Patent Description:
Low-illumination cameras are widely applied to military, security protection, public safety, and other fields because they can still capture clear images under low-illumination conditions.

Currently, most low-illumination cameras need to use an infrared lamp to supplement light in a low-illumination scenario, so that scene brightness can be improved. However, after the infrared lamp is used to supplement light, light collected by the camera includes visible light and near-infrared light. Wavelengths of the visible light and the near-infrared light differ greatly. If the two are mixed together, a captured image is subjected to a severe color cast. To enable the low-illumination camera to output a color image with realistic colors, a beam splitter structure may be added to a transmission path of an imaging beam of the low-illumination camera, to split an imaging beam formed by focusing by an imaging lens module into visible light and near-infrared light, so that the visible light and the near-infrared light can be separately processed and then fused. In this way, the low-illumination camera can output a color image with realistic colors. However, in the low-illumination camera, the addition of the beam splitter structure inevitably introduces a chromatic aberration and an off-axis aberration. To ensure quality of the color image output by the low-illumination camera, a parameter of another optical structure (such as the imaging lens module) in an imaging beam path needs to be changed to balance the chromatic aberration and the off-axis aberration, so as to minimize an overall chromatic aberration and off-axis aberration caused by structures in the imaging beam path of the camera. Moreover, a larger chromatic aberration and off-axis aberration introduced by the beam splitter structure indicate greater difficulty in adjusting the parameter of the another optical structure, and greater difficulty in correcting the chromatic aberration and the off-axis aberration of the camera.

<CIT> discloses a visible light/long-wave infrared broad band spectrum joint focusing optical imaging system.

<CIT> discloses a device for the frequency-division processing of short wave infrared and visible light of shooting/photographing equipment.

<CIT> discloses a camera module. The camera module comprises a lens and a shell.

<CIT> discloses a device and a method for detecting a blood vessel. The device comprises a visible light source, an optical fiber coupler, a lighting optical fiber, an imaging receiving channel, an infrared beam splitter, a far infrared lens zoom system, a far infrared detector, a visible light lens zoom system, a visible light image sensor and an image processing system.

<CIT> discloses a thermal image low-light fusion objective optical system.

<CIT> discloses a device for real time taking and self-adaptive fusion of infrared light images and visible light images.

<CIT> discloses an infrared cut-off filter with a low-angle effect.

<CIT> discloses a dichroic mirror having a first portion including an H material layer having a high refractive index, and an M material layer having an intermediate refractive index, the H material layer and the M material layer being laminated repeatedly; and a second portion including an H material layer having a high refractive index, and an L material layer having a low refractive index, the H material layer and the L material layer being laminated repeatedly.

<CIT> discloses an optical and infrared tracking system for use in a missile launcher to split the optical information received from a target into visible light portions and near infrared components.

<CIT> discloses a device for splitting light between the visible light spectrum and the near infrared light spectrum, particularly for separating reflected light between the visible light spectrum and the near infrared light spectrum, in determining multiple characteristics of product in a product scanning system.

Embodiments of this application provide a beam splitter apparatus, a beam splitter lens module, a camera, and an electronic device, to reduce a chromatic aberration and an off-axis aberration introduced by a beam splitter structure, and reduce difficulty in correcting a chromatic aberration and an off-axis aberration of a camera.

To achieve the foregoing objective, the invention is defined by the features of the independent claims. Preferred features are defined in the dependent claims.

<NUM>: imaging lens module; <NUM>: beam splitter structure; <NUM>: first right angle prism; <NUM>: first right angle surface; <NUM>: second right angle surface; <NUM>: first inclined surface; <NUM>: second right angle prism; <NUM>: third right angle surface; <NUM>: fourth right angle surface; <NUM>: second inclined surface; <NUM>: beam splitter film; <NUM>: visible light sensor; <NUM>: near-infrared light sensor; <NUM>: image fusion module; <NUM>: beam splitter lens module; <NUM>: imaging lens module; <NUM>: lens barrel; <NUM>: imaging lens group; <NUM>: beam splitter apparatus; <NUM>: housing; <NUM>: connecting structure; <NUM>: beam splitter plate; <NUM>: transmissive plate; <NUM>: first surface; <NUM>: second surface; 101a: first transmissive plate; 1011a: first surface; 1012a: second surface; 101b: second transmissive plate; 1011b: first surface; 1012b: second surface; <NUM>: beam splitter film; <NUM>: first antireflective film; <NUM>: second antireflective film; <NUM>: third antireflective film; <NUM>: fourth antireflective film; <NUM>: fifth antireflective film; <NUM>: sixth antireflective film; <NUM>: visible light sensor; <NUM>: near-infrared light sensor; and <NUM>: camera host.

