Terahertz radiation detection device and electronic device

Abstract

Provided is a terahertz radiation detection device capable of efficiently detecting radiation in a long-wavelength region from far-infrared light to at or above the terahertz range. The terahertz radiation detection device includes an imaging lens, a detection element, and a filter unit. The imaging lens faces a subject. The detection element detects terahertz radiation generated from the subject among light incident through the imaging lens. The filter unit includes: a silicon substrate that is disposed closer to the subject than the detection element and absorbs visible light and near-infrared light; and a plurality of structures periodically arranged on the silicon substrate. The filter unit transmits THz radiation incident on the structures. The structures prevent the reflection of light from far-infrared light wavelengths to predetermined wavelengths including THz radiation wavelengths.

Description

Terahertz wave detection device and electronic device

[0001] The present disclosure relates to a terahertz wave detecting device and an electronic device equipped with the terahertz wave detecting device.

[0002] Conventionally, solid-state imaging elements such as CCD (Charge Coupled Device) and CMOS (Complementary Metal Oxide Semiconductor) image sensors have been used as solid-state imaging devices in electronic devices equipped with an imaging function, such as digital still cameras, digital video cameras, in-vehicle cameras, mobile phones (smartphones), personal computers, and IoT (Internet of Things) devices. The wavelength range of detection for solid-state imaging devices has been further expanded, and development of infrared imaging devices and terahertz wave imaging devices has also been active.

[0003] The issues here are the removal of light (or electromagnetic waves) other than the wavelength to be detected and the efficiency of light (or electromagnetic waves). Therefore, even if an attempt is made to provide an optical filter effect for light (or electromagnetic waves) with long wavelengths using a thin film, the materials that can be used are extremely limited. Therefore, for far-infrared light and long wavelength regions beyond the terahertz (THz) region, it is desirable to form an optical filter using a structure or an absorbing material. Patent Document 1 listed below discloses a technology for cutting only near-infrared light using a metamaterial and an absorbing material.

[0004] Japanese Patent Application Laid-Open No. 2021-174009

[0005] Meanwhile, there has long been a demand for optical filters that absorb visible to near-infrared light in order to efficiently detect far-infrared light and wavelengths longer than the terahertz (THz) range. The technology disclosed in Patent Document 1 uses a metamaterial and an absorbing material to absorb near-infrared light, but does not absorb visible light.

[0006] The present disclosure has been made in consideration of the above circumstances, and aims to provide a terahertz wave detection device and electronic equipment that can efficiently detect far-infrared light in the long wavelength range beyond the terahertz region.

[0007] One aspect of the present disclosure is a terahertz wave detection device comprising: an imaging lens facing a subject; a detection element that detects THz (terahertz) waves generated from the subject among light incident through the imaging lens; a silicon substrate that is arranged on the subject side of the detection element and absorbs visible light and near-infrared light; and a filter unit that includes a plurality of structures periodically arranged on the silicon substrate and transmits the THz waves that have entered the structures, wherein the structures prevent reflection of light between wavelengths of far-infrared light and a predetermined wavelength that includes the wavelength of the THz waves.

[0008] Another aspect of the present disclosure is a terahertz wave detection device comprising: a silicon lens that faces a subject and absorbs visible light and near-infrared light; and a detection element that detects THz (terahertz) waves generated from the subject from light incident through the silicon lens, wherein the silicon lens includes a plurality of structures periodically arranged on a light incident surface and on a surface opposite the light incident surface, and transmits the THz waves that are incident on the structures and prevents reflection of light between the wavelength of far-infrared light and a predetermined wavelength that includes the wavelength of the THz waves.

[0009] Another aspect of the present disclosure is an electronic device equipped with a terahertz wave detection device, comprising: an imaging lens facing a subject; a detection element that detects THz (terahertz) waves generated from the subject out of light incident through the imaging lens; a silicon substrate that is arranged on the subject side of the detection element and absorbs visible light and near-infrared light; and a filter section that includes a plurality of structures periodically arranged on the silicon substrate and transmits the THz waves that have entered the structures, wherein the structures prevent reflection of light in a range from the wavelength of far-infrared light to a predetermined wavelength that includes the wavelength of the THz waves.

