DE102017113954B3 - High-opening fiber collimator - Google Patents

Abstract

An aspherical fiber collimator (1) having an input (1.1) for inputting light from an optical fiber and an output (1.2) for outputting light collimated along a longitudinally disposed optical axis (A)
a focusing aspherical round-optical element (2) whose focal point (F) lies on the input side on the optical axis (A),
- A fiber receptacle (4) for receiving the optical fiber such that the exit surface of the optical fiber is perpendicular to the optical axis (A) and the focal point (F) of the aspheric round-optical element (2), characterized in that the opening angle (α ) of the focusing aspheric round-optical element (2) is at least so large that (1 - 3 · 10 ^-13 ) · 100 percent of the optical radiation energy exiting the optical fiber into the aperture angle (α) of the focusing aspherical round-optical element (2) fall.

Description

The invention relates to a fiber collimator for producing collimated light from light which is fed by a fiber.

From the prior art, cf. z. B. the DE 10 2017 205 590 B3 , Fiber collimators are known in which a converging lens is captured in a housing. Along the optical axis, the housing of such known fiber collimators has a fiber coupling opposite the lens for receiving an optical fiber. The fiber coupling is arranged so that the exit surface of the optical fiber is at the focal point of the condenser lens. From the exit face of the optical fiber, rays emerge in a solid angle dependent beam intensity distribution determined by the numerical aperture of the optical fiber.

The optical effect of the converging lens of conventional fiber collimators is to have a subspace angle range | θ | ≤ θ _L to receive and collapse partial beams of input beams emerging from the fiber, this partial space angle range being determined by the numerical aperture of the converging lens. Instead of the convergent lens, it is also possible to use a round optical assembly consisting of several optical elements.

Furthermore, fiber collimators are known from the prior art, in which the converging lens or at least one element of such a round optical assembly is designed as an aspherical lens and which are referred to below as aspherical fiber collimators. By means of such aspherical fiber collimators, spherical aberrations or aperture errors in beam collimating can be avoided or reduced.

In prior art fiber collimators, the condenser lens or optical assembly is selected such that its numerical aperture is equal to or slightly greater than the numerical aperture of the optical fiber to limit the diameters of such condenser lenses or optical assemblies, thereby facilitating their fabrication.

Under this condition, therefore, the aperture angle of the lens or the round optical assembly of the prior art is equal to or slightly greater than the aperture angle associated with the numerical aperture of the optical fiber. Then, the collimated output beam approximately has a Gaussian profile at which the beam intensity with respect to the central beam intensity along the optical axis decreases to a value of approximately 1 / e ² as a function of the distance to the optical axis according to a Gaussian function. Thus, when entering such a fiber collimator, the beam emerging from the optical fiber is trimmed to those beams whose beam intensity is at least approximately 13.5% of the central beam intensity along the optical axis. As a consequence of this beam intensity truncation, the wavefront actually obtained at the output of the fiber collimator has significant deviations from a plane wavefront that would correspond to perfect collimating of the output beam.

The invention is based on the object of specifying an improved aspherical fiber collimator with which a collimated exit beam can be produced on the exit side, whose wavefront has smaller deviations from a planar wavefront than fiber collimators according to the prior art. In particular, the invention is based on the object to provide such an improved fiber collimator for optical fibers with a particularly high numerical aperture, which also has the advantage of a particularly short overall length. In addition, the invention is based on the object of specifying an optical system with which light fed into an optical fiber can be transformed into collimated outgoing light, which has a smaller deviation from a planar wavefront than in known optical systems.

The object is achieved in terms of the aspherical fiber collimator according to the invention by an aspherical fiber collimator having the features of claim 1. With regard to the optical system, the object is achieved by an optical system having the features of claim 12.

Advantageous embodiments of the invention are the subject of the dependent claims.

An aspherical fiber collimator has an input for feeding light from an optical fiber and an output for outputting light collimated along a longitudinally arranged optical axis. The aspherical fiber collimator comprises a focusing aspherical round-optical element whose object-side focal point is on the input side on the optical axis.

The aspherical fiber collimator further comprises a fiber receptacle for receiving the optical fiber such that the exit surface of the optical fiber is perpendicular to the optical axis and comprises the focal point of the aspherical round optical element, that is in the focal plane of the aspherical round optical element.

According to the invention, the opening angle α of the focusing aspheric round-optical element is at least so large that (1 - 3 · 10 ^-13 ) · 100 percent of the optical radiation energy emitted by the optical fiber fall within the aperture angle α of the focusing aspheric round-optical element. The minimum aperture angle α of the focusing aspheric round-optical element thus results from the numerical aperture NA of the optical fiber according to the relationship $$\alpha =2\cdot \text{atan}\left(\text{tan}\left(\text{asin}\left(NA\right)\right)\cdot \sqrt{-\frac{1}{2}\text{ln}\left(3\cdot {10}^{-13}\right)}\right)$$

If a proportion P ≥ 1 - 3 · 10 ^{-13 of} the radiation energy emerging from the optical fiber is to be incident on the opening angle α of the focusing aspheric round-optical element, then the required opening angle α generally results $$\alpha =2\cdot \text{atan}\left(\text{tan}\left(\text{asin}\left(NA\right)\right)\cdot \sqrt{-\frac{1}{2}\text{ln}\left(1-P\right)}\right)$$

Advantageously, edge rays of the light emitted by the exit surface of the optical fiber are thereby received, which can not be absorbed due to the limited aperture of fiber collimators according to the prior art. This results in an improved quality of the wavefront of the collimated light emerging at the aspherical fiber collimator. In particular, a smaller deviation from a plane wavefront is effected, in particular, higher order deviations corresponding to Zernike polynomials of a higher order are reduced.