The terms "first" and "second" in the embodiments of this application are merely intended for a purpose of description, and shall not be understood as an indication or implication of relative importance or implicit indication of a quantity of indicated technical features. Therefore, a feature limited by "first" or "second" may explicitly or implicitly include one or more features.

<FIG> is a diagram of an imaging beam path of a camera according to some embodiments of this application. The camera is a low-illumination camera, and the camera can output a color image. As shown in <FIG>, an imaging lens module <NUM> focuses and forms an imaging beam a. The imaging beam a is incident into a beam splitter structure <NUM>, and is split into visible light b and near-infrared light c by the beam splitter structure <NUM>. The visible light b is incident into a visible light sensor <NUM>, and the visible light sensor <NUM> converts the visible light b into a visible light signal. The near-infrared light c is incident into a near-infrared light sensor <NUM>, and the near-infrared light sensor <NUM> converts the near-infrared light c into a luminance signal. Both the visible light sensor <NUM> and the near-infrared light sensor <NUM> are connected to an image fusion module <NUM>, and the image fusion module <NUM> separately processes the visible light signal and the luminance signal, and fuses a processed visible light signal and a processed luminance signal.

It can be learned from <FIG> that the beam splitter structure <NUM> is located in a transmission path of the imaging beam of the camera. <FIG> is a schematic diagram of a structure of the beam splitter structure <NUM> according to some embodiments of this application. As shown in <FIG>, the beam splitter structure <NUM> includes a beam splitter film <NUM>, and a first right angle prism <NUM> and a second right angle prism <NUM> that are configured to support the beam splitter film <NUM>. The first right angle prism <NUM> has a first right angle surface <NUM>, a second right angle surface <NUM>, and a first inclined surface <NUM>. The second right angle prism <NUM> has a third right angle surface <NUM>, a fourth right angle surface <NUM>, and a second inclined surface <NUM>. The first inclined surface <NUM> and the second inclined surface <NUM> are disposed in parallel and opposite to each other, and the beam splitter film <NUM> is sandwiched between the first inclined surface <NUM> and the second inclined surface <NUM>. The imaging beam a focused by the imaging lens module is incident into the beam splitter structure <NUM> from the first right angle surface <NUM> along a direction perpendicular to the first right angle surface <NUM>. After the visible light b and the near-infrared light c in the imaging beam a are separated by the beam splitter film <NUM>, the visible light b is emergent out of the beam splitter structure <NUM> from the third right angle surface <NUM> along a direction perpendicular to the third right angle surface <NUM>, and the near-infrared light c is emergent out of the beam splitter structure <NUM> from the second right angle surface <NUM>.

When an inclination angle θ of the beam splitter film <NUM> is equal to <NUM>°, as shown in <FIG>, the separated near-infrared light c is emergent out of the beam splitter structure <NUM> from the second right angle surface <NUM> along a direction perpendicular to the second right angle surface <NUM>. A transmission path length l<NUM> of the separated near-infrared light c in the first right angle prism <NUM> is equal to a transmission path length l<NUM> of the separated visible light b in the second right angle prism <NUM>.

When the inclination angle θ of the beam splitter film <NUM> is greater than <NUM>°, as shown in <FIG>, a part that is of the first right angle prism <NUM> and that is adjacent to the second right angle surface <NUM> is cut off, and the part cut off is a part enclosed by a dashed line shown in <FIG>. In this way, the separated near-infrared light c can be emergent out of the beam splitter structure <NUM> from a surface <NUM> formed after the cutting and along a direction perpendicular to the surface <NUM>, and a transmission path length l<NUM> of the separated near-infrared light c in the first right angle prism <NUM> is equal to a transmission path length l<NUM> of the separated visible light b in the second right angle prism <NUM>.

When the inclination angle θ of the beam splitter film <NUM> is less than <NUM>°, as shown in <FIG>, a region that is on the first right angle prism <NUM> and that is adjacent to the second right angle surface <NUM> is supplemented with a part of a prism, and the supplementary part is a part enclosed by a dashed line shown in <FIG>. In this way, the separated near-infrared light c can be emergent out of the beam splitter structure <NUM> from a surface <NUM> formed after the supplementation and along a direction perpendicular to the surface <NUM>, and a transmission path length l<NUM> of the separated near-infrared light c in the first right angle prism <NUM> is equal to a transmission path length l<NUM> of the separated visible light b in the second right angle prism <NUM>.