[0010] 1 is a cross-sectional view showing an example of the configuration of a terahertz imaging device to which a terahertz wave detecting device according to a first embodiment of the present disclosure is applied; FIG. 2 is a plan view of the bandpass filter shown in FIG. 1 as seen from the light incident surface; FIG. 3 is a graph showing the transmittance in the THz band of a silicon substrate provided with a structure according to the first embodiment and a planar silicon substrate; FIG. 4 is a graph showing the transmittance from the visible light wavelength range to a wavelength of 2 mm according to the first embodiment; FIG. 5 is a cross-sectional view (part 1) showing the process procedure of a method for forming a bandpass filter according to the first embodiment of the present disclosure; FIG. 6 is a cross-sectional view (part 2) showing the process procedure of a method for forming a bandpass filter according to the first embodiment of the present disclosure; FIG. 7 is a cross-sectional view showing an example of the configuration of a terahertz imaging device to which a terahertz wave detecting device according to a second embodiment of the present disclosure is applied; FIG. 8 is a graph showing the transmittance from the visible light wavelength range to a wavelength of 2 mm according to the second embodiment; FIG. 9 is a cross-sectional view showing an example of the configuration of a terahertz imaging device to which a terahertz wave detecting device according to a third embodiment of the present disclosure is applied; FIG. 10 is a cross-sectional view showing an example of the configuration of a terahertz imaging device to which a terahertz wave detecting device according to a fourth embodiment of the present disclosure is applied; FIG. 11 is a cross-sectional view showing an example of the configuration of a terahertz imaging device to which a terahertz wave detecting device according to a fifth embodiment of the present disclosure is applied. 11A is a cross-sectional view showing an example of the configuration of a bandpass filter according to a sixth embodiment of the present disclosure. FIG. 11B is a plan view of the bandpass filter shown in FIG. 11A as seen from the light incident surface. FIG. 11C is a graph showing the transmittance of far-infrared light of a silicon substrate provided with a structure and a planar-structure silicon substrate in the sixth embodiment. FIG. 11D is a cross-sectional view showing an example of the configuration of a bandpass filter according to a seventh embodiment of the present disclosure. FIG. 13A is a plan view of the bandpass filter shown in FIG. 13A as seen from the light incident surface. FIG. 13B is a cross-sectional view of an example of the configuration of a bandpass filter according to an eighth embodiment of the present disclosure. FIG. 14A is a plan view of the bandpass filter shown in FIG. 14A as seen from the light incident surface. FIG. 14C is a cross-sectional view showing an example of the configuration of a terahertz imaging device to which a terahertz wave detection device according to a ninth embodiment of the present disclosure is applied. FIG. 14D is a plan view of a silicon lens according to the ninth embodiment as seen from the light incident surface. FIG. 14E is a graph showing the absorptance of silicon from wavelengths of 0.45 μm to 1.5 μm. FIG. 14F is a block diagram showing another example of the configuration of an electronic device. FIG. 14G is a diagram showing an example of a schematic configuration of an endoscopic surgery system to which the present technology is applied.Fig. 21 is a block diagram showing an example of the functional configuration of the camera head and the CCU shown in Fig. 19. Fig. 22 is a block diagram showing an example of a schematic configuration of a vehicle control system to which the present technology is applied. Fig. 23 is an explanatory diagram showing an example of the installation positions of the outside-of-vehicle information detection unit and the imaging unit shown in Fig. 21.

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings referred to in the following description, identical or similar parts will be designated by identical or similar reference numerals, and redundant description will be omitted. However, it should be noted that the drawings are schematic, and the relationship between thickness and planar dimensions, the thickness ratio of each device and each component, etc., may differ from the actual ones. Therefore, specific thicknesses and dimensions should be determined with reference to the following description. Furthermore, it goes without saying that the drawings may include parts with different dimensional relationships and ratios.

[0012] Furthermore, the definitions of directions such as up and down in the following description are merely for the convenience of explanation and do not limit the technical concept of the present disclosure. For example, if an object is rotated 90 degrees and observed, up and down are converted to left and right and read as such, and if it is rotated 180 degrees and observed, up and down are inverted and read as such. Note that the effects described in this specification are merely examples and are not limiting, and other effects may also be present.

[0013] First Embodiment Fig. 1 is a cross-sectional view showing an example of the configuration of a terahertz imaging device to which a terahertz wave detection device according to a first embodiment of the present disclosure is applied. Fig. 1 shows an X-axis, a Y-axis, and a Z-axis that are perpendicular to each other. The X-axis and the Y-axis correspond to the lateral direction (horizontal direction), and the Z-axis corresponds to the longitudinal direction (vertical direction). The +Z-axis corresponds to the upward direction, and the -Z-axis corresponds to the downward direction.

[0014] As shown in FIG. 1A, the terahertz imaging device 1A includes an imaging lens 11, a sensor 12, and a band-pass filter 13 (an example of a filter unit). The imaging lens 11 may be composed of, for example, two lenses 111 and 112. The imaging lens 11 guides light from an object OBJ to the sensor 12, and forms an image on a pixel array unit (not shown) of an imaging element 121 (an example of a detection element). The imaging lens 11 also performs focus adjustment and drive control based on a control signal output from a lens control unit (not shown), and sets the aperture to a specified aperture value.

[0015] The sensor 12 is composed of an imaging element 121 and a case 122 (an example of a package) that houses the imaging element 121. The case 122 is formed of, for example, an insulating material and has an opening on the side facing the imaging lens 11, from which the imaging element 121 is exposed. The opening of the case 122 is sealed with a cover glass 123.

