocessor with the necessary associated components to generate and display. or transmit on demand a time ordered random number. Interruption of the light transmitted through the fibre optic bundle, harassment of the electronic monitor, or electronic failure will clear the random number generator with only the last undisturbed number remaining in the memory of the unit. These electronic components are housed in a small, secure, tamper-indicating container. The order of the random number generated within the monitor is known only to the organisation which has installed the seal. The random number sequence generated by each seal is, of course, also unique to that seal alone.

The random number generated by the monitor may be displayed on demand to either the inspector, the facility operator where the seal is installed, or the number may be transmitted to the organisational headquarters.

In order that the invention may be readily understood one example of a sealing device in accordance with the invention and such a device incorporated in a security device will now be described with reference to the accompanying drawings in which: Figure 1 shows a schematic view of the field identifiable field optical security device incorporating a fibre optic sealing device in accordance with the invention, Figure 2 is a view of an assembled sealing device including a fibre locking assembly block and a fibre optic bundle, Figures 3 and 4 show a hand-held microscope, illuminator, seal and fibre locking assembly block in more detail, and Figure 5 is an exploded view, showing the internal construction of the fibre locking assembly block of the sealing device.

Referring now to the drawings, Figures 1 to 4 show a field assembled, fibre optic sealing device 1, fibre optic bundle 2 and fibre-locking block assembly 4 inserted in the indexing stage 6 of the hand-held field microscope 8 and illuminator 10 and the camera 12 used to take an identification photo micrograph.

To assembly the device 1 the following operations are performed: an appropriate length of fibre optic bundle material is cut to the length required to apply the seal. Two tapered collars 14 and 16, as shown in Figures 3 and 5, are inserted over the ends of the fibre optic bundle. Approximately 1+ inch of a plastic jacketing surrounding the fibre optic bundle is removed from each end of the bundle. One end 20 of the fibre optic bundle 2 is fully inserted into one of the openings 22 in a bottom face 24 of the fibre locking assembly block 4. A tapered collar 14 is securely seated into one passageway 26. The free end of the fibre optic bundle is threaded through the object to be sealed and is then inserted into the remaining cylindrical passageway 28 in block 4. The tapered collar 16 is seated and secured. On completion of these steps the fibre optic bundle 2 is now firmly held in place by the tapered collars 14 and 16. The interior components 30, 32, 34 and 36 of the fibre locking assembly block (shown in Figure 5) flatten the optical fibres permiting them to easily intersect at interaction 40 and pass through each other and through openings 42 and 46 at the opposite faces 44 and 48 of the fibre locking block 4.

The seal is completed by inserting and firmly seating the tapered collars 50 and 52 in the top openings 42 and 46 of the top faces 44 and 48 of the assembly block 4.

This operation brings the fanned fibres termini 54 and 56 into two circular bundles and holds them securely in place.

The identity and optical integrity of the device is established in the field by inserting the fibre locking block 4 of the completed seal into the indexing stage 6 of the hand held microscope illuminator 8 and 10. The symmetry of the fibre locking assembly block permits either bundle end to be observed under the microscope 8. The orientation of the fibre licking assembly may be determined by the presence of the symbol such as "+" 58 in a viewing port 60 on the side of the indexing stage 6. The opposite end of the fibre optic bundle is illuminated through a 60 degree prism 62 by a small pen-sized flashlight 10. A reticle 64 lies in a plane between the light source 10 immediately above the ends of the fibre bundle being illuminated. The reticle 64 contains at least one inscribed, opaque line 66 whose width is equal or slightly greater than diameters of the fibres used in the fibre bundle 2. This reticle may be rotated through 180 degrees and the reticle holder 68 is appropriately indexed so that it is possible to measure the angle of rotation of the reticle 64. Rotation of the reticle 64 permits the controlled illumination of every fibre in the bundle. In addition, the image of this line reticle transmitted by the fibre optic bundle will be scrambled or decoded at the opposite end of the bundle because of the random orientation of the fibres in the two ends of the fibre optic bundle. Under the microscope the line image will appear as a series of randomly distributed, darkened fibres, which will resume light transmission as the reticle is rotated.

