KR20120069406A - Optical image modulator having correction function for incident angle of incident light and optical apparatus comprising the same - Google Patents

Abstract

PURPOSE: An optical image modulator having a function for correcting the incidence angle of incident light and an optical device including the same are provided to reduce the variation of resonance wavelength according to section of an optical image modulator by reducing the incidence angle of incident light. CONSTITUTION: A perpendicular prism(36A) with the refractive index of 1.5 is formed as an optical element on a reflection barrier layer(22) so that the bottom surface of the perpendicular prism contacts the reflection barrier layer. The perpendicular prism arranged to become thinner from a first section(A) through a second section(B) to a third section(C) of an optical modulator(20). Incident light through an inclined surface of the perpendicular prism is refracted at a refraction angle obtained by the Snell's law.

Description

Optical image modulator having correction function for incident light and optical device comprising same

One embodiment of the present invention relates to an optical device, and more particularly, to an optical image modulator having an incident angle correction function of incident light.

When the inclined light is used as the incident light in the reflective optical image modulator, since the effective light path is increased in the quantum well layer, more light absorption may occur. Therefore, the thickness of the cavity in the optical image modulator can be reduced, so that modulation at low voltage is possible.

However, if the incident angle of the incident light increases by more than 45 °, the Fabry-Perot resonance wavelength is greatly changed even with minute fluctuations in the incident angle. Therefore, in the case of the reflective optical image modulator using inclined light as incident light, the incident light may be used under the condition that the incident angle of the incident light is 45 ° or less.

Light incident on the optical image modulator is incident through the lens. Since the lens has an aperture, the incident angle of the incident light may vary according to the area of the light incident surface of the optical image modulator according to the F-number of the lens. In addition, the viewing angle according to the size of the optical image modulator may vary depending on the area of the light incident surface of the optical image modulator.

As such, the angle of incidence of incident light incident on the optical image modulator may vary according to various factors, and thus uniform light modulation characteristics of the optical image modulator may be degraded due to the change of incident light.

One embodiment of the present invention provides an optical image modulator capable of reducing an incident angle change of incident light.

One embodiment of the invention provides an optical device comprising such an optical image modulator.

An optical image modulator according to an embodiment of the present invention includes a plurality of unit light modulators and optical elements, wherein the plurality of unit light modulators form an array, and the optical elements are light of the array than when there is no optical element. The incident angle of incident light incident on the incident surface is reduced.

In such an optical image modulator, the light incident surface of the optical element and the light incident surface of the array may be non-parallel.

The optical element may be a refractive optical system that refracts incident light incident upon itself to be incident on a light incident surface of the array.

The light incident surface of the optical element may be flat or curved.

The optical element may be a prism.

An anti-reflection film may be provided between the optical element and the plurality of unit light modulators.

In accordance with another aspect of the present invention, an optical device includes a lens for collecting light reflected from a subject, an optical image modulator for modulating the light passing through the lens, and an optical image sensor for sensing light modulated by the optical image modulator. Wherein the optical image modulator is an optical image modulator according to an embodiment of the present invention described above.

Such optics may include a light reflector that reflects light emitted from the optical image modulator to the optical image sensor.

The light reflector may include a light reflection layer and a light refraction layer for optical path compensation of light reflected by the light image modulator. The light refraction layer may be a prism.

An optical image modulator according to an embodiment of the present invention can reduce the incident angle of incident light. Accordingly, it is possible to reduce the change in the resonant wavelength according to each region of the optical image modulator and the change in reflectance difference according to the resonant wavelength, thereby improving the uniformity and reliability of the light modulation characteristics of the light modulator.

1 is a plan view of an optical image modulator according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of FIG. 1 taken in a 2-2 'direction.
3 shows an example of the optical element 36 of FIG. 2.
4 shows an optical image modulator according to another embodiment of the present invention.
5 is a perspective view illustrating a lens viewing angle for an optical image modulator.
6 is a view showing a part of the configuration of an optical device according to an embodiment of the present invention.
FIG. 7 is a cross-sectional view schematically illustrating the configuration of the light modulation layer of FIG. 6.

Hereinafter, an optical image modulator and an optical apparatus including the same according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In this process, the thicknesses of layers or regions illustrated in the drawings are exaggerated for clarity.

1 is a plan view of an optical image modulator according to an embodiment of the present invention.

Referring to FIG. 1, the optical image modulator 30 includes a plurality of unit light modulators 34 in the light incident region 32. The plurality of unit light modulators 34 form an array. The plurality of light modulators 34 may form two columns of Y rows. In Fig. 1, a plurality of unit optical modulators 34 form an array in two rows and three columns, but the number of rows Y within the size of the optical image modulator 30 is 2.3.4. Can be The plurality of unit light modulators 34 are covered with an optical element 36. The optical element 36 corrects an incident angle of incident light incident on the light incident region 32, thereby optically measuring an incident angle of incident light incident on an array of a plurality of unit light modulators 34 in the light incident region 32. The element 36 serves to reduce it than when it is absent. For example, the optical element 36 has an angle of incidence (eg, 22.5 °) of the center light of the incident light incident on the unit light modulator 34 in the second area B of the array in the light incident area 32 greater than 22.5 °. It serves to reduce to small angles. The optical element 36 may be various types of optical materials that play this role. In FIG. 2, the optical element 36 is symbolically represented in place of various types of optical materials which play the above role. Thus, the optical element 36 of FIG. 2 does not suggest an optical material having a uniform thickness. Various examples of the optical element 36 are described below.

FIG. 2 illustrates a cross-sectional view of FIG. 1 in the 2-2 'direction, and since the plurality of unit light modulators 34 have the same configuration, a plurality of unit lights forming an array in the light incident region 32 are provided for convenience. The modulator 34 is represented by one light modulator 20. In other words, the optical modulator 20 in FIG. 2 represents an optical modulator array composed of a plurality of optical modulators 34.

Referring to FIG. 2, the light incident surface of the light modulator 20 is covered with the antireflection film 22. The antireflection film 22 may be, for example, a transparent epoxy film. An optical element 36 is provided on the antireflection film 22. The optical element 36 is transparent to incident light. In FIG. 2, A, B, and C mean first to third regions A, B, and C in the array of FIG. 1. An incident angle of incident light L1-L3 incident on the first to third regions A, B, and C of the light modulator 20 by the optical element 36 is reduced. In FIG. 2, n0, n1 and n2 represent the refractive indices of the external medium of the optical image modulator, the refractive index of the optical element 36 and the refractive index of the light modulator 20, respectively. The relationship between each refractive index is n0 <n1 <n2. According to this refractive index relationship and Snell's law, the angle of refraction of the incident light L1-L3 incident on the optical element 36 is smaller than the incident light. Since the angle of refraction of the optical element 36 becomes the angle of incidence of the optical modulator 20, when there is an optical element 36 that satisfies the index of refraction, eventually, when the incident light L1-L3 is incident on the optical modulator 20. The incident angle of is smaller than when the optical element 36 is absent. Incident light L1-L3 incident on the light modulator 20 may be incident through the lens 38. In this case, the lens 38 and the optical element 36 may lie on the same optical axis. Therefore, the center of the light incident surface of the optical element 36, for example, the region corresponding to the second region B of the optical modulator 20, is on the focal plane S1 of the lens 38 on the optical axis. It can be located at However, since the light incident surface of the optical modulator 20 is inclined with the lens 38 at a predetermined angle, for example, 22.5 °, the second area of the light modulator 20 at the light incident surface of the optical element 36. The other area except for the area corresponding to (B) may deviate from the focal plane S1 of the lens 38. In consideration of this, it can be seen that the incident light L1-L3 incident on the optical element 36 represents the center light of the light incident on the first to third regions A-C of the optical modulator 20. The light incident on the optical element 36 actually forms a cone with the incident light L1-L3 as the center light. Therefore, in the first to third regions AC of the light modulator 20, light L11, L21, L31, which form a cone around the incident light L1-L3, passes through the optical element 36. do. Incident angles of the lights L11, L21, and L31 constituting the cone may be larger or smaller than the center lights L1-L3. As a result, the incident angle of the light incident on the first to third regions A-C of the optical modulator 20 has a given range around the incident angle of the incident light L1-L3 which is the center light. For example, when the focal plane S1 of the lens 38 and the light incidence plane of the light modulator 20 are inclined at 22.5 ° and the cone angle is about 20 ° around the incident light L1-L3 as the center light. The incident light of the lights L11, L21, and L31 constituting the cone of the light modulator 20 may be at least 2.5 ° and at most 42.5 °. In other words, when the viewing angle of the lens 38 is not considered, the incident angle of light incident on each area of the optical modulator 20 may vary from 2.5 ° to 42.5 °. Similar to the incident light L1-L3, which is the center light, the incident light L11, L21, L31 forming a cone around the center light is refracted while passing through the optical element 36. Accordingly, when the incident light beams L11, L21, and L31 constituting the cone are incident on the first to third regions A-C of the light modulator 20, the incident angle becomes smaller than when the optical element 36 is absent. Consequently, due to the presence of the optical element 36, the range of the incident angle of the incident light incident on each area AC of the optical modulator 20 becomes smaller than when the optical element 36 is absent, and the maximum incident angle is greater than 42.5 °. Can be small.

As the optical element 36 is provided, the incident angle of incident light incident on the optical modulator 20 decreases, thereby reducing the resonance wavelength, for example, the variation of the FP (Fabry-Perot) resonance wavelength, in each region of the optical modulator 20. In addition, the reflectance difference according to the resonance wavelength in each region can be reduced. Therefore, more uniform light modulation characteristics can be obtained in the entire region of the light modulator 20.

3 shows an example of the optical element 36 of FIG. 2.

Referring to FIG. 3, as the optical element 36, a rectangular prism 36A having a refractive index of 1.5 is provided on the antireflection film 22. The bottom surface of the right prism 36A is in contact with the antireflection film 22. Incident light is incident on the inclined surface of the right angle prism 36A. The right angle prism 36A may be disposed to become thinner toward the first to third regions A, B, and C of the light modulator 20. An angle θ1 (hereinafter, referred to as a prism angle) formed between the bottom surface of the rectangular prism 36A and the inclined surface may be, for example, 15 °. The incident angle θ2 of the incident light L2 with respect to the second region B of the light modulator 20 may be 22.5 ° before passing through the right angle prism 36A. The incident light L2 is refracted while passing through the right angle prism 36A. The angle of refraction θ3 of the incident light L2 in the rectangular prism 36A can be obtained by Snell's law. The angle θ4 between the refracted light L2r and the normal line 20L perpendicular to the light incident surface of the light modulator 20 is equal to a value obtained by subtracting the prism angle θ1 from the refractive angle θ3 of the incident light L2. In FIG. 3, the angle θ4 between the refracted light L2r and the normal 20L perpendicular to the light incident surface of the light modulator 20 is 8.94 °. This angle θ4 is an incident angle of the incident light L2 with respect to the second region B of the optical modulator 20. Although the incident angle of the incident light L2 to the second region B of the optical modulator 20 was 22.5 ° before passing through the right angle prism 36A, the incident angle of the incident light L2 after passing through the right angle prism 36A. Decreases to 8.94 °. Therefore, the change of the FP resonance wavelength in each region A-C of the optical modulator 20 can be reduced, and the difference in reflectance for each resonance wavelength can be reduced. 2 and 3, the light incident on the light modulator 20 is reflected from the upper and lower DBR layers (not shown) of the light modulator 20, but the light reflected from the light modulator 20 is not shown for convenience. .

On the other hand, the reason that the incident angle of the incident light (L1-L3) is changed according to each area of the light incident surface of the optical modulator 20, as described above, the area of the optical modulator 20 in addition to the area of the lens 38 and the focal length There is a viewing angle of the lens 38 according to. The second incident light L2 on the same optical axis as the lens 38 is not affected by the viewing angle of the lens 38. However, the first and the third incident light (L1, L3) that is not is affected by the viewing angle. Accordingly, the incident angles of the first and third incident lights L1 and L3 may be different from the incident angle of the second incident light L2, for example, 22.5 °. For example, when the effective focus of the lens 38 is 6.0 mm and the area of the light incident surface of the light modulator 20 is 4 mm x 4 mm, the viewing angle is ± 8 ° with respect to the second incident light L2. . Considering this viewing angle, the incident angle of the first incident light L1 incident on the first region A of the optical modulator 20 is the viewing angle (8 degrees) at the incident angle of the second incident light L2 (eg, 22.5 °). The angle of incidence of the third incident light L3 incident on the third region C of the optical modulator 20 may be 30.5 ° after adding the viewing angle to the incident angle of the second incident light L2. have.

The optical modulator according to another embodiment of the present invention compensates for the incident angle of the incident light L1-L3 according to the viewing angle of the lens 38, thereby improving the modulation characteristics of the optical modulator.

4 shows an optical modulator according to another embodiment of the present invention.

Referring to FIG. 4, a second prism 36B is provided on the antireflection film 22. The light incident surface 36S of the second prism 36B is a curved surface. The light incident surface 36S is incident light L1-L3 incident on each region of the light incident surface 36S of the second prism 36B corresponding to the first to third regions AC of the light modulator 20. The incidence angles 36θ1, 36θ2, and 36θ3 have the same curvature. The light incident surface 36S that satisfies such curvature conditions can be obtained as follows. Hereinafter, each area of the light incident surface 36S of the second prism 36B corresponding to the first to third areas AC of the light modulator 20 is referred to as the first to third areas A1, B1, and C1. This is called. If the incidence angles 36θ1, 36θ2, 36θ3 of the incident light L1-L3 incident on the first to third regions A1, B1, C1 of the second prism 36B are the same, the refractive angles are the same, and the optical modulator The conditions of the incident light incident on the respective areas of 20 are the same, and as a result, the influence of the viewing angle of the lens 38 can be compensated for. The incident surface 36S in which the incident angles 36θ1, 36θ2, 36θ3 of the incident light L1-L3 are equal can be obtained as follows.

Specifically, the incident angle of the second incident light L2 to the optical modulator 20 is 22.5 °, the effective focus of the lens 38 is 6.0 mm, and the area of the light incident surface of the optical modulator 20 is 4 mm * 4 mm. When the viewing angle is 8 °, the incident angle 36θ1 of the incident light L1-L3 incident on the first to third regions A1-C1 of the second prism 36B to compensate for the viewing angle of the lens. Since 36θ2 and 36θ3) must be the same, the following equation 1 holds.

[Equation 1]

36θ1 = 36θ2 = 36θ3

The incident angle 36θ1 of the first incident light L1 is 14.5 ° + β1, the incident angle 36θ2 of the second incident light L2 is 22.5 ° + β2, and the incident angle 36θ3 of the third incident light L3 is 30.5 °. + β3. Therefore, Equation 1 may be expressed as Equation 2.

[Equation 2]

14.5 ° + β1 = 22.5 ° + β2 = 30.5 ° + β3

In Equation 2, β1 is a normal line 36P1 perpendicular to the light incident surface 36S and a normal line perpendicular to the light incident surface 20S of the light modulator 20 in the first region A1 of the second prism 36B. The angle between (20P) is shown. β2 represents an angle between a normal line 36P2 perpendicular to the light incident surface 36S in the second region B1 and a normal line 20P perpendicular to the light incident surface 20S of the light modulator 20. β3 represents an angle between the normal line 36P2 perpendicular to the light incident surface 36S in the third region C1 and the normal line 20P perpendicular to the light incident surface 20S of the light modulator 20.

The light incident surface 36S of the second prism 36B is a curved surface that satisfies the expression (2). When the area of the light incident surface 20S of the light modulator 20 is changed or the focal length and / or the area of the aperture surface of the lens is changed, the viewing angle of the lens may be larger or smaller than 8 °, so that the second prism 36B The incident angles of the first and third incident lights L1 and L3 with respect to the normal line 20P perpendicular to the light incident surface 20S of the light modulator 20 at the light incident surface 36S of FIG. Since β1 and β3 may also vary, the curvature of the light incident surface 36S of the second prism 36B may vary.

Since the light incident surface 20S of the light modulator 20 has a two-dimensional area, as shown in FIG. 5, the viewing angle of the lens 38 is the longitudinal axis (Y-Y ′) of the light incident surface 20S and The viewing angles α1 and α2 in the horizontal axis X-X 'direction exist. The curved shape of the light incident surface 36S of the second prism 36B shown in FIG. 4 is a shape for compensating the viewing angle α1 in the longitudinal axis (Y-Y ') direction. As can be seen in FIG. 5, the viewing angles in the longitudinal axis (Y-Y ') and the horizontal axis (X-X') direction may be the same or different depending on the light incident surface 20S of the light modulator 20. If the horizontal and vertical lengths of the light incident surface 20S of the optical modulator 20 are the same, the viewing angles α1 and α2 in the vertical axis (Y-Y ') and the horizontal axis (X-X') directions are the same, and the horizontal and vertical lengths are the same. If the lengths are different, the viewing angles α1 and α2 may be different. When the vertical axis Y-Y 'and the horizontal axis X-X' direction viewing angles α1 and α2 are the same, the light of the second prism 36 for compensating the horizontal axis X-X 'direction viewing angle α2 The curved shape of the incident surface 36S is the same as that of FIG. 4. Therefore, when the viewing angles α1 and α2 in the longitudinal axis Y-Y 'and the horizontal axis X-X' direction are the same, the light incident surface 36S of the second prism 36 has the same curvature in the horizontal and vertical directions. It can be a surface. When the viewing angles α1 and α2 in the longitudinal axis (Y-Y ') and the horizontal axis (X-X') direction are different, the light incident surface 36S of the second prism 36 has a curved surface having a different curvature in the horizontal and vertical directions. Can be.

6 shows a partial configuration of an optical device according to an embodiment of the present invention. The optical device may be, for example, a stereo camera.

Referring to FIG. 6, light reflected from a subject (not shown) passes through the first lens LL1. The light passing through the first lens LL1 is sequentially reflected by the optical image modulator 60 and the light reflector 70, and then enters the image sensor 90 through the second lens LL2. The first lens LL1 may be the lens 38 of FIG. 2.

The optical image modulator 60 includes a light modulation layer 60A and a light refraction layer 60B that reduces the angle of incidence of light incident on the light modulation layer 60A. Light incident on the light modulation layer 60A is modulated and emitted to the light reflector 70. The light modulation layer 60A may include a lower DBR layer 62, a multiple quantum well layer (MQW) 64, and an upper DBR layer 66 sequentially stacked as illustrated in FIG. 7. The light modulation layer 60A may be a conventional reflective light modulator. The light modulation layer 60A may be the light modulator 20 of FIGS. The light refraction layer 60B may be an optical element 36 of FIG. 2, a prism 36A of FIG. 3, or a second prism 36B of FIG. 4. The light reflector 70 reflects the light incident from the optical image modulator 60 to the second lens LL2. The light reflector 70 includes a light reflecting layer 70A and a light refracting layer 70B. The light reflection layer 70A serves to reflect light incident through the light refraction layer 70B. The light reflective layer 70A may be, for example, a mirror or a reflective coating layer. The light reflective layer 70A may be a layer coated on the corresponding side of the light refraction layer 70B. The light reflection layer 70A is inclined at a predetermined angle, for example, 45 °, with respect to the light modulation layer 60A. Accordingly, the light reflected by the light reflector 70 may be incident to the second lens LL2. The light refraction layer 70B refracts the light incident from the light modulator 60 into the light reflection layer 70A. The light refraction layer 70B is attached to the light reflection surface of the light reflection layer 70A. The optical refraction layer 70B may be the same as the optical refraction layer 60B included in the optical image modulator 60. For example, the optical refraction layer 60B included in the optical image modulator 60 and the optical refraction layer 70B of the light reflector 70 have a prism having a predetermined prism angle, for example, a prism angle of 15 °. It may be three prisms 36A. The light refracting layer 70B of the light reflector 70 is provided to compensate for the light path of the light passing through the light refracting layer 60B of the optical image modulator 60. Accordingly, the light refraction layer 70B of the light reflector 70 is disposed opposite to the light refraction layer 60B of the optical image modulator 60. That is, light passing through the thin portion of the light refraction layer 60B of the optical image modulator 60 passes through the thick portion of the light refraction layer 70B of the light reflector 70. An antireflection film may be coated on the light incident surfaces of the light refraction layers 60B and 70B. The second lens LL2 serves to condense the light incident from the light reflector 70 to the image sensor 90. The second lens LL2 and the image sensor 90 may be provided in parallel. The image sensor 90 may be, for example, a Charge Coupled Device (CCD) or a Complementary Metal Oxide Semiconducor (CMOS) sensor.

Meanwhile, in the description of FIGS. 2 to 4, the optical element 36, the prism 36A, and the second prism 36B have been described separately from the optical modulator 20 for convenience, but the optical image according to the embodiment of the present invention is described. The modulator includes an optical element 36, a prism 36A or a second prism 36B together with the light modulator 20, and may also include an anti-reflection film 22.

While many details are set forth in the foregoing description, they should be construed as illustrative of preferred embodiments, rather than to limit the scope of the invention. Therefore, the scope of the present invention should not be defined by the described embodiments, but should be determined by the technical spirit described in the claims.

20, 30: Optical image modulator 20L: Normal normal to optical modulator
20P: Normal normal to the optical modulator 20S: Light incident surface of the optical modulator
22: antireflection film 32: light incident region
34: unit light modulator 36: optical element 36A: prism.
36B: second prism 36S: light incident surface of second prism
36P1-36P3: Normal in the first to third regions of the light incident surface 36S
38: lens 60: light modulator
60A: light modulation layer 60B, 70B: light refraction layer
70: light reflector 70A: light reflection layer
90: image sensor
A, B, C: first to third regions A1, B1, C1: first to third regions
LL1, LL2: First and second lenses L2r: Refractive light
L1-L3: first to third incident light
L11, L21, L31: incident light forming a cone
S1: focal plane
α1: longitudinal lens viewing angle
α2: horizontal lens direction angle

Claims (11)

A plurality of unit light modulators; And
An optical element;
The plurality of unit light modulators form an array,
And the optical element reduces an incident angle of incident light incident on the light incident surface of the array than when the optical element is absent. The method of claim 1,
And the light incidence plane of the optical element and the light incidence plane of the array are non-parallel. The method of claim 1,
And a light incident surface of the optical element is a plane. The method of claim 1,
And a light incident surface of the optical element is a curved surface. The method according to claim 3 or 4,
And the optical element is a prism. The method of claim 1,
And a light incident surface of the optical element coated with an antireflective film. The method of claim 1,
And an anti-reflection film between the plurality of unit light modulators and the optical element. A lens for condensing the light reflected from the subject;
An optical image modulator for modulating light passing through the lens; And
An optical image sensor for sensing light modulated by the optical image modulator;
The optical image modulator is the optical image modulator of claim 1. The method of claim 8,
An optical reflector for reflecting light emitted from the optical image modulator to the optical image sensor. The method of claim 9,
And the light reflector comprises a light reflecting layer and a light refracting layer for optical path compensation of light reflected by the light image modulator. 11. The method of claim 10,
The optical refraction layer is a prism.

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