In one embodiment of the invention, the round optical aspheric element in an aspherical fiber collimator intended to receive light from an optical fiber having a numerical aperture of at most 0.15 has a numerical aperture of at least 0.5. Advantageously, in this embodiment, it is possible to record all edge rays through the aspherical fiber collimator whose beam intensity is at least ^{5.times.10.sup.-7} % of the central beam intensity along the optical axis. Thus, a particularly flat wavefront can be achieved with particularly small deviations of higher order.

In one embodiment of the invention, the round optical aspherical element in an aspherical fiber collimator has a numerical aperture of at least 0.6. Advantageously, a particularly flat wavefront can be achieved with particularly small deviations of higher order, if light from optical fibers with a numerical aperture of at most 0.15 is fed in.

In one embodiment of the invention, the aspheric round optical element has a focal length of at least 20mm. In this way, aspheric round-optical elements can advantageously be used which have a low surface curvature and can be manufactured easily and accurately.

In one embodiment of the invention, the round-optical element is designed as a plano-convex or biconvex aspherical lens and provided for a diffraction-limited focusing of collimated rays in the focal point. By means of such lenses with at least one aspherical surface, a particularly high collimation effect for monochromatic light can be achieved, provided that the exit surface of the fiber is correctly adjusted in the distance corresponding to the wavelength to the plane surface of the aspherical lens.

In one embodiment of the invention, the aspherical fiber collimator is adjustable. In this case, the focusing aspherical round-optical element in a socket with a fine thread, which is arranged coaxially to the optical axis of the round-optical element a fine thread, taken.

In this case, furthermore, the fiber receptacle is sleeve-shaped and takes up the socket concentrically. The fiber receptacle comprises a fiber coupling for receiving the optical fiber.

The fiber coupling lies opposite the round optical element along the optical axis. The sleeve-shaped fiber receptacle has a radially outwardly projecting fixing stop.

The fiber receptacle also has an eccentric receptacle for rotatably receiving an eccentric fixing screw in the sleeve casing, wherein the screw axis of the fixing screw in the radial direction, that is perpendicular to the optical axis runs.

On the inside of the sleeve sheath of the fiber receptacle, a fine thread is arranged, which engages in the fine thread of the socket and which converts a rotational movement of the fiber receptacle relative to the frame in a longitudinal displacement of the fiber receptacle relative to the socket.

The fiber collimator further comprises an adjustment tray, which surrounds the fiber receptacle annular concentric to the optical axis and which is rotatable relative to the fiber receptacle and at the same time is rotationally fixed relative to the socket.

The adjustment tray comprises a longitudinally movable, so coaxial to the optical axis movable, fixing half-shell. The Fixierhalbschale has a recessed along one part of the circumference fixing slot for receiving the screw head of the fixing screw.

Due to its eccentricity, the fixing screw causes a longitudinal movement of the Fixierhalbschale with a rotation in the fixing slot. In this case, the adjustment shell is pressed in a fixing position against the fixing stop adhesive and released in a release position of this.

By means of the fiber coupling, a coaxial, centered and tilt-free arrangement of the fiber exit surface of an inserted optical fiber is achieved. By rotation of the fiber receptacle relative to the socket is dissolved in the fixing screw, mediated by the fine thread of the socket and the fiber receptacle, the distance between the round-optical element and the fiber exit surface changed. Thus, it is possible by simple rotation to determine and adjust an optimal for the injected wavelength position of the fiber exit surface. If such a position found, it is possible by tightening the fixing screw in the fixing position to generate a static friction between the Fixierhalbschale and the projecting fixing stop of the fiber receptacle, which prevents further rotational movement of the adjustment shell relative to the socket. Since the adjustment shell is rotatably coupled to the socket, thus a rotation and thus, over the fine thread of the socket and the fiber receptacle, a longitudinal displacement between the fiber receptacle and the socket prevented. Thus, the fiber exit surface remains at the optimal position once determined along the optical axis.

Advantageously, the frictional force for fixing in the longitudinal direction between the fixing half-shell and the fiber receptacle acts. Since the Fixierhalbschale is longitudinally movable to the socket, no force is transmitted to the socket. Thus, it is avoided that in the fixation under the action of a fixing force changes the position of the socket with the composite round optical element, for example, decentered or that under the influence of the fixing force tensions in the round optical element arise, which could affect the optical effect.

In one embodiment of the invention, the adjustable aspherical fiber collimator further includes a housing surrounding the fiber receptacle and the adjustment cup. The housing has a longitudinally recessed operating handle, through which the adjustment tray is rotatably accessible. The housing further has a bore which is arranged radially above the eccentric receiver and through which the fixing screw is accessible. The housing is rotatably arranged to the fiber intake. An advantage of this embodiment is that the housing provides a comfortable gripping surface, which facilitates the rotation of the adjustment tray. The housing further facilitates the handling of the fiber collimator and can also be performed dust-tight closing.