The magnification and the field of view of the hand-held microscope is adjusted so that all of the fibres at the light transmitting end of the bundle can be observed. The eye piece 70 of the microscope 8 is equipped with an additional, rotatable reticle 72, with which the observer may measure width the distance of a single fibre from the centre of the field of view of the microscope as well as the angle through which the reticle must be rotated from a fixed, indexed point in order to intersect the image of the fibre end. To identify a seal, the observer notes the polar coordinates of a small selected number of fibres whose illumination can be controlled by the rotatable line reticle 64.

The position of the line reticle may be fixed at 0 or it may be set at some other predetermined angle by the observer. A serial number on the block and the reticle degree are recorded in a notebook. The observer then measures for the specifically darkened fibre, the radial distance from the centre of the field of view and angle of the fibre from the 0 point, using the reticle in the eye piece of the microscope. This information is also recorded in the same field notebook. In addition to the polar coordinates of this particular group of fibres, the observer may in addition record information on the size, colour, imperfections in the fibre ends and the light transmitting properties of the fibres.

On a subsequent visit the identity and optical integrity of the seal is re-established by inserting the seal into the stage of the hand- held microscope and re-confirming the polar coordinates data and characteristics previously recorded at the time that the seal was assembled.

For certain seal applications, it may be desirable to supplement the type of information obtained using the illumination and eye piece reticles by making a photo micrograph of all of the fibres in the end of the bundle being observed. This photo micrograph may be made by attaching camera 12 fitted with an adapter 74 to the microscope occular. It is recommended that if a Polaroid camera is to be used for the initial photo micrograph taken immediately after the assembly of the seal, Type 105PIN film be used in order that a negative of the fibre bundle image may be obtained. This negative is then marked with the serial number of the seal, the angular position of the line reticle, and is filed for future reference. On subsequent occasions when the identity and integrity of the seal must be checked, a Polaroid (R.T.M.) positive print is made and the original negative is placed over the positive print. Even extremely small variations in fibre position, shape imperfection and light transmitting properties can be detected in this manner. The probability that this degree of replication can be counterfeited is highly unlikely and therefore this seal represents a maximum level of protection.

The present fibre optic sealing device design can, if the situation requires, be sup plemented by an electronic monitor which continuouksly checks the optical integrity and the identity of the device during periods when the seal must be left unattended. The condition of the seal may be reported oa a fixed schedule by the host facility where the seal has been applied and checked by an inspector during a routine inspection.

It is possible that the output of the monitor can be transmitted directly to the headquarters of the inspecting agency if very prompt notification of a seal failure or of an attempt to remove the seal is required.

As shown in Figure 5, tapered collars 14, 16, 50 and 52 have two parts a collet 76 and a collar 90. Bore 78 receives fibre optic bundle 2 and outer wall 80 engages an inner wall of the passageway. Tapered portion 82 has a slit 84 which extends through 6 bore 78. Collar 90 has an outer wall which tightly (interference fit) engages the inner cylindrical wall of passageway 26. Slope 94 is a few degrees different than the slope of taper 82. Consequently, when collar 90 is forced inward, taper 82 compresses to decrease bore 78, gripping bundle 2. Fibre spreading inserts 96 have faces 98, which abut collets 76, and internal faces 100 which are configured to abut and interengage similar internal faces. Tapers 102 direct fibres in bundles 2 into spreading channels 1f)4, which extend across the inserts in one direction, and which are laterally restricted in a transverse direction. The combined inserts fan fibres at their intersection, facilitating random interspersions of the fibre ends in interstices between previously inserted fibres.

Internal tapers 106 and external slopes 108 assure correct interfitting of the inserts.

WHAT I CLAIM IS:- 1. A fibre optic sealing device comprising a block having two intersecting passageways within the block, the passageways having openings in spaced relationship on facial areas of the block and bundle holding means in each passageway of the block, each bundle holding means means being arranged to hold a fibre optic bundle in its respective passageway.

2. A fibre optic sealing device as claimed in Claim 1, wherein the holding means includes mounting means for mounting a portion of a fibre optic bundle in an opening at the end of a passageway in the block.

3. A fibre optic sealing device as claimed in Claim 2, wherein the mounting means comprises a collet having an inner bore for receiving a fibre optic bundle, the collet having a first outer portion which engages the wall of the passageway and a tapered second outer portion with a slit extending from the tapered second outer portion to the bore of the collet and a collar having an outer portion adapted to fit within the passageway wall and a tapered inner opening for cooperating with the tapered second outer portion of the collet to compress the tapered portion of the collet onto a fibre optic bundle in the bore.

