(19)
(11)EP 2 556 393 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
19.02.2020 Bulletin 2020/08

(21)Application number: 11766782.4

(22)Date of filing:  08.04.2011
(51)International Patent Classification (IPC): 
G02B 3/00(2006.01)
G02B 27/02(2006.01)
G02B 6/02(2006.01)
G01S 3/00(2006.01)
(86)International application number:
PCT/US2011/031698
(87)International publication number:
WO 2011/127355 (13.10.2011 Gazette  2011/41)

(54)

BULLET LENS DESIGN FOR THE DASAL SEEKER

KUGELFÖRMIGER LINSENENTWURF FÜR EIN DASAL-SUCHGERÄT

MODÈLE DE LENTILLE EN FORME DE BALLE POUR CHERCHEUR LASER DASALS


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 08.04.2010 US 321893 P

(43)Date of publication of application:
13.02.2013 Bulletin 2013/07

(73)Proprietor: BAE Systems Information and Electronic Systems Integration Inc.
Nashua, NH 03062 (US)

(72)Inventors:
  • CHOINIERE, Michael J.
    Merrimack, New Hampshire 03054 (US)
  • BOWER, Chris M.
    Nashua, New Hampshire 03063 (US)
  • LYNCH, James R. III
    Amherst, New Hampshire 03031 (US)
  • WAY, Carl Alan
    Nashua, New Hampshire 03062 (US)
  • HATCH, Marcus
    Waltham, Massachusetts 02452 (US)

(74)Representative: BAE SYSTEMS plc Group IP Department 

Farnborough Aerospace Centre Farnborough Hampshire GU14 6YU
Farnborough Aerospace Centre Farnborough Hampshire GU14 6YU (GB)


(56)References cited: : 
EP-A1- 0 699 450
JP-A- 61 018 904
JP-A- 2007 132 792
US-A- 5 953 477
JP-A- 61 018 904
JP-A- 63 168 058
US-A- 5 138 677
US-A1- 2006 045 444
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    RELATED APPLICATIONS


    FIELD OF THE INVENTION



    [0001] The invention relates to apparatus and methods for uniform angle resolution over the entire FOV.

    BACKGROUND OF THE INVENTION



    [0002] The known collection optic assembly illustrated in Figures 1 and 2, consists of a barrel spherical collection lens 9 and seven bundles of fiber optic strands 11, each bundle 11 dedicated to a specific photon sensing detector (not shown). Each fiber bundle 11 contains over 1000 fiber optic strands. One fiber optic bundle 13 is located in the center of the six surrounding bundles 15. All seven fiber optic bundles 11 are pre-cast and end polished to precision diameters prior to assembly. This center bundle 13 is aligned to the system boresight axis. In the such a configuration, these six surrounding bundles are spaced at 60° with respect to each other and inclined at 14 ° with respect to the center bundle.They are also sized and positions to be in tangential contact to the center bundle and to each other. These bundles are epoxied into a ferrule (not shown) having precision sized gap and precision angled holes. Precision ferrules, fixtures and skilled technicians are required to properly fabricate and assemble the collection optic assembly. As illustrated in Figure 2, significant space is left in the ferrule between the bundles 13,15 to allow for the correct orientation with respect to the barrel lens 9. In this previous configuration, it was necessary to maintain a precision air gap 17 between the polished ends of the seven fiber bundle to the rear surface of the collection lens within +/- .00254 cm (.001 inches) or less.

    [0003] The previous design yielded poor gain curve performance in the center of the field of view (FOV), thereby resulting in poor angle resolution. This was a key system performance parameter of seekers since most weapon systems typically track in the center of the FOV at the termination range.

    [0004] Expensive component costs and fixture costs. Difficult assembly requiring skilled technicians. High number of assembly process steps.

    [0005] What is needed, therefore, are techniques to optimize the seeker gain curves to generate a uniform angle performance over the 14 degree linear field of view (FOV). Published application document EP 0 699 450 A1 discloses an endoscopic apparatus comprising a bullet collection lens and a fibre optic bundle. Patent abstract of Japan 61018904 discloses a terminal member comprising thin wall shrink sleeves and a collar disposed around a plurality of fibre optic bundles.