In one embodiment of the invention, the housing projects beyond the round-optical element on the output side, wherein an internal thread is arranged in the output-side projection. At the pointing to the round optical element end of the internal thread a stop is also arranged. The internal thread and the stop are designed so that a captive optical component in a housing with a complementary external thread and with a complementary stop without adjustment screwed to the adjustable fiber collimator, the stopper acts as a mating surface.

An advantage of this embodiment is that the solid reference of the stop of the fiber collimator housing for abutment of the housing of another optical component whose optical axis is centered and aligned collinear to the optical axis of the fiber collimator. Thus, the only degree of freedom in the alignment of the further optical component is the adjustment of the distance to the round optical element along the optical axis, which can be done easily by rotation of the adjustment tray with the fixing screw loosened. This embodiment is therefore particularly suitable for the construction of composite optics. In a particularly preferred embodiment, the further optical component is designed as a beam expander.

In one embodiment of the invention, the socket and the adjustment shell are rotatably connected to each other by means of at least one driver, wherein the driver is guided by a radial slot in the jacket of the fiber receptacle. With this embodiment, a large rotational play, corresponding to a large adjustment range for the position of the fiber exit surface along the optical axis, can be achieved with a sufficient static strength of the fiber collimator. This rotational play is determined by the length of the radial slot in the circumferential direction. In a particularly preferred embodiment, the radial slot extends over a quarter to a third of the shell circumference of the fiber receptacle.

In one embodiment of the invention, the adjustment shell comprises a guide half-shell, through which the at least one driver is guided. The guide half shell is by means of a Sliding bearing rotatably coupled to the Fixierhalbschale, wherein the sliding bearing has a longitudinal clearance between the Fixierhalbschale and the guide half-shell along the optical axis.

Due to the longitudinal play of the sliding bearing, it is possible to move the fixing half-shell along the optical axis between the release position and the fixing position, without transferring this longitudinal movement to a longitudinal movement of the guide half-shell, which thus remains stationary relative to the socket. This allows a particularly simple coupling between the guide half shell and the socket. In a particularly preferred variant of this embodiment, the drivers are designed as pins or pins whose radially inner end is received in a blind hole in the outer casing of the socket and whose radially outer end is received in a blind hole in the inner surface of the guide half-shell.

In one embodiment of the invention, a plurality of blind holes for receiving in each case a driver along a circumference in the outer jacket of the socket are arranged so that covers at each rotation angle of the socket relative to the fiber receiving the radial slot each having a plurality of blind holes. An advantage of this embodiment is that a driver for the rotationally fixed coupling of the socket with the guide half-shell can be arranged in a blind hole that a large, preferably symmetrical rotational play is achieved, the relative to a large Justage- or adjustment for longitudinal displacement of the socket corresponds to the fiber absorption.

An optical system for generating light collimated along an optical axis comprises an aspherical fiber collimator according to the invention. In the fiber receptacle of the aspherical fiber collimator, an optical fiber is recorded whose numerical aperture is at most 0.25. The round optical element of the aspherical fiber collimator, which is preferably designed as an aspherical lens, has a numerical aperture of at least 0.6.

Advantageously, such a system is suitable for coupling light by means of optical fibers known from the prior art and providing collimated light with a wavefront of very high quality for further optical processing on the exit side. In particular, such a system can be made with optical fibers of larger numerical aperture, as they are increasingly used in the field of optical communications technology.

Embodiments of the invention will be explained in more detail below with reference to a drawing.

• 1 schematisch einen asphärischen Faserkollimator nach dem Stand der Technik,
• 2 und 3 schematisch den Strahlengang in einem hochöffnenden asphärischen Faserkollimator,
• 4 einen schematischen Längsschnitt durch einen justierbaren asphärischen Faserkollimator,
• 5 eine schematische Draufsicht auf eine Faseraufnahme, umgeben von einer Justageschale,
• 6 eine schematische Ansicht von unten auf einen justierbaren asphärischen Faserkollimator ohne Gehäuse,
• 7 eine schematische Ansicht von oben auf einen justierbaren asphärischen Faserkollimator mit Gehäuse und
• 8 eine schematische Ansicht von unten auf einen justierbaren asphärischen Faserkollimator mit Gehäuse.

Show:

• 1 1 schematically shows an aspherical fiber collimator according to the prior art,
• 2 and 3 schematically the beam path in a high-opening aspherical fiber collimator,
• 4 a schematic longitudinal section through an adjustable aspherical fiber collimator,
• 5 a schematic plan view of a fiber receptacle surrounded by an adjustment tray,
• 6 a schematic view from below of an adjustable aspherical fiber collimator without housing,
• 7 a schematic top view of an adjustable aspherical fiber collimator with housing and
• 8th a schematic view from below of an adjustable aspherical fiber collimator with housing.

Corresponding parts are provided in all figures with the same reference numerals.

1 schematically shows the beam path in an aspherical fiber collimator 1 according to the prior art, the rotationally symmetrical to an optical axis A is trained. At the optical input 1.1 of the fiber collimator 1 becomes light, preferably monochromatic laser light, of an entrance beam IT fed by an optical fiber, not shown. At the optical output 1.2 of the fiber collimator 1 occurs collimated light in an exit beam AS out.

