JP2012049226A - Light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light source device configured to emit radiation light beams from a plurality of LED light sources after synthesizing the radiation light beams, which can emit light beams having a plurality of peak wavelengths over a continuous and wide wavelength range and provide high luminance.SOLUTION: The light source device comprises a first LED light source and a second LED light source having peak wavelengths close to each other, and a dichroic mirror which synthesizes a light beam radiated from the first LED light source and a light beam radiated from the second LED light source. The dichroic mirror is arranged in such a state that each of the incidence angle of the radiation light beam from the first LED light source and the incidence angle of the radiation light beam from the second LED light source becomes 5-40°.

Description

  The present invention relates to a light source for exposure when performing an exposure process in a manufacturing process of a semiconductor, a liquid crystal substrate, a color filter, or the like, or a light source device used as a light source in a projector apparatus.

  For example, as an exposure light source used when performing an exposure process in a manufacturing process of a semiconductor, a liquid crystal substrate, a color filter or the like, a plurality of LED elements in an ultraviolet wavelength region as shown in FIG. There is known a light source device that has an LED light emitting unit 80, and that is configured to condense radiated light emitted from the LED light emitting unit 80 by an appropriate condensing optical system and emit it to the exposure surface S ( For example, see Patent Document 1.) In FIG. 5, reference numeral 81 is an elliptical reflecting mirror, 82 is a spherical lens, 83 is a conical reflecting mirror, 84 is a translucent rod, 85 is a condenser lens, and 86 is a relay lens.

However, since the light source device having such a configuration can emit only monochromatic light having a relatively narrow wavelength range centered on the peak wavelength of the LED element, for example, wavelength light corresponding to the individual exposure sensitivity of the photosensitive resin. Therefore, there is a problem that it cannot be used as an exposure light source for performing an exposure process in a manufacturing process of a color filter or the like.
In addition, various losses occur in the process of condensing the light emitted from the LED element by the condensing optical system, so that the light use efficiency is lowered and it is not possible to obtain sufficiently high luminance light. There is a problem.

On the other hand, there has been proposed a light source device configured to synthesize and emit light emitted from each of a plurality of LED light sources having different peak wavelengths selected in a visible wavelength range using, for example, a dichroic mirror. Yes.
As shown in FIG. 6, the light source device includes two LED light sources 90A and 90B having different peak wavelengths within a predetermined wavelength range in the visible range, a dichroic mirror 91, a first LED light source 90A, and a second LED light source 90A. And a collimator lens 93 which is arranged on the front side in the light emission direction of each of the LED light sources 90B and emits the emitted light from the LED light sources to the dichroic mirror as parallel light.
In this light source device, the light emitted from the first LED light source 90A is transmitted through the dichroic mirror 91 and the light reflected from the dichroic mirror 91 is synthesized from the light emitted from the second LED light source 90B. The

  However, when the radiated light emitted from each of the plurality of LED light sources whose peak wavelengths are close to each other is synthesized by the dichroic mirror, the plurality of LED light sources and the dichroic mirror are simply combined with the optical system configured as described above. It has been found that it is not possible to emit light having a sufficiently high luminance simply by arranging the components.

JP 2007-041467 A

  The present invention has been made on the basis of the above circumstances, and in a configuration that synthesizes and emits the emitted light of a plurality of LED light sources, a continuous wide wavelength range having a plurality of peak wavelengths. It is an object of the present invention to provide a light source device that can emit light and obtain high luminance.

The light source device of the present invention includes a first LED light source and a second LED light source whose peak wavelengths are close to each other,
A dichroic mirror that combines the emitted light emitted from the first LED light source and the emitted light emitted from the second LED light source;
The dichroic mirror is disposed in a state where the incident angle of the emitted light from the first LED light source and the incident angle of the emitted light from the second LED light source are both 5 to 40 °. It is characterized by.

  In the light source device of the present invention, the difference between the peak wavelength of the first LED light source and the peak wavelength of the second LED light source is preferably 30 nm or less.

  According to the light source device of the present invention, the dichroic mirror has an incident angle of the emitted light from the first LED light source and an incident angle of the emitted light from the second LED light source of 5 to 40 °. In such a state, since the arrangement is arranged, the light utilization efficiency (combination efficiency) can be increased, so that light in a continuous wide wavelength range having a plurality of peak wavelengths can be emitted. In addition, the amount of radiated light can be increased over the entire required wavelength range, and high luminance can be obtained.

