JP2008276007A - Optical device and exposure device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical device capable of suppressing decrease in the light output, and to provide an exposure device. <P>SOLUTION: The optical device 10 includes a laser light source 12 which emits a laser light of short wavelength range (for example, 160 to 500 nm), a lens 14, a transparent member 16, and an optical fiber 18. Furthermore, the optical device is configured so that light density on a contact surface 20 between the transparent member 16 and optical fiber 18 is 140 [W/mm<SP>2</SP>] or lower. Consequently, decrease in light output due to fusion can be suppressed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical device and an exposure apparatus, and more particularly to an optical device and an exposure apparatus that connect optical members such as optical fibers and transparent members to propagate light such as laser light.

  Conventionally, as an optical device that propagates laser light by connecting an optical member such as an optical fiber or a transparent member, Patent Document 1 discloses that a coreless fiber is fusion-bonded to an output end of a fiber, and an output beam is at the end of the coreless fiber. A technique for setting the optical path length so as not to be lost is disclosed, and it is disclosed that, particularly when the length of the coreless fiber is set to 1 mm or less, the injury is reduced.

  Patent Document 2 discloses a device in which a light guide rod having the same refractive index as that of the core portion of the optical fiber and an outer diameter matching the outer diameter of the optical fiber is integrated by heat fusion on the input end face of the optical fiber. Has been.

The laser module in Patent Document 3, a pigtail type laser module, the optical power density of 15W / mm ² or less at the fiber input end face or exit end face exposed to air or a 60~800W / mm ² Is disclosed.

Further, Patent Document 4 discloses a receptacle-type laser module in which a transparent member is brought into contact with a fiber incident end face, and light from a semiconductor laser is collected from the transparent member side and guided to the optical fiber, and is incident on the transparent member. Has disclosed a laser module having an optical density of 10 W / mm ² or less.
International Publication No. 2004/68230 Pamphlet Japanese Patent Laid-Open No. 5-288967 JP 2007-25431 A JP 2006-286866 A

  However, when the technique described in Patent Document 1 is used for the incident portion of a pigtail type laser module, there is a problem that the coreless fiber end may be contaminated if the light output is high, and the life may be shortened. there were. On the other hand, when used in a receptacle-type laser module, it may be possible to position the fiber end in the beam propagation direction by abutting the optical fiber against a transparent member such as a stub. The phenomenon of fusing between the fiber and the stub occurs. In this case, there is a problem that the fused portion is easily peeled off by vibration or the like, and the coupling loss to the optical fiber increases.

  Further, in the technique described in Patent Document 2, when the optical output is high when used in a receptacle type laser module as in the technique of Patent Document 1, the fusion phenomenon occurs, and the coupling loss to the optical fiber is reduced. There is a problem of increasing. In addition, when the output of incident light is high, there is also a problem that contamination occurs on the fiber end face.

Moreover, in the technique described in Patent Document 3, contamination cannot be prevented if the light density exceeds 15 W / mm ² at the fiber incident end face or the output end face, but the core diameter of the fiber incident end is determined. The upper limit of the optical output is determined by the fiber diameter, and there is a problem that the optical output cannot be increased too much.

  Further, the technique described in Patent Document 4 has a problem that the fusion phenomenon occurs as in the technique of Patent Document 1 and the coupling loss to the optical fiber increases.

  For example, when a light source having a short wavelength such as 405 nm is used, it is known that contamination occurs at the end of the fiber, resulting in a decrease in light output, resulting in a quality problem. In particular, it is known that when the light output density is increased, the decrease in output due to contamination becomes remarkable on the surface where a transparent member such as glass is in contact with air.

  In order to suppress the decrease in light output due to this contamination, it is conceivable to reduce the light output density. However, conventionally, it has been unclear how much the light output density can be reduced to suppress the decrease in light output due to contamination. .

  Further, as described above, when high-power light is incident in a configuration in which a transparent member is connected to the end of the fiber, glass may be fused between both end faces. There is a possibility that even a slight vibration applied to the fiber may cause separation, and there is a problem that transmission loss increases due to light scattering caused by unevenness on the separation surface, which affects reliability.