    SUMMARY OF THE INVENTION



    [0006] One embodiment of the present invention provides an optic assembly, the assembly comprising, a bullet collection lens having a curved end and a flat end, a plurality of fiber optic fiber bundles, and the fiber optic bundles being parallel to a central channel and abutting a flat side of the bullet collection lens,
    further comprising thin wall shrink sleeving disposed around each fiber optic bundles in the plurality of fiber optic bundles,
    a collar disposed around the plurality of fiber optic bundles.
    wherein the collar is disposed proximate to an end of the plurality of fiber optic bundles, and the end of the plurality is polished and flush with the collar.

    [0007] A yet further embodiment of the present invention provides such an optical assembly wherein the bullet lens is configured to optimize a spot size being ported to fibers within the plurality of fiber optic fiber bundles.

    [0008] Still another embodiment of the present invention provides such an optical assembly wherein each fiber optic bundle comprises a plurality of fiber optic fibers surrounded by a conformable sleeve.

    [0009] A still further embodiment of the present invention provides such an optical assembly wherein the plurality of fiber optic bundle comprises seven fiber optic bundles.

    [0010] One embodiment of the present invention provides a method for the manufacturing of an optical assembly; the method comprising: assembling a plurality of fiber optic bundles within a collar, including a thin wall shrink sleeving disposed around each fibre optic bundle; aligning ends of bundles within the plurality of fiber optic bundles with each other such that the ends of bundles are substantially coplanar; polishing the ends of bundles flush to the collar; applying the ends to a flat surface of a bullet collection lens, the bullet collection lens having a curved end and a flat end.

    [0011] Another embodiment of the present invention provides such a method further comprising inspecting the plurality of fiber optic bundles after the assembling a plurality of fiber optic bundles

    [0012] A further embodiment of the present invention provides such a method, the method further comprising inspecting aligned ends of the bundles.

    [0013] Yet another embodiment of the present invention provides such a method, the method further comprising inspecting the ends once polished flush with the collar.

    [0014] A yet further embodiment of the present invention provides such a method further comprising inspecting the optical assembly once completed.

    BRIEF DESCRIPTION OF THE DRAWINGS



    [0015] 

    Figure 1 is a diagram illustrating a prior art optic assembly.

    Figure 2 is a diagram illustrating a plan view of a prior art optic assembly.

    Figure 3 is a elevation view illustrating an optic assembly configured in accordance with the main embodiment of the present invention.

    Figure 4 is a plan view illustrating a cross section of an optic assembly configured in accordance with the main embodiment of the present invention.

    Figure 5 is a flowchart of a method for manufacturing an optical assembly configured according to another main embodiment of the present invention.


    DETAILED DESCRIPTION



    [0016] The main embodiment of the present invention, illustrated in Figure 3 provides a bullet collection lens 12 having a curved end 14 and a flat end 16. A plurality of fiber optic bundles 18 are collected into a collar 20. Bundles 18 are formed by many optical fibers 22 surrounded by a conformable sheath or sleeving 24. The collar 20 compresses the bundles 18 together, deforming the rounded bundles 18 into a "flower" shaped cross section illustrated in Figure 4. The fiber bundles 18, are aligned such that they have a flat end. The end of the now assembled plurality of fiber bundles is polished flush to the collar 20 allowing for a smooth joint to the flat surface of the bullet collection lens 12. The fiber optical bundles 18 are abutted to the flat surface 16 of the bullet lens at their polished end flush with the collar 20. The bundles 18 may be secured to the collar 20 and to the ends of the fiber bundles 18. The bundles 18 are thus in contact with the lens 12 in a way that is substantially free of gaps.

    [0017] The previous design rejected energy in the surrounding bundles (the energy exceeded the NA limits of the fibers), resulting in flat gain curves at the center of the FOV. In contrast to the previous design, bullet lens, by collecting all the energy, provides a uniform transform between amplitude and angle space, thus excellent angle response over the FOV of the seeker.

    [0018] By altering the lens design from the spherical lens to the bullet lens, and by making the surrounding bundles parallel to the center channel, the numerical aperture (NA) of the fibers are now matched with the bullet lens performance.