[0016] The image sensor 121 is assumed to have, for example, 67 vertical pixels and 67 horizontal pixels at a 0.3 mm pitch, and an effective diameter of 20 mm x 20 mm. The image sensor 121 absorbs THz waves (terahertz waves) incident through the cover glass 123 and generates heat. The image sensor 121 then generates a potential difference caused by the heat in each pixel and outputs a signal based on this potential difference to the outside. The terahertz image sensor 1A of this embodiment can detect THz waves using this signal.

[0017] It is known that THz waves are generated, for example, from the human body. The image sensor 121 can detect various pieces of information about the human being as a detection target by detecting the THz waves generated from the human body using multiple pixels. The terahertz image sensor 1A of this embodiment may also be used to detect THz waves other than those generated from the human body.

[0018] The imaging lens 11 according to the first embodiment of the present disclosure has a two-group, medium aperture configuration and achieves an F-number of 0.68. For long wavelengths such as THz waves, the spot diameter increases in proportion to the wavelength. As a result, the imaging element 121 can only resolve images with low frequencies. Therefore, taking advantage of the fact that the F-number is proportional to the spot diameter, an imaging lens with a low F-number, i.e., an F-number brighter than 0.8, is required. In this design, an F-number of 0.68 is used to capture light (electromagnetic waves) with wavelengths of 0.3 mm to 0.7 mm. The imaging lens 11 is, for example, a "Tsurupica (registered trademark)" lens manufactured by VACS Co., Ltd.

[0019] The imaging lens 11 is made up of two groups of lenses 111 and 112, but since the lenses 111 and 112 are manufactured as plano-convex or plano-concave, it is desirable to manufacture them as convex-plano and concave-plano at the location where there is a line between the upper lenses 111. Similarly, it is assumed that the lower lens 112 will be overlapped with the plano-convex.

[0020] A bandpass filter 13 is disposed near the aperture of the imaging lens 11. As shown in Fig. 1(b) , the bandpass filter 13 has, for example, a plurality of cylindrical convex structures 132 formed on a first surface S1 of a 2 mm thick silicon substrate 131, and a plurality of cylindrical convex structures 133 formed on a second surface S2. Note that, as an example of the structures 132 and 133, in addition to cylindrical shapes, conical convex structures may also be used.

[0021] 2 is a plan view of the bandpass filter 13, as viewed from, for example, the first surface S1. A plurality of structures 132 are made of silicon and are periodically arranged on the first surface S1 of the silicon substrate 131 at a pitch of 0.34 mm. Each structure 132 has a diameter of 0.221 mm and a height of 0.1 mm. Similarly, a plurality of structures 133 are periodically arranged on the second surface S2 of the silicon substrate 131 at a pitch of 0.34 mm.

[0022] FIG. 3 is a graph showing the THz band transmittance of a silicon substrate 131 provided with structures 132 and 133 and a planar silicon substrate. In FIG. 3, the vertical axis represents transmittance, and the horizontal axis represents wavelength. The thick dotted line R1 in FIG. 3 represents the transmittance when multiple structures 132 are formed only on the first surface S1 of the silicon substrate 131 (hereinafter referred to as a single-surface microstructure). The thin dotted line R2 in FIG. 3 represents the transmittance when multiple structures 132 are formed on the first surface S1 of the silicon substrate 131 and multiple structures 133 are formed on the second surface S2 (hereinafter referred to as a two-surface microstructure). The dashed-dotted line R3 in FIG. 3 represents the transmittance of only one surface of the planar silicon substrate. The solid line R4 in FIG. 3 represents the transmittance of both surfaces of the planar silicon substrate.

[0023] The transmittance R3 of a silicon substrate per surface is approximately 70%, while the transmittance R4 of a silicon substrate per two surfaces is approximately 50%. However, the transmittance R1 of the single-surface microstructure is 90% or more over the entire wavelength range of 0.3 mm to 0.7 mm used, and in particular, it reaches nearly 100% transmittance at the central wavelength of 0.5 mm. The transmittance R2 of the double-surface microstructure also reaches nearly 100% transmittance at the central wavelength of 0.5 mm, which is twice the transmittance of flat silicon.

[0024] Figure 17 is a graph showing the absorptance of silicon from wavelengths of 0.45 μm to 1.5 μm. In Figure 17, the vertical axis represents transmittance and the horizontal axis represents wavelength. As shown in Figure 17, silicon has the property of absorbing light from the visible light region to wavelengths of 1 μm at a thickness of about several μm. In other words, it does not transmit light in the wavelength range absorbed by silicon.

