JP5412253B2 - Light emitting device - Google Patents

Description

  The present invention relates to a light emitting device that irradiates light from a light emitting element that emits monochromatic light and light obtained by converting the light by a wavelength conversion element using a condenser lens.

  A conventional light emitting device of this type is shown in FIGS. The light emitting device emits white light from yellow light obtained by converting blue light from the blue LED 1 by a yellow phosphor (referred to as a wavelength conversion element) 2 and blue light emitted without being converted by the wavelength conversion element 2. It is a white LED light source. The white light causes the light source image P to appear on the irradiation surface 20 by the refractive lens 6. Here, the light source image P is shown in perspective.

  FIG. 10A shows a case where a white LED light source is arranged at a focal position with respect to blue light. The blue light X1 travels parallel to the optical axis after passing through the refractive lens 6. FIG. 10B shows a case where the white LED light source is arranged at the focal position for yellow light. The yellow light Y1 travels parallel to the optical axis after passing through the refractive lens 6.

  In any of the above cases, since the light source image P has a larger light emitting surface of the wavelength conversion element 2 than the light emitting surface of the blue LED 1, the yellow light pattern Py is larger than the blue light pattern Px. For this reason, although the part which the blue light pattern Px and the yellow light pattern Py overlap becomes a white pattern, since yellow light increases around the light source image P, color unevenness generate | occur | produces. At this time, as shown in FIG. 11, in the refractive lens of the optical glass, since the long wavelength light has a higher refractive index than the short wavelength light, the blue light is refracted more than the yellow light, and the blue light Since the pattern Px is reduced and the yellow light pattern Py is enlarged, the color unevenness becomes more prominent.

  By the way, there is known a light emitting device that suppresses color unevenness around irradiated light by diffusing light from a white LED light source on an exit surface of a refractive lens (see, for example, Patent Documents 1 and 2). As shown in FIG. 12A, this apparatus condenses the light from the white LED light source by the blue LED 1 and the wavelength conversion element 2 on the substrate 4 by the refractive lens 6, and the light is emitted to the exit surface 7 of the refractive lens 6. Blue light 11 and yellow light 12 are emitted by being diffused by the light diffusion member 8 such as the formed diffusion-treated surface or convex lens group. If this device does not include the light diffusing member 8, as shown in FIG. 12 (b), the beam angle of the blue light 11 is narrower than the beam angle of the yellow light 12. By providing the diffusing member 8, the blue light 11 and the yellow light 12 are diffused, and the color unevenness is reduced.

  However, since the apparatus shown in FIG. 12A uniformly diffuses blue light and yellow light regardless of the light color, each beam angle becomes wide and the condensing action becomes weak as a whole. Since the light diffusing member 8 lowers the light transmittance of the lens, the irradiation efficiency deteriorates.

  As another example, a light-emitting device that collects and emits light from an LED by a diffraction grating lens is known (see, for example, Patent Document 3). However, this device improves the concentration of light from the LED and does not suppress uneven color of the irradiated light.

JP 2007-5218 A JP 2007-265964 A JP 2006-24378 A

  The present invention solves the above-described problem. In a light-emitting device that mixes light from a monochromatic light-emitting element and light converted by a wavelength conversion element, collects the light by a lens, and emits the light. An object of the present invention is to provide a light-emitting device that can efficiently reduce color unevenness.

In order to achieve the above object, a first aspect of the present invention is directed to a solid-state light emitting device that emits light having a first spectral distribution, and a second light having a longer wavelength than the solid light-emitting element that receives the light of the first spectral distribution. A wavelength conversion element that converts the wavelength of light into light having a spectral distribution, and emits the second spectral distribution light from the wavelength conversion element and the light of the first spectral distribution that has not been wavelength-converted by the wavelength conversion element A solid-state light emitting element, a wavelength converting element, and a light emitting device having an optical axis common to each other, wherein the optical element is a diffractive lens. There, as viewed from the irradiation surface, the first spectral focus for light distribution than focus for the second spectral distribution of the light Chi lifting the optical properties to be farther from the diffraction lens, the diffractive lens concentric A solid-state light emitting element Θb is an angle formed by a straight line AB passing through the outer edge of the diffractive lens and a point B passing through the outer edge of the diffractive lens and straddling the optical axis. An angle formed by a straight line CD connecting the point C passing through the outer edge of the conversion element and the point D passing through the outer edge of the diffractive lens and across the optical axis and the point C opposite to the optical axis is defined as θcd, When the diffraction angle of the outer edge of the diffractive lens with respect to the light of the first spectral distribution is φ1, and the diffraction angle of the outer edge of the diffractive lens with respect to the light of the second spectral distribution is φ2, θab−φ1 = This is configured to satisfy the relationship of θcd−φ2 .