4. A fibre optic scaling device as claimed in any preceding claim and including spreading means mounted in the passageways near an intersection of the passageways and each arranged to receive a fibre optic bundle and to orient the individual fibres in each bundle in a laterally spread position.

5. A fibre optic sealing device as claimed in Claim 4, wherein the spreading means comprises an insert having an outer portion arranged to fit in one of the passageways, and having a distal end facing outward in the passageway and a proximal end near the intersection of the passageways, each insert having a bore extending inward from its distal end and having a spreading channel extending inward from its distanl end and having a spreading channel extending inward from the bores, the channel being generally rectangular in cross section and having a transverse dimension less than a similar transverse diametrical dimension of the bore, whereby fibres in a bundle located in the bore and the channels are spread and fanned outward in the channel.

6. A fibre optic sealing device of Claim 5 wherein the proximal end of each insert is shaped so as to interengage and abut the proximal end ^ of the corresponding other insert.

7. A fibre optic sealing device as claimed in any preceding claim wherein the holding means include clamping means for clamping the free end of a fibre optic bundle at the opening of a passageway.

8. A fibre optic sealing device as claimed in any preceding claim wherein the block is generally angular in configuration with first and second major parallel faces connetced by angularly related side faces, with opposite side faces being generally parallel and wherein the passageways extend through the block with openings in opposite side faces.

9. A fibre optic sealing device as claimed in any preceding claim and including a fibre optic bundle having a first end positioned in one of the passageways, a medial portion extending from the block and a second end remote from the block.

10. A fibre optic sealing device as claimed in Claim 9 wherein a portion of the first end of the fibre optic bundle which is positioned within an intersection of the passageways in the block comprises fibres arranged to receive randomly crossed fibres in interstices between fibres.

11. A fibre optic sealing device as claimed in Claim 9 or 10 wherein a terminus of the first end is tightly held in a facial opening at the end of the first passageway and wherein a portion of the fibre optic bundle which emerges from an opening at the opposite end of the first passageway is tightly held in that opening.

12. A fibre ontic sealing device as claimed in any of Claims 9, 10 or 11 wherein the free end of the fibre optic bundle has

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (21)

**WARNING** start of CLMS field may overlap end of DESC **. It is possible that the output of the monitor can be transmitted directly to the headquarters of the inspecting agency if very prompt notification of a seal failure or of an attempt to remove the seal is required. As shown in Figure 5, tapered collars 14, 16, 50 and 52 have two parts a collet 76 and a collar 90. Bore 78 receives fibre optic bundle 2 and outer wall 80 engages an inner wall of the passageway. Tapered portion 82 has a slit 84 which extends through 6 bore 78. Collar 90 has an outer wall which tightly (interference fit) engages the inner cylindrical wall of passageway 26. Slope 94 is a few degrees different than the slope of taper 82. Consequently, when collar 90 is forced inward, taper 82 compresses to decrease bore 78, gripping bundle 2. Fibre spreading inserts 96 have faces 98, which abut collets 76, and internal faces 100 which are configured to abut and interengage similar internal faces. Tapers 102 direct fibres in bundles 2 into spreading channels 1f)4, which extend across the inserts in one direction, and which are laterally restricted in a transverse direction. The combined inserts fan fibres at their intersection, facilitating random interspersions of the fibre ends in interstices between previously inserted fibres. Internal tapers 106 and external slopes 108 assure correct interfitting of the inserts. WHAT I CLAIM IS:-

1. A fibre optic sealing device comprising a block having two intersecting passageways within the block, the passageways having openings in spaced relationship on facial areas of the block and bundle holding means in each passageway of the block, each bundle holding means means being arranged to hold a fibre optic bundle in its respective passageway.

2. A fibre optic sealing device as claimed in Claim 1, wherein the holding means includes mounting means for mounting a portion of a fibre optic bundle in an opening at the end of a passageway in the block.

3. A fibre optic sealing device as claimed in Claim 2, wherein the mounting means comprises a collet having an inner bore for receiving a fibre optic bundle, the collet having a first outer portion which engages the wall of the passageway and a tapered second outer portion with a slit extending from the tapered second outer portion to the bore of the collet and a collar having an outer portion adapted to fit within the passageway wall and a tapered inner opening for cooperating with the tapered second outer portion of the collet to compress the tapered portion of the collet onto a fibre optic bundle in the bore.

