CN115113375B - Camera module and camera device - Google Patents
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- CN115113375B CN115113375B CN202211012245.7A CN202211012245A CN115113375B CN 115113375 B CN115113375 B CN 115113375B CN 202211012245 A CN202211012245 A CN 202211012245A CN 115113375 B CN115113375 B CN 115113375B
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Abstract
The invention discloses a camera module and a camera device. The camera shooting module comprises an optical system, a planar lens group and a sensor, wherein the optical system, the planar lens group and the sensor are sequentially arranged along the transmission direction of incident light, the optical system comprises at least one lens and is used for correcting aberration, the planar lens group comprises at least one planar lens, the incident light is transmitted by the optical system to form first corrected light, the first corrected light is incident to the planar lens group at a Brewster angle and is transmitted by the planar lens group to form linearly polarized light, and the sensor is located on the transmission path of the linearly polarized light. According to the camera module and the camera device provided by the embodiment of the invention, the incident light is converted into the linearly polarized light by arranging the planar lens group, the sensor utilizes the linearly polarized light to image, and high precision can be achieved without accurate radiation calibration, so that the imaging quality is improved.
Description
Technical Field
The invention relates to the technical field of optical imaging, in particular to a camera module and a camera device.
Background
Fig. 1 is a schematic structural diagram of an existing infrared camera module, and as shown in fig. 1, the existing infrared camera module includes an optical system 10', a filter 11' and a sensor 12', the optical system 10' is used for reducing aberration, the filter 11 'is used for filtering stray light with an unwanted wavelength, and the sensor 12' is used for converting an optical signal into an electrical signal, and after the electrical signal is processed, a shot picture can be finally output.
The filter 11' is coated on the surface of the planar lens, and only the wavelength of light is selected, so that the imaging quality of the infrared camera module cannot be further improved.
Disclosure of Invention
The invention provides a camera module and a camera device, which are used for improving the imaging quality.
According to an aspect of the present invention, there is provided a camera module, comprising an optical system, a planar lens set and a sensor sequentially arranged along a propagation direction of an incident light;
the optical train including at least one lens, the optical train for correcting aberrations;
the planar lens group includes at least one planar lens;
the incident light is transmitted by the optical system to form a first correction light;
the first correction light ray is incident to the plane lens set at the Brewster angle and forms linearly polarized light ray after being transmitted by the plane lens set;
the sensor is positioned on the propagation path of the linearly polarized light.
Optionally, an incident angle of the first correcting light ray on the planar lens group is θ 1 ，θ 1 =arctan(n 2 /n 1 )；
Wherein n is 1 Is the refractive index of air, n 2 Is the refractive index of the planar lens.
Optionally, the planar lens group includes a plurality of planar lenses arranged in parallel, and a plane of each of the planar lenses is perpendicular to the optical axis direction of the optical system.
Optionally, the camera module further includes a light path adjusting unit, where the light path adjusting unit is located on a propagation path of the first correction light;
the light path adjusting unit comprises a first reflecting surface and a second reflecting surface;
the first correction light ray is emitted by the first reflecting surface and the second reflecting surface in sequence and then enters the plane lens group at the Brewster angle.
Optionally, the optical path adjusting unit includes a square prism and an equilateral right-angled triple prism, the first reflecting surface is located on the square prism, and the second reflecting surface is located on the equilateral right-angled triple prism;
the four-prism comprises a first incident surface and a first emergent surface which are respectively adjacent to the first reflecting surface;
the equilateral right-angle triple prism comprises a second incident surface and a second emergent surface which are respectively adjacent to the second reflecting surface;
the first correction light ray sequentially enters the first incident surface of the four-prism, is reflected by the first reflecting surface and exits from the first exit surface to reach the second incident surface of the equilateral right-angle triple prism; after the light is incident from the second incident surface of the equilateral right triangular prism, reflected from the second reflecting surface and emitted from the second emergent surface, the light is incident to the plane lens group at the Brewster angle;
the first incident surface is perpendicular to the optical axis direction of the optical system, the first reflecting surface intersects with the first incident surface, and the first emergent surface is perpendicular to the propagation direction of the first correction light reflected by the first reflecting surface;
the second incident surface is perpendicular to the propagation direction of the first correction light emitted through the first emitting surface, the second reflecting surface is parallel to the optical axis direction of the optical system, and the second emitting surface is perpendicular to the first correction light reflected through the second reflecting surface.
Optionally, the refractive index of the four prisms is n 3 ，n 3 ≥1/sinθ 2 ；
Wherein, theta 2 The incident angle of the first correction ray on the first reflecting surface is used.
Optionally, the refractive index of the equilateral right triangular prism is n 4 ，n 4 ≥1/sinθ 3 ；
And θ 3 is an incident angle of the first correction light ray on the second reflecting surface.