  The present invention has been made in consideration of the above facts, and an object thereof is to provide an optical device and an exposure apparatus that can suppress a decrease in light output.

In order to achieve the above object, the invention according to claim 1 is in contact with a light source that outputs light of a predetermined wavelength, a first optical member that transmits light of the predetermined wavelength, and the first optical member. A second optical member that transmits light of the predetermined wavelength, wherein the predetermined wavelength is 160 to 500 [nm], and the first optical member and the second optical The light density at the contact surface with the member is 140 [W / mm ² ] or less.

According to this invention, the optical device is configured such that the light density at the contact surface between the first optical member and the second optical member through which light of a predetermined wavelength is transmitted is 140 [W / mm ² ] or less. Therefore, it is possible to prevent fusion at the contact surface and suppress a decrease in light output.

In addition, as described in claim 2, of the first optical member and the second optical member, the light on the end surface on the side where the light enters or exits and on the side exposed to the air By adopting a configuration in which the density is 8 [W / mm ² ] or less, contamination of the end face can be prevented and a decrease in light output can be suppressed.

  According to a third aspect of the present invention, the second optical member includes an optical fiber and a third optical member provided between the optical fiber and the first optical member, and the optical fiber And the third optical member may be fusion-connected. The third optical member may be formed by fusion-connecting a plurality of optical members.

  According to a fourth aspect of the present invention, it is preferable that the light condensing position is a position other than the contact surface.

  In addition, as described in claim 5, it is preferable that the first optical member and the second optical member each have a diameter larger than a beam diameter of the transmitted light.

  Further, according to a sixth aspect of the present invention, of the first optical member and the second optical member, the end surface on the side on which the light is incident and the end surface on the side exposed to the air is the light. It is preferable to incline with respect to the direction orthogonal to the main axis.

  According to a seventh aspect of the present invention, at least one of the first optical member and the second optical member may include quartz.

In addition, as described in claim 8, at least one of the first optical member and the second optical member is an optical fiber, and the output of the light is a cross-sectional area of the core of the optical fiber × 8 [ It is good also as a structure which is more than W / mm < ² >].

According to a ninth aspect of the present invention, at least one of the first optical member and the second optical member is an optical fiber, and an output of the light is a cross-sectional area of the optical fiber × 8 [W / mm ² ] or more.

In addition, as described in claim 10, at least one of the first optical member and the second optical member is an optical fiber, and the output of the light is a cross-sectional area of a ferrule that holds the optical fiber × It is good also as a structure which is 8 [W / mm < ² >] or more.

In addition, as described in claim 11, at least one of the first optical member and the second optical member is an optical fiber, and the output of the light is a cross-sectional area of the core of the optical fiber × 140 [ It is good also as a structure which is more than W / mm < ² >].

According to a twelfth aspect of the present invention, at least one of the first optical member and the second optical member is an optical fiber, and the output of the light is a cross-sectional area of the optical fiber × 140 [W / mm ² ] or more.

In addition, as described in claim 13, at least one of the first optical member and the second optical member is an optical fiber, and the output of the light is a cross-sectional area of a ferrule that holds the optical fiber × It is good also as a structure which is 140 [W / mm < ² >] or more.

  Furthermore, as described in claim 14, the predetermined wavelength may be 370 to 500 [nm].

  An exposure apparatus according to a fifteenth aspect includes the optical device according to any one of the first to fourteenth aspects.

  According to the present invention, it is possible to suppress a decrease in light output.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 shows a schematic configuration of an optical device 10 according to an embodiment of the present invention. As shown in FIG. 1, the optical device 10 includes a laser light source 12, a lens 14 as a condensing optical system, a transparent member 16, and an optical fiber 18.

  The laser light source 12 is composed of, for example, a semiconductor laser and emits laser light having a short wavelength (for example, 160 to 500 nm). Note that a wavelength of less than 160 nm is a wavelength that cannot be used practically in consideration of light absorption of the transparent member 16, and a wavelength of more than 500 nm cannot oscillate when gallium nitrite or the like is used as a constituent material of the laser light source 12, for example. Is the wavelength. Therefore, in the present embodiment, the short wavelength region is defined as 160 to 500 nm.

  The lens 14 condenses the laser light L emitted from the laser light source 12 near the contact surface between the transparent member 16 and the optical fiber 18 at a predetermined magnification (for example, 4 times). The condensing position of the laser light L is preferably shifted from the contact surface in the main axis direction of the laser light L to be within the optical fiber 18 or the transparent member 16. Thereby, the light density of the contact surface can be reduced.

  The transparent member 16 is made of, for example, a glass member made of quartz, and is in optical contact with the optical fiber 18, for example. The optical fiber 18 has a configuration in which a clad 18B is formed around a core 18A. The transparent member 16 has an outer diameter larger than the beam diameter of the laser light L that passes through the transparent member 16, and the laser light L cannot be emitted.

  Further, the transparent member 16 is cut obliquely so that the incident end face 16A forms an angle θ with respect to the direction orthogonal to the main axis direction of the laser light L. Thereby, the return light to the laser light source 12 side can be reduced, and the coupling efficiency with respect to the optical fiber 18 can also be improved. Note that the AR coating may be applied to the incident end face 16A without being cut obliquely. Thereby, the return light can be reduced.

  By the way, when a laser beam having a wavelength of 370 to 500 nm is transmitted through a transparent member (glass stub) made of quartz glass, the incident / exit end of the transparent member is contaminated according to the light density, and the contamination decreases. Although it is known that an object adheres, as a result of intensive studies, the present inventor has found that there is a linear correlation between the degree of output decrease and the light density. This will be described below.

  The present inventor condenses the emitted light of the laser driven at 50 to 400 mW with a lens so as to have a predetermined power density, and arranges a transparent member made of a glass member at the condensing point, and the transparent member The time-dependent change in the transmittance of the laser beam was measured while changing the light density by moving the laser beam along the main axis of the laser beam.

The result is shown in FIG. The horizontal axis is the light density (W / mm ² ) at the incident end face of the laser beam of the transparent member, and the vertical axis is the degree of decrease in light output due to contamination, that is, the degree of decrease in transmittance per hour of light transmitted through the transparent member. Is shown. In the figure, the vertical axis represents the decrease in transmittance. In the figure, the circles indicate actual measurement points, and the straight lines shown in the figure are straight lines obtained by the least square method. And the formula representing the straight line is as follows.

LogR = −6.5 + 0.9 × Log (P / S) (1)
Here, R is the degree of decrease in transmittance per time, P is the output value (W) of the laser beam, and S is the beam area (mm ² ) at the incident end face of the transparent member.

For example, when the laser light transmittance is defined as the lifetime of the laser light source when the laser light transmittance is reduced by 20% from a predetermined predetermined transmittance, the output decreases due to contamination when a laser with a lifetime of 10,000 (10 ⁴ ) hours is used. If the target is to suppress the amount to 1/10 or less, that is, 2% or less of the decrease in the transmittance until the lifetime of the laser light source, the decrease is 0.02 / 10 ⁴ = 2.0 × 10. ^-6 . The light density corresponding to this value is 8 [W / mm ² ] from FIG.

Therefore, in the configuration shown in FIG. 1, the light density at the incident end face 16A of the transparent member 16 is, for example, 8 [W / mm ² ] or less, so that a decrease in light output due to contamination can be suppressed. Specifically, the output value of the laser light source 12, the magnification of the lens 14, and the principal axis direction of the laser light of the transparent member 16 so that the light density at the incident end face 16 </ ^b > A of the transparent member 16 is 8 [W / mm ² ] or less. And the like, and the refractive index of the transparent member 16 are set.

  In addition, when laser light having a wavelength of 370 to 500 nm is irradiated onto a contact surface in which a transparent member (glass stub) made of quartz glass and an optical fiber made of quartz are optically contacted, the contact surface is melted. May wear. This fused portion is easily peeled off by slight vibrations, and when peeling occurs, transmission loss increases rapidly due to light scattering due to unevenness on the surface, leading to a sudden failure.

  As a result of intensive studies, the present inventor measured the relationship between the sudden failure rate and the light density at the contact surfaces of the transparent member and the optical fiber, and obtained the results shown in FIG.

As shown in the figure, it was found that when the light density at the contact surface is 140 [W / mm ² ] or less, no sudden failure occurs. Accordingly, in the configuration of FIG. 1, the light output at the contact surface 20 between the transparent member 16 and the optical fiber 18 is set to be, for example, 140 [W / mm ² ] or less, thereby reducing the light output due to fusion. Can be suppressed. Specifically, the output value of the laser light source 12, the magnification of the lens 14, the transparent member 16 so that the light density at the contact surface 20 between the transparent member 16 and the optical fiber 18 is 140 [W / mm ² ] or less. The length of the laser beam in the principal axis direction, the refractive index of the transparent member 16, and the like are set.

  Here, sudden failure means that the output of laser light that has passed through a transparent member and an optical fiber is monitored in a time-lapse test, and the light output when ACC (Auto Current Control) driving is suddenly changed. When the light output becomes 0.8 times or less in the state or when the APC (Auto Power Control) drive is performed, the drive current of the laser light source suddenly changes to 1.2 times the drive current in the normal state This is the case when the above is reached, and particularly when the light output before the sudden change or the degree of change in the drive current cannot be predicted.

From the above, when the beam area at the incident end face 16A exposed to the air of the transparent member 16 is S1 [mm ² ] and the beam area at the contact surface 20 between the transparent member 16 and the optical fiber 18 is S2 [mm ² ], By making the optical output P in the optical device 10 satisfy the following expression, it is possible to suppress a decrease in optical output due to contamination or fusion.

P [W] ≦ 8 [W / mm ² ] × S1 [mm ² ] (2)
P [W] ≦ 140 [W / mm ² ] × S2 [mm ² ] (3)
If P is set so as to satisfy both the conditions (2) and (3), a decrease in light output due to contamination and fusion can be suppressed.

Thus, in this embodiment, since the optical device 10 is configured so that the light density at the incident end face 16A of the transparent member 16 is 8 [W / mm ² ] or less, it is possible to suppress a decrease in light output due to contamination. it can.

Further, since the optical device 10 is configured such that the light density at the contact surface 20 between the transparent member 16 and the optical fiber 18 is 140 [W / mm ² ] or less, it is possible to suppress a decrease in light output due to fusion. it can.

  In the present embodiment, the case where the present invention is applied to the optical device 10 configured such that the laser light from the laser light source 12 passes through the lens 14 and the transparent member 16 and enters the optical fiber 18 has been described. Not only this but the structure which outputs the laser beam which injected into the optical fiber 18 to the transparent member 16 side, ie, the case where the transparent member 16 and the optical fiber 18 are used as a radiation | emission part of a laser beam, or bundle fiber which bundled this two or more The present invention can also be applied to.

Moreover, you may comprise the transparent member 16 by a some member. In this case, a decrease in light output due to contamination can be suppressed by making the light density of the incident end face of the member into which the laser light is incident be 8 [W / mm ² ] or less among the plurality of members. Moreover, the fall of the light output by melt | fusion can be suppressed by making the light density in the contact surface of several members become 140 [W / mm < ² >] or less.

  Further, the optical device 10 can be used in an exposure apparatus using this as a light source for exposure, for example, an exposure apparatus for performing exposure for wiring formation of a printed board.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected to the same part as 1st Embodiment, and the detailed description is abbreviate | omitted.

  FIG. 4 shows a schematic configuration of the optical device 10A according to the present embodiment. As shown in the figure, the optical device 10A is illustrated in that a second transparent member 22 having the same outer diameter as the outer diameter of the optical fiber 18 is provided between the transparent member 16 and the optical fiber 18. 1 is different from the optical device 10 shown in FIG.

  The second transparent member 22 has an outer diameter larger than the beam diameter of the laser light L that passes through the second transparent member 22, and the laser light L cannot be emitted. The second transparent member 22 can be a glass stub made of, for example, quartz. Alternatively, a coreless fiber may be used, or as shown in FIG. 5, a fiber stub composed of an optical fiber including a core 22A and a clad 22B having a core diameter larger than the beam diameter of the transmitted laser light L may be used.

  The contact surface 24 between the transparent member 16 and the second transparent member 22 is optically contacted, and the contact surface 20 between the second transparent member 22 and the optical fiber 18 is fusion-connected.

Even in such a configuration, the optical device 10 is configured such that the light density at the incident end surface 16A of the transparent member 16 is 8 [W / mm ² ] or less, thereby suppressing a decrease in light output due to contamination. Can do.

Further, by configuring the optical device 10 so that the light density at the contact surface 24 between the transparent member 16 and the second transparent member 22 is 140 [W / mm ² ] or less, the light output is reduced due to fusion. Can be suppressed.

  Thus, in this embodiment, since the 2nd transparent member 22 is provided between the transparent member 16 and the optical fiber 18, compared with the optical device 10 shown in FIG. The light density at the incident end face 16A and the light density at the contact surface 24 between the transparent member 16 and the second transparent member 22 can be reduced, and the decrease in light output due to contamination and fusion can be further suppressed.

The transparent member 16 may be composed of a plurality of transparent members. Even in this case, the optical device 10 is configured so that the light density at the incident end surface of the transparent member exposed to air, that is, the transparent member closest to the lens 14 is 8 [W / mm ² ] or less. Therefore, a decrease in the light output due to contamination can be suppressed, and the optical device 10 is configured so that the light density at the contact surface between the transparent members is 140 [W / mm ² ] or less, so that the light output due to fusion is achieved. Can be suppressed.

  Also in the present embodiment, as in the first embodiment, the laser light incident on the optical fiber 18 is output to the second transparent member 22 and the transparent member 16 side, that is, the transparent member 16 and the second member. The present invention can also be applied to the case where the transparent member 22 and the optical fiber 18 are used as a laser beam emitting portion, or to a bundle fiber in which a plurality of these are bundled.

  Moreover, although this embodiment demonstrated the case where the 2nd transparent member 22 was the same as the outer diameter of the optical fiber 18, it is not restricted to this, As a structure which has an outer diameter larger than the outer diameter of the optical fiber 18 Also good. Furthermore, as shown in FIG. 6, the outer diameter of the second transparent member 22 is the same as the outer diameter of the optical fiber 18 at the contact surface 20 with the optical fiber 18, and the outer diameter increases toward the transparent member 16 side. It is good also as a taper type member which becomes large.

  Further, the second transparent member 22 may be formed by fusion-bonding a plurality of fiber stubs, coreless fibers, or quartz stubs having different diameters. In that case, the surface area of the contact surface 24 between the second transparent member 22 and the transparent member 16 can be increased by increasing the diameter in steps from the optical fiber 18 side. It becomes possible to do.

  Next, examples of the present invention will be described.

  A semiconductor laser with a wavelength of 370 nm to 500 nm, which is currently available, a lens for condensing the laser light emitted from the semiconductor laser to the optical fiber side at a magnification of 4 times, and an optical fiber so that it can be connected at a condensing point A receptacle-type optical device in which a transparent member made of quartz integrated with a sleeve is arranged so that an optical fiber can be inserted into and removed from the sleeve was manufactured.

  After the coreless fiber having the same outer diameter as that of the transparent member and the optical fiber is fused and connected to the incident side of the optical fiber, the coreless fiber (corresponding to the second transparent member) is cut off in the vicinity of a desired length and polished. As a result, a fiber having a desired length of coreless fiber was obtained. This fiber was inserted into the sleeve and brought into contact with the transparent member (optical contact), and light was incident on the fiber to investigate the failure due to contamination and fusion.

  In the case of the receptacle type optical device as described above, a failure due to fusion does not occur at the connection surface between the coreless fiber and the optical fiber because it is originally fused, and the contact surface between the transparent member 16 and the coreless fiber. Occurs. Since the contact surface is shifted in the main axis direction of the laser beam by the length of the coreless fiber as compared with the case where no coreless fiber is provided, the light density at the contact surface can be reduced. Therefore, a highly reliable receptacle-type optical device using a higher-output light source can be manufactured.

In the optical device having such a configuration, the light density at the contact surface between the transparent member and the coreless fiber is 140 [W / mm ² ] or less, and the light density at the incident end surface of the transparent member is 8 [W / mm ² ] or less. Designed to be

Specifically, the output P [W] beam area S1 of the semiconductor laser may satisfy the above expression (2). However, the beam area S1 has a major axis radius when the beam shape is an ellipse. When r1 and the minor axis radius are r2, it is expressed by (r1 × r2 × π). Here, the vertical radiation half-angle of the laser light emitted from the semiconductor laser is NA _、, the horizontal radiation half-angle is NA _// , the length of the laser light in the principal axis direction of the transparent member is L _sab , and the refraction of the transparent member is When the rate is n _stab, the length of the laser beam of the coreless fiber in the principal axis direction is L _cf , and the lens magnification is α, the major axis radius r1 and the minor axis radius r2 are expressed by the following equations.

_{r1 = (L stab + L cf} ) × NA ⊥ / n stab × 1 / α ··· (4)
_{r2 = (L stab + L cf} ) × NA // / n stab × 1 / α ··· (5)
Therefore, by setting the length L _stab of the transparent member and the length L _cf of the coreless fiber so as to satisfy the following formula, it is possible to suppress a decrease in light output due to contamination.

_{P ≦ 8 × (L stab +} L cf) × NA ⊥ / n stab × 1 / α ×
_{(L stab + L cf) ×} NA // / n stab × 1 / α × π ··· (6)
Similarly, the beam area S2 is represented by (r3 × r4 × π) where the major axis radius is r3 and the minor axis radius is r4 if the beam shape is an ellipse. The major axis radius r3 and the minor axis radius r4 are expressed by the following equations.

_{r3 = L cf × NA ⊥ /} n stab × 1 / α ··· (7)
_{r4 = L cf × NA // /} n stab × 1 / α ··· (8)
Therefore, by setting the length L _stab of the transparent member and the length L _cf of the coreless fiber so as to satisfy the following formula, it is possible to suppress a decrease in light output due to fusion.

_{P ≦ 140 × L cf × NA} ⊥ / n stab × 1 / α ×
_{L cf × NA // / n stab} × 1 / α × π ··· (9)
Furthermore, by setting the diameter φstab of the transparent member so as to satisfy all of the following expressions, a configuration in which the beam cannot be emitted can be obtained.

φstab <r1 × 2 (10)
φstab <r2 × 2 (11)
Further, by setting the diameter φcf of the transparent member so as to satisfy all of the following expressions, a configuration in which the beam cannot be formed can be obtained.

φcf <r3 × 2 (12)
φcf <r4 × 2 (13)
In the fabricated optical device, the area S of the emission shape of the end face of the semiconductor laser is 7 × 1 [μm ² ], the vertical radiation angle θ _⊥ is 42 °, the horizontal radiation angle θ _// is 16 °, and the laser The light output P was 500 mW. In this configuration, the coreless fiber length _{L cf} the 0.9 mm, the length _{L stab} of the transparent member was 3.0 mm. The light density at the contact surface between the transparent member and the coreless fiber was 42 W / mm ² , and it was confirmed that no failure due to fusion occurred. The light output density at the incident end face of the transparent member was 6.1 W / mm ² , and the decrease in light output due to contamination was negligible.

In this configuration, when an optical fiber having an outer diameter of 125 μm is used, the coreless fiber is designed to have a beam diameter of 125 μm in the Fast direction on the incident surface of the coreless fiber, and the optical output of the coreless fiber incident surface is 140 [W / mm ² ], the highest output light source can be realized, but the output at this time is about 630 mW.

Further, when the length L _stab of the transparent member was shortened to 2.0 mm and the output P of the semiconductor laser was 500 mW, the light output was reduced due to contamination. This was because the light density at the incident end face of the transparent member was 12 [W / mm ² ]. Then, the length L _stab of the transparent member was reset so as to satisfy the above expression (6). _{Specifically, NA ⊥ = 0.383, NA //} = 0.141, a n _stab = 1.46, because it is P = _500mW, L stab = 3.0mm or more, the diameter 520μm or more transparent members By using, a light source with negligible degradation due to contamination could be produced.

In the receptacle type optical device, the outer diameter of the transparent member is set to 125 μm, and the light density at the incident end face of the transparent member is set to 8 [W / mm ² ] which is an upper limit value for preventing contamination. The optical device was configured to measure the output of the laser beam causing contamination at the incident end face, and it was about 100 mW. Therefore, in the case of this configuration, if the light density at the incident end face of the transparent member is 8 [W / mm ² ] or less, the output of the laser light can be 100 mW or more.

Similarly, in the above receptacle-type optical device, the outer diameter of the transparent member is set to 125 μm, and the light density at the contact surface between the transparent member and the coreless fiber is 140 [W / It was about 1.7 W when the optical device was configured to be mm ² ] and the output of the laser beam causing fusion at the contact surface was measured. Therefore, in the case of this configuration, when the light density at the contact surface is 140 [W / mm ² ] or less, the output of the laser light can be 1.7 W or more.

In the above receptacle type optical device, the core diameter of the optical fiber is set to 60 μm, and the light density at the contact surface between the transparent member and the coreless fiber is 140 [W / mm, which is an upper limit for preventing fusion. ² ] and the output of the laser beam that causes fusion at the contact surface was measured and found to be about 400 mW. Therefore, in the case of this configuration, when the light density at the contact surface is 140 [W / mm ² ] or less, the output of the laser light can be 400 mW or more.

  In addition, the above results were the same even when a fiber stub was used instead of the coreless fiber.

In addition, by setting it as the structure of this invention, a high output light source can be used compared with the conventional optical device. Specifically, when the output of the light source is equal to or larger than the cross-sectional area of the core of the optical fiber × 8 [W / mm ² ], for example, a conventional pigtail laser can be used for the core of the optical fire bar without passing through a transparent member. In the form of direct input, contaminants are generated at the interface of the fiber end face that is in contact with the outside air. However, with the configuration of the present invention, contamination occurs on the end face of the optical member in contact with the outside air as described above even when the output of the light source is the above output. Can be suppressed.

Further, when the output of the light source is equal to or larger than the cross-sectional area of the optical fiber × 8 [W / mm ² ], for example, the fiber end face in contact with the outside air in a form in which the conventional coreless fiber is directly input to the fiber fused to the tip. Contaminants are generated at the interface of the light source. However, by adopting the configuration of the present invention, even when the output of the light source is the above output, the occurrence of contamination can be suppressed at the end face of the optical member in contact with the outside air as described above.

Further, when the output of the light source is equal to or larger than the ferrule cross-sectional area × 8 [W / mm ² ], in the form of direct incidence to the optical fiber held by the conventional ferrule, it is formed at the interface of the fiber end face in contact with the outside air. Contaminants are generated, but with the configuration of the present invention, even when the output of the light source is the above output, the occurrence of contamination can be suppressed on the end face of the optical member in contact with the outside air as described above.

Further, when the output of the light source is equal to or larger than the cross-sectional area of the core of the optical fiber × 140 [W / mm ² ], there is a problem of fusion in the form of the conventional receptacle using the glass stub and the fiber in contact with each other. However, with the configuration of the present invention, even if the output of the light source is the above output, as described above, the fusion can be suppressed and a high output light source can be used.

In addition, when the output of the light source is equal to or larger than the cross-sectional area of the optical fiber × 140 [W / mm ² ], a receptacle that uses a coreless fiber or an optical fiber fused with a fiber stub in contact with a glass stub is used. In the embodiment, a fusion problem may occur. However, with the configuration of the present invention, even if the output of the light source is the above output, the fusion can be suppressed and a high output light source can be used as described above.

Further, when the output of the light source is 140 [W / mm ² ] or more of the ferrule cross-sectional area, the conventional glass stub and the receptacle that uses the fiber held around the ferrule in contact with the ferrule have a fusion problem. However, with the configuration of the present invention, even if the output of the light source is the above output, as described above, it is possible to suppress fusion and use a high output light source.

  Note that the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention can also be applied to a design modified within the scope of the claims.

It is a schematic block diagram of the optical device which concerns on 1st Embodiment. It is a graph which shows the relationship between a light density and the fall of the light output by contamination. It is a graph which shows the relationship between a light density and a sudden failure rate. It is a schematic block diagram of the optical device which concerns on 2nd Embodiment. It is a schematic block diagram which shows the modification of the optical device which concerns on 2nd Embodiment. It is a schematic block diagram which shows the modification of the optical device which concerns on 2nd Embodiment.

Explanation of symbols

10, 10A Optical device 12 Laser light source (light source)
14 Lens 16 Transparent member (first optical member)
16A Incident end face 18 Optical fiber 18A Core 18B Clad 20 Contact surface 22 Transparent member (third optical member)

Claims (15)

A light source that outputs light of a predetermined wavelength; a first optical member that transmits light of the predetermined wavelength; a second optical member that is in contact with the first optical member and transmits light of the predetermined wavelength; An optical device comprising:
The predetermined wavelength is 160 to 500 [nm], and the light density at the contact surface between the first optical member and the second optical member is 140 [W / mm ² ] or less. Optical device. Of the first optical member and the second optical member, the light density at the end surface on the side where the light enters or exits and on the side exposed to the air is 8 [W / mm ² ] or less. The optical device according to claim 1, wherein the optical device is provided.   The second optical member includes an optical fiber and a third optical member provided between the optical fiber and the first optical member, and the optical fiber and the third optical member are fused. The optical device according to claim 1, wherein the optical device is connected.   The optical device according to claim 1, wherein the light condensing position is a position other than the contact surface.   The said 1st optical member and the said 2nd optical member each have a diameter larger than the beam diameter of the said light to permeate | transmit, Each of Claims 1-4 characterized by the above-mentioned. Optical device.   Of the first optical member and the second optical member, the end surface on the light incident side and the end surface exposed to the air is inclined with respect to the direction orthogonal to the main axis of the light. The optical device according to claim 1, wherein the optical device is an optical device.   The optical device according to claim 1, wherein at least one of the first optical member and the second optical member includes quartz. At least one of the first optical member and the second optical member is an optical fiber, and the output of the light is a cross-sectional area of the core of the optical fiber × 8 [W / mm ² ] or more. The optical device according to any one of claims 2 to 7. At least one of the first optical member and the second optical member is an optical fiber, and the output of the light is not less than the cross-sectional area of the optical fiber × 8 [W / mm ² ]. The optical device according to any one of claims 2 to 7. At least one of the first optical member and the second optical member is an optical fiber, and the output of the light is a cross-sectional area of a ferrule holding the optical fiber × 8 [W / mm ² ] or more. The optical device according to any one of claims 2 to 7, wherein: At least one of the first optical member and the second optical member is an optical fiber, and the output of the light is a cross-sectional area of the core of the optical fiber × 140 [W / mm ² ] or more. The optical device according to any one of claims 1 to 7. At least one of the first optical member and the second optical member is an optical fiber, and the output of the light is a cross-sectional area of the optical fiber × 140 [W / mm ² ] or more. The optical device according to claim 1. At least one of the first optical member and the second optical member is an optical fiber, and the output of the light is a cross-sectional area of a ferrule holding the optical fiber × 140 [W / mm ² ] or more. The optical device according to any one of claims 1 to 7, wherein:   The optical device according to any one of claims 1 to 13, wherein the predetermined wavelength is 370 to 500 [nm].   An exposure apparatus comprising the optical device according to claim 1.

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