In the embodiment shown in <FIG>, <FIG>, or <FIG>, a transmission path length of the visible light in the imaging beam a in the beam splitter structure <NUM> is L<NUM>=l<NUM>+l<NUM>= D = L × cos θ. A transmission path length of the near-infrared light in the imaging beam a in the beam splitter structure <NUM> is L<NUM>=l<NUM>+l<NUM>=l<NUM>+l<NUM>= D = L × cos θ. It can be learned from above that L<NUM>=L<NUM>, and both L<NUM>, and L<NUM> are equal to a projection length of the beam splitter film <NUM> on an optical axis of the imaging beam a. l<NUM> is a transmission path length of the imaging beam a in the first right angle prism <NUM> before the imaging beam a is incident into the beam splitter film <NUM>. D is a thickness of the beam splitter structure <NUM> along the optical axis direction of the imaging beam. To ensure that the first right angle prism <NUM> and the second right angle prism <NUM> can be obtained by processing, a dimension of D is usually in centimeters. L is a width of the beam splitter film <NUM> in an inclination direction of itself. L × cos θ represents the projection length of the beam splitter film <NUM> on the optical axis of the imaging beam a. An optical path of the visible light in the imaging beam a in the beam splitter structure <NUM> is D<NUM>= n<NUM> × L<NUM>. An optical path of the near-infrared light in the imaging beam a in the beam splitter structure <NUM> is D<NUM>= n<NUM> × L<NUM>. A material of the first right angle prism <NUM> is the same as a material of the second right angle prism <NUM>, and n<NUM> is a refractive index of the material of the first right angle prism <NUM> or the second right angle prism <NUM>. The visible light and the near-infrared light in the imaging beam a have relatively long optical paths when transmitted in the beam splitter structure <NUM>, which causes a relatively large chromatic aberration and off-axis aberration, and make it relatively difficult to correct a chromatic aberration and an off-axis aberration of the camera.

To resolve the foregoing problem, this application provides an electronic device. The electronic device includes but is not limited to a mobile phone terminal, an in-vehicle terminal, and a smart wearable device, the electronic device includes a camera, and the camera is a low-illumination camera that can output a color image.

This application provides a camera. <FIG> is a schematic diagram of a structure of a camera according to some embodiments of this application. As shown in <FIG>, the camera includes a beam splitter lens module <NUM>. The beam splitter lens module <NUM> is configured to focus to form an imaging beam, and split the imaging beam into visible light and near-infrared light.

<FIG> is a schematic diagram of a structure of the beam splitter lens module <NUM> according to some embodiments of this application. As shown in <FIG>, the beam splitter lens module <NUM> includes an imaging lens module <NUM> and a beam splitter apparatus <NUM>. The imaging lens module <NUM> is configured to focus to form an imaging beam. The imaging lens module <NUM> may be a common C/CS lens module with a relatively long back focal length, or may be a fixed-focus or zoom lens module. This is not specifically limited herein. The beam splitter apparatus <NUM> is configured to split the imaging beam formed by focusing by the imaging lens module <NUM> into visible light and near-infrared light.

<FIG> is a cutaway drawing of the imaging lens module of the beam splitter lens module shown in <FIG>. As shown in <FIG>, the imaging lens module <NUM> includes a lens barrel <NUM> and an imaging lens group <NUM> disposed in the lens barrel <NUM>. The lens barrel <NUM> is configured to fix the imaging lens group <NUM>. A material of the lens barrel <NUM> includes but is not limited to metal and plastic. The lens barrel <NUM> has an image side end A, and the image side end A is an end that is of the lens barrel <NUM> and that is close to an image side. The imaging lens group <NUM> includes at least one lens, the imaging lens group <NUM> is configured to focus to form an imaging beam, the imaging lens group <NUM> has an image side surface B, and the image side surface B is a surface that is of the imaging lens group <NUM> and that faces the image side.

<FIG> is a cutaway drawing of the beam splitter apparatus of the beam splitter lens module shown in <FIG>. As shown in <FIG>, the beam splitter apparatus <NUM> includes a housing <NUM>, a connecting structure <NUM>, and a beam splitter plate <NUM>. A material of the housing <NUM> includes but is not limited to metal and plastic, and the housing <NUM> is provided with a light inlet C. The connecting structure <NUM> is disposed on a housing edge at the light inlet C, and the connecting structure <NUM> includes but is not limited to a screw thread and a buckle. The beam splitter plate <NUM> is disposed obliquely in the housing <NUM>, and the beam splitter plate <NUM> can separate visible light from near-infrared light in an imaging beam incident from the light inlet C.

An embodiment of this application provides a beam splitter plate <NUM>. The beam splitter plate <NUM> includes a transmissive plate and a beam splitter film. The transmissive plate is a light-transmitting plate-like structure. The beam splitter film is supported on the transmissive plate and is parallel to the transmissive plate. The beam splitter film is configured to reflect visible light and transmit near-infrared light, or the beam splitter film is configured to reflect near-infrared light and transmit visible light. A thickness d of the transmissive plate satisfies that when the beam splitter plate is disposed obliquely in a transmission path of the imaging beam of the camera, transmission path lengths of visible light and near-infrared light in the imaging beam in the transmissive plate are both less than a projection length of the beam splitter film on an optical axis of the imaging beam.