[0025] FIG. 4 is a graph showing transmittance from the visible light wavelength range up to a wavelength of 2 mm. In FIG. 4, the vertical axis represents transmittance, and the horizontal axis represents wavelength. The dotted line R11 in FIG. 4 represents the transmittance when multiple structures 132 are formed only on the first surface S1 of the silicon substrate 131 (hereinafter referred to as a single-surface microstructure). The dashed-dotted line R12 in FIG. 4 represents the transmittance when multiple structures 132 are formed on the first surface S1 of the silicon substrate 131 and multiple structures 133 are formed on the second surface S2 (hereinafter referred to as a double-surface microstructure). In FIG. 4, the influence of the structures 132 and 133 gradually decreases at wavelengths of 0.3 mm or less, and transmittance characteristics equivalent to those of planar silicon are observed at wavelengths of several micrometers. Furthermore, at longer wavelengths, the transmittance R11 of the single-surface microstructure maintains a high transmittance of approximately 90% or more (a transmittance of 0.9 is shown in FIG. 4) up to a wavelength of 1 mm, and approaches the characteristics of planar silicon as the wavelength increases. The transmittance R12 of the two-sided microstructure also maintains a high transmittance of between about 80% and about 90% up to a wavelength of 1 mm, and approaches the characteristics of planar silicon as the wavelength becomes longer.

[0026] (Dimensions of Structures) The structures 132 and 133 satisfy the following conditions: Condition (a) 0.2<p / λm<0.8, p: period of the structures, λm: central wavelength of antireflection Condition (b) 0.01<h / λm<0.4, h: height of the structures, λm: central wavelength of antireflection Condition (c) 0.4<l / p<0.9, p: period of the structures, 1: diameter of the structures

[0027] Condition (a) is determined as follows. Condition (a) in the first embodiment is 0.68. To obtain an anti-reflection effect from the structures 132 and 133 against incident transmitted light, a moderate wave effect is required. If the period p of the structures 132 and 133 exceeds the central wavelength λm of the anti-reflection, the anti-reflection effect caused by the interaction decreases, and the properties of the planar silicon become dominant, resulting in an increase in reflectivity, making this unsuitable. Therefore, one wavelength period is the upper limit. Conversely, if the period p of the structures 132 and 133 is sufficiently smaller than the central wavelength λm of the anti-reflection, the effects of wave overlap emerge, increasing the diffraction phenomenon and reducing the zeroth-order transmitted light. Light other than the zeroth-order light undesirably causes blurring during imaging. For this reason, the adjustment is 0.2. Therefore, the wavelength of light that prevents reflection can be controlled by adjusting the spacing p between the structures 132 and 133 between 0.2 and 0.8.

[0028] Condition (b) is determined as follows. Condition (b) in the first embodiment is 0.2. Typically, a single-layer thin-film AR coating is applied with a thickness of λ / 4. The height h of the structures 132 and 133 also has properties similar to those of a λ / 4 coating. The optimum condition is approximately 0.25 λm, and at 0.5 λm, which is the reflective condition for a thin film, the structure behaves the same as a silicon flat surface. Therefore, the upper limit is approximately 0.4, which is smaller than 0.5, and is where the effect begins to be seen. Similarly, the lower limit continues to be seen until the structure behaves (states) the same as a silicon flat surface, so numerically, 0.01 is the lower limit. Therefore, the wavelength of light that prevents reflection can be controlled by adjusting the height h of the structures 132 and 133 between 0.01 and 0.4.

[0029] Condition (c) is determined as follows. Condition (c) in the first embodiment is 0.65. To obtain an anti-reflection effect from the structures 132 and 133 against incident transmitted light, a moderate wave effect is required. This condition represents the ratio of the projected area of ​​the structures 132 and 133, and is commonly referred to as fill. When the fill value is 0.7, the square of the area ratio becomes approximately 0.5 (half), resulting in high efficiency of wave superposition above and below the structures 132 and 133. Since even the slightest effect can be obtained with the structures 132 and 133, the numerical value is determined by the manufacturing conditions. The upper limit is 0.9; if this value is exceeded, there will be no gap between adjacent structures 132 and 133, making it impossible to fabricate them, and so this value is used. Furthermore, if the structure is too thin, it cannot be fabricated. Furthermore, it will be prone to breakage, which will pose durability issues. Therefore, the lower limit is 0.3. Therefore, the distance p between the structures 132 and 133 can be controlled by adjusting the diameter of the structures 132 and 133 between 0.4 and 0.9.

[0030] 5A and 5B are cross-sectional views showing the process steps of a method for forming the bandpass filter 13 according to the first embodiment of the present disclosure. The bandpass filter 13 is manufactured using various types of equipment, such as a film-forming apparatus (including a CVD (Chemical Vapor Deposition) apparatus and a sputtering apparatus), an ion implantation apparatus, a heat treatment apparatus, an etching apparatus, a CMP (Chemical Mechanical Polishing) apparatus, and a bonding apparatus. Hereinafter, these apparatuses will be collectively referred to as manufacturing apparatuses.