    [0019] As illustrated in Figure 5, the system is produced by a method comprising several steps. The optical fiber bundles are assembled with a conformable sleeve 32. The bundles thus formed are aligned within the collar such that the end of the bundle is flush with the surface of the collar 34. The ends are polished 36 and the polished ends of the assembly are coupled to the bullet lens 38. After each step in the process, inspection 40, 42, 44 may occur allowing for improved quality control.

    [0020] An additional benefit of the bullet lens design was: it simplified the fabrication of the fiber bundles and the assembly of the system. The fiber bundles are constructed as a grouping rather as separate bundles, reducing the fabrication time. The assembly process of the fiber bundles to the lens requires multiple fabrication steps to set the lens spacing and the orientation of the fibers to the lens. The bullet lens design simple allows the fibers to be ganged together and butted to the base of the bullet lens.


    Claims

    1. An optic assembly, said assembly comprising:

    a bullet collection lens (12) with a curved (14) and a flat (16) end;

    a plurality of fiber optic fiber bundles (18); and

    said fiber optic bundles being parallel to a central channel and abutting a flat side of said bullet collection lens,

    further comprising thin wall shrink sleeving (24) disposed around each fiber optic bundles in said plurality

    of fiber optic bundles,

    a collar (20) disposed around said plurality of fiber optic bundles,

    wherein said collar is disposed proximate to an end of said plurality of fiber optic bundles, and said end of said plurality is polished and flush with said collar.


     
    2. The optic assembly of claim 1, wherein each said fiber optic bundle comprises a plurality of fiber optic fibers surrounded by a conformable sleeve.
     
    3. The optic assembly of claim 1 wherein said plurality of fiber optic bundle comprises seven fiber optic bundles.
     
    4. A method for the manufacturing of an optical assembly; said method comprising:

    assembling a plurality of fiber optic bundles (18) within a collar (20), including a thin wall shrink sleeving (14) disposed around each fiber optic bundle;

    aligning ends of bundles within said plurality of fiber optic bundles with each other such that said ends of bundles are substantially coplanar;

    polishing said ends of bundles flush to said collar applying ends to a flat surface of a bullet collection lens (12), the bullet connection lens having a curved end (14) and a flat end (16).


     
    5. The method of claim 4, said method further comprising inspecting said plurality of fiber optic bundles after said assembling a plurality of fiber optic bundles.
     
    6. The method of claim 4, said method further comprising inspecting aligned ends of said bundles.
     
    7. The method of claim 4, said method further comprising inspecting said ends once polished flush with said collar.
     
    8. The method of claim 4 further comprising inspecting said optical assembly once completed.
     


    Ansprüche

    1. Optische Anordnung, wobei die Anordnung umfasst:

    eine Bullet-Sammellinse (12) mit einem gekrümmten (14) und einem flachen (16) Ende;

    eine Mehrzahl von faseroptischen Faserbündeln (18); und

    wobei die faseroptischen Bündel parallel zu einem mittigen Kanal und an einer flachen Seite der Bullet-Sammellinse anliegen,

    ferner umfassend einen dünnwandigen Schrumpfschlauch (24), der um jedes faseroptische Bündel in der Mehrzahl von faseroptischen Bündeln angeordnet ist,

    einen Kranz (20), der um die Mehrzahl von faseroptischen Bündeln angeordnet ist,

    wobei der Kranz nahe einem Ende der Mehrzahl von faseroptischen Bündeln angeordnet ist, und das Ende der Mehrzahl poliert und mit dem Kranz bündig ist.


     
    2. Optische Anordnung nach Anspruch 1, wobei jedes faseroptische Bündel eine Mehrzahl von faseroptischen Fasern umfasst, die von einer konformen Hülse umgeben sind.
     
    3. Optische Anordnung nach Anspruch 1, wobei die Mehrzahl von faseroptischen Bündeln sieben faseroptische Bündel umfasst.
     