Optionally, the thickness of the planar lens is d, d = (λ k)/((4 n) 2 2 -2) 1/2 )；
Wherein λ is the wave of the incident lightLong, k is a positive integer, n 2 Is the refractive index of the planar lens.
Optionally, the incident light is an infrared light;
the material of the planar lens comprises any one of fused quartz, crown glass, dense crown glass, barium crown glass, flint glass, barium flint glass and heavy flint glass.
According to another aspect of the present invention, there is provided an image pickup apparatus including any one of the image pickup modules of the first aspect.
The camera module and the camera device provided by the embodiment of the invention comprise an optical system, a planar lens group and a sensor which are sequentially arranged along the transmission direction of incident light, wherein the optical system comprises at least one lens and is used for correcting aberration, the planar lens group comprises at least one planar lens, the incident light is transmitted by the optical system to form first corrected light, the first corrected light is incident to the planar lens group at a Brewster angle and is transmitted by the planar lens group to form linearly polarized light, and the sensor is positioned on the transmission path of the linearly polarized light. The sensor utilizes the linearly polarized light to image, and can achieve quite high precision without accurate radiation calibration, thereby being beneficial to improving the imaging quality.
It should be understood that the statements in this section are not intended to identify key or critical features of the embodiments of the present invention, nor are they intended to limit the scope of the invention. Other features of the present invention will become apparent from the following description.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a conventional infrared camera module;
fig. 2 is a schematic structural diagram of a camera module according to an embodiment of the present invention;
FIG. 3 is a schematic structural diagram of a planar lens assembly according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of an optical path of a first corrective light ray at an interface of a planar lens according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of another camera module according to an embodiment of the present invention;
fig. 6 is a schematic view of a main view structure of a camera module according to an embodiment of the present invention;
fig. 7 is a schematic top view of a camera module according to an embodiment of the present invention;
fig. 8 is a schematic diagram of an optical path of another first corrective ray at a planar lens interface according to an embodiment of the present invention.
Detailed Description
In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
Fig. 2 is a schematic structural diagram of a camera module according to an embodiment of the present invention, as shown in fig. 2, the camera module according to the embodiment of the present invention includes an optical system 10, a planar lens group 13, and a sensor 14, which are sequentially disposed along a propagation direction of an incident light 100, where the optical system 10 includes at least one lens, the optical system 10 is used for correcting aberration, the planar lens group 13 includes at least one planar lens 131, the incident light 100 is transmitted by the optical system 10 to form a first corrected light 200, the first corrected light 200 is incident to the planar lens group 13 at a brewster angle and is transmitted by the planar lens group 13 to form a linearly polarized light 300, and the sensor 14 is located on a propagation path of the linearly polarized light 300.
The camera module provided by the embodiment of the invention can be applied to camera devices such as a mobile phone or an infrared camera, for example, the camera module is applied to a front infrared camera of the mobile phone, but is not limited thereto.
Specifically, as shown in fig. 2, when the camera module is applied to an infrared camera, and the infrared camera takes a pattern through the camera module, the formed picture may generate an aberration, for example: spherical aberration, coma, astigmatism, field curvature and distortion. In the present embodiment, by disposing the optical train 10 on the propagation path of the incident light ray 100, the above-described aberration can be corrected, thereby contributing to improvement of the imaging quality.
For example, as shown in fig. 2, the optical train 10 includes four lenses, and the four lenses are all aspheric lenses, so that the aberration formed can be minimized to improve the imaging quality, but not limited thereto, and in other embodiments, a person skilled in the art can set the number of lenses and parameters of each lens in the optical train 10 according to actual requirements.
Fig. 3 is a schematic structural diagram of a planar lens assembly according to an embodiment of the present invention, as shown in fig. 2 and fig. 3, the planar lens assembly 13 includes at least one planar lens 131, and a first corrected light ray 200 formed by transmitting an incident light ray 100 through the optical system 10 is incident on the planar lens assembly 13 at a brewster angle, where when natural light is reflected and refracted on a medium interface, the reflected light and the refracted light are both partially polarized light, and the reflected light is linearly polarized light only when an incident angle is a specific angle, and a vibration direction of the reflected light is perpendicular to the incident plane, where the specific angle is called the brewster angle, and this rule is called the brewster law. In the present embodiment, the first correcting light ray 200 transmitted through the planar lens 131 in the planar lens group 13 can be partially polarized light by setting the first correcting light ray 200 to be incident to the planar lens group 13 at the brewster angle, and the first correcting light ray 200 transmitted through the planar lens group 13 can be linearly polarized light 300 by setting the number of the planar lenses 131 in the planar lens group 13.
Further, as shown in fig. 2, the sensor 14 includes a substrate 141 and a sensor pixel array 142 disposed on the substrate 141, the sensor 14 is disposed on a propagation path of the linearly polarized light beam 300, so that the linearly polarized light beam 300 is irradiated on the sensor pixel array 142, and the sensor pixel array 142 converts the linearly polarized light beam 300 into an electrical signal.