[0031] In FIG. 5A(1), a silicon substrate 14 is prepared, and the manufacturing equipment stacks a photoresist 15 made of, for example, silicon oxide (SiO2) on a first surface S1 (an example of a light incident surface) of the silicon substrate 14 (FIG. 5A(2)), and places a shaped mask 16 on the top surface of the photoresist 15 (FIG. 5A(3)).

[0032] In the state of Fig. 5A(3), the manufacturing equipment transfers the shape by exposure and removes the developed photoresist 15 (Fig. 5B(1)). In the state of Fig. 5B(1), the mask 16 is removed, and convex portions 151 and concave portions 152 of the photoresist 15 are formed on the first surface S1 of the silicon substrate 14.

[0033] In Fig. 5B(2), the manufacturing equipment performs etching to form recessed portions 17 by digging into the silicon substrate 14 in the recessed portions 152 of the photoresist 15. At this point, the silicon substrate 131 is formed. The manufacturing equipment then performs resist stripping and cleaning to remove the protruding portions 151 of the photoresist 15, completing the microstructure (Fig. 5B(3)).

[0034] <Effects of First Embodiment> As described above, according to the first embodiment, silicon substrate 131 is disposed closer to subject OBJ than sensor 12, and the absorption of visible light and near-infrared light by silicon is utilized to block these wavelengths of visible light and near-infrared light, and a plurality of periodically arranged structures 132 are formed on first surface S1 of silicon substrate 131, and structures 132 are given the function of preventing reflection of light within a wavelength range of 1 mm, which includes the wavelength of THz waves (0.3 mm to 0.7 mm), and silicon is used as a reflective material for other wavelengths, so that the entire structure functions as bandpass filter 13. Therefore, a bandpass filter 13 that has high light utilization efficiency and cuts out unnecessary light can be realized.

[0035] Furthermore, according to the first embodiment, THz waves incident on the first surface S1 of the silicon substrate 131 from the object OBJ can be transmitted to the sensor 12 by the plurality of structures 132 arranged on the first surface S1 of the silicon substrate 131, and conversely, THz waves emitted from the sensor 12 to the second surface S2 of the silicon substrate 131 are prevented from being reflected by the plurality of structures 133 arranged on the second surface S2 of the silicon substrate 131, thereby preventing the THz waves from escaping from the bandpass filter 13 to the sensor 12 and further improving the light utilization efficiency.

[0036] Furthermore, according to the first embodiment, the wavelength of light that is prevented from being reflected by the structures 132 and 133 can be controlled by adjusting the spacing p at which the structures 132 and 133 are arranged between 0.2 and 0.8, and by adjusting the height h of the structures 132 and 133 between 0.01 and 0.4.

[0037] Furthermore, according to the first embodiment, by disposing the silicon substrate 131 in the air near the aperture in the imaging lens 11, it is not necessary to secure a position for the silicon substrate 131 separately from the imaging lens 11, which is advantageous for miniaturizing the terahertz imaging device. Furthermore, since the silicon substrate 131 is disposed in the air near the aperture in the imaging lens 11, light incident through the imaging lens 11 can be received without leakage.

[0038] Furthermore, according to the first embodiment, in the case of THz waves with a long wavelength of 0.7 mm, only low-frequency images are resolved because the spot diameter of the imaging lens 11 increases in proportion to the wavelength. Therefore, by using an imaging lens with an F number of 0.8 or brighter as the imaging lens 11, it is possible to capture images of light (electromagnetic waves) with a wavelength of 0.3 mm to 0.7 mm, which is the wavelength of terahertz waves.

[0039] Second Embodiment A second embodiment of the present disclosure is an example in which a plurality of band-pass filters are arranged near the aperture of an imaging lens. Fig. 6 is a cross-sectional view showing an example of the configuration of a terahertz imaging device to which a terahertz wave detection device according to the second embodiment of the present disclosure is applied. In Fig. 6, the same parts as those in Fig. 1 above are assigned the same reference numerals, and detailed description thereof will be omitted.

[0040] 6( a), the terahertz imaging device 1B has, for example, four bandpass filters 201, 202, 203, and 204 (hereinafter referred to as bandpass filters 20) arranged near the aperture of the imaging lens 11. As shown in FIG. 6( b), each of the four bandpass filters 20 has, for example, a plurality of cylindrical convex structures 212 formed on a first surface S1 of a 2 mm thick silicon substrate 211, and a plurality of cylindrical convex structures 213 formed on a second surface S2.

[0041] Figure 7 is a graph showing transmittance from the visible light wavelength range up to a wavelength of 2 mm. In Figure 7, the vertical axis represents transmittance, and the horizontal axis represents wavelength. The dotted line R21 in Figure 7 represents the transmittance when multiple structures 212 are formed only on the first surface S1 of the silicon substrate 211 (hereinafter referred to as a four-sided microstructure). The dashed-dotted line R22 in Figure 7 represents the transmittance when multiple structures 212 are formed on the first surface S1 of the silicon substrate 211 and multiple structures 213 are formed on the second surface S2 (hereinafter referred to as an eight-sided microstructure).