In the beam splitter plate provided in this embodiment of this application, because the beam splitter film is configured to reflect visible light and transmit near-infrared light, or the beam splitter film is configured to reflect near-infrared light and transmit visible light, visible light and near-infrared light in an imaging beam path can be separated by using the beam splitter film. Moreover, the beam splitter film is supported on the transmissive plate and is parallel to the transmissive plate, and the thickness d of the transmissive plate satisfies that when the beam splitter plate is disposed obliquely in the transmission path of the imaging beam of the camera, the transmission path lengths of the visible light and the near-infrared light in the imaging beam in the transmissive plate are both less than the projection length of the beam splitter film on the optical axis of the imaging beam. Assuming that an inclination angle of the beam splitter plate is θ, and a width of the beam splitter film along an inclination direction of the beam splitter plate is L, the projection length of the beam splitter film on the optical axis of the imaging beam a is L × cosθ. When the beam splitter film is disposed at the same inclination angle in the transmission path of the imaging beam a and supported by two right angle prisms, as shown in <FIG>, <FIG>, or <FIG>, transmission path lengths of the visible light and the near-infrared light in the imaging beam in the two right angle prisms are L<NUM> and L<NUM>, L<NUM>=L<NUM>, and L<NUM> and L<NUM> are both equal to L × cosθ. It can be learned from above that the transmission path lengths of the visible light and the near-infrared light in the imaging beam are both less than L<NUM> or L<NUM>. When a material used for the beam splitter plate is the same as the material of the first right angle prism <NUM> or the second right angle prism <NUM> in the embodiment shown in <FIG>, <FIG>, or <FIG>, the visible light and the near-infrared light in the imaging beam have relatively short optical paths when transmitted in the transmissive plate, which causes a relatively small chromatic aberration and off-axis aberration, and helps reduce difficulty in correcting a chromatic aberration and an off-axis aberration of the camera.

It should be noted that, in the description of this embodiment of this application, because a thickness of the beam splitter film is very small, the thickness of the beam splitter film is ignored.

Specifically, <FIG> is a schematic diagram of a structure of a beam splitter plate <NUM> which is not an embodiment of this application. As shown in <FIG>, the beam splitter plate <NUM> includes a transmissive plate <NUM> and a beam splitter film <NUM>. A material of the transmissive plate <NUM> includes but is not limited to optical glass. The transmissive plate <NUM> has a first surface <NUM> and a second surface <NUM> opposite to each other, and the first surface <NUM> and the second surface <NUM> are perpendicular to a thickness direction of the transmissive plate <NUM>. The beam splitter film <NUM> is disposed on the first surface <NUM>. The structure is simple and is easy to implement.

When the beam splitter plate <NUM> described in the foregoing example is mounted in the imaging beam path, and the imaging beam a is incident from a surface that is on the beam splitter film <NUM> and that is in a direction away from the transmissive plate <NUM> (that is, a light receiving surface R of the beam splitter plate <NUM>), as shown in <FIG>, the imaging beam a is incident into the beam splitter plate <NUM> from the light receiving surface R. The beam splitter film <NUM> reflects one (for example, near-infrared light c) of the near-infrared light and the visible light in the imaging beam, and transmits the other (for example, visible light b) of the near-infrared light and the visible light. The near-infrared light c does not pass through the transmissive plate <NUM>, and a transmission path length of the near-infrared light c in the beam splitter plate <NUM> is L<NUM>=<NUM>. The visible light b passes through the beam splitter plate <NUM>, and a transmission path length of the visible light b in the beam splitter plate <NUM> is L<NUM>= d/cos β. According to a light refraction law, n=sin δ/sin β. δ=<NUM>°-θ can be learned from <FIG>. L<NUM>= d × n/sin θ can be deduced from that. n is a refractive index of the material of the transmissive plate <NUM>. Because the thickness d of the transmissive plate <NUM> satisfies that the transmission path lengths of the visible light and the near-infrared light in the imaging beam a are both less than the projection length of the beam splitter film <NUM> on the optical axis of the imaging beam a, and the projection length of the beam splitter film <NUM> on the optical axis of the imaging beam a is L × cos θ , L<NUM>= d × n/sin θ <L × cos θ , and L<NUM>=<NUM>< L × cos θ , from which d< L sin θ cosθ/n can be deduced. Therefore, in the embodiment shown in <FIG>, the thickness d of the transmissive plate <NUM> satisfies that the transmission path lengths of the visible light and the near-infrared light in the imaging beam a are both less than the projection length of the beam splitter film <NUM> on the optical axis of the imaging beam a, that is, the thickness d of the transmissive plate <NUM> satisfies d< L sin θ cos θ/n.