The invention of claim 2 is the light-emitting device according to claim 1, wherein the diffractive lens is one which is laminated diffractive lens which combined a plurality of single-layer type diffractive lens.

According to a third aspect of the present invention, in the light emitting device according to the first aspect, the diffractive lens has a refracting surface and a total reflection surface, and has the diffraction grating on the exit surface.

According to a fourth aspect of the present invention, in the light emitting device according to the first aspect, the diffractive lens has a refracting surface and a total reflection surface, and has the diffraction grating on the incident surface.

According to the first aspect of the present invention, the focus of the light having the first spectral distribution (for example, blue light) is made farther from the diffraction lens than that of the light having the second spectral distribution (for example, yellow light) by using the diffraction lens. Since it is located at a far position, the irradiation pattern of the light of the second spectral distribution on the outer edge side of the light source image on the irradiation surface is relatively smaller than in the case of using a refractive lens. For this reason, the ratio of the light of the first spectral distribution increases at the periphery of the light source image, the light of the second spectral distribution can be made inconspicuous, and color unevenness can be reduced efficiently without using a diffusing member. can do. In addition, since the maximum emission angle after exiting the diffraction lens for the light with the first spectral distribution and the maximum exit angle after exiting the diffraction lens for the light with the second spectral distribution are equal, the light source image of the irradiation surface The irradiation patterns of the light with the first spectral distribution and the light with the second spectral distribution can be overlapped at the periphery, and color unevenness can be further reduced.

According to the invention of claim 2 , the laminated diffractive lens suppresses unnecessary diffracted light and color unevenness, and reduces the wavelength dependency of diffraction efficiency, compared to a single-layer diffractive lens. This enables diffraction of light in a wide wavelength region.

According to the third aspect of the present invention, it is possible to obtain irradiation light with little color misregistration, and it is possible to control light condensing on the exit surface by using the refracting surface and the total reflection surface. Compared with a diffractive lens that does not have the light efficiency, the light utilization efficiency can be improved.

According to the invention of claim 4 , since the light diffracted on the incident surface can be condensed and irradiated on the exit surface using the refracting surface and the total reflection surface, the diffraction lens having no refracting surface and the total reflection surface can be applied. In comparison, the light utilization efficiency can be improved.

1 is a cross-sectional view of a light emitting device according to a first embodiment of the present invention. The figure for demonstrating operation | movement of the light-emitting device. (A) is a figure which shows the condensing state by the diffraction lens of the light-emitting device, (b) is a fragmentary sectional view of the diffraction lens. (A) The figure which shows the condensing condition and irradiation pattern when making blue light into parallel light with the same diffraction lens, (b) The condensing condition and irradiation pattern when making yellow light into parallel light with the same diffraction lens FIG. Sectional drawing of the light-emitting device which concerns on the 2nd Embodiment of this invention. Sectional drawing of the light-emitting device which concerns on the 3rd Embodiment of this invention. (A) is a diffraction efficiency characteristic figure of the laminated | stacked diffraction lens of the light-emitting device, (b) is a diffraction efficiency characteristic figure of a single layer type | mold diffraction lens. Sectional drawing of the light-emitting device which concerns on the 4th Embodiment of this invention. Sectional drawing of the light-emitting device which concerns on the 5th Embodiment of this invention. (A) is a figure which shows the structure and irradiation pattern in the case of refracting blue light into parallel light in the conventional light emitting device, (b) is the structure and irradiation pattern in the case of refracting yellow light into parallel light in the light emitting device. FIG. The figure which shows the refractive index of optical glass. (A) is sectional drawing in case the light-diffusion member is provided in the output surface of the conventional light-emitting device, (b) is sectional drawing in case the light-diffusion member is not provided in the output surface of the light-emitting device.