    4. Verfahren zur Herstellung einer optischen Anordnung, wobei das Verfahren umfasst:

    Zusammenlegen einer Mehrzahl von faseroptischen Bündeln (18) innerhalb eines Kranzes (20), umfassend einen dünnwandigen Schrumpfschlauch (14), der um jedes faseroptische Bündel angeordnet ist;

    Ausrichten von Enden von Bündeln innerhalb der Mehrzahl von faseroptischen Bündeln miteinander, derart dass die Enden von Bündeln im Wesentlichen koplanar sind;

    Polieren der Enden von Bündeln bündig mit dem Kranz;

    Anbringen der Enden an einer flachen Oberfläche einer Bullet-Sammellinse (12), wobei die Bullet-Sammellinse ein gekrümmtes Ende (14) und ein flaches Ende (16) aufweist.


     
    5. Verfahren nach Anspruch 4, wobei das Verfahren ferner ein Prüfen der Mehrzahl von faseroptischen Bündeln nach dem Zusammenlegen einer Mehrzahl von faseroptischen Bündeln umfasst.
     
    6. Verfahren nach Anspruch 4, wobei das Verfahren ferner ein Prüfen von ausgerichteten Enden der Bündel umfasst.
     
    7. Verfahren nach Anspruch 4, wobei das Verfahren ferner einer Prüfen der Enden umfasst, sobald sie bündig mit dem Kranz poliert sind.
     
    8. Verfahren nach Anspruch 4, ferner umfassend ein Prüfen der optischen Anordnung nach ihrer Fertigstellung.
     


    Revendications

    1. Ensemble optique, ledit ensemble comprenant :

    une lentille de collecte de type balle (12) avec une extrémité incurvée (14) et une extrémité plate (16) ;

    une pluralité de faisceaux de fibres de fibre optique (18) ; et

    lesdits faisceaux de fibres optiques étant parallèles à un canal central et contigus à un côté plat de ladite lentille de collecte de type balle,

    comprenant en outre un manchon rétractable à paroi mince (24) disposé autour de chaque faisceau de fibres optiques dans ladite pluralité de faisceaux de fibres optiques,

    une collerette (20) disposée autour de ladite pluralité de faisceaux de fibres optiques,

    dans lequel ladite collerette est disposée à proximité d'une extrémité de ladite pluralité de faisceaux de fibres optiques, et ladite extrémité de ladite pluralité est polie et au niveau de ladite collerette.


     
    2. Ensemble optique selon la revendication 1, dans lequel chaque dit faisceau de fibres optiques comprend une pluralité de fibres de fibre optique entourées par un manchon conformable.
     
    3. Ensemble optique selon la revendication 1, dans lequel ladite pluralité de faisceaux de fibres optiques comprend sept faisceaux de fibres optiques.
     
    4. Procédé pour la fabrication d'un ensemble optique ; ledit procédé comprenant :

    l'assemblage d'une pluralité de faisceaux de fibres optiques (18) dans une collerette (20),

    la fourniture d'un manchon rétractable à paroi mince (14) disposé autour de chaque faisceau de fibres optiques ;

    l'alignement des extrémités des faisceaux dans ladite pluralité de faisceaux de fibres optiques les unes avec les autres de sorte que lesdites extrémités des faisceaux soient sensiblement coplanaires ;

    le polissage desdites extrémités des faisceaux pour qu'elles soient au niveau de ladite collerette ;

    l'application desdites extrémités à une surface plate d'une lentille de collecte de type balle (12), la lentille de collecte de type balle ayant une extrémité incurvée (14) et une extrémité plate (16).


     
    5. Procédé selon la revendication 4, ledit procédé comprenant en outre l'inspection de ladite pluralité de faisceaux de fibres optiques après ledit assemblage d'une pluralité de faisceaux de fibres optiques.
     
    6. Procédé selon la revendication 4, ledit procédé comprenant en outre l'inspection des extrémités alignées desdits faisceaux.
     
    7. Procédé selon la revendication 4, ledit procédé comprenant en outre l'inspection desdites extrémités une fois polies pour qu'elles soient au niveau de ladite collerette.
     
    8. Procédé selon la revendication 4, comprenant en outre l'inspection dudit ensemble optique une fois achevé.
     




    Drawing




















    Cited references

    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description