When the beam splitter film <NUM> is configured to reflect near-infrared light and transmit visible light, to increase a transmittance of the visible light at the second surface <NUM> of the transmissive plate <NUM>, in some examples, as shown in <FIG>, the beam splitter plate <NUM> further includes a first antireflective film <NUM>. The first antireflective film <NUM> is attached to the second surface <NUM>. The first antireflective film <NUM> is configured to increase a transmittance of visible light emergent out of the transmissive plate <NUM> from the second surface <NUM>, and the transmitted visible light passes through the first antireflective film <NUM>.

When the beam splitter film <NUM> is configured to reflect visible light and transmit near-infrared light, to increase a transmittance of the near-infrared light at the second surface <NUM> of the transmissive plate <NUM>, in some examples, as shown in <FIG>, the beam splitter plate <NUM> further includes a second antireflective film <NUM>. The second antireflective film <NUM> is attached to the second surface <NUM>. The second antireflective film <NUM> is configured to increase a transmittance of near-infrared light emergent out of the transmissive plate <NUM> from the second surface <NUM>, and the transmitted near-infrared light passes through the second antireflective film <NUM>.

<FIG> is a schematic diagram of a structure of a beam splitter plate <NUM> according to some other examples of this application. As shown in <FIG>, the beam splitter plate <NUM> includes a transmissive plate <NUM> and a beam splitter film <NUM>. A material of the transmissive plate <NUM> includes but is not limited to optical glass. The transmissive plate <NUM> has a first surface <NUM> and a second surface <NUM> opposite to each other, and the first surface <NUM> and the second surface <NUM> are perpendicular to a thickness direction of the transmissive plate <NUM>. The beam splitter film <NUM> is attached to the second surface <NUM>. The structure is simple and is easy to implement.

When the beam splitter plate <NUM> described in the foregoing example is mounted in the imaging beam path, and the imaging beam a is incident from the first surface <NUM> (that is, a light receiving surface R of the beam splitter plate <NUM>), as shown in <FIG>, the imaging beam a is incident into the beam splitter plate <NUM> from the light receiving surface R. The beam splitter film <NUM> reflects one (for example, near-infrared light c) of the near-infrared light and the visible light in the imaging beam, and transmits the other (for example, visible light b) of the near-infrared light and the visible light. The near-infrared light c passes through the transmissive plate <NUM> twice, and a transmission path length of the near-infrared light c in the beam splitter plate <NUM> is L<NUM>= <NUM> × d/cos β. The visible light b passes through the beam splitter plate <NUM> once, and a transmission path length of the visible light b in the beam splitter plate <NUM> is L<NUM>= d/cos β. According to a light refraction law, n=sin δ/sin β. δ=<NUM>°-θ can be learned from <FIG>. L<NUM>= d × n/sin θ and <NUM>×d×n/sin θ can be deduced from that. n is a refractive index of the material of the transmissive plate <NUM>. Because the thickness d of the transmissive plate <NUM> satisfies that the transmission path lengths of the visible light and the near-infrared light in the imaging beam a are both less than the projection length of the beam splitter film <NUM> on the optical axis of the imaging beam a, and the projection length of the beam splitter film <NUM> on the optical axis of the imaging beam a is L × cos θ , L<NUM>= d ×n/sinθ < L × cos θ , and L<NUM>= <NUM> × d × n/sin θ < L × cos θ , from which d< L sin θ cos θ/<NUM>n can be deduced. Therefore, in the embodiment shown in <FIG>, the thickness d of the transmissive plate <NUM> satisfies that the transmission path lengths of the visible light and the near-infrared light in the imaging beam a are both less than the projection length of the beam splitter film <NUM> on the optical axis of the imaging beam a, that is, the thickness d of the transmissive plate <NUM> satisfies d< L sin θ cos θ/ 2n.

To increase transmittances of visible light and near-infrared light at the first surface <NUM> of the transmissive plate <NUM>, in some embodiments, as shown in <FIG>, the beam splitter plate <NUM> further includes a third antireflective film <NUM>. The third antireflective film <NUM> is attached to the first surface <NUM>. The third antireflective film <NUM> is configured to increase transmittances of visible light and near-infrared light that are incident into the transmissive plate <NUM> from the first surface <NUM>, and the visible light and the near-infrared light in the imaging beam pass through the third antireflective film <NUM>.

<FIG> is a schematic diagram of a structure of a beam splitter plate <NUM> according to some other embodiments of this application. As shown in <FIG>, the beam splitter plate <NUM> includes a first transmissive plate 101a, a second transmissive plate 101b, and a beam splitter film <NUM>. Materials of the first transmissive plate 101a and the second transmissive plate 101b include but are not limited to optical glass. The first transmissive plate 101a has a first surface 1011a and a second surface 1012a opposite to each other, and the first surface 1011a and the second surface 1012a are perpendicular to a thickness direction of the first transmissive plate 101a. The second transmissive plate 101b has a first surface 1011b and a second surface 1012b opposite to each other, and the first surface 1011b and the second surface 1012b are perpendicular to a thickness direction of the second transmissive plate 101b. The beam splitter film <NUM> is sandwiched between the second surface 1012a and the first surface 1011b. The beam splitter film <NUM> is configured to reflect visible light and transmit near-infrared light, or the beam splitter film <NUM> is configured to reflect near-infrared light and transmit visible light. The structure is simple and easy to implement, and can perform waterproof and dustproof protection on the beam splitter film.