(First embodiment)
A light emitting device according to a first embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the light emitting device 10 of the present embodiment receives a blue LED (solid light emitting element) 1 that emits blue light (light having a first spectral distribution) and blue light, and more than that. A wavelength conversion element 2 that converts the wavelength into yellow light having a long wavelength (light having a second spectral distribution) and emits the light; a yellow light from the wavelength conversion element 2; a blue light that is not wavelength-converted by the wavelength conversion element 2; And an optical element 3 that collects and irradiates the light. The blue LED 1, the wavelength conversion element 2, and the optical element 3 have a common optical axis. The blue LED 1 and the wavelength conversion element 2 are provided on an LED mounting board (not shown), and are housed and fixed together with the optical element 3 in, for example, a cylindrical housing (not shown).

  The blue LED 1 is a short-wavelength solid-state light source that emits light with high energy, and may be an ultraviolet light-emitting diode or the like. The material thereof is, for example, an InGaN-based member, but is not particularly limited.

  The wavelength conversion element 2 is a conversion element that uses a phosphor or the like as its material, and emits light having a longer wavelength, that is, light having lower energy after receiving light from the solid state light emitting element. Here, the wavelength conversion element 2 is, for example, a YAG (Yttrium Aluminum Garnet) fluorescence that converts light in a wavelength band of 380 nm to 480 nm into light of 480 nm to 780 nm as a yellow light emitting phosphor that converts blue light into yellow light. Body, BOS (Barium ortho-Silicate) phosphor, etc. can be used.

  The wavelength conversion element 2 is formed by filling a phosphor layer containing a yellow light-emitting phosphor in a recess provided on the mounting surface side of an LED mounting substrate (not shown), and is mounted in the recess. By covering the blue LED chip with a phosphor layer, yellow light is emitted by exciting the yellow light emitter with blue light.

  A part of the blue light from the blue LED 1 incident on the wavelength conversion element 2 is emitted through the wavelength conversion element 2 as it is without being converted by the wavelength conversion element 2. At this time, the unconverted blue light and the converted yellow light are mixed to produce white light, and a white LED light source is formed by the blue LED 1 and the wavelength conversion element 2. In this white LED light source, the emission area of the blue LED 1 is smaller than the emission area of yellow light by the wavelength conversion element 2.

  The optical element 3 is a diffractive lens using a diffraction phenomenon, and a general optical glass material such as acrylic or polycarbonate is used as a light transmission member thereof. The diffractive lens 3 has a concentric diffraction grating 31, and when viewed from the irradiation surface 20 perpendicular to the optical axis, the focal point F1 (FIG. 2) for blue light is farther from the diffractive lens 3 than the focal point F2 for yellow light. With optical properties

  FIG. 2 is a diagram for explaining the operation of the light emitting device 10. In the case where the blue LED 1 a is disposed at the position of the focal point F 1 that is separated from the diffractive lens 3 by the focal length f 1 of the blue light, The case where the blue LED 1 is virtually arranged at the position of the focal point F2 separated by the focal length f2 is shown. The blue light from the blue LED 1a passes through the diffraction lens 3 and then travels parallel to the optical axis. The yellow light emitted from the center of the wavelength conversion element 2 travels parallel to the optical axis after passing through the diffraction lens 3. Actually, the blue light is emitted from the blue LED 1 arranged at the focal point F2, so that the image is not formed on the irradiation surface 20, but is formed in the image range of yellow light.

  As shown in FIG. 3A, the diffractive lens 3 is composed of a diffraction grating 31 of a sawtooth phase type diffractive optical element, and incident light is diffracted by the diffractive lens 3 and collected at a focal point F based on the wavelength. The In addition, as shown in FIG. 3B, the diffractive lens 3 can control the phase of light by shaving the light transmitting substrate with a fineness of the optical wavelength dimension order so that the following formula 1 is satisfied. it can. The diffraction lens 3 has a sufficiently smaller grating period and groove depth than the shapes shown in FIGS. 3 (a) and 3 (b).

[Equation 1]
nL2 + L3-L1 = mλ (1)
Here, L1 is the height of the diffraction grating 31, n is the refractive index of the diffractive lens material, m is the diffraction order (integer), and λ is the design wavelength. At this time, when an equiphase wavefront 30 of light is formed along the optical axis with respect to the design wavelength λ, and light having a different wavelength is passed through the diffraction lens 3, the light having the longer wavelength is changed to the light having the shorter wavelength. In comparison, the point of strengthening (focal point) is closer to the diffractive lens 3. That is, in the diffractive lens 3, the long wavelength light bends better than the short wavelength light, and the refraction relationship between the long wavelength and the short wavelength is opposite to that of the refractive lens.