The optical effect is achieved by a plano-convex aspherical lens 2 scored, whose plane first surface 2.1 on the exit surface of the coaxial to the optical axis A arranged, not shown optical fiber has and the opposite second surface to the output 1.2 of the fiber collimator 1 has. The aspherical lens 2 is in a version 3 taken and has an optically effective diameter D on. The exit surface of the fiber is in focus F the aspherical lens 2 arranged.

The convex aspherical second surface 2.2 of the aspherical lens 2 is shaped so that the exit surface of the optical fiber for a certain predetermined wavelength input light at the focal point of the aspherical lens 2 located. The Focal length of the aspherical lens 2 f = 10.9 mm with a numerical aperture of 0.25. Light emerging from the optical fiber becomes at an aperture angle α in the aspherical lens 2 coupled.

Turns into such an aspherical fiber collimator 1 Light from an optical fiber formed as a single-mode fiber with a numerical aperture of 0.15 coupled, the beam intensity is at the edge of the collimated exit beam AS to approximately 0.01% of the central beam intensity on the optical axis A dropped off and abruptly drops to zero from there.

der gesamten aus der optischen Faser austretenden Energie in den Faserkollimator 1 eingekoppelt. Somit liegen 13,5% der gesamten von der optischen Faser emittierten Strahlungsenergie außerhalb des Öffnungswinkels α der Linse 2. Dadurch werden Abweichungen höherer Ordnung beziehungsweise eine verminderte Güte der Wellenfront des kollimierten Austrittsstrahlenbündels AS bewirkt.A perfectly flat wavefront can be achieved with such an aspherical fiber collimator 1 in the prior art, neglecting the spherical aberration can not be achieved because of the optical fiber rays with a beam intensity of less than about 1 / e ^{2 of} the central beam intensity are not coupled because they are not in the opening angle α the lens 2 fall. Thus only $100\%\cdot \frac{1}{2\pi }{\displaystyle {\int }_{\phi =0}^{2\pi }{\displaystyle {\int }_{r=-\sqrt{2}}^{\sqrt{2}}{e}^{-r^2}}}rdrd\phi =100\%\cdot \left(1-\frac{1}{e^2}\right)=86.5\%$

the total energy exiting the optical fiber into the fiber collimator 1 coupled. Thus, 13.5% of the total radiant energy emitted by the optical fiber is outside the aperture angle α the lens 2 , As a result, deviations of a higher order or a reduced quality of the wavefront of the collimated exit beam become AS causes.

These disadvantages are obtained with an aspherical fiber collimator according to the invention 1 fixed with enlarged numerical aperture, for which the beam path in 2 is shown schematically. The aspherical fiber collimator 1 has a numerical aperture of 0.5 at a focal length of f = 10 mm and a lens diameter of D = 9.7 mm, which is the same as in the prior art embodiment. Takes one such aspherical fiber collimator 1 Light from a single-mode fiber optical fiber having a numerical aperture of 0.15 is at the outer edge of the exit beam AS the beam intensity dropped to below 5 × 10 ^-7 % of the central beam intensity. Thus, only 3 × 10 ^-13 % of the total radiant energy emitted by the optical fiber is outside the aperture angle α the lens 2 , This allows an improved quality of the wavefront of the collimated exit beam AS achieve.

3 schematically shows the beam path for a further embodiment of an aspherical fiber collimator according to the invention 1 with a numerical aperture of 0.6 at a focal length of f = 10mm and a lens diameter of D = 11.5 mm, unchanged from the prior art embodiment. The opening angle α the aspherical lens 2 is thus 74 °.

Takes one such aspherical fiber collimator 1 Light from a designed as a single-mode fiber optical fiber with a numerical aperture of 0.15, so is at the outer edge of the opening angle α limited entrance beam IT and thus also at the outer edge of the exit beam AS the beam intensity dropped to below 2 × 10 ^-10 % of the central beam intensity. Thus, only 1.2 × 10 ^-15 % of the total radiant energy emitted by the optical fiber is outside the aperture angle α the lens 2 ,

In many applications of optical fibers, for example in telecommunications, today optical fibers are used with a numerical aperture between 0.12 to 0.15. However, optical fibers having a larger numerical aperture have advantages such as a shortened length of optical arrangements for coupling or decoupling light into or out of the optical fiber. The use of such optical fibers with increased numerical aperture in prior art fiber collimators results in a disproportionately higher loss of optical throughput relative to the aperture increase and a reduced wavefront quality.

Thus, there is a further advantage of inventive high-opening aspheric fiber collimators 1 in that they can be coupled to optical fibers with increased numerical aperture, reducing the loss of optical throughput and degradation of wavefront quality over coupling of such optical fibers to prior art fiber collimators.

It is known that the focus position of a lens 2 depending on the wavelength of the focused light. Thus, it is advantageous to have the focal distance between the exit surface of the optical fiber and the lens 2 in a fiber collimator 1 adapt. An easy adaptability of the focal distance is particularly advantageous for a high-open aspherical fiber collimator 1 because even with a slight deviation of the position of the exit surface of the optical fiber from the wavelength-dependent focal point of the aspherical lens 2 leads to distortions of the exit-side wavefront, which dominates the wavefront distortions caused by the edge modulation of the beam intensity in the case of aperture limitation. The effectiveness of a high-opening aspherical fiber collimator 1 can therefore be degraded for many applications, though no possibility of an exact and well reproducible adjustment of the fiber exit surface relative to the aspherical lens 2 provided.

