JP2006301023A - Light source and linear light source apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source capable of further narrowing a line width of light converged by a lens. <P>SOLUTION: The light source 10 is equipped with a semiconductor laser element 11, a lens 12 and an optical fiber 13. In the NFP of a laser beam output from the semiconductor laser element 11, the full width half maximum is greater in the x direction than in the y direction. The lens 12 converges the laser beam output from the semiconductor laser element 11 in the incident end 13A of the optical fiber 13. In this incident end 13A, the intensity distribution of the laser beam converged by the lens 12 has a width greater in the x direction than in the y direction. The optical fiber 13 leads the laser beam entered in the incident end 13A to the exiting end 13B and emits it outside from there. In the xy cross section of the optical fiber 13, the width of the core is maximum in the x direction and minimum in the y direction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light source device and a line light source device.

  The line light source device condenses and irradiates light in a line shape, and is used as a light source when optically inspecting scratches or foreign matters on the surface of a semiconductor wafer, a liquid crystal panel, or the like. In order to perform such an inspection with high accuracy, it is desired that the line width of the irradiation light is narrow and the light intensity is high on the inspection surface.

As a line light source device intended to collect such light in a line shape, one disclosed in Patent Document 1 is known. The line light source device disclosed in this document uses a plurality of surface emitting LEDs (light emitting diodes) arranged in a line.
JP 2004-6583 A

  However, in the line light source device disclosed in Patent Document 1, since the spatial coherence of light output from the LED is low, even if the light is collected by a lens, the line width of the collected light is reduced. It is difficult to make it narrower than several tens of μm.

  The present invention has been made to solve the above-described problems, and can further reduce the line width of light when condensed by a lens, and has a high degree of spatial freedom using an optical fiber. And it aims at providing a line light source device.

  The light source device according to the present invention includes (1) a light emitting element that outputs light, (2) a lens that condenses the light output from the light emitting element, and (3) light collected by the lens is incident on the incident end. And an optical fiber that guides the incident light from the incident end to the exit end and emits the guided light from the exit end to the outside. Furthermore, in the cross section perpendicular to the longitudinal direction of the optical fiber, the width of the core portion in the first direction is the maximum, and the width of the core portion in the second direction is the minimum. Furthermore, it is more preferable that the first direction and the second direction are orthogonal to each other.

  In this light source device, the light output from the light emitting element is condensed on the incident end of the optical fiber by the lens. When the light condensed by the lens is incident on the incident end of the optical fiber, the incident light is guided from the incident end to the exit end and is emitted to the outside from the exit end. Here, in the cross section perpendicular to the longitudinal direction of the optical fiber, the width of the core portion in the first direction is the maximum, and the width of the core portion in the second direction is the minimum. For this reason, when light that has entered the optical fiber and has reached the exit end is emitted from the exit end to the outside, the near field pattern (hereinafter referred to as “NFP”) of the exit light is also generated. The width in the second direction is minimized.

  In the light source device according to the present invention, the light emitting element is a semiconductor laser element, and at the incident end of the optical fiber, the full width at half maximum in the first direction of the intensity distribution of the light collected by the lens is larger than the full width at half maximum in the second direction. Is preferred. In the light source device according to the present invention, at the incident end of the optical fiber, the width in the first direction of the core portion is larger than the full width at half maximum in the first direction of the intensity distribution, and the width in the second direction of the core portion is the intensity distribution. It is preferably larger than the full width at half maximum in the second direction. In this case, the light reaching the incident end of the optical fiber can efficiently enter the optical fiber.

  The line light source device according to the present invention includes a plurality of sets of the above-described light source devices according to the present invention, and the optical fibers included in each of the plurality of sets of light source devices are lined so that the first directions at the respective emission ends coincide with each other. It is characterized by being arranged in a shape. The line light source device according to the present invention preferably further includes a cylindrical lens that inputs light emitted from the emission ends of the plurality of optical fibers and collects the input light in a line shape. .

  In this line light source device, the light output from each set of light emitting elements is condensed on the incident end of the optical fiber by a lens. When the light condensed by the lens is incident on the incident end of the optical fiber, the incident light is guided from the incident end to the exit end and is emitted to the outside from the exit end. The light emitted from the emission end of each pair of optical fibers is converged in the second direction by the cylindrical lens and condensed into a line extending in the first direction. Here, in the cross section of each optical fiber, the width of the core portion in the first direction is the largest, and the width of the core portion in the second direction is the smallest. Therefore, when light that has entered each optical fiber and has reached the output end is output from the output end to the outside, the NFP of the output light also has a minimum width in the second direction. Therefore, the light emitted from the emission end of each optical fiber can be condensed into a narrow line shape by the cylindrical lens.

  According to the present invention, the light line width can be further reduced when the light is collected by the lens.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. For convenience of explanation, an xyz rectangular coordinate system is set and shown in the figure.