[0042] In Figure 7, the transmittance is 0 from the visible light wavelength range up to a wavelength of 1 μm. The transmittances R21 and R22 drop sharply on the shorter wavelength side, with a wavelength of 0.3 mm as the boundary. On the longer wavelength side, the transmittance R21 of the four-sided microstructure maintains a high transmittance of approximately 70% or more (a transmittance of 0.7 is shown in Figure 7) up to a wavelength of 1 mm, and as the wavelength becomes longer, the transmittance approaches the characteristics of planar silicon and gradually decreases. The transmittance R22 of the eight-sided microstructure also maintains a high transmittance of approximately 60% up to a wavelength of 1 mm, and as the wavelength becomes longer, the transmittance approaches the characteristics of planar silicon and gradually decreases.

[0043] In this way, the four bandpass filters 20 cut off the short wavelength side at 0.3 mm or less, and on the long wavelength side, they cut off light (electromagnetic waves) longer than the wavelength being used, although they cannot strictly cut off the long wavelength side at the wavelength of 0.7 mm being used. In terahertz imaging here, imaging becomes difficult, particularly as the wavelength becomes longer, due to the principle described above. Even without cutting, it is not possible to image light (electromagnetic waves) with a wavelength of 1 mm on a 0.3 mm square pixel. Therefore, even if the long wavelength side cannot be strictly cut off, the terahertz imaging device 1B as a whole can still function.

[0044] <Effects of the Second Embodiment> As described above, according to the second embodiment, by stacking, for example, four silicon substrates 211 on which a plurality of structures 212 and 213 are arranged, it is possible to obtain high characteristics of the bandpass filter 20.

[0045] Third Embodiment A third embodiment of the present disclosure is an example in which a bandpass filter is arranged closer to the subject than the imaging lens. Fig. 8 is a cross-sectional view showing an example of the configuration of a terahertz imaging device to which a terahertz wave detection device according to the third embodiment of the present disclosure is applied. In Fig. 8, the same parts as those in Fig. 1 above are assigned the same reference numerals, and detailed description thereof will be omitted.

[0046] 8A, the terahertz imaging device 1C has a bandpass filter 31 disposed in the air on the subject OBJ side of the imaging lens 11. As shown in FIG. 8B, the bandpass filter 31 has, for example, a plurality of cylindrical convex structures 312 formed on a first surface S1 of a 2 mm thick silicon substrate 311, and a plurality of cylindrical convex structures 313 formed on a second surface S2.

[0047] <Effects of the Third Embodiment> As described above, according to the third embodiment, by disposing the silicon substrate 311 in the air on the subject OBJ side of the imaging lens 11, when it is necessary to remove the band-pass filter 31, the band-pass filter 31 can be easily removed without having to make any modifications to the imaging lens 11.

[0048] <Fourth Embodiment> A fourth embodiment of the present disclosure is an example in which multiple bandpass filters are arranged near the aperture of the imaging lens, and crystal quartz is used for sealing the imaging element of the sensor instead of the cover glass that seals it. Fig. 9 is a cross-sectional view showing an example of the configuration of a terahertz imaging device to which a terahertz wave detection device according to the fourth embodiment of the present disclosure is applied. In Fig. 9, the same parts as those in Fig. 1 above are assigned the same reference numerals, and detailed description thereof will be omitted.

[0049] 9A, the terahertz imaging device 1D has, for example, three band-pass filters 401, 402, and 403 (hereinafter referred to as band-pass filters 40) arranged in the air on the subject OBJ side of the imaging lens 11. As shown in FIG. 9B, each of the three band-pass filters 40 has, for example, a plurality of cylindrical convex structures 412 formed on a first surface S1 of a 2-mm-thick silicon substrate 411, and a plurality of cylindrical convex structures 413 formed on a second surface S2.

[0050] The sensor 42 of the terahertz imaging device 1D is composed of an imaging element 421 and a case 422 that houses the imaging element 421. The opening of the case 422 is sealed with crystal quartz 43 (an example of a filter section) instead of the cover glass 123.

[0051] The crystal quartz 43 has a different absorption range from silicon. That is, when light other than light in the visible light range up to 1 μm in wavelength that is absorbed by the three bandpass filters 40 is incident on the crystal quartz 43, the crystal quartz 43 transmits light of THz waves with wavelengths of 0.3 mm to 0.7 mm, for example, and guides it to the image sensor 421.

[0052] <Effects of the Fourth Embodiment> As described above, according to the fourth embodiment, when three bandpass filters 40 are combined with crystal quartz 43, crystal quartz 43 has an absorption region different from that of silicon, so that it is possible to cut out unwanted light in a region different from that of silicon, thereby efficiently blocking unwanted light.