4. A fibre optic scaling device as claimed in any preceding claim and including spreading means mounted in the passageways near an intersection of the passageways and each arranged to receive a fibre optic bundle and to orient the individual fibres in each bundle in a laterally spread position.

5. A fibre optic sealing device as claimed in Claim 4, wherein the spreading means comprises an insert having an outer portion arranged to fit in one of the passageways, and having a distal end facing outward in the passageway and a proximal end near the intersection of the passageways, each insert having a bore extending inward from its distal end and having a spreading channel extending inward from its distanl end and having a spreading channel extending inward from the bores, the channel being generally rectangular in cross section and having a transverse dimension less than a similar transverse diametrical dimension of the bore, whereby fibres in a bundle located in the bore and the channels are spread and fanned outward in the channel.

6. A fibre optic sealing device of Claim 5 wherein the proximal end of each insert is shaped so as to interengage and abut the proximal end ^ of the corresponding other insert.

7. A fibre optic sealing device as claimed in any preceding claim wherein the holding means include clamping means for clamping the free end of a fibre optic bundle at the opening of a passageway.

8. A fibre optic sealing device as claimed in any preceding claim wherein the block is generally angular in configuration with first and second major parallel faces connetced by angularly related side faces, with opposite side faces being generally parallel and wherein the passageways extend through the block with openings in opposite side faces.

9. A fibre optic sealing device as claimed in any preceding claim and including a fibre optic bundle having a first end positioned in one of the passageways, a medial portion extending from the block and a second end remote from the block.

10. A fibre optic sealing device as claimed in Claim 9 wherein a portion of the first end of the fibre optic bundle which is positioned within an intersection of the passageways in the block comprises fibres arranged to receive randomly crossed fibres in interstices between fibres.

11. A fibre optic sealing device as claimed in Claim 9 or 10 wherein a terminus of the first end is tightly held in a facial opening at the end of the first passageway and wherein a portion of the fibre optic bundle which emerges from an opening at the opposite end of the first passageway is tightly held in that opening.

12. A fibre ontic sealing device as claimed in any of Claims 9, 10 or 11 wherein the free end of the fibre optic bundle has

an outer covering removed from a length df the bundle from a remote terminus of the bundle at least as far along the bundle as a distance from an intersection to an opening of the second passageway in the block.

13. A fibre optic sealing device as claimed in any preceding claim and further including means for mounting the block in a holder with one opening of each passageway extending toward the holder, and wherein the holder has means for communicating a light source with one opening of the block.

14. A fibre optic sealing device as claimed in Claim 13 wherein the means for communicating a light source includes selective means for controlling the light source for selective illumination of optic fibre termini in the one opening.

15. A fibre optic sealing device as claimed in Claim 14 wherein the selective means comprises means for interposing a reticle between the light source and the fibre termini and means for moving the reticle.

16. A fibre optic sealing device as claimed in Claim 15 wherein the reticle comprises a opaque line diametrically positioned across an optical axis connecting a light source and a medial portion of fibre termini and wherein the means for moving the reticle is positioned.

17. A fibre optic sealing device as claimed in any of Claims 1 to 8 and including a fibre optic bundle having a plurality of coextensive and coterminal optical fibres held together with portions of the fibre near one end of the bundle threaded between portions of the fibres near the opposite end of the bundle in random arrangement, means to hold separately first and second remote termini of the bundle of fibres, means for introducing light into the first termini, and means for observing light in the second termini, and means for predeterminately interrupting light in the first termini and means for recording locus of fibre ends in the second termini showing characteristics of interrupted light.

18. A fibre optic sealing device as claimed in Claim 17 wherein the means for interrupting light comprises movable reticle means positioned between a light source and the first termini.

19. A fibre optic sealing device as claimed in Claim 19 wherein the movable reticle means comprises an opaque area on a transplant portion of a wheel mounted for rotation in a light path between the light source and the first termini.

20. A fibre optic sealing device substantially as hereinbefore described with reference to Figures 2 and 5 of the accompanying drawings.

21. A fibre optic sealing device incorporated in a security device substantially as hereinbefore described with reference to Figures 1, 3 and 4 of the accompanying drawings.