  FIG. 1 is an explanatory diagram of a light source device 10 according to the present embodiment. The light source device 10 includes a semiconductor laser element 11, a lens 12 and an optical fiber 13. 1A shows the configuration of the light source device 10, FIG. 1B shows the intensity distribution of laser light at the incident end of the optical fiber 13, and FIG. 1C shows the incident end of the optical fiber 13. The fiber structure in is shown. The optical axis is the z direction.

  The semiconductor laser element 11 is a light emitting element that outputs laser light from an active layer 11a sandwiched between an upper cladding layer 11b and a lower cladding layer 11c. The cross-sectional shape of the active layer 11a at the emission end is substantially rectangular and has a long side in the x direction. In the NFP of the laser beam output from the semiconductor laser element 11, the full width at half maximum in the x direction is larger than the full width at half maximum in the y direction. In general, the NFP of the light emitted from the semiconductor laser element is elliptical, and its aspect ratio (= major axis / minor axis) is 3 to 10. The larger the output power, the larger the aspect ratio.

  The lens 12 receives the laser beam output from the semiconductor laser element 11 and focuses the laser beam on the incident end 13 </ b> A of the optical fiber 13. At this time, the width in the x direction of the intensity distribution of the laser light collected by the lens 12 at the incident end 13A of the optical fiber 13 is larger than the width in the y direction perpendicular to the width (FIG. 5B).

  In the optical fiber 13, the laser beam condensed by the lens 12 is incident on the incident end 13A, the incident laser beam is guided from the incident end 13A to the exit end 13B, and the guided laser beam is emitted from the exit end 13B. To the outside. The optical fiber 13 has a core part 13a and a clad part 13b surrounding the core part 13a. In the xy cross section perpendicular to the longitudinal direction of the optical fiber 13, the width of the core portion 13a in the x direction is the largest, and the width of the core portion 13a in the y direction is the smallest ((c) in the figure).

  At the incident end 13A of the optical fiber 13, the width in the x direction of the core portion 13a is larger than the full width at half maximum in the x direction of the light intensity distribution, and the width in the y direction of the core portion 13a is in the y direction of the light intensity distribution. It is preferably larger than the full width at half maximum. By doing in this way, the light which reached | attained the incident end 13a of the optical fiber 13 can inject into the optical fiber 13 efficiently. The cross-sectional shape of the core portion 13a of the optical fiber 13 may be elliptical or rectangular.

  In the light source device 10, the light output from the active layer 11 a of the semiconductor laser element 11 is condensed on the incident end 13 a of the optical fiber 13 by the lens 12. When the laser light condensed by the lens 12 enters the incident end 13A of the optical fiber 13, the incident laser light is guided from the incident end 13A to the emission end 13B and emitted from the emission end 13B to the outside. .

  Here, in the present embodiment, at the incident end 13A of the optical fiber 13, the width in the x direction of the intensity distribution of the laser beam collected by the lens 12 is larger than the width in the y direction ((b) in the figure). The width of the core portion 13a in the x direction is the largest, and the width of the core portion 13a in the y direction is the smallest ((c) in the figure). Therefore, the light that has reached the incident end 13a of the optical fiber 13 can be efficiently incident on the optical fiber 13. Further, when the light that has entered the optical fiber 13 and has reached the emission end 13B is emitted from the emission end 13B to the outside, the NFP of the emission light also has a minimum width in the y direction. Therefore, the light emitted from the exit end 13B of the optical fiber 13 can be narrowed by condensing the light with the lens.

FIG. 2 is an explanatory diagram of the line light source device 20 according to the present embodiment. Line light source device 20 is provided with four semiconductor laser device ₁₁ 1 _{to 11} 4, four lenses ₁₂ 1 _{to 12} 4, four optical fibers _131-134 and the cylindrical lens 21. 2A shows the configuration of the line light source device 20, and FIG. 2B shows the fiber structure at the exit end of each of the _four optical fibers 13 _{1 to} 13 ₄ .

The first set of semiconductor laser elements 11 ₁ , lens 12 ₁ and optical fiber 13 ₁ , the second set of semiconductor laser elements 11 ₂ , lens 12 ₂ and optical fiber 13 ₂ , the third set of semiconductor laser elements 11 ₃ , The lens 12 ₃ and the optical fiber 13 ₃ , and the fourth set of semiconductor laser elements 11 ₄ , the lens 12 ₄ and the optical fiber 13 ₄ have the same configuration as the light source device 10 described above.

The optical fibers 13 _{1 to} 13 ₄ included in each of these four sets of light source devices are linear so that the x direction at each emission end (that is, the direction in which the width of the core portion 13b at the emission end is the maximum) coincides. (Figure (b)). In addition, it is preferable that each of the _four optical fibers 13 _{1 to} 13 ₄ is arranged and fixed at regular intervals within a certain range including each emission end.

The cylindrical lens 21 inputs laser light emitted from the emission ends of the _four optical fibers 13 _{1 to} 13 ₄ and condenses the inputted laser light in a line shape. The cylindrical lens 21 has a uniform yz cross-sectional shape along the x direction, and can converge the laser light emitted from the emission ends of the _four optical fibers 13 _{1 to} 134 in the y direction. it can. The cylindrical lens 21 may be a plano-convex lens, a biconvex lens, or a cylindrical lens.