The following are examples of an aspherical fiber collimator 1 described in which the fiber exit surface relative to the aspherical lens 2 is adjustable. Advantageously, these embodiments improve the quality of the exit-side wavefront especially for applications where a high-open aspherical fiber collimator is intended to receive light of different wavelength from an optical fiber.

4 shows a schematic longitudinal section through an adjustable aspherical fiber collimator 1 that is rotationally symmetric to an optical axis A is trained. At the optical input 1.1 of the fiber collimator 1 is light, preferably monochromatic laser light, fed by an optical fiber, not shown. At the optical output 1.2 of the fiber collimator 1 occurs collimated light.

The optical effect is through an aspherical lens 2 scored, their first surface 2.1 on the exit surface of the coaxial to the optical axis A arranged, not shown optical fiber has and the opposite second surface to the output 1.2 of the fiber collimator 1 has. The aspherical lens 2 is shaped so that the collimated light at the output 1.2 a plane wavefront perpendicular to the optical axis A having. The present is the aspherical lens 2 a plano-convex lens, wherein the first surface 2.1 are designed as planar surface and the opposite second surface as aspherical surface. Instead of the plano-convex lens 2 it is also possible to use a biconvex lens whose first and / or the second surface can be designed as an aspherical surface. Likewise, instead of the aspherical lens 2 Also, a multi-part optical element, for example, a captured optical element with a plurality of partial lenses used.

The aspherical lens 2 is made of a tubular socket 3 held along the optical axis A extends and is arranged coaxially thereto. At its outlet side arranged end has the socket 3 an internal lens holder 3.1 with an annular end face 3.2 on. The plane surface 2.1 the lens 2 lies along an outer ring on the face 3.2 perpendicular to the optical axis A on. The face 3.2 is manufactured so precisely that by tilting the plane surface 2.1 relative to the optical axis A caused deviation of the collimated light at the output 1.2 from a plane wavefront is negligible. Negligible is a wavefront deviation for monochromatic light which is smaller than λ / 10, where λ is the wavelength of the injected monochromatic light. The Lens 2 is in the lens holder 3.1 fastened with known from the prior art method, for example, cemented. The Lens 2 is to the optical axis A centered, wherein the centering can also be done by methods of the prior art, for example by means of a Autokollimationsfernrohrs.

At its entrance end, the socket has 3 on an outer lateral surface 3.3 a taper of the outer diameter. In the area of rejuvenation is a socket thread 3.4 in the outer jacket surface 3.3 incorporated.

On a circumference approximately centrally arranged along the longitudinal extent are in the outer circumferential surface 3.3 Equidistant blind holes introduced.

The version 3 is along the optical axis A from a sleeve-shaped fiber receptacle 4 enclosed, which is also coaxial with the optical axis A is arranged. The fiber intake 4 has an inner hollow cylinder with an inner circumferential surface 4.1 for receiving the hollow cylindrical socket 3 on. The inner lateral surface 4.1 the fiber intake 4 leads the outer surface 3.3 the version 3 so accurate that when shifting the fiber intake 4 along the optical axis A relative to the version 3 the tilting of the fiber intake 4 relative to the version 3 is limited so far that this tilting no or at most a negligible deviation of the collimated light at the output 1.2 caused by a flat wavefront.

At its entrance end, the inner circumferential surface 4.1 a for the tapering of the outer diameter of the outer lateral surface 3.3 the version 3 corresponding taper of the inner diameter. In the area of the rejuvenation is a receptacle thread 4.2 incorporated, which in the Fassungsfeingewinde 3.4 the version 3 intervenes. The fine thread 3.4 . 4.2 are manufactured so that the thread pitch on the required accuracy of the adjustment of the longitudinal distance along the optical axis A between the version 3 and the fiber intake 4 is tuned. The thread pitch is further tuned to a required axial Verfahrbereich for the adjustment of this longitudinal distance with a by a rotational clearance between the fiber intake 4 and the version 3 limited rotation is achieved, as explained in more detail below.

At its entrance end, the fiber intake 4 centered to the optical axis A a fiber coupling 4.3 with a receiving socket 4.3.1 for guiding the exit end fiber end of a optical fiber and with a fiber stop 4.3.2 on. The receiving socket 4.3.1 causes one to the optical axis A centered, coaxial alignment of the exit end fiber end. The fiber stop 4.3.2 defines the position of the fiber exit surface along the optical axis A , Fiber couplings are well known in the art and are available in various standardizations such as screw-type fiber connector (FC) fiber couplings or straight tip (ST) bayonet-type fiber couplings.

On a circumference are in the sleeve-shaped fiber intake 4 As radially outwardly projecting openings comprising a radial slot and an eccentric receiving 4.5 brought in. The radial slot 4.4 extends over about one third of the circumference and covers the blind holes in the longitudinal extent 3.5 the version 3 , Thus, through the radial slot some blind holes 3.5 accessible.

The eccentric recording 4.5 lies opposite the radial slot on the circumference. The eccentric recording 4.5 has an eccentric thread 4.5.1 on. In the eccentric recording 4.5 is an eccentric fixing screw 5 with a corresponding external screw thread 5.1 screwed. Alternatively, other rotatable attachments of a fixing screw 5 in the eccentric recording 4.5 possible.