  The diffractive lens 3 can be manufactured by forming a mask pattern on a silica wafer by photolithography and then forming a fine structure by etching, or forming a mold by nanoimprint or the like.

  FIG. 4A shows an irradiation pattern when the blue LED 1 and the wavelength conversion element 2 are arranged at the blue light focal point F1 of the diffractive lens 3. Here, for easy understanding, blue light is shown on the upper side of the paper surface of the optical axis, and yellow light is shown on the lower side. FIG. 4B shows an irradiation pattern when the blue LED 1 and the wavelength conversion element 2 are arranged at the position of the focal point F2 of the yellow light of the diffraction lens 3.

  In the case of FIG. 4A, the blue light X1 emitted from the center on the optical axis of the blue LED 1 passes through the diffraction lens 3 and proceeds parallel to the optical axis, and yellow emitted from the center of the wavelength conversion element 2. The light Y1 travels so as to approach the optical axis. Of the blue light, the blue light X2 passing through the outer edge of the blue LED 1 and the outer edge of the diffractive lens 3 and passing through the optical axis and the point B opposite to the point A is the diffractive lens 3. And is irradiated on the irradiation surface 20 farthest from the optical axis in the blue light. Further, among yellow light, yellow light Y2 passing through the outer edge of the wavelength conversion element 2 and passing through the outer edge of the diffractive lens 3 and passing through the optical axis and the point D opposite to the point C is Y In the yellow light, the irradiation surface 20 is irradiated farthest from the optical axis.

  At this time, since the blue light is less refracted than the yellow light in the diffractive lens 3, the blue light X2 is relatively away from the optical axis and the yellow light Y2 is closer to the optical axis than in the case of the refractive lens. . That is, in the light source image P, the irradiation pattern Px of the blue light X2 is enlarged, the irradiation pattern Py of the yellow light Y2 is reduced, and the pattern diameters are close to each other.

  In the case of FIG. 4B, the yellow light Y1 travels parallel to the optical axis after passing through the diffraction lens 3, and the blue light X1 travels so as to approach the optical axis. In the light source image P, similarly to FIG. 4A, the irradiation pattern Px of the blue light X2 is enlarged and the irradiation pattern Py of the yellow light Y2 is reduced, so that the overlapping of both patterns increases. Here, since the focal length f2 of yellow light is shorter than the focal length f1 of blue light, the entire apparatus is shortened compared to the case of FIG.

  According to the present embodiment, the irradiation pattern diameters of blue light and yellow light can be made closer, the ratio of blue can be increased at the periphery of the light source image P on the irradiation surface 20, and yellow can be made inconspicuous. It is possible to reduce the color misregistration in the outline portion of the white light due to. Further, since no diffusing member is used, the light can be efficiently irradiated without lowering the light transmittance.

(Second Embodiment)
A light emitting device according to a second embodiment of the present invention will be described with reference to FIG. In the figure, a straight line connecting point A passing through the outer edge of the blue LED 1 and point B opposite to the point A passing through the outer edge of the diffractive lens 3 and straddling the optical axis is defined as AB. Further, a straight line connecting a point C passing through the outer edge of the wavelength conversion element 2 and a point D passing through the outer edge of the diffraction lens 3 and straddling the optical axis is defined as CD. Further, an angle formed by the straight line AB with the optical axis is θab, and an angle formed by the straight line CD with the optical axis is θcd. Further, the diffraction angle with respect to blue light at the outer edge of the diffraction lens 3 is φ1, and the diffraction angle with respect to yellow light at the outer edge of the diffraction lens is φ2. At this time, the light emitting device 10 of the present embodiment is configured to satisfy the relationship of the following formula 2.

[Equation 2]
θab−φ1 = θcd−φ2 (2)
In Equation 2, θab−φ1 represents the maximum emission angle after the blue light is emitted from the diffraction lens 3, and θcd−φ2 represents the maximum emission angle after the yellow light is emitted from the diffraction lens 3.