In the line light source device 20, light output from the semiconductor laser element 11 _n is focused on the incident end of the optical fiber 13 _n by the lens 12 _n. When the laser beam condensed by the lens 12 _n is incident on the incident end of the optical fiber 13 _n , the incident laser beam is guided from the incident end to the exit end and is emitted to the outside from the exit end. Here, n is an arbitrary integer from 1 to 4. The laser beams emitted from the respective emission ends of the _four optical fibers 13 _{1 to} 13 ₄ are converged in the y direction by the cylindrical lens 21 and condensed into a line extending in the x direction.

Here, in the present embodiment, at the incident end of each optical fiber 13 _n , the width in the x direction of the intensity distribution of the laser light collected by the lens 12 _n is larger than the width in the y direction, and the x of the core portion. The width in the direction is the maximum, and the width in the y direction of the core portion is the minimum. From this, the light that has reached the incident end of each optical fiber 13 _n can efficiently enter the optical fiber 13 _n . Further, when light that has entered the optical fibers 13 _n and reaches the output end is output from the output end to the outside, the NFP of the output light also has the minimum width in the y direction. Therefore, the light emitted from the emission end of each optical fiber 13 _n can be condensed into a narrow line by the cylindrical lens 21.

Further, the line light source device 20 according to this embodiment, be provided four sets of the light source device, a laser beam emitted from each set of optical fibers _131-134, respectively exit end by the cylindrical lens 21 line It is condensed into a shape. Therefore, the light collected and output from the line light source device 20 is in the form of a line that is long in the x direction.

Note that each of the optical fibers 13 _{1 to} 13 ₄ has an arbitrary length and has flexibility, so that the degree of freedom of the irradiation direction and irradiation position is high. The semiconductor laser device 11 ₁ to 11 ₄ is each arranged is optional, may be integrated as a semiconductor laser array. Further, instead of the cylindrical lens 21, it may be provided individually lens the outgoing end of the optical fibers 13 _n.

  Next, specific examples of the light source device 10 according to the embodiment will be described. Here, a semiconductor laser element that oscillates laser light having a wavelength of 405 nm in a multimode is used. FIG. 3 is a table summarizing the specifications of the light source devices of Examples 1 to 3.

  In this figure, for each of Examples 1 to 3, the full width at half maximum (FWHM) of the NFP in the x direction and y direction of the NFP of the laser light output from the semiconductor laser element 11 is focused on the incident end of the optical fiber 13. The full width at half maximum (FWHM) of the intensity distribution of the laser light in each of the x direction and the y direction, the widths in the x direction and the y direction of the core portion 13a of the optical fiber 13, and the core portion 13a with respect to the cladding portion 13b of the optical fiber 13 The relative refractive index difference Δn is shown.

  In any light source device of any of the embodiments, the width in the x direction of the core portion 13a is larger than the full width at half maximum in the x direction of the light intensity distribution at the incident end of the optical fiber 13, and the width in the y direction of the core portion 13a. Is larger than the full width at half maximum in the y direction of the light intensity distribution. By doing in this way, the light which reached | attained the incident end of the optical fiber 13 can inject into the optical fiber 13 efficiently.

It is explanatory drawing of the light source device 10 which concerns on this embodiment. It is explanatory drawing of the line light source device 20 which concerns on this embodiment. It is the table | surface which summarized the item of each light source device of Examples 1-3.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Light source device, 11 ... Semiconductor laser element, 12 ... Lens, 13 ... Optical fiber, 20 ... Line light source device, 21 ... Cylindrical lens

Claims (5)

A light emitting element that outputs light;
A lens for collecting the light output from the light emitting element;
The light collected by the lens is incident on the incident end, the incident light is guided from the incident end to the exit end, and the guided light is emitted from the exit end to the outside;
With
In the cross section perpendicular to the longitudinal direction of the optical fiber, the width of the core portion in the first direction is the maximum, and the width of the core portion in the second direction is the minimum.
A light source device characterized by that. The light emitting element is a semiconductor laser element;
The full width at half maximum in the first direction of the intensity distribution of light collected by the lens at the incident end of the optical fiber is greater than the full width at half maximum in the second direction;
The light source device according to claim 1.   At the incident end of the optical fiber, the width of the core portion in the first direction is larger than the full width at half maximum of the intensity distribution in the first direction, and the width of the core portion in the second direction is the width of the intensity distribution. The light source device according to claim 2, wherein the light source device is larger than the full width at half maximum in the second direction. A plurality of light source devices according to any one of claims 1 to 3,
The optical fibers included in each of the plurality of sets of light source devices are arranged in a line so that the first directions at the respective emission ends coincide.
A line light source device.   The line light source device according to claim 4, further comprising a cylindrical lens that inputs light emitted from an emission end of each of the plurality of optical fibers and collects the input light in a line shape.

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