With continued reference to fig. 2, the sensor 14 may be electrically connected to an external image processor via a connection 15 to transmit the electrical signal to the image processor, where the electrical signal is processed and the captured picture is finally output.
It should be noted that different polarization states can be generated by different objects or different states of the same object, so as to form different polarization spectrums. The traditional infrared technology measures the intensity of radiation of an object, while polarization measures the contrast of the radiation of the object in different polarization directions, so that objects with the same radiation intensity and different polarizations can be distinguished by using polarized light.
In this embodiment, the incident light 100 is converted into the linearly polarized light 300 by the planar lens group 13, so that the light refracted to the sensor 14 is the linearly polarized light 300 with the polarization direction parallel to the propagation direction of the light, and the sensor 14 performs imaging by using the linearly polarized light 300, so that a relatively high precision can be achieved without accurate radiation calibration, thereby contributing to improving the imaging quality.
It should be noted that, the number of the planar lenses 131 in the planar lens group 13 may be set according to practical requirements, as shown in fig. 2, the planar lens group 13 may include only one planar lens 131, as shown in fig. 3, and the planar lens group 13 may also include a plurality of planar lenses 131 (e.g., 6), which is not limited in the embodiment of the present invention.
It can be understood that when the first correcting light ray 200 is incident to the planar lens 131 at the brewster angle, the refracted light is partially polarized light, and therefore, when the number of the planar lenses 131 in the planar lens group 13 is sufficiently large, the finally refracted light can be considered as linearly polarized light whose polarization direction is the propagation direction of the parallel light, approximately. That is, the greater the number of the planar lenses 131, the stronger the linear polarization characteristic of the linearly polarized light beam 300, but the smaller the number of the planar lenses 131, the more the miniaturization of the camera module is facilitated, and those skilled in the art can set the number of the planar lenses 131 in the planar lens group 13 according to actual needs.
Fig. 4 is a schematic diagram of an optical path of a first correcting light ray at a planar lens interface according to an embodiment of the present invention, as shown in fig. 3 and fig. 4, and optionally, an incident angle θ of the first correcting light ray 200 at the planar lens group 13 is 1 ，θ 1 =arctan(n 2 /n 1 ) Wherein n is 1 Is the refractive index of air, n 2 Is the refractive index of the planar lens.
Specifically, as shown in fig. 3 and 4, when the first correcting light ray 200 is incident at brewster's angle, i.e. the incident angle θ of the first correcting light ray 200 on the planar lens group 13 1 At Brewster's angle, the reflected light and the refracted light are perpendicular to each other. As shown in fig. 4, θ 1 Is the angle of incidence, θ 4 Refractive index of air n for the angle of refraction 1 Refractive index of the planar lens is n 2 From the law of refraction, one can obtain:
n 1 sin(θ 1 )=n 2 sin(θ 4 )；
when a light ray is incident at Brewster's angle, the reflected light is perpendicular to the refracted light, then:
n 1 sin(θ 1 )=n 2 sin(90°-θ 1 )=n 2 cos(θ 1 )；
further obtaining:
θ 1 =arctan(n 2 /n 1 )。
therefore, in the present embodiment, the incident angle θ of the first correcting light ray 200 on the plane lens group 13 is set 1 Satisfies theta 1 =arctan(n 2 /n 1 ) So that first corrective light ray 200 is incident upon planar lens group 13 at brewster's angle.
Fig. 5 is a schematic structural diagram of another camera module according to an embodiment of the present invention, fig. 6 is a schematic structural diagram of a front view of a camera module according to an embodiment of the present invention, and fig. 7 is a schematic structural diagram of a top view of a camera module according to an embodiment of the present invention, as shown in fig. 5-7, optionally, the planar lens group 13 includes a plurality of planar lenses 131 arranged in parallel, and a plane of each planar lens 131 is perpendicular to the optical axis direction of the optical system 10.
As described above, the larger the number of the planar lenses 131 is, the stronger the linear polarization characteristic of the linearly polarized light beam 300 is, and therefore, the arrangement of the plurality of planar lenses 131 in the planar lens group 13 is helpful to improve the linear polarization characteristic of the linearly polarized light beam 300, and is further helpful to improve the imaging quality.
Further, as shown in fig. 3, by arranging a plurality of planar lenses 131 in parallel and overlapping, the incident angle of the first correcting light ray 200 on each planar lens 131 can be the same, that is, the incident angle of the first correcting light ray 200 on each planar lens 131 is brewster's angle, which helps to realize the conversion of the first correcting light ray 200 into the linearly polarized light ray 300; meanwhile, the occupied space of the planar lens group 13 can be reduced, and the miniaturization arrangement can be realized.