[0053] Fifth Embodiment A fifth embodiment of the present disclosure is an example in which a bandpass filter is used to seal a sensor instead of a cover glass used to seal the sensor. The fifth embodiment of the present disclosure is an example in which a bandpass filter made of a silicon substrate is used to seal a sensor instead of a cover glass used to seal the sensor. Fig. 10 is a cross-sectional view showing an example of the configuration of a terahertz imaging device to which a terahertz wave detection device according to a fifth embodiment of the present disclosure is applied. In Fig. 10, the same parts as those in Fig. 1 above are assigned the same reference numerals, and detailed description thereof will be omitted.

[0054] 10( a), the terahertz imaging device 1E guides light from an object OBJ to a sensor 51 via an imaging lens 11, and forms an image on a pixel array section (not shown) of an imaging element 511. The sensor 51 is composed of the imaging element 511 and a case 512 that houses the imaging element 511. The opening of the case 512 is sealed with a band-pass filter 52 instead of the cover glass 123.

[0055] As shown in FIG. 10(b), the bandpass filter 52 is formed by forming a plurality of cylindrical convex structures 522 on a first surface S1 of a 2 mm thick silicon substrate 521, and forming a plurality of cylindrical convex structures 523 on a second surface S2.

[0056] <Effects of Fifth Embodiment> As described above, according to the fifth embodiment, instead of using the cover glass 123 for sealing the package 512 that houses the image sensor 511, the package 512 is sealed by the bandpass filter 52, thereby reducing the number of components in the terahertz image capturing device 1E. Note that the bandpass filter 52 can also be disposed near the sealing cover glass 123. In this way, it is not necessary to secure a position for the bandpass filter 52 separately from the package 512, which is advantageous for reducing the size of the terahertz image capturing device 1E.

[0057] Sixth Embodiment A sixth embodiment of the present disclosure is an example of a bandpass filter for far-infrared light. Fig. 11A is a cross-sectional view showing an example of the configuration of a bandpass filter according to the sixth embodiment of the present disclosure.

[0058] 11A , the terahertz imaging device 1F has a bandpass filter 61. As in the first embodiment, the bandpass filter 61 is disposed, for example, near the aperture of the imaging lens 11. The bandpass filter 61 has, for example, a plurality of cylindrical convex structures 612 formed on a first surface S1 of a silicon substrate 611 having a thickness of 2 mm. The first surface S1 is a surface on which light from an object OBJ is incident.

[0059] 11B is a plan view of the bandpass filter 61, as viewed from, for example, the first surface S1. The structures 612 are made of silicon and are periodically arranged on the first surface S1 of the silicon substrate 611 at a pitch of 4.0 μm. Each structure 612 has a diameter of 2.6 μm and a height of 1.5 μm.

[0060] Figure 12 is a graph showing the transmittance of far-infrared light for a silicon substrate 611 provided with structures 612 and a planar silicon substrate. In Figure 12, the vertical axis represents transmittance, and the horizontal axis represents wavelength. The dashed-dotted line R31 in Figure 12 represents the transmittance when multiple structures 612 are formed on the first surface S1 of the silicon substrate 611 (hereinafter referred to as a single-surface microstructure). The dotted line R32 in Figure 12 represents the reflectance of the single-surface microstructure. The thick line R33 in Figure 12 represents the transmittance of the planar silicon substrate. The diagonal line R34 in Figure 3 represents the reflectance of the planar silicon substrate.

[0061] The transmittance R31 of the single-surface microstructure is 90% or more (shown as 0.9 in FIG. 12) at wavelengths longer than 5 μm for far-infrared light, and reaches nearly 100% transmittance particularly at wavelengths from 7 μm to 13 μm. On the other hand, the reflectance R32 of the single-surface microstructure reaches nearly 0% reflectance at wavelengths from 7 μm to 13 μm. The transmittance R33 of the planar silicon substrate is constant at 70% transmittance. The reflectance R34 of the planar silicon substrate is constant at 30% transmittance.

[0062] Thus, by using the bandpass filter 61, the terahertz imaging device 1F of the sixth embodiment of the present disclosure can guide far-infrared light from the subject OBJ incident through the imaging lens 11 to the sensor 12 and form an image on the pixel array section (not shown) of the imaging element 121.

[0063] <Operation and Effects of Sixth Embodiment> As described above, according to the sixth embodiment, the bandpass filter 61 for far-infrared light can be formed.

[0064] Seventh Embodiment A seventh embodiment of the present disclosure is an example in which the structure of a bandpass filter is formed in a concave shape. Fig. 13A is a cross-sectional view showing an example of the configuration of a bandpass filter according to the seventh embodiment of the present disclosure.

[0065] 13A , the terahertz imaging device 1G has a bandpass filter 71. As in the first embodiment, the bandpass filter 71 is disposed, for example, near the aperture of the imaging lens 11. The bandpass filter 71 has, for example, a plurality of cylindrical recess structures 712 formed on a first surface S1 of a silicon substrate 711 having a thickness of 2 mm. The first surface S1 is a surface on which light from an object OBJ is incident.

[0066] 13B is a plan view of the bandpass filter 71, as viewed from, for example, the first surface S1. The structures 712 are made of silicon and are periodically arranged on the first surface S1 of the silicon substrate 711 at a pitch of 0.34 mm. Each structure 712 has a diameter of 0.221 mm and a height of 0.1 mm.

[0067] <Effects of the Seventh Embodiment> As described above, the seventh embodiment can provide the same effects as the first embodiment. Note that, as an example of the structure 712, in addition to a cylindrical structure, it may also be a structure having a conical recess.

[0068] 14A is a cross-sectional view illustrating an example of the configuration of a bandpass filter according to an eighth embodiment of the present disclosure.

[0069] 14A , the terahertz imaging device 1H has a bandpass filter 81. As in the first embodiment, the bandpass filter 81 is disposed, for example, near the aperture of the imaging lens 11. The bandpass filter 81 has, for example, a plurality of hexagonal prism-shaped convex structures 812 formed on a first surface S1 of a silicon substrate 811 having a thickness of 2 mm. The first surface S1 is a surface on which light from an object OBJ is incident.

[0070] 14B is a plan view of bandpass filter 81 as viewed from, for example, first surface S1. Multiple structures 812 are made of silicon and are periodically arranged on first surface S1 of silicon substrate 811 at a pitch of 0.34 mm. Each structure 712 has a diameter of 0.221 mm and a height of 0.1 mm.

[0071] <Effects of the Eighth Embodiment> As described above, the eighth embodiment can provide the same effects as the first embodiment. Note that, as an example of the structure 812, in addition to the hexagonal prism shape, it may be a hexagonal pyramidal convex structure or a concave structure.

[0072] Ninth Embodiment A ninth embodiment of the present disclosure is an example in which an imaging lens is arranged using a lens formed from a silicon substrate. Fig. 15 is a cross-sectional view showing an example of the configuration of a terahertz imaging device to which a terahertz wave detection device according to the ninth embodiment of the present disclosure is applied. In Fig. 9, the same parts as those in Fig. 1 above are assigned the same reference numerals, and detailed description thereof will be omitted.

[0073] 15A, the terahertz imaging device 1I includes a sensor 12 and a silicon lens 91. The silicon lens 91 may be composed of, for example, two lenses 911 and 912. The silicon lens 91 guides light from an object OBJ to the sensor 12 and forms an image on a pixel array section (not shown) of an imaging element 121 (an example of a detection element). The silicon lens 91 also performs focus adjustment and drive control based on a control signal output from a lens control section (not shown), and sets the aperture to a specified aperture value.

[0074] 15B, each of the two lenses 911, 912 of the silicon lens 91 according to the ninth embodiment of the present disclosure has, for example, a plurality of cylindrical convex structures 922 formed on a first surface S1 of a 2 mm thick silicon substrate 921, and a plurality of cylindrical convex structures 923 formed on a second surface S2. Note that, as an example of the structures 922, 923, in addition to cylindrical shapes, they may also be conical concave structures.

[0075] 16 is a plan view of the silicon lens 91 as viewed from, for example, the first surface S1 of the silicon substrate 921. A plurality of structures 922 are made of silicon and are periodically arranged on the first surface S1 of the silicon substrate 921 at a pitch of 0.34 mm. Each structure 922 has a diameter of 0.221 mm and a height of 0.1 mm. Similarly, a plurality of structures 923 are periodically arranged on the second surface S2 of the silicon substrate 921 at a pitch of 0.34 mm.

[0076] Thus, the terahertz imaging device 1I of the ninth embodiment of the present disclosure uses the silicon lens 91 to absorb visible light and near-infrared light from the object OBJ that is incident on the silicon lens 91, and guides only the THz waves to the sensor 12, where they are imaged on the pixel array section (not shown) of the imaging element 121.

[0077] <Effects of the ninth embodiment> As described above, according to the ninth embodiment, even if the imaging lens 11 is replaced with the silicon lens 91, the same effects as those of the first embodiment can be obtained, and the reduction in the number of parts can contribute to the miniaturization of the terahertz imaging device 1I.

[0078] <Other Embodiments> As described above, the present technology has been described using the first to ninth embodiments. However, the descriptions and drawings that form part of this disclosure should not be understood to limit the present technology. Upon understanding the gist of the technical content disclosed in the first to ninth embodiments, it will be apparent to those skilled in the art that various alternative embodiments, examples, and operational techniques may be included in the present technology. Furthermore, the configurations disclosed in the first to ninth embