JP6746934B2 - Light source - Google Patents

Description

The present invention relates to a light source device, and particularly to a light source device including a plurality of LED elements.

Conventionally, optical processing technology utilizing light has been used in various fields. For example, an exposure apparatus is used for fine processing using light. In recent years, the exposure technique has been developed in various fields and is used for producing a relatively large pattern among three-dimensional processing and for three-dimensional fine processing. More specifically, the exposure technique is used, for example, for manufacturing an electrode pattern of an LED, a manufacturing process of a MEMS (Micro Electro Mechanical Systems) represented by an acceleration sensor, and the like.

In these light processing techniques, a discharge lamp having high brightness has been used as a light source. However, as the solid-state light source technology has advanced in recent years, it has been studied to use a light source in which a plurality of LED elements are arranged. As such a technique, for example, Patent Document 1 discloses an exposure apparatus in which a unit including a plurality of LED elements is used as a light source, and a fly-eye lens is arranged between the light source and a mask.

JP, 2004-335953, A

When used as a light source for an exposure apparatus, it is necessary to always perform exposure with a desired dose amount, and therefore it is necessary to monitor the brightness of light emitted from the light source. By the way, when the light source is a discharge lamp, it is possible to detect the light extracted through, for example, a pinhole at any position on the optical path, and monitor the light output from the light source based on the detected light amount. Is.

However, if the light source is composed of multiple LEDs and the light is detected through a pinhole at any position on the optical path, the light emitted from all LED elements is detected at this detection point. It is not always done. Since there is inevitable variation in characteristics among the LED elements, not all LED elements change the luminous intensity to the same extent. That is, in the case of such a configuration, when the output of the light source is controlled based on the detected light amount, there is a possibility that the desired dose amount cannot be realized.

In view of the above problems, it is an object of the present invention to realize a light source device capable of controlling the output from the light source with high accuracy even when the light source is composed of a plurality of LEDs.

The light source device according to the present invention is
A light source unit including a plurality of LED elements;
A first optical system for collimating the light emitted from the light source unit,
A second optical system that collects a plurality of lights emitted from the first optical system,
And a photodetector arranged at a position different from the position where the second optical system collects light and at which the plurality of lights emitted from the first optical system are collected. Characterize.

According to the above configuration, the photodetector is arranged at a condensing position different from the position where the second optical system condenses. Therefore, the light emitted from the plurality of LEDs is guided to the photodetector. As a result, the light detected by the light detection unit reflects all the data of the light emitted from the plurality of LEDs forming the light source unit. As a result, by controlling the light source according to the amount of light detected by the light detection unit, the illuminance of the light guided to the subsequent stage of the second optical system can be accurately controlled. Further, since the photodetector is not arranged at the position where it is condensed by the second optical system, it does not block the optical path from the light source to the optical system arranged in the subsequent stage of the second optical system.

In the above configuration, a reflection optical system that transmits a part of the light and reflects a part of the light is provided.
The light transmitted by the reflective optical system may be collected and incident on the photodetector. In this case, the light reflected by the reflective optical system may be guided to an optical system, which is arranged in the subsequent stage of the second optical system and is suitable for the intended use.

In addition, as another configuration, a reflection optical system that transmits a part of light and reflects a part of light is provided.
The light reflected by the reflective optical system may be collected and incident on the photodetector. In this case, the light transmitted by the reflective optical system may be guided to an optical system arranged in the subsequent stage of the second optical system according to the intended use.

In the above configuration, the reflective optical system may be arranged in the subsequent stage of the second optical system. In this case, the photodetector may be arranged at a position optically equivalent to the focal point of the second optical system. That is, the convergence angle of the light traveling from the reflective optical system to the focal point of the second optical system and the convergence angle of the light traveling from the reflective optical system to the light receiving surface of the photodetector may be substantially the same.

Further, in the above configuration, the incident surface may include an integrator optical system arranged at the focal position of the second optical system.

The light emitted from the LED element has less radiant luminous flux than that of the lamp. Therefore, for use as a light source device for exposure, for example, it is necessary to collect light emitted from a plurality of LED elements as much as possible. For this purpose, it is necessary to increase the number of LED elements arranged as a light source.

By the way, since the wiring pattern for power supply is indispensable for the LED element, it is not possible to arrange the LED element itself in close contact with each other. That is, when arranging a plurality of LED elements, there is no choice but to leave a constant space between adjacent LED elements. The region forming this interval constitutes a region that does not emit light (non-light emitting region). Therefore, even if a plurality of LED elements are simply arranged and the light emitted from each LED element is condensed, a non-light emitting region is inevitably generated. Therefore, simply condensing the light emitted from the plurality of LED elements causes a decrease in the brightness on the irradiation surface.

According to the above configuration, the light emitted from the plurality of LED elements is condensed after being collimated in the first optical system. Thereby, the light emitted from each LED element can be imaged at the condensing position, and the light utilization efficiency can be improved. Further, by adjusting the arrangement of the first optical system (collimator lens), it is possible to narrow the interval between the light beams emitted from the LED elements, and thus a light source with a small non-light emitting region is configured. As a result, a light source device with high brightness is realized even when the light source unit is composed of LED elements.

Further, the integrator optical system may be configured by a light guide member that guides the light incident from the incident surface to the emission surface while repeating the reflection on the inner surface.

According to this configuration, since light having high radiation intensity is condensed on the incident surface of the light guide member, light with high brightness and uniform illuminance distribution is emitted from the exit surface of the light guide member. be able to. In addition, the light guide member can be configured by, for example, a rod integrator or a light tunnel.

Further, the integrator optical system may be configured by a fly-eye lens in which a plurality of lenses are arranged in a matrix.

With the fly-eye lens, the illuminance distribution on the irradiation surface can be made uniform. As a result, a light source device with high brightness and uniform illuminance distribution can be realized.

According to the present invention, a light source device capable of controlling output from a light source with high accuracy is realized in a configuration including a plurality of LED elements.

It is drawing which shows typically an example of the optical system of the light source device of 1st embodiment. It is drawing which shows typically an example of the optical system of the light source device of 1st embodiment. It is drawing which shows typically an example of the optical system of the light source device of 1st embodiment. It is drawing which shows typically an example of the optical system of the light source device of 2nd embodiment. It is drawing which shows typically an example of the optical system of the light source device of 3rd embodiment. It is drawing which shows an example of a structure of an exposure apparatus typically.

Hereinafter, the light source device of the present invention will be described with reference to the drawings. Note that the dimensional ratio in each drawing does not necessarily match the actual dimensional ratio.

[First embodiment]
FIG. 1 is a drawing schematically showing an example of an optical system of the light source device of the first embodiment. The light source device 1 includes a light source unit 2, a first optical system 5, a second optical system 7, an integrator optical system 8, a reflection optical system 31, and a light detection unit 33.

The light source unit 2 includes a plurality of LED elements 3. In the present embodiment, as an example, the plurality of LED elements 3 are arranged on a predetermined plane. However, in the present invention, the arrangement mode of the plurality of LED elements 3 may be any one.

The first optical system 5 is an optical system that collimates the light emitted from each of the plurality of LED elements 3, and includes a plurality of collimating lenses 6 arranged corresponding to each LED element 3.

The second optical system 7 is an optical system that focuses the light emitted from the first optical system 5 on the focal point 7 f of the second optical system 7.

In this embodiment, the integrator optical system 8 is composed of a rod integrator 9. The rod integrator 9 is arranged such that its incident surface 9a is located at the focal point 7f of the second optical system 7. However, in the present specification, “to be placed at the focal position” means that the position is perfectly coincident with the focal position and that the lens is moved by a distance of ±10% in the direction parallel to the optical axis 11 with respect to the focal length. It is assumed to be a concept including position. The optical axis 11 in FIG. 1 is an axis orthogonal to the incident surface of the integrator optical system 8, that is, the incident surface 9a of the rod integrator 9.

The rod integrator 9 guides the light incident on the incident surface 9a to the exit surface 9b while repeating the total reflection on the side surface, and thereby has a function of making the illuminance distribution of the light on the exit surface 9b uniform. It is an example of (light guide). Such a light guide member is composed of, for example, a columnar member made of a light transmissive material such as glass or resin, a hollow member having an inner surface formed of a reflecting mirror, or the like. The latter structure is sometimes called a light tunnel. In addition, the light guide member may have a plurality of optical paths divided therein in a direction parallel to the optical axis.

The reflective optical system 31 in the present embodiment transmits most of the light (90% or more and 99.9% or less of the incident light amount as an example) and only a part of the light (0.01% or more and 10% of the incident light amount as an example). It is an optical system that reflects the following) and is composed of, for example, a beam splitter. The light emitted from the plurality of LED elements 3 and collimated by the first optical system 5 has a smaller divergence angle as it passes through the second optical system 7. Then, of this light, most of the light passes through the reflective optical system 31 and is guided to the incident surface 9 a of the rod integrator 9. Further, after passing through the second optical system 7, a part of the light is reflected by the reflective optical system 31 and guided to the light receiving surface of the photodetector 33.

The light detection unit 33 is a device that generates an electric signal in accordance with the amount of received light, and a photodetector including a photodiode or the like can be used, for example. In the configuration of the present embodiment, the light receiving surface of the light detection unit 33 is arranged at the position 7f' equivalent to the focus 7f of the second optical system 7.

According to the above configuration, a part of the light emitted from all the LED elements 3 is incident on the light detection unit 33. Therefore, the amount of light detected by the light detection unit 33 reflects the data of the amount of light emitted from all the LED elements 3. Therefore, by controlling the output of the light source unit 2 according to the amount of light detected by the light detection unit 33, the illuminance of the light guided to the subsequent stage of the integrator optical system 8 can be accurately adjusted. Although not shown in FIG. 1, the light source device 1 may be configured to include a control unit for controlling the output of the light source unit 2. In this case, the control unit can control the amount of light emitted from the light source unit 2 by controlling the amount of current supplied to the light source unit 2, for example.

In FIG. 1, the light receiving surface of the photodetector 33 is arranged at the position 7f′ equivalent to the focus 7f of the second optical system 7, but as shown in FIG. 2, it is displaced from the position 7f′. It may be arranged at a different position (in FIG. 2, the position 7f' is not shown for convenience of illustration). In this case, the light emitted from each LED element 3 is incident on the light receiving surface of the light detection unit 33 with a certain area. However, also in this configuration, the amount of light detected by the light detection unit 33 reflects the data of the amount of light emitted from all the LED elements 3. However, as shown in FIG. 1, by arranging the light receiving surface of the photodetector 33 at a position 7f′ equivalent to the focal point 7f, variation in the light amount due to the angle is suppressed, and thus the light source unit with higher accuracy. Information about the light output of 2 can be detected.

Further, as shown in FIG. 3, the light reflected by the reflective optical system 31 is guided to the incident surface 9a of the rod integrator 9, while the light transmitted through the reflective optical system 31 is guided to the light receiving surface of the photodetector 33. It may be configured.

[Second embodiment]
FIG. 4 is a drawing schematically showing an example of the optical system of the light source device of the second embodiment. For convenience of illustration, it is illustrated in a manner different from that of the first embodiment. The same components as those in the first embodiment are designated by the same reference numerals.

The light source device 1 shown in FIG. 4 includes a condensing optical system 35 different from the second optical system 7. The light emitted from the plurality of LED elements 3 is collimated by the first optical system 5. Then, most of this light, after passing through the reflection optical system 31, is condensed by the second optical system 7 on the incident surface 9a of the rod integrator 9, which is an example of the integrator optical system 8. Further, a part of the light after being collimated by the first optical system 5 is reflected by the reflective optical system 31 and then condensed by the condensing optical system 35 on the light receiving surface of the photodetector 33. In the configuration of FIG. 4, the light receiving surface of the light detection unit 33 is arranged at the focal point 35f of the condensing optical system 35.

Even in such a configuration, since a part of the light emitted from all the LED elements 3 is incident on the light detecting section 33, the amount of light detected by the light detecting section 33 is from all the LED elements 3. The data of the emitted light quantity is reflected. Therefore, by controlling the output of the light source unit 2 according to the amount of light detected by the light detection unit 33, the illuminance of the light guided to the subsequent stage of the integrator optical system 8 can be accurately adjusted.

In the configuration of FIG. 4, the second optical system 7 and the condensing optical system 35 do not necessarily have to have the same focal length. Further, as in the first embodiment described above, the light receiving surface of the light detection unit 33 may be arranged at a position deviated from the focus 35f of the condensing optical system 35. Further, the light reflected by the reflective optical system 31 may be guided to the incident surface 9a of the rod integrator 9, while the light transmitted through the reflective optical system 31 may be guided to the light receiving surface of the photodetector 33.

[Third embodiment]
FIG. 5 is a drawing schematically showing an example of the optical system of the light source device of the third embodiment. The light source device 1 of the present embodiment is different from the first embodiment in that the integrator optical system 8 is composed of a fly-eye lens 10.

Even when the integrator optical system 8 is configured by the fly-eye lens 10 as in the present embodiment, high-intensity light is condensed on the incident surface of the fly-eye lens 10. As a result, high-intensity light is emitted from the fly-eye lens 10. In addition, in the above-described other configuration, the integrator optical system 8 may be configured by the fly-eye lens 10.

[Another embodiment]
Hereinafter, another embodiment will be described.

<1> The light source device 1 described in each embodiment can be used as a light source for an exposure device or a projector.

FIG. 6 is a drawing schematically showing the configuration of an exposure apparatus including the light source device 1 of the first embodiment. The exposure device 19 is provided with a projection optical system 15 and a mask 16 at the subsequent stage of the integrator optical system 8, and a projection lens 17 as necessary. The mask 16 is installed at a position where it is projected by the projection optical system 15, and a photosensitive substrate 18 as a target for printing a pattern image of the mask 16 is installed at a stage subsequent to the mask 16. When light is emitted from the light source unit 2 in this state, the light is condensed by the second optical system 7, and then is irradiated on the projection optical system 15 as light whose illuminance distribution is uniformized by the rod integrator 9. To be done. The projection optical system 15 projects this light onto the photosensitive substrate 18 directly or via the projection lens 17 as a pattern image of the mask 16.

In particular, when the light source unit 2 is composed of a plurality of LED elements 3 like the exposure device 19, the rising time is very short, unlike when the light source is composed of a lamp. Further, the LED element 3 has a theoretical problem that the light output decreases as the temperature rises. Therefore, in the case where the exposure process is continuously performed, the next exposure process may be started before the temperature is completely lowered, and in this case, the dose amount may change in each process.

However, as described above, the light detection unit 33 detects the light amount in which the data of the light emitted from the plurality of LED elements 3 is reflected. Therefore, by controlling the output of the light source unit 2 in accordance with the detection result of the light detection unit 33, the dose amount with which the photosensitive substrate 18 is irradiated can be accurately adjusted.

The exposure device 19 may include the light source device 1 of each of the embodiments after the second embodiment. The same applies to projectors.

<2> In each of the above-described embodiments, the light source device 1 may include an optical system such as a reflective optical system as appropriate for the purpose of changing the optical path.

1: Light source device 2: Light source part 3: LED element 5: First optical system 6: Collimating lens 7: Second optical system 7f: Focus of second optical system 8: Integrator optical system 9: Rod integrator 9a: Rod integrator Incident surface 9b: Exit surface of rod integrator 10: Fly-eye lens 11: Optical axis 15: Projection optical system 16: Mask 17: Projection lens 18: Photosensitive substrate 19: Exposure device 31: Reflection optical system 33: Photodetection unit 35 : Focusing optics

Claims (6)

A light source section in which a plurality of LED elements are arranged on a plane;
A first optical system in which a plurality of collimating lenses is arranged corresponding to each of the LED elements, and collimates the lights emitted from the plurality of LED elements;
A second optical system that collects a plurality of lights emitted from the first optical system,
A reflective optical system that transmits some light and reflects some light,
An integrator optical system in which the incident surface is arranged at the focal position of the second optical system,
Unlike positions condensed by the second optical system, a focus and a position optically equivalent to said second optical system, a plurality of the light emitted from said first optical system is focused A light source device, comprising: a light detection unit disposed at a predetermined position. The light source device according to claim 1, wherein the light transmitted by the reflective optical system is collected and incident on the light detection unit. The light source device according to claim 1, wherein the light reflected by the reflective optical system is collected and incident on the photodetection unit. The light source device according to claim 2, wherein the reflective optical system is arranged in a stage subsequent to the second optical system. 5. The integrator optical system is configured by a light guide member that guides the light incident from the incident surface to the exit surface while repeatedly reflecting the light on the inner surface . the light source device according to an item. The integrator optical system, a light source device according to claim 1, wherein a plurality of lenses is configured in a fly-eye lenses arranged in a matrix form.

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