By turning the socket 3 relative to the fiber intake 4 becomes by means of the fine thread 3.4 . 4.2 a longitudinal displacement along the optical axis and thus a change in the distance between the exit surface of the optical fiber and the plane surface 2.1 the lens 2 causes. Because the location of the focal point F the lens 2 along the optical axis A depends on the wavelength λ, the fiber collimator 1 thus by simple rotation of the socket 3 relative to the fiber intake 4 be adapted to laser sources of different wavelength λ.

In a simple way, such a rotation by means of an adjustment tray 6 be implemented, which is the fiber intake 4 with the enclosed version 3 encloses. The adjustment cup 6 is in longitudinal extension of inner radial end rings 6.3 . 6.4 limited. The exit-side end ring 6.4 is in radial guide grooves 4.7 guided by the radially projecting fixing stop 4.6 on the one hand and from the radially projecting enclosure of the eccentric recording 4.5 and formed by the radially projecting enclosure of the radial slot on the other hand. Thus, the adjustment shell 6 relative to the fiber intake 4 rotatable and in the by the longitudinal clearance of the exit-side end ring 6.4 in the guide grooves 4.7 given limits also longitudinally displaceable along the optical axis A ,

The adjustment cup 6 is through a guide half shell 6.1 and a fixing half shell 6.2 formed, each about about half the circumference of the adjustment shell 6 extend. The half-shells 6.1 . 6.2 are by means of plain bearings 7 in the longitudinal direction, ie parallel to the optical axis A , movable against each other and in the direction of a rotational movement about the fiber intake 4 or about the optical axis A coupled together.

As in figure 5 shown in more detail, the guide half-shell 6.1 at the end of its circumference a bridge 6.1.1 on. The fixation half shell 6.2 has at the opposite end of its circumference a recess 6.2.1 on that the jetty 6.1.1 with a longitudinal play along the optical axis A receives. Through a coaxial to the optical axis A arranged tour of the bridge 6.1.1 is a pen 7.1 guided. Leadership and pen 7.1 are as plain bearings 7 executed. The ends of the pen 7.1 are in the forked ends around the recess 6.2.1 the fixing half shell 6.2 held.

As better visible in 6 is shown in the fixing half shell 6.2 a longitudinally extending fixing slot along its circumference 6.2.2 introduced in which the fixing screw 5 with a clearance coaxial to the optical axis A is guided. The fixing screw 5 has an eccentric screw head 5.2 on, so a screw head 5.2 which is not concentric with the longitudinal axis of the screw outer thread 5.1 is arranged. In the screw head 5.2 is concentric with the longitudinal axis of the screw outer thread 5.1 a driving profile designed as a hexagon socket. The person skilled in the art is familiar with other driving profiles from his specialist knowledge, for example a slot profile, a star-shaped profile with rounded or flattened cams or a multi-tooth profile, which can also be used here. The screw head 5.2 leads the fixation slot 6.2.2 on the outlet-side inner edge 6.2.3 ,

The fixing screw 5 is arranged and shaped so that in a fixing position, the fixing half shell 6.2 against the fixing stop 4.6 the fiber intake 4 is pressed. This is the adjustment shell 6 due to the stiction between the fixing half shell 6.2 and the fiber intake 4 rotatably with the fiber intake 4 coupled. In a release position of the fixing screw 5 is the fixation half shell 6.2 rotatable relative to the fiber intake 4 ,

The fixation half shell 6.2 radially opposite is the guide half-shell 6.1 to the fiber intake 4 arranged and with the in the fiber receptacle 4 lying version 3 coupled, as shown in FIG 4 can be seen in more detail. This is in the inner wall of the guide half shell 6.1 a bolt or pin-shaped driver 6.1.2 introduced radially inward. The radially inner end of the follower 6.1.2 is perfectly fitting to the blind holes 3.5 in the outer lateral surface 3.3 the version 3 executed.

Before mounting the adjustment cup 6 is first by means of a tool not shown by rotation of the socket 3 opposite the fiber intake 4 a wavelength dependent predetermined distance of the fiber stop 4.3.2 relative to the plane surface 2.1 in the version 3 captured lens 2 produced. As a result, the exit surface of one in the fiber coupling 4.3 introduced fiber approximately in the focus F the lens 2 brought. The guide half shell 6.1 is on the fiber intake 4 put on and by means of the sliding bearing 7 with the likewise attached Fixierhalbschale 6.2 connected. This is the driver 6.1.2 in a blind hole 3.5 introduced.

Preferably, this is a blind hole 3.5 selected, which lies centrally in the radial slot in the circumferential direction.

When the fixing screw is loosened 5 is the adjustment shell 6 rotatable relative to the fiber intake 4 , A rotary movement of the adjustment shell 6 is about the driver 6.1.2 to the version 3 transfer. The rotational movement of the socket 3 effected via the Fassungsfeingewinde 3.4 and the pickup thread 4.2 a longitudinal movement of the socket 3 relative to the fiber intake 4 and thus also relative to the exit surface of the introduced fiber. Thus, in a very simple manner, a wavelength-dependent necessary correction of the distance of the fiber from the plane surface 2.1 the lens 2 make, so that the exit surface of the fiber over a certain adjustable wavelength range always in the wavelength-dependent focal point F the lens 2 can be brought. The adjustable wavelength range is determined by the rotational play of the socket 3 relative to the fiber intake 4 certainly. This rotation is on the one hand by the radial slot in the fiber intake 4 in cooperation with the driver 6.1.2 limited. This rotational game is the other by the recess 6.2.1 in cooperation with the fixing screw 5 limited.