Meanwhile, as shown in fig. 5 to 7, each component in the camera module can be fixed in a lens barrel (not shown in the figures), and the plane of the planar lens 131 in the planar lens group 13 is perpendicular to the optical axis direction of the optical system 10, which is beneficial to accurately assembling the planar lens group 13, reduces the process difficulty, and is easy to implement.
With continuing reference to fig. 5 to 7, optionally, the camera module according to the embodiment of the present invention further includes an optical path adjusting unit 16, where the optical path adjusting unit 16 is located on the propagation path of the first calibration light 200. The optical path adjusting unit 16 includes a first reflective surface 21 and a second reflective surface 22, and the first calibration light beam 200 is emitted by the first reflective surface 21 and the second reflective surface 22 in sequence and then enters the planar lens group 13 at the brewster angle.
As shown in fig. 5-7, the light path adjusting unit 16 is disposed on the propagation path of the first correcting light ray 200 to change the propagation direction of the first correcting light ray 200, so that the first correcting light ray 200 is incident to the planar lens group 13 at the brewster angle.
Specifically, the optical path adjusting unit 16 includes a first reflecting surface 21 and a second reflecting surface 22, and the first correcting light beam 200 is reflected twice by the first reflecting surface 21 and the second reflecting surface 22, and then enters the planar lens group 13 at the brewster angle, so that the conversion of the linearly polarized light beam 300 is realized while the planar lens group 13 is horizontally disposed.
With continued reference to fig. 5 to 7, optionally, the optical path adjusting unit 16 includes a quadrangular prism 161 and an equilateral right triangular prism 162, the first reflecting surface 21 being located on the quadrangular prism 161, and the second reflecting surface 22 being located on the equilateral right triangular prism 162. The four prisms 161 further include first incident surfaces 23 and first exit surfaces 24 adjacent to the first reflection surfaces 21, respectively. The equilateral right triangular prism 162 includes a second entrance face 25 and a second exit face 26 adjacent 22, respectively, to the second reflective face. The first correction light ray 200 sequentially enters through the first incident surface 23 of the four-prism 161, is reflected by the first reflecting surface 21 and exits through the first exiting surface 24 to reach the second incident surface 25 of the equilateral right-angled triple prism 162; and is incident on the planar lens group 13 at the brewster angle after being incident on the second incident surface 25 of the equilateral right triangular prism 162, reflected by the second reflecting surface 22, and emitted from the second emitting surface 26. The first incident surface 23 is perpendicular to the optical axis direction of the optical system 10, the first reflecting surface 21 intersects with the first incident surface 23, and the first emitting surface 24 is perpendicular to the propagation direction of the first calibration light 200 reflected by the first reflecting surface 21; the second incident surface 25 is perpendicular to the propagation direction of the first calibration light beam 200 emitted through the first emitting surface 24, the second reflecting surface 22 is parallel to the optical axis direction of the optical train 10, and the second emitting surface 26 is perpendicular to the first calibration light beam 200 reflected by the second reflecting surface 22.
Specifically, as shown in fig. 5 to 7, the first incident surface 23 of the four prisms 161 is perpendicular to the optical axis direction of the optical system 10, and the propagation direction of the first calibration light beam 200 is not changed after the first incident surface 23 enters. The first reflecting surface 21 intersects the first incident surface 23, so that the first correction light ray 200 changes its traveling direction after being reflected by the first reflecting surface 21 to travel toward the equilateral right triangular prism 162. The first exit surface 24 is perpendicular to the propagation direction of the first calibration light beam 200 reflected by the first reflection surface 21, so that the propagation direction of the first calibration light beam 200 after exiting through the first exit surface 24 is not changed.
Further, with continued reference to fig. 5-7, the second incident surface 25 of the equilateral right triangular prism 162 is perpendicular to the propagation direction of the first calibration light beam 200 exiting through the first exit surface 24, and the propagation direction of the first calibration light beam 200 does not change after entering through the second incident surface 25. The second reflecting surface 22 is parallel to the optical axis direction of the optical system 10, so that the first calibration light 200 changes the propagation direction after being reflected by the second reflecting surface 22 to propagate to the planar lens group 13, and meanwhile, the precise assembly of the equal-side right-angled triangular prism 162 is facilitated, the process difficulty is reduced, and the implementation is easy. The second exit surface 26 is perpendicular to the first calibration light beam 200 reflected by the second reflection surface 22, so that the propagation direction of the first calibration light beam 200 after exiting through the second exit surface 26 is not changed.
As can be seen from the above, the first correcting light ray 200 is reflected by the first reflecting surface 21 and the second reflecting surface 22, and then enters the planar lens group 13 at the brewster angle, so that the setting angle of the first reflecting surface 21 and the second reflecting surface 22 can be determined according to the brewster angle.