When the beam splitter plate <NUM> described in the foregoing embodiment is mounted in the imaging beam path, and the imaging beam a is incident from the first surface 1011a (that is, a light receiving surface R of the beam splitter plate <NUM>), as shown in <FIG>, the imaging beam a is incident into the beam splitter plate <NUM> from the light receiving surface R. The beam splitter film <NUM> reflects one (for example, near-infrared light c) of the near-infrared light and the visible light in the imaging beam, and transmits the other (for example, visible light b) of the near-infrared light and the visible light. The near-infrared light c passes through the first transmissive plate 101a twice, and a transmission path length of the near-infrared light c in the beam splitter plate <NUM> is L<NUM>= <NUM> × d<NUM> /cos β. The visible light b passes through the first transmissive plate 101a and the second transmissive plate 101b, and a transmission path length of the visible light b in the beam splitter plate <NUM> is L<NUM>= (d<NUM> +d<NUM> ) / cos β = d/cos β. According to a light refraction law, n=sin δ/sin β. δ=<NUM>°-θ can be learned from <FIG>. L<NUM>=d × n/sin θ and L<NUM>= <NUM> × d<NUM> × n/sin θ can be deduced from that. n is a refractive index of the material of the transmissive plate <NUM>. d<NUM> is a thickness of the first transmissive plate 101a. d<NUM> is a thickness of the second transmissive plate 101b. Because the thickness d of the transmissive plate <NUM> satisfies that the transmission path lengths of the visible light and the near-infrared light in the imaging beam a are both less than the projection length of the beam splitter film <NUM> on the optical axis of the imaging beam a, and the projection length of the beam splitter film <NUM> on the optical axis of the imaging beam a is L × cos θ , L<NUM>= d × n/sin θ < L × cos θ , and L<NUM>= <NUM> × d<NUM> ×n/sinθ < L × cos θ , from which d< L sin θ cos θ/n and d<NUM>≤d<NUM> can be deduced. Therefore, in the embodiment shown in <FIG>, the thickness d of the transmissive plate <NUM> satisfies that the transmission path lengths of the visible light and the near-infrared light in the imaging beam a are both less than the projection length of the beam splitter film <NUM> on the optical axis of the imaging beam a, that is, the thickness d of the transmissive plate <NUM> satisfies d< L sin θ cos θ/n and d<NUM>≤d<NUM>.

To increase transmittances of visible light and near-infrared light at the first surface 1011a of the first transmissive plate 101a, in some embodiments, as shown in <FIG>, the beam splitter plate <NUM> further includes a fourth antireflective film <NUM>. The fourth antireflective film <NUM> is attached to the first surface 1011a of the first transmissive plate 101a. The fourth antireflective film <NUM> is configured to increase transmittances of visible light and near-infrared light that are incident into the first transmissive plate 101a from the first surface 1011a of the first transmissive plate 101a, and the visible light and the near-infrared light in the imaging beam pass through the fourth antireflective film <NUM>.

When the beam splitter film <NUM> is configured to reflect near-infrared light and transmit visible light, to increase a transmittance of the visible light at the second surface 1012b of the second transmissive plate 101b, in some embodiments, as shown in <FIG>, the beam splitter plate <NUM> further includes a fifth antireflective film <NUM>. The fifth antireflective film <NUM> is attached to the second surface 1012b of the second transmissive plate 101b. The fifth antireflective film <NUM> is configured to increase a transmittance of visible light emergent out of the second transmissive plate 101b from the second surface 1012b of the second transmissive plate 101b, and the transmitted visible light passes through the fifth antireflective film <NUM>.

When the beam splitter film <NUM> is configured to reflect visible light and transmit near-infrared light, to increase a transmittance of the near-infrared light at the second surface 1012b of the second transmissive plate 101b, in some embodiments, as shown in <FIG>, the beam splitter plate <NUM> further includes a sixth antireflective film <NUM>. The sixth antireflective film <NUM> is attached to the second surface 1012b of the second transmissive plate 101b. The sixth antireflective film <NUM> is configured to increase a transmittance of near-infrared light emergent out of the second transmissive plate 101b from the second surface 1012b of the second transmissive plate 101b, and the transmitted near-infrared light passes through the sixth antireflective film <NUM>.