  Here, the blue LED 1, the wavelength conversion element 2, and the diffraction lens 3 form a rotating body having radii d 1, d 2, and d 3, respectively, and the blue light X 2 from the point A and the yellow light Y 2 from the point C are Crosses the optical axis. Here, the maximum emission angles of blue light and yellow light are the radii d1, d2, and d3 of the blue LED 1, the wavelength conversion element 2, and the diffraction lens 3, respectively, the focal lengths f1, f2, and the diffraction angle of the diffraction lens 3. It is designed to be equal to each other using φ1, φ2, etc.

  According to the present embodiment, since the maximum emission angles of blue light and yellow light are equal, the irradiation patterns Px and Py of the blue light X2 and yellow light Y2 from the diffraction lens 3 are substantially matched on the irradiation surface 20. It is possible to increase the ratio of blue at the periphery of the light source image P and make yellow more inconspicuous, and the color unevenness of white light is further improved.

(Third embodiment)
A light emitting device according to a third embodiment of the present invention will be described with reference to FIGS. In this embodiment, the diffractive lens 3 is a laminated diffractive lens in which a plurality of (here, two) single-layer diffractive lenses are combined.

  The laminated diffractive lens 3 includes two single-layer diffractive lenses 3a and 3b. The single-layer diffractive lenses 3a and 3b have the same configuration as that of the diffractive lens of the above-described embodiment, and have concentric grating periodic structures that are basically equal to each other, but the concave and convex directions of the diffraction gratings 31a and 31b are They are opposite to each other, and the height of each lattice and the material forming the lattice are different. The laminated diffractive lens 3 is a set of diffraction gratings whose phase difference always approaches one period regardless of the wavelength. Here, the diffraction efficiency is enhanced by optimizing the height of the diffraction grating and the material forming the diffraction grating and facing each other at intervals of several micrometers. In addition, the incident surface side of the single layer type diffractive lens 3a has a convex lens shape in order to improve the light collecting property.

  7A shows the diffraction characteristics of the laminated diffractive lens 3, and FIG. 7B shows the diffraction characteristics of the single-layer diffractive lens. In the case of a single-layer diffractive lens, the diffraction efficiency of the first-order diffracted light decreases as it goes away from the design wavelength, and it cannot be made uniform throughout the visible light region. It may become. On the other hand, the laminated diffractive lens 3 complements the wavelength dependency of diffraction efficiency by combining two single-layer diffractive lenses, generates no unnecessary diffracted light, and has high diffraction efficiency over the entire visible light region. Can have.

  According to the present embodiment, unnecessary diffracted light is suppressed and color unevenness is reduced, and light in a wide wavelength region in the entire visible light region can be diffracted compared to the case of using a single-layer diffractive lens. It becomes.

(Fourth embodiment)
A light emitting device according to a fourth embodiment of the present invention will be described with reference to FIG. In the light emitting device 10 of the present embodiment, the diffractive lens 3 has a refracting surface 34 and a total reflection surface 35, and has a diffraction grating 31 on the exit surface 36.

  In the present embodiment, the blue LED 1 and the wavelength conversion element 2 are mounted on the LED mounting substrate 4, and the LED mounting substrate 4 is fixed to the main body substrate 5. The blue LED 1 is a wavelength conversion element 2 that is mounted at the center of a cylindrical recess formed on the mounting surface of the LED mounting substrate 4 and is formed by filling the cylindrical recess with a resin containing a yellow light-emitting phosphor. Covered to form a white LED light source.

  The diffractive lens 3 is a hybrid lens having a recess 32 formed so as to surround the front of the wavelength conversion element 2 on the light exit surface 21 side, and is fixed to the main body substrate 5 using an adhesive, a lens folder, or the like. . The diffractive lens 3 includes a convex incident surface 33 positioned on the bottom surface of the concave portion 32, a refractive surface 34 formed by the inner surface of the concave portion 32, and a part of light incident from the incident surface 33 and the refractive surface 34. It has a total reflection surface 35 that reflects, and an output surface 36 that emits incident light from the incident surface 33 and reflected light from the total reflection surface 35. In the diffractive lens 3, the diffraction grating 31 is formed on the exit surface 36, the entrance surface 33 faces the front of the light exit surface 21 of the wavelength conversion element 2, and the refracting surface 34 tapers toward the opening of the recess 32.

  According to the present embodiment, the incident light from the white LED light source is primarily condensed by the convex refractive lens of the incident surface 33, and then blue light and yellow light are generated by the diffraction grating 31 of the output surface 36. The light source images P that are diffracted so as to approach each other and are irradiated so as to overlap each other on the irradiation surface 20 are obtained. At this time, incident light from the white LED light source is collected by light control using the refracting surface 34 and the total reflection surface 35, so that the amount of light is smaller than that of a diffractive lens without the refracting surface 34 and the total reflection surface 35. Many of the light exit surfaces 36 can be focused and light utilization efficiency can be improved.

(Fifth embodiment)
A light emitting device according to a fifth embodiment of the present invention will be described with reference to FIG. In the light emitting device 10 of the present embodiment, the diffractive lens 3 has a refracting surface 34 and a total reflection surface 35, and a diffraction grating 31 on the incident surface 33.

  According to the present embodiment, the incident light from the white LED light source is diffracted by the diffraction grating 31 of the incident surface 33 so that the blue light and the yellow light are close to each other, and is emitted from the output surface 36. Can be obtained. Further, since the light diffracted by the incident surface 33 can be condensed and irradiated by light control using the refracting surface 34 and the total reflection surface 35, the diffraction lens having no refracting surface 34 and the total reflection surface 35 can be applied. In comparison, the light utilization efficiency can be improved.

  In addition, this invention is not limited to the structure of the said various embodiment, A various deformation | transformation is possible suitably in the range which does not change the meaning of invention. For example, in the various embodiments described above, the wavelength conversion element 2 has shown the case where the blue light of the input light is converted into the outgoing light of yellow light, but it may be converted between other colors. Also, the blue LED 1 and the wavelength conversion element 2 may be integrated, for example, modularized in a cylindrical shape.

1 Blue LED (solid state light emitting device)
DESCRIPTION OF SYMBOLS 10 Light-emitting device 2 Wavelength conversion element 20 Irradiation surface 3 Optical element, diffraction lens, laminated diffraction lens 3a, 3b Single layer type diffraction lens 31 Diffraction grating 33 Incident surface 34 Refraction surface 35 Total reflection surface 36 Output surface F1 Blue of diffraction lens Focus on light (focus on light of first spectral distribution)
F2 diffractive lens focus on yellow light (focus on light of second spectral distribution)
X1, X2 Blue light (light with first spectral distribution)
Y1, Y2 Yellow light (light with second spectral distribution)

Claims (4)

A solid-state light emitting device that emits light having a first spectral distribution and a wavelength that receives the light of the first spectral distribution, converts the wavelength into light having a second spectral distribution longer than that, and emits the light. A conversion element; and an optical element that collects and irradiates the light having the second spectral distribution from the wavelength conversion element and the light having the first spectral distribution that has not been wavelength-converted by the wavelength conversion element. A light emitting device in which the solid light emitting element, the wavelength converting element, and the optical element have a common optical axis,
The optical element is a diffractive lens, and has an optical characteristic that a focal point with respect to the light with the first spectral distribution is farther from the diffractive lens than a focal point with respect to the light with the second spectral distribution as viewed from the irradiation surface. equity Chi,
The diffractive lens has a concentric diffraction grating,
An angle formed by a straight line AB connecting the point A passing through the outer edge of the solid-state light emitting element and the point B passing through the outer edge of the diffractive lens and across the optical axis with respect to the point A is θab age,
An angle formed by a straight line CD passing through the outer edge of the wavelength conversion element and a point D passing through the outer edge of the diffractive lens and across the optical axis from the point C opposite to the optical axis is θcd. age,
The diffraction angle with respect to the light of the first spectral distribution at the outer edge of the diffractive lens is φ1,
When the diffraction angle with respect to the light of the second spectral distribution at the outer edge of the diffractive lens is φ2,
A light-emitting device configured to satisfy the relationship θab−φ1 = θcd−φ2 . The light-emitting device according to claim 1, wherein the diffractive lens is a laminated diffractive lens in which a plurality of single-layer diffractive lenses are combined. The light-emitting device according to claim 1, wherein the diffractive lens has a refracting surface and a total reflection surface, and has the diffraction grating on an exit surface. The light-emitting device according to claim 1, wherein the diffractive lens has a refracting surface and a total reflection surface, and has the diffraction grating on an incident surface.

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