Illustratively, as shown in fig. 5-7, taking the brewster angle as 45 °, the incident light ray 100 vertically enters after passing through the optical system 10 to form a first corrected light ray 200, and the first corrected light ray 200 passes through the first incident surface 23 horizontally disposed on the quadrangular prism 161, is reflected by the first reflecting surface 21 to form a light ray having an angle of 45 ° with the optical axis direction (vertical direction) of the optical system 10, and then perpendicularly hits the second incident surface 25 of the equilateral right-angled triangular prism 162 (one right-angle side of the equilateral right-angled triangular prism 162). The vertically cathetized first corrective light ray 200 is reflected by second reflective surface 22 (the hypotenuse) of equilateral right triangular prism 162 and emerges vertically from second exit surface 26 (the other cathetized side of equilateral right triangular prism 162).
Further, since the planar lens group 13 is horizontally disposed, the first corrective light ray 200 emitted from the second emission surface 26 is incident on the planar lens group 13 at 45 ° (i.e., brewster angle), which realizes the conversion of the linearly polarized light ray.
Note that by changing the refractive index and the thickness of the planar lens 131 in the planar lens group 13, the brewster angle of the planar lens group 13 can be made 45 °.
With continued reference to fig. 6, angle HKM =45 °, so angle HKP =180 ° -, HKM =180 ° -45 ° =135 °, so the incident angle and the reflection angle of the first correction light ray 200 at the first reflection surface 21 can be found to be:
135°/2=67.5°；
with continued reference to fig. 6, the dotted line at point K is the normal to the first reflecting surface 21, so ≈ PKF =90 ° -67.5 ° =22.5 °, thereby obtaining the setting angle of the first reflecting surface 21.
Further, with continued reference to fig. 6, the required field of view of the equilateral right triangular prism 162 is determined by the size of the pixel area in the sensor 14, and the maximum field of view obtained by the equilateral right triangular prism 162 is the side AB, which therefore also determines the size of the side EG of the quadrangular prism 161, i.e. the length of the side AB of the quadrangular prism 161 may be equal to the length of the side EG, that is to say, the area of the first exit face 24 of the equilateral right triangular prism 162 may be set according to the second reflection face 22 of the equilateral right triangular prism 162.
Meanwhile, the edge DF is in the horizontal direction, the edge DE may be in the vertical direction, and since ═ PKF =22.5 °, the four edges EG, DE, DF, and GF may form the rectangular prism 161.
As shown in fig. 6, the edge DE is a vertical direction, which helps to reduce the volume of the rectangular prism 161, thereby facilitating a compact design, but is not limited thereto.
With continued reference to FIG. 6, aOptionally, the refractive index of the four prisms 161 is n 3 ，n 3 ≥1/sinθ 2 (ii) a Wherein, theta 2 Is the incident angle of the first correcting ray 200 on the first reflecting surface 21.
Specifically, as shown in fig. 6, according to the refractive index formula:
n 3 sin(θ 2 )=n 1 sin(θ 5 )；
wherein n is 3 Is the refractive index, θ, of the quadrangular prism 161 2 Is the incident angle, n, of the first correcting ray 200 on the first reflecting surface 21 1 Is the refractive index of air, which is 1, theta 5 Is the refraction angle of the first corrected light ray 200 at the first reflecting surface 21. When the first correction light ray 200 is totally reflected on the first reflection surface 21, the refraction angle theta 5 =90 °, sin (θ) 5 ) =1, can calculate refractive index n 3 The lowest value of (c):
n 3 =1/sin(θ 2 )=1/sin(67.5°)≈1.08239。
therefore, in the present embodiment, the refractive index n by the quadrangular prism 161 is set 3 ≥1/sinθ 2 I.e. the refractive index n of the quadrangular prism 161 3 Greater than or equal to 1.08239, the first calibration beam 200 can be totally reflected by the first reflecting surface 21.
Since the plane mirror reflection may lose a part of energy, compared with the case where the first reflecting surface 21 is configured as a plane mirror, the present embodiment may change the optical path of the first correcting light beam 200 by using the total reflection principle of the four prisms 161, so as to minimize the loss of light.
With continued reference to FIG. 6, the equilateral right triangular prism 162 optionally has an index of refraction n 4 ，n 4 ≥1/sinθ 3 (ii) a Wherein, theta 3 Is the angle of incidence of the first correcting ray 200 on the second reflecting surface 22.
Specifically, as shown in fig. 6, according to the refractive index formula:
n 4 sin(θ 3 )=n 1 sin(θ 6 )；
wherein n is 4 Is the refractive index, theta, of the equilateral right triangular prism 162 3 For the first correcting light ray 200 entering at the second reflecting surface 22Angle of incidence, n 1 Is the refractive index of air, which is 1, theta 6 Is the angle of refraction of the first corrective ray 200 at the second reflective surface 22. When the first correction light ray 200 is totally reflected on the second reflecting surface 22, the refraction angle theta 6 =90 °, i.e. sin (θ) 6 ) =1, the refractive index n can be calculated 4 Minimum value of (c):
n 4 =1/sin(θ 3 )=1/sin(45°)≈1.41421。
therefore, in the present embodiment, the refractive index n by providing the equilateral right-angled triangular prism 162 4 ≥1/sin(θ 3 ) I.e. refractive index n of equilateral right-angled triangular prism 162 4 Greater than or equal to 1.41421, the first calibration beam 200 can be totally reflected by the second reflecting surface 22.
Since the plane mirror reflection may lose a part of energy, compared to the case where the second reflective surface 22 is configured as a plane mirror, the present embodiment can minimize the loss of light by changing the optical path of the first calibration light 200 according to the total reflection principle of the equilateral right-angled triple prism 162.
It should be noted that the optical path adjusting unit 16 is not limited to the arrangement of the four prisms 161 and the equilateral right triangular prism 162, and in other embodiments, the optical path adjusting unit 16 may also include two plane mirrors, and the two plane mirrors are respectively used as the first reflecting surface 21 and the second reflecting surface 22 to achieve the adjustment of the optical path, and those skilled in the art can set the optical path according to actual requirements.
Fig. 8 is a schematic diagram of an optical path of another first corrective light ray at the planar lens interface according to the embodiment of the present invention, as shown in fig. 8, optionally, the thickness of the planar lens 131 is d, d = (λ k)/((4 n =) 2 2 -2) 1/2 ) (ii) a Wherein λ is the wavelength of incident light, k is a positive integer, n 2 Is the refractive index of the planar lens 131.
Specifically, as shown in fig. 8, the optical paths from the point R to the point T and from the point S to the point T are equal, so that the optical path difference between the two reflected lights of the first correcting light ray 200 on the plane lens 131 is the straight line OS and the polygonal line OQR.
As shown in fig. 8, OS = OR sini =2 d tan r sini;
OQ=QR=d/cosr；
therefore, the optical path difference δ = n 2 *（OQ+QR）-n 1 *OS=（n 2 *2*d）/cosr-n 1 *2*d*tanr*sini=2*d*（n 2 -n 1 *sini*sinr）/cosr；
From the refractive index formula:
Sini=n 2* sinr/n 1 ；
obtaining by solution:
δ=2*d*n 2 *cosr=2*d*(n 2 2 -n 1 2 *sin 2 i) 1/2 ；
in the present embodiment, n 1 Is a refractive index of air, therefore, n 1 And =1. Further, there is half-wave loss in the reflection process of the first correction light ray 200 from the optically thinner medium (air) to the optically denser medium (planar lens), and in order to make the two reflected light beams reflected by the planar lens 131 cancel interference and increase the transmittance, the calculation formula can be obtained:
δ=2*d*(n 2 2 -n 1 2 *sin 2 i) 1/2 = λ k (k =0,1,2,3 … … is an integer);
the formula can be obtained through calculation:
d=(λk)/((4n 2 2 -2) 1/2 )。
illustratively, taking the wavelength λ =0.93 μm of the incident light as an example, by setting d = (0.93 k)/((4 n) 2 2 -2) 1/2 ) The optical path difference of the two reflected lights of the first correction light 200 on the planar lens 131 is used to perform interference cancellation on the two reflected lights, so that the light intensity of the transmitted light can be increased, the energy of the 930nm refracted light can be enhanced, the anti-reflection effect on the 930nm light is achieved, and the effect of filtering light with wavelengths outside 930nm is achieved.
Alternatively, the incident light is infrared light, and the material of the planar lens 131 includes any one of fused quartz, crown glass, dense crown glass, barium crown glass, flint glass, barium flint glass, and dense flint glass.
Specifically, the incident light is infrared light, and infrared imaging and infrared detection functions can be realized.
The wavelength of the infrared light may be set according to actual requirements, for example, the wavelength is 930nm, but is not limited thereto, and those skilled in the art may set the wavelength according to actual requirements.
Further, fused quartz (SiO 2), crown glass (K6, K8, K9), dense crown glass (ZK 6, ZK 8), barium crown glass (BaK), flint glass (F1), barium flint glass (BaF 8), and dense flint glass (ZF 5, ZF 6) have good transmittance for infrared light (e.g., light having a wavelength of 930 nm), and therefore, the above-described materials can be selected as the material of the flat lens 131.
In addition, the above formula of geometric optics is more applicable when the thickness d of the planar lens 131 is two orders of magnitude or more greater than the wavelength of the incident light, and thus d is greater than or equal to 93 μm when the incident light is 930nm wavelength infrared light.
Further, the appropriate thickness d and material of the planar lens 131 may be computationally determined by taking different values for k.
Illustratively, a program is written below using python to calculate how many microns the thickness value of d is when k takes on different values. The thickness of the planar lens is required to be as small as possible, so that the number of the planar lenses can be increased as much as possible in a limited space.
The python program is as follows:
import numpy as np
import matplotlib.pyplot as plt
n = refractive index
k=np.linspace(200,300,101,dtype=int)
print(k)
a=np.sqrt(4*n*n-2)
d=0.93*k/a
print(d)
By bringing in refractive indices of different materials one can get:
1. when the planar lens material is SiO2, the refractive index n =1.45843, and d =109um can be calculated by a program;
2. when the planar lens material is K6, the refractive index n =1.5111, and d =125um can be calculated by a program;
3. when the planar lens material is K8, the refractive index n =1.5159, and d =129um can be calculated by a program;
4. when the plane lens material is K9, the refractive index n =1.5163, and d =104um can be calculated by a program;
5. when the planar lens material is ZK6, the refractive index n =1.61263, d =94um can be calculated by a program;
6. when the planar lens material is ZK8, the refractive index n =1.614, and d =108um can be calculated by a program;
7. when the planar lens material is BaK2, the refractive index n =1.53988, d =155um can be calculated by a program;
8. when the planar lens material is F1, the refractive index n =1.60328, and d =95um can be calculated by a program;
9. when the planar lens material is BaF8, the refractive index n =1.6259, and d =121um can be calculated by a program;
10. when the planar lens material is ZF5, the refractive index n =1.73977, and d =129um can be calculated by a program;
11. when the planar lens material is ZF6, the refractive index n =1.75496, d =99um can be calculated using a program.
The minimum thickness values of the planar lens are calculated by substituting the refractive indexes into ZK6 and F1 materials, so that the planar lens adopts the ZK6 and F1 materials, the thickness value of the planar lens can be ensured to be as small as possible, and the number of the planar lens can be increased in a limited space as much as possible.
It can be understood that, when the number of the planar lenses is large enough, the light finally refracted by the planar lenses can be approximately considered as linearly polarized light, and the polarization direction of the light is the propagation direction of the parallel light.
It should be noted that, nowadays, the accuracy and sensitivity of infrared detection are higher and higher, the temperature difference of the detectable target is smaller and smaller, but the probability of target discovery and identification is still not very high due to the limitation of clutter background signal. By using the camouflage technology, a noise source with the same temperature is placed around a target object, so that the existing thermal infrared imager cannot identify the target object.
In the invention, an infrared polarization imaging technology is adopted, which has the following advantages:
(1) Infrared polarization measurements can be made with considerable accuracy without requiring accurate radiometric calibration, since the degree of polarization is a ratio of the radiation values.
(2) The infrared polarization degree of the ground object background in the natural environment is very small (< 1.5%), while the infrared polarization degree of the metal material target is relatively large and reaches 2% -7%, so that the difference between the polarization degree of a vehicle taking the metal material as a main body and the polarization degree of the ground object background is also large. The difference of the polarization values of the two objects reaches 1%, and the difference between the two objects can be well distinguished by adopting an infrared polarization imaging technology. There are significant advantages to using infrared polarization imaging techniques to identify vehicle targets in the background of the surface feature.
(3) Camouflage paint is often used in military applications to camouflage targets, and the emissivity of metal panels painted with infrared camouflage paint can change. The thermal infrared camouflage paint with lower radiance can enable the target to have lower gray value in an infrared radiation intensity image, compared with the common material, the camouflage paint can effectively weaken the infrared characteristic of the target, and the purpose of camouflage the target in an infrared band is achieved. However, the polarization degree of the target plate after camouflage is not greatly changed along with the change of the emissivity, and the influence of the camouflage method for changing the emissivity of the metal plate on the half polarization degree is smaller. The object that has been camouflaged in the polarized image loses the camouflaging effect and is easily found.
In summary, the existing infrared camera adopts a light intensity imaging technology, which is greatly influenced by environmental factors, and under a severe environment, due to too weak light intensity, imaging is difficult to achieve. The polarization imaging technology adopted by the invention can carry out image acquisition operation in a severe environment, and has absolute advantages in the aspects of inhibiting background noise, improving shooting distance, acquiring detailed characteristics, identifying target camouflage and the like.
Based on the same inventive concept, an embodiment of the present invention further provides a camera apparatus, where the camera apparatus includes the camera module according to any embodiment of the present invention, and therefore, the camera apparatus provided in the embodiment of the present invention has the technical effects of the technical solutions in any embodiment described above, and the explanations of the structures and terms that are the same as or corresponding to those in the embodiment described above are not repeated herein.
The image capturing device provided in the embodiment of the present invention may be a mobile phone or an infrared camera, and may also be any electronic product having an image capturing function, which is not particularly limited in the embodiment of the present invention.
The above-described embodiments should not be construed as limiting the scope of the invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions may be made, depending on design requirements and other factors. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (9)
1. A camera module is characterized by comprising an optical system, a plane lens set and a sensor which are sequentially arranged along the transmission direction of incident light;
the optical train including at least one lens, the optical train for correcting aberrations;
the planar lens group comprises at least one planar lens;
the incident light is transmitted by the optical system to form a first correction light;
the first correction light is incident to the plane lens group at the Brewster angle and forms linearly polarized light after being transmitted by the plane lens group;
the sensor is positioned on the propagation path of the linearly polarized light;
for any of the planar lenses, the thickness of the planar lens is d, d = (λ k)/((4 n) 2 2 -2) 1/2 ) (ii) a Wherein λ is the wavelength of the incident light, k is a positive integer, n 2 Is the refractive index of the planar lens.
2. The camera module of claim 1,
the first correction lightThe incident angle of the planar lens group is theta 1 ，θ 1 =arctan(n 2 /n 1 )；
Wherein n is 1 Is the refractive index of air, n 2 Is the refractive index of the planar lens.
3. The camera module of claim 1,
the plane lens group comprises a plurality of plane lenses which are arranged in parallel, and the plane of each plane lens is perpendicular to the optical axis direction of the optical system.
4. The camera module of claim 1,
the camera module further comprises a light path adjusting unit, and the light path adjusting unit is positioned on a propagation path of the first correction light;
the light path adjusting unit comprises a first reflecting surface and a second reflecting surface;
and the first correction light ray is emitted by the first reflecting surface and the second reflecting surface in sequence and then enters the plane lens group at the Brewster angle.
5. The camera module of claim 4,
the light path adjusting unit comprises a four-prism and an equilateral right-angle triple prism, the first reflecting surface is positioned on the four-prism, and the second reflecting surface is positioned on the equilateral right-angle triple prism;
the four-prism comprises a first incident surface and a first emergent surface which are respectively adjacent to the first reflecting surface;
the equilateral right-angle triple prism comprises a second incident surface and a second emergent surface which are respectively adjacent to the second reflecting surface;
the first correction light ray sequentially enters the first incident surface of the four-prism, is reflected by the first reflecting surface and exits from the first exit surface to reach the second incident surface of the equilateral right-angle triple prism; after the light is incident from the second incident surface of the equilateral right triangular prism, reflected from the second reflecting surface and emitted from the second emergent surface, the light is incident to the plane lens group at the Brewster angle;
the first incident surface is perpendicular to the optical axis direction of the optical system, the first reflecting surface intersects with the first incident surface, and the first emergent surface is perpendicular to the propagation direction of the first correction light reflected by the first reflecting surface;
the second incident surface is perpendicular to the propagation direction of the first correction light emitted through the first exit surface, the second reflecting surface is parallel to the optical axis direction of the optical system, and the second exit surface is perpendicular to the first correction light reflected through the second reflecting surface.
6. The camera module of claim 5,
the refractive index of the four prisms is n 3 ，n 3 ≥1/sinθ 2 ；
Wherein, theta 2 The incident angle of the first correction ray on the first reflecting surface is used.
7. The camera module of claim 5,
the refractive index of the equilateral right-angle triangular prism is n 4 ，n 4 ≥1/sinθ 3 ；
Wherein, theta 3 The incident angle of the first correction ray on the second reflecting surface is adopted.
8. The camera module of claim 1,
the incident light is infrared light;
for any of the planar lenses, the material of the planar lens comprises any one of fused quartz, crown glass, dense crown glass, barium crown glass, flint glass, barium flint glass and dense flint glass.
9. A camera device, characterized in that it comprises a camera module according to any one of claims 1-8.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| GB1460299A (en) * | 1973-10-03 | 1976-12-31 | Ferranti Ltd | Polarisers |
| CN109343167A (en) * | 2018-12-14 | 2019-02-15 | 三明福特科光电有限公司 | It can be seen that, infrared extendable High Extinction Ratio devating prism |
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| GB605489A (en) * | 1943-04-01 | 1948-07-23 | Kodak Ltd | Improvements in or relating to light polarizers |
| JPH07198357A (en) * | 1993-12-28 | 1995-08-01 | Omron Corp | Optical apparatus |
| US5882774A (en) * | 1993-12-21 | 1999-03-16 | Minnesota Mining And Manufacturing Company | Optical film |
| TWI304157B (en) * | 2002-11-27 | 2008-12-11 | Asml Netherlands Bv | Lithographic apparatus and device manufacturing method |
| CN101477045B (en) * | 2009-01-16 | 2011-11-30 | 南京航空航天大学 | Glass prism SPR sensor detection system based on P polarized light |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| GB1460299A (en) * | 1973-10-03 | 1976-12-31 | Ferranti Ltd | Polarisers |
| CN109343167A (en) * | 2018-12-14 | 2019-02-15 | 三明福特科光电有限公司 | It can be seen that, infrared extendable High Extinction Ratio devating prism |
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