In some embodiments, the thickness d of the transmissive plate <NUM> is less than <NUM>. In this way, the thickness of the transmissive plate <NUM> is relatively small, and when the beam splitter plate <NUM> is disposed obliquely in the transmission path of the imaging beam of the camera, the transmission path lengths of the visible light b and the near-infrared light c in the imaging beam a in the transmissive plate <NUM> are relatively small, which causes a relatively small chromatic aberration and off-axis aberration, and reduces difficulty in correcting a chromatic aberration and an off-axis aberration of the camera.

In some embodiments, the inclination angle θ of the beam splitter plate <NUM> is <NUM>° to <NUM>°. When the inclination angle of the beam splitter plate <NUM> is within this range, visible light and near-infrared light can be separated.

In some embodiments, as shown in <FIG>, the beam splitter apparatus <NUM> further includes a visible light sensor <NUM> and a near-infrared light sensor <NUM>. The visible light sensor <NUM> is disposed in the housing <NUM>, and the visible light sensor <NUM> is configured to convert the visible light b reflected or transmitted by the beam splitter plate <NUM> into a visible light signal. The near-infrared light sensor <NUM> is disposed in the housing <NUM>, and the near-infrared light sensor <NUM> is configured to convert the near-infrared light c transmitted or reflected by the beam splitter plate <NUM> into a luminance signal.

In this way, the beam splitter plate <NUM>, the visible light sensor <NUM>, and the near-infrared light sensor <NUM> are integrated in the same housing, so that accuracy of optical paths from the beam splitter plate <NUM> to the visible light sensor <NUM> and from the beam splitter plate <NUM> to the near-infrared light sensor <NUM> can be ensured.

In some embodiments, the beam splitter apparatus <NUM> further includes a visible light filter (not shown in the figure), the visible light filter is disposed between the beam splitter plate <NUM> and the near-infrared light sensor <NUM>, and the visible light filter is configured to filter out visible light in the near-infrared light reflected or transmitted by the beam splitter plate <NUM>. In this way, the visible light and the near-infrared light can be further separated, to avoid interference from the visible light to sensing and collection of the near-infrared light.

In some embodiments, the beam splitter apparatus <NUM> further includes a near-infrared light filter (not shown in the figure), the near-infrared light filter is disposed between the beam splitter plate <NUM> and the visible light sensor <NUM>, and the near-infrared light filter is configured to filter out near-infrared light in the visible light reflected or transmitted by the beam splitter plate <NUM>. In this way, the near-infrared light and the visible light can be further separated, to avoid interference from the near-infrared light to sensing and collection of the visible light.

<FIG> is a cutaway drawing of the beam splitter lens module shown in <FIG>. As shown in <FIG>, the housing <NUM> of the beam splitter apparatus <NUM> is connected to the image side end A of the lens barrel <NUM> of the imaging lens module <NUM> by using the connecting structure <NUM>, and the light inlet C of the beam splitter apparatus <NUM> is opposite to the image side surface B of the imaging lens group <NUM> of the imaging lens module <NUM>. In this way, the beam splitter lens module is assembled, and the beam splitter apparatus can be assembled with different imaging lens modules to form beam splitter lens modules having different functions, which makes it unnecessary to develop a new beam splitter lens module, thereby saving development costs of the beam splitter lens module.

<FIG> is a schematic diagram of a structure of a beam splitter lens module <NUM> according to some other embodiments of this application. <FIG> is a cutaway drawing of the beam splitter lens module shown in <FIG>. As shown in <FIG> and <FIG>, the beam splitter lens module <NUM> includes a lens barrel <NUM>, an imaging lens group <NUM>, and a beam splitter plate <NUM>. The lens barrel <NUM> is configured to fix the imaging lens group <NUM> and the beam splitter plate <NUM>. A material of the lens barrel <NUM> includes but is not limited to metal and plastic. The imaging lens group <NUM> is disposed in the lens barrel <NUM>, the imaging lens group <NUM> includes at least one lens, and the imaging lens group <NUM> is configured to focus to form an imaging beam. The beam splitter plate <NUM> is the same as the beam splitter plate <NUM> in the beam splitter apparatus <NUM>, the beam splitter plate <NUM> is disposed obliquely in the lens barrel <NUM>, the beam splitter plate <NUM> is located on an image side of the imaging lens group <NUM>, and a light receiving surface R of the beam splitter plate <NUM> faces an image side surface B of the imaging lens group.

In this way, the imaging lens group <NUM> and the beam splitter plate <NUM> are integrated into the lens barrel <NUM>, so that relative position accuracy between the imaging lens group <NUM> and the beam splitter plate <NUM> can be ensured, and accuracy of an optical path from the imaging lens group <NUM> to the beam splitter plate <NUM> can be ensured.