For a symmetrical adjustability by a predetermined center wavelength, it is therefore advantageous, the Justierschale 6 to arrange so that at the center wavelength of the driver 6.1.2 in the circumferential direction approximately centrally located in the radial slot and the fixing screw 5 in the circumferential direction approximately centrally in the recess 6.2.1 lies. Therefore, an equidistant sufficiently dense arrangement of blind holes is particularly advantageous 3.5 on a circumference of the outer circumferential surface 3.3 , so always a blind hole 3.5 with only a slight deviation from the preferred center position relative to the radial slot for receiving the driver 6.1.2 is available. Thus, a rotational or adjustment movement is made possible, which extends in each sense of direction about half the length of the radial slot in the circumferential direction. The longitudinal displacement of the socket 3 relative to the fiber intake 4 along the optical axis A causes over the driver 6.1.2 a longitudinal displacement and the Justagerings 6 relative to the fiber intake 4 , The guide grooves 4.7 as well as the radial slot and the recess 6.2.1 are dimensioned in the longitudinal direction along the optical axis so that a longitudinal clearance is effected, which covers at least the longitudinal displacement area generated by the adjustment movement.

For improved operability is sleeve-shaped to the fiber intake 4 a housing 8th arranged, which with the fiber intake 4 rotatably connected. As in the 7 and 8th recognizable, the housing has 8th a slot-shaped operator handle 8.1 and radially opposite a bore 8.2 on. The operator grip 8.1 is in the radial direction over the guide half-shell 6.1 arranged and allows the rotation of the guide half-shell 6.1 relative to the housing 8th , and thus also relative to the fiber intake 4 , with loosening fixing screw 5 , The hole 8.2 is in the radial direction over the fixing screw 5 arranged, passing through the hole 8.2 through the driving profile of the fixing screw 5 is accessible by means of a corresponding to this driving profile shaped tool, in this case by means of a hexagonal wrench.

After one during assembly of the fiber collimator 1 made displacement of the fiber exit surface in the vicinity of the wavelength-dependent focal point F the lens 2 An adjustment can be made simply and precisely as follows. First, through the hole 8.2 through the fixing screw 5 placed in the release position and thus the rotational mobility of the housing 8th and the one with the case 8th connected fiber intake 4 relative to the version 3 produced. Thereafter, by the operator grip 8.1 the guide half shell 6.1 relative to the housing 8th around the optical axis A turned. About the drivers 6.1.2 causes this rotational movement a concurrent rotational movement of the socket 3 relative to the fiber intake 4 ,

By means of the interlocking fine thread 3.4 . 4.2 This rotational movement is in a shift between the version 3 and the fiber intake 4 along the optical axis A translated. Thus, the fiber exit surface of the fiber receptacle 4 held fiber relative to a focal point F the one of the version 3 held lens 2 along the optical axis A be moved. When the fiber exit surface in the wavelength-dependent focal point F the lens 2 is located, the fixing screw 5 turned into the fixing position and thus another rotation between version 3 and fiber intake 4 prevented. As a result, the fiber exit surface remains as adjusted in the wavelength-dependent focal point F the lens 2 ,

In this case, the friction force required for fixing between the Fixierhalbschale 6.2 and the fixing stopper 4.6 in the longitudinal direction coaxial to the optical axis A applied. Compared to known from the prior art fixing devices in which usually by means of a grub screw acting in a radial direction friction force is applied, the inventive solution for fixing has the advantage that a decentering between the socket 3 and the fiber intake 4 is avoided as a result of a force applied on one side in the fixation.

The friction force required for fixing is between the fixing half shell 6.2 and the fixing stopper 4.6 generated. Because the version 3 about the drivers 6.1.2 with the guide half shell 6.1 coupled, which because of the sliding bearing 7 a longitudinal play against the fixing half shell 6.2 However, this frictional force is not on the version 3 and therefore not on the lens 2 transfer. Another advantage of the fixation solution according to the invention is therefore that during fixing no mechanical stresses on the socket 3 be transferred and the lens 2 remains unchanged in its shape and in its optical properties during fixation.

As in 4 recognizable, the housing has 8th at the outlet end an internal thread 8.3 and a housing stop 8.4 on. In the internal thread 8.3 a corresponding external thread of a further optical component, not shown, can be screwed in, wherein the housing stop 8.4 a defined distance of the further optical component along the optical axis A to the fiber stop 4.3.2 the fiber coupling 4.3 certainly. The further optical component can be formed, for example, as a beam expander. The housing stop 8.4 as well as a corresponding stop of the further optical component can be made very precisely, so that merely by screwing together the fiber collimator 1 with the other optical component a adjustment-free assembly is possible.

LIST OF REFERENCE NUMBERS

1

fiber collimator

1.1

entrance

1.2

output

2

lens

2.1

plane surface

3

version

3.1

lens holder

3.2

face

3.3

outer jacket surface

3.4

Cupping thread, fine thread

3.5

blind

4

fiber intake

4.1

inner jacket surface

4.2

Receptacle thread, fine thread

4.3

fiber coupling

4.3.1

receiving socket

4.3.2

fiber stop

4.5

Exzenteraufnahme

4.5.1

Exzenterinnengewinde

4.6

Fixieranschlag

4.7

guide

5

fixing screw

5.1

Screw external thread

5.2

screw head

6

Justageschale

6.1

Guiding half-shell

6.1.1

web

6.1.2

takeaway

6.2

Fixierhalbschale

6.2.1

recess

6.2.2

fixing slot

6.2.3

inner edge

6.3

end ring

6.4

end ring

7

bearings

7.1

pen

8th

casing

8.1

Operating penetration

8.2

drilling

8.3

inner thread

8.4

housing stop

A

optical axis

AS

Exit radiation beam

IT

Input beam

F

focus

f

focal length

D

Lens diameter

α

opening angle

Claims (12)

An aspherical fiber collimator (1) having an input (1.1) for inputting light from an optical fiber and an output (1.2) for outputting light collimated along a longitudinally arranged optical axis (A), comprising - a focusing aspherical round optical element (2 ) whose focal point (F) is located on the input side on the optical axis (A), - a fiber receptacle (4) for receiving the optical fiber such that the exit surface of the optical fiber is perpendicular to the optical axis (A) and the focal point (F) of the aspheric round-optical element (2), characterized in that the aperture angle (α) of the focusing aspheric round-optical element (2) is at least so large that (1 - 3 · 10 ^-13 ) · 100 percent of that of the optical fiber emerging optical radiation energy in the opening angle (α) of the focusing aspherical round-optical element (2) fall. Aspherical fiber collimator (1) after Claim 1 , characterized in that when coupling light from an optical fiber having a numerical aperture of at most 0.15, the aspheric round-optical element (2) has a numerical aperture of at least 0.5. Aspherical fiber collimator (1) according to one of the preceding claims, characterized in that the aspherical round-optical element (2) has a focal length (f) of at least 20 mm. Aspheric fiber collimator (1) according to one of the preceding claims, characterized in that the aspherical round optical element (2) is designed as a plano-convex aspherical lens for a diffraction-limited focusing of collimated beams at the focal point (F). Aspheric fiber collimator (1) according to one of the preceding Claims 1 to 3 , characterized in that the aspherical round-optical element (2) is designed as a biconvex aspherical lens (2) and is provided for a diffraction-limited focusing of collimated rays in the focal point (F). Aspheric fiber collimator (1) according to one of the preceding claims, characterized in that - the focusing aspherical round-optical element (2) is held in a socket (3) with a fine thread (3.4), - that the fiber receptacle (4) supports the socket (3 ) concentrically receives and sleeve-shaped and a fiber coupling (4.3) for receiving the optical fiber, a radially outwardly projecting Fixieranschlag (4.6), an Exzenteraufnahme (4.5) for rotatably receiving an eccentric fixing screw (5) in the sleeve casing and on the inside the sleeve sheath arranged fine thread (4.2), which is in the fine thread (3.4) of the socket (3) and which converts a rotational movement in a longitudinal displacement of the fiber receptacle (4) relative to the socket (3) comprises, and - that the aspherical fiber collimator one Includes fiber receiving (4) annularly enclosing and rotatable thereto and the socket (3) non-rotatable adjustment sheath (6), wherein the Justag (6) has a fixing half-shell (6.2) which can be moved longitudinally relative to the holder (3) and has a fixing slot (6.2.2) recessed along the circumference for receiving the screw head (5.2) of the fixing screw (5), and wherein the adjusting tray (6 ) is pressed against the fixing stop (4.6) in a fixing position by means of the fixing screw (5) and is released from it in a release position. Aspherical fiber collimator (1) after Claim 6 , further comprising a housing (8) surrounding the fiber receptacle (4) and the adjustment sheath (6), having an operating passage (8.1) and a bore (8.2), the housing (8) being rotationally fixed to the fiber receptacle (4) and the bore (8.2 ) are arranged radially above the eccentric receptacle (4.5) and wherein the operating passage (8.1) for rotation of the adjustment tray (6) is provided. Aspherical fiber collimator (1) after Claim 6 or 7 , characterized in that the housing (8) on the output side an internal thread (8.3) and a stop (8.4), which are formed so that a seized optical component with a complementary external thread and with a complementary stop without adjustment with the adjustable fiber collimator (1 ) is screwed. Aspheric fiber collimator (1) after one of Claims 6 to 8th , characterized in that the socket (3) and the adjustment tray (6) by means of at least one driver (6.1.2) are rotatably connected, which is guided by a radial slot in the jacket of the fiber receptacle (4). Aspheric fiber collimator (1) after one of Claims 6 to 9 , characterized in that the adjustment tray (6) comprises a guide half-shell (6.1), which guides the at least one driver (6.1.2) and by means of a sliding bearing (7) rotatably and with a longitudinal clearance with the fixing half shell (6.2) is coupled. Aspherical fiber collimator (1) after Claim 9 or 10 , characterized in that blind holes (3.5) for receiving in each case a driver (6.1.2) along a circumference in the outer casing of the socket (3) are arranged so that at each rotation angle of the socket (3) relative to the fiber receptacle (4) of the radial slot each covers a plurality of blind holes (3.5). An optical system for generating light collimated along an optical axis (A), comprising an aspherical fiber collimator (1) Claim 1 and an optical fiber accommodated in the fiber receptacle (4) of the aspherical fiber collimator (1), wherein the numerical aperture of the optical fiber is 0.25 and the round optical element (2) of the aspherical fiber collimator (1) has a numerical aperture of at least 0, 6 has.

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