It is explanatory drawing which shows the outline of a structure in an example of the optical system which concerns on the light source device of this invention. It is a figure for demonstrating the wavelength selection characteristic of a dichroic mirror, Comprising: It is the wavelength selection characteristic about (A) P polarization component, and (B) The wavelength selection characteristic about S polarization component. It is explanatory drawing which shows roughly the spectral distribution curve of the synthetic | combination light of the emitted light from a 1st LED element, and the emitted light from a 2nd LED element. It is explanatory drawing which shows the outline of a structure in the other example of the optical system which concerns on the light source device of this invention. It is explanatory drawing which shows the outline of a structure of the optical system in an example of the light source device using the conventional LED element. It is explanatory drawing which shows the outline of a structure of the optical system in the other example of the light source device using the conventional LED element.

Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 is an explanatory diagram showing an outline of a configuration in an example of an optical system according to the light source device of the present invention.
The optical system includes a first LED light source and a second LED light source that emit light having peak wavelengths λ ₁ [nm] and λ ₂ [nm] (λ ₁ > λ ₂ ) that are close to each other. The first LED element 10 constituting the first LED light source and the light emitting surface of the first LED element 10 at a position in front of the light emission direction of the first LED light source. A disk-shaped dichroic mirror 50 disposed in a state inclined with respect to a central axis (hereinafter referred to as “reference axis”) C1 of the light emitting surface 10A extending in a direction perpendicular to 10A, and a light emitting surface 20A The second LED light source is arranged so as to be inclined and extended with respect to the other surface 50B of the dichroic mirror 50 in a state where the central axis C2 intersects with the position on the reference axis C1 on the other surface 50B of the dichroic mirror 50. And a second LED elements 20.

The first LED element 10 and the second LED element 20 are such that at least part of the spectral distribution curve of the emitted light of the first LED element 10 and the spectral distribution curve of the emitted light of the second LED element 20 overlap. It has a peak wavelength λ ₁ and a peak wavelength λ ₂ .
Furthermore, the wavelength at which the reflectance of the dichroic mirror 50 is 50% and the transmittance is 50% is the spectral distribution curve of the emitted light of the first LED element 10 and the spectral distribution curve of the emitted light of the second LED element 20. Are configured to be in the overlapping wavelength range.

  For example, when configuring a light source device for an ultraviolet exposure device, an LED light source including an LED element having a peak wavelength within a wavelength range of 250 to 450 nm is used. For example, a light source device for a projector device is configured. Includes an LED light source including an LED element having a peak wavelength in each wavelength range of a red region (420 to 470 nm), a green region (510 to 555 nm), and a blue region (605 to 650 nm), or a cyan region, An LED light source including an LED element having a peak wavelength in each wavelength range in the magenta region and the yellow region is used.

When configuring the light source device of ultraviolet ray exposure apparatus, the difference in the peak wavelength lambda ₂ of the peak wavelength lambda ₁ of the first LED element 10 and the second LED element 20 (peak interval), for example, 30nm or less For example, the thickness is preferably 10 to 20 nm. Thereby, the radiant intensity (light emission wavelength characteristic) of the light in the wavelength range including the peak wavelength of the LED element in the radiated light from one LED element can be emphasized by the radiated light from the other LED elements, The luminance of light in the necessary wavelength region can be improved reliably.

  In addition, the etendue (radiation area × solid angle) of each LED element is preferably set to the same size, so that the emitted light from each LED element can be efficiently synthesized.

The dichroic mirror 50 is reflected in the wavelength range between the peak wavelength lambda ₁ and the peak wavelength lambda ₂ of the second LED element 20 of the first LED element 10 - transparent translation Wavelength (boundary wavelength) lambda ₀₁ (lambda ₂ <has a lambda ₀₁ <lambda _1), reflection - transmitting light from transmitting the converted wavelength lambda ₀₁ long wavelength, the reflected - a wavelength selective property of reflecting short wavelength light than the transparent translation wavelength lambda _01.

A collimator lens 61 (62) that emits radiated light from the LED element 10 (20) as parallel light is positioned at a position in front of the light emitting direction of each of the LED elements 10 and 20, respectively. 20) is arranged so as to be positioned on the central axis C1 (C2) of the light exit surface 10A (20A), and the emitted light from the first LED element 10 is substantially collimated by the first collimator lens 61. And is irradiated onto one surface 50A of the dichroic mirror 50. Further, the emitted light from the second LED element 20 is made substantially parallel light by the second collimator lens 62, and the irradiation area of the first LED element 10 is irradiated on the other surface 50 </ b> B of the first dichroic mirror 50. The emitted light is irradiated so as to overlap with the outgoing region of the transmitted light that has passed through the first dichroic mirror 50.
Further, a condenser lens 65 that condenses the light emitted from the dichroic mirror 50 and irradiates it to the light introducing section 68 of the exposure apparatus is positioned on the reference axis C1 at a position in front of the dichroic mirror 50. It is arranged so that.

Thus, in this optical system, the dichroic mirror 50 is configured such that the incident angle of the radiated light from the first LED element 10 (angle formed with respect to the normal of the one surface 50A of the first dichroic mirror 50) θ ₁ , The incident angle of the emitted light from the second LED element 20 (angle formed with respect to the normal of the other surface 50B of the first dichroic mirror 50) θ ₂ is 5 to 40 °. ing.
When the incident angle θ ₁ and the incident angle θ ₂ are larger than 40 °, sufficient light emission intensity cannot be obtained as shown in the result of an experimental example described later. In addition, the reason why the lower limit of the incident angle θ ₁ and the incident angle θ ₂ is set to 5 ° is that the light source device (optical system) is actually configured with the incident angle θ ₁ and the incident angle θ ₂ smaller than 5 °. This is because it is difficult.

In the optical system configured as described above, the radiated light emitted from the first LED element 10 that is made substantially parallel light by the first collimator lens 61 and is incident on the one surface 50A of the dichroic mirror 50 at the incident angle θ ₁ is Radiated light emitted from the second LED element 20 that passes through the dichroic mirror 50 and is made substantially parallel light by the second collimator lens 62 and is irradiated onto the other surface 50B of the dichroic mirror 50 at an incident angle θ _2. Is reflected by the other surface 50B of the dichroic mirror 50, so that the radiated light from the first LED element 10 is transmitted through the dichroic mirror 50 and the radiated light from the second LED element 20 is dichroic mirror. 50 is combined with the reflected light reflected by the first dichroic mirror 50, and the combined light emitted from the first dichroic mirror 50 is It is incident on one end surface 68A of the condensed light introducing portion of the ultraviolet exposure device (e.g., a fly-eye) 68 by the condenser lens 65.

Thus, according to the light source device including the optical system configured as described above, the dichroic mirror 50 has the incident angle θ ₁ of the radiation emitted from the first LED element 10 and the radiation from the second LED element 20. Since the light incident angle θ ₂ is arranged in a state where all of the light incident angles θ ₂ are 5 to 40 °, the light use efficiency (combination efficiency) can be increased, so that the wavelength λ ₁ It is possible to emit light in a continuous wide wavelength range having peak wavelengths at [nm] and λ ₂ [nm], and to increase the amount of radiated light over the entire required wavelength range to obtain high luminance. Can do.

The reason why the above-described effect is obtained in the synthesis of the radiated light from each LED element by the optical system having the above-described configuration is considered as follows.
For example, the light emitted from the first LED element 10 having a peak wavelength λ ₁ of 405 nm and the light emitted from the second LED element 20 having a peak wavelength λ ₂ of 385 nm are converted into a reflection-transmission conversion wavelength λ _01. In the case where the light is synthesized by the dichroic mirror 50 having a wavelength of 395 nm, the emitted light from the first LED element 10 and the emitted light from the second LED element 20 are both polarized. However, for the sake of convenience, assuming that the P-polarized component and the S-polarized component are included to the same extent, the emitted light from the first LED element 10 and the emitted light from the second LED element 20 are respectively transmitted to the dichroic mirror 50. for example for 40 ° incident angle larger than theta _1, when it is incident at theta _2, the dichroic mirror 50, for P-polarized light component, in FIG. 2 (a) As shown by line, reflection - transmission conversion wavelength lambda ₀₁ (395 nm) is shifted to the short wavelength side (shift amount Δλ in this example -4 nm), the S-polarized light component, indicated by the broken line in FIG. 2 (B) As described above, the reflection-transmission conversion wavelength λ ₀₁ (395 nm) is shifted to the longer wavelength side (in this example, the shift amount Δλ is +4 nm), and the shift amount of the reflection-transmission conversion wavelength λ ₀₁ is from the first LED element 10. The incident angle θ ₁ of the emitted light with respect to the dichroic mirror 50 and the incident angle θ ₂ of the emitted light from the second LED element 20 with respect to the dichroic mirror 50 become larger.

Therefore, in the radiated light from the first LED element 10, for the P-polarized component, light in substantially the entire wavelength range is transmitted through the dichroic mirror 50, but for the S-polarized component, FIG. As indicated by the broken line in B), the reflection-transmission conversion wavelength λ ₀₁ (395 nm) is shifted to the long wavelength side (λ _{01 ″} = 399 nm), and the reflection-transmission conversion wavelength is shifted to the long wavelength side. The light on the shorter wavelength side is reflected, and the radiation intensity decreases. In addition, regarding the radiated light from the second LED element 20, for the S-polarized component, light in substantially the entire wavelength range is reflected by the dichroic mirror 50, but for the P-polarized component, FIG. As shown by the broken line in (A), the reflection-transmission conversion wavelength λ ₀₁ (395 nm) is shifted to the short wavelength side (λ ₀₁ ′ = 391 nm), and thus the reflection-transmission conversion wavelength is shifted to the short wavelength side. Longer-wavelength light passes through the dichroic mirror 50, and the radiation intensity decreases.
Then, in the radiated light from the first LED element 10, the decrease in the radiant intensity of light having a wavelength shorter than the reflection-transmission conversion wavelength λ ₀₁ of the dichroic mirror 50 is compensated by the radiated light from the second LED element 20. In addition, in the radiation light from the second LED element 20, the radiation intensity of the light having a wavelength longer than the reflection-transmission conversion wavelength λ ₀₁ of the dichroic mirror 50 is reduced by the radiation light from the first LED element 20. Therefore, the radiated light from the first LED element 10 is transmitted through the dichroic mirror 50, and the radiated light from the second LED element 20 is reflected by the dichroic mirror 50. , The original reflection-transmission conversion wavelength λ ₀₁ (395 nm) of the dichroic mirror 50, as shown by a broken line in FIG. In the wavelength range (non-effective light emission region) X1 (8 nm in this example) corresponding to the shift amount Δλ of the reflection-transmission conversion wavelength λ ₀₁ of the dichroic mirror 50 as the heart, it is indicated by the hatched portion in FIG. Loss occurs, and sufficient light emission intensity cannot be obtained.

However, the incident angle θ of the magnitude that the radiated light from the first LED element 10 and the radiated light from the second LED element 20 are set within the range of 5 to 40 ° with respect to the dichroic mirror 50, respectively. _By being configured to be incident at ₁ and θ ₂ , it is possible to avoid a shift of the reflection-transmission conversion wavelength of the dichroic mirror 50 due to the magnitude of the incident angle of light with respect to the dichroic mirror 50. The dichroic mirror 50 reflects light having a wavelength shorter than the reflection-transmission conversion wavelength λ ₀₁ (395 nm) for both the P-polarized component and the S-polarized component, as indicated by the solid line in FIG. It has the desired wavelength selection characteristic that transmits light having a wavelength longer than λ ₀₁ (395 nm).
Therefore, the P-polarized component and the S-polarized component in the emitted light from the first LED element 10 both have light in substantially the entire wavelength range transmitted through the dichroic mirror 50 and from the second LED element 20. In both the P-polarized component and the S-polarized component of the radiated light, substantially all of the wavelength range is reflected by the other surface 50B of the dichroic mirror 50, and the resultant light thus obtained has a sufficient radiant intensity. A wavelength range (ineffective light emission region) that cannot be obtained is not formed, and has spectral distribution characteristics as shown by a solid line in FIG. 3, so that the light use efficiency (synthesis efficiency) can be increased. It is considered possible.

  As mentioned above, although one Embodiment of the light source device of this invention was described, this invention is not limited to the thing of the said structure.

FIG. 4 is an explanatory diagram showing an outline of a configuration in another example of the optical system according to the light source device of the present invention.
The optical system includes light emitted from the first LED light source 101 that emits light having peak wavelengths λ ₁ [nm] and λ ₂ [nm] (λ ₁ > λ ₂ ) close to each other, and 2, which synthesizes radiated light from the two LED light sources 201, and is arranged at a position where the disk-shaped dichroic mirror 51 and the dichroic mirror 51 are spaced apart and arranged on one surface side of the dichroic mirror 51. In addition, the first LED light source 101 and the second LED light source 201, and the reflection mirror 70 disposed on the other surface side of the dichroic mirror 51 so that the reflection surface 70A faces the dichroic mirror 51 are provided.

  The first LED light source 101 is radiated from the first LED element 10 and the first LED element 10 arranged in a state where the optical axis coincides with the central axis of the light emitting surface of the first LED element 10. For example, it is configured by a parabolic mirror 102 that emits light as substantially parallel light. The second LED light source 201 has the same configuration as that of the first LED light source 101, and includes the LED element 20 and the parabolic mirror 202.

The dichroic mirror 51 is reflected in the wavelength range between the peak wavelength lambda ₁ and the peak wavelength lambda ₂ of the second LED element 20 of the first LED element 10 - transparent translation Wavelength (boundary wavelength) lambda ₀₁ (lambda ₂ <has a lambda ₀₁ <lambda _1), reflection - from transparent translation wavelength lambda ₀₁ reflects light of a long wavelength, the reflected - a wavelength selection characteristics for transmitting light having a shorter wavelength than the transmission conversion wavelength lambda _01.

In this optical system, the radiated light from the first LED light source 101 that is incident on the other surface 51B of the dichroic mirror 51 at an incident angle θ ₁ having a size set in the range of 5 to 40 ° is reflected. The reflected light reflected by the mirror 70 is reflected by the other surface 51B of the dichroic mirror 51 and is incident on the one surface 51A of the dichroic mirror 51 at an incident angle θ ₂ having a size set within a range of 5 to 40 °. The incident radiated light from the second LED light source 201 is transmitted through the dichroic mirror 51, whereby the radiated light from the first LED light source 101 and the radiated light from the second LED light source 201 are combined.

Also in the light source device having the optical system having such a configuration, the same effect as that having the optical system having the configuration shown in FIG. 1, that is, the incident angle of the light with respect to the dichroic mirror 50 is caused. It is possible to avoid the shift of the reflection-transmission conversion wavelength, and there is no formation of a wavelength range (ineffective emission region) in which sufficient radiation intensity cannot be obtained. ) Can be increased, so that light in a continuous wide wavelength range having peak wavelengths at wavelengths λ ₁ [nm] and λ ₂ [nm] can be emitted, and the amount of radiated light can be reduced over the entire required wavelength range. The luminance can be increased over a wide range, and high luminance can be obtained.

Hereinafter, experimental examples performed for confirming the effects of the present invention will be described.
<Experimental example 1>
As the dichroic mirror (50), five types of optical systems (1) to (5) were prepared. The dichroic mirror used in the optical system (1) has a reflectance of 50% and a transmittance of 395 nm wavelength light when light is incident at an incident angle of 45 ° (hereinafter referred to as “set incident angle”). Is made to be 50%. In the case of the optical system (2), the reflectance is 50% and the transmittance is 50% for light having a wavelength of 395 nm at a set incident angle of 40 °. The same applies to each of the set incident angles from the optical system (3) to the optical system (5).
In addition, the first LED element (10) has a peak wavelength (λ ₁ ) of 405 nm and a half width at 10 nm, and the second LED element (20) has a peak wavelength (λ ₂ ) of 385 nm and a half width at half maximum. In each optical system, the incident angles θ ₁ and θ ₂ with respect to the dichroic mirror (50) are set to the same magnitude as the set incident angle of the dichroic mirror (50). About each optical system (1)-(5), the total energy amount of the 375 nm-415 nm wavelength light radiate | emitted from a dichroic mirror (50) was measured. The results are shown in Table 1 below. In Table 1, the total energy amount in each optical system is a relative value when the total energy in the optical system (2) is “1.00”.

From the above results, according to the optical systems (2) to (4) according to the present invention, the dichroic mirror has the incident angle θ ₁ of the radiated light from the first LED light source and the second LED light source. The arrangement is such that the incident angle θ _{2 of the} radiated light is 5 to 40 ° in all cases, so that the amount of radiated light can be increased over the entire required wavelength range and high brightness can be achieved. It was confirmed that it can be obtained.

DESCRIPTION OF SYMBOLS 10 1st LED element 10A Light-emitting surface 20 2nd LED element 20A Light-emitting surface C1 Reference | standard axis | shaft (central axis of the light-emitting surface of a 1st LED element)
C2 Central axis of light emitting surface of second LED element 50, 51 Dichroic mirror 50A, 51A One surface 50B, 51B Other surface 61 First collimator lens 62 Second collimator lens 65 Condenser lens 68 Light introducing portion 68A One end surface 70 Reflective mirror 70A Reflective surface 80 LED light emitting unit 81 Ellipsoidal reflective mirror 82 Spherical lens 83 Conical reflective mirror 84 Translucent rod 85 Condenser lens 86 Relay lens 90A First LED light source 90B Second LED light source 91 Dichroic mirror 93 Collimator lens S Exposure surface 101 First LED light source 201 Second LED light source 102, 202 Parabolic mirror

Claims (2)

A first LED light source and a second LED light source whose peak wavelengths are close to each other;
A dichroic mirror that combines the emitted light emitted from the first LED light source and the emitted light emitted from the second LED light source;
The dichroic mirror is disposed in a state where the incident angle of the emitted light from the first LED light source and the incident angle of the emitted light from the second LED light source are both 5 to 40 °. A light source device.   The light source device according to claim 1, wherein a difference between a peak wavelength of the first LED light source and a peak wavelength of the second LED light source is 30 nm or less.

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