In some embodiments, as shown in <FIG> and <FIG>, a first opening 111a is enclosed by an image side end of the lens barrel <NUM>, and visible light or near-infrared light transmitted by the beam splitter plate <NUM> can be emergent from the first opening 111a. A second opening 111b is provided on a side wall of the lens barrel <NUM>, and near-infrared light or visible light reflected by the beam splitter plate <NUM> can be emergent from the second opening 111b.

In some embodiments, as shown in <FIG>, the beam splitter lens module <NUM> further includes a visible light sensor <NUM> and a near-infrared light sensor <NUM>. The visible light sensor <NUM> is disposed outside the lens barrel <NUM> and fixed to the lens barrel <NUM>, and the visible light sensor <NUM> is configured to convert the visible light b reflected or transmitted by the beam splitter plate <NUM> into a visible light signal. The near-infrared light sensor <NUM> is disposed outside the lens barrel <NUM> and fixed to the lens barrel <NUM>, and the near-infrared light sensor <NUM> is configured to convert the near-infrared light c transmitted or reflected by the beam splitter plate <NUM> into a luminance signal.

In this way, the beam splitter plate <NUM>, the visible light sensor <NUM>, and the near-infrared light sensor <NUM> are fixed together, so that accuracy of optical paths from the beam splitter plate <NUM> to the visible light sensor <NUM> and from the beam splitter plate <NUM> to the near-infrared light sensor <NUM> can be ensured.

In some embodiments, the beam splitter lens module <NUM> further includes a visible light filter (not shown in the figure), the visible light filter is disposed between the beam splitter plate <NUM> and the near-infrared light sensor <NUM>, and the visible light filter is configured to filter out visible light in the near-infrared light reflected or transmitted by the beam splitter plate <NUM>. In this way, the visible light and the near-infrared light can be further separated, to avoid interference from the visible light to sensing and collection of the near-infrared light.

In some embodiments, the beam splitter lens module <NUM> further includes a near-infrared light filter (not shown in the figure), the near-infrared light filter is disposed between the beam splitter plate <NUM> and the visible light sensor <NUM>, and the near-infrared light filter is configured to filter out near-infrared light in the visible light reflected or transmitted by the beam splitter plate <NUM>. In this way, the near-infrared light and the visible light can be further separated, to avoid interference from the near-infrared light to sensing and collection of the visible light.

As shown in <FIG>, the camera further includes a camera host <NUM>, and the camera host <NUM> includes an image fusion module (not shown in the figure). The image fusion module is electrically connected to the visible light sensor <NUM>, and the image fusion module is electrically connected to the near-infrared light sensor <NUM>. The image fusion module is configured to perform separate image processing on the visible light signal converted by the visible light sensor <NUM> and the luminance signal converted by the near-infrared light sensor <NUM>, and fuse a processed visible light signal and a processed luminance signal.

In the descriptions of this specification, the described specific features, structures, materials, or characteristics may be combined in an appropriate manner in any one or more of the embodiments or examples.

Claim 1:
A beam splitter apparatus (<NUM>), comprising:
a housing (<NUM>), provided with a light inlet (C);
a connecting structure (<NUM>), disposed on a housing edge at the light inlet (C), wherein the connecting structure (<NUM>) is configured to connect to an image side end of a lens barrel (<NUM>) of an imaging lens module (<NUM>), so that the light inlet (C) is opposite to an image side surface (B) of an imaging lens group (<NUM>) of the imaging lens module (<NUM>); and
a beam splitter plate (<NUM>), disposed obliquely in the housing (<NUM>) and in a transmission path of an imaging beam of a camera, comprising:
a transmissive plate (<NUM>) that is a light-transmitting plate-like structure; and
a beam splitter film (<NUM>), supported on the transmissive plate (<NUM>) and parallel to the transmissive plate (<NUM>), wherein the beam splitter film (<NUM>) is configured to reflect visible light and transmit near-infrared light, or the beam splitter film (<NUM>) is configured to reflect near-infrared light and transmit visible light, wherein
a thickness of the transmissive plate (<NUM>) satisfies that when the beam splitter plate (<NUM>) is disposed obliquely in the transmission path of the imaging beam of the camera, transmission path lengths of visible light and near-infrared light in the imaging beam in the transmissive plate are both less than a projection length of the beam splitter film on an optical axis of the imaging beam,
wherein the transmissive plate (<NUM>) has a first surface (<NUM>) and a second surface (<NUM>) opposite to each other; and
the beam splitter film (<NUM>) is attached to the second surface (<NUM>), and
wherein the beam splitter plate (<NUM>) further comprises:
a third antireflective film (<NUM>), attached to the first surface (<NUM>), wherein the third antireflective film (<NUM>) is configured to increase transmittances of visible light and near-infrared light that are incident into the transmissive plate (<NUM>) from the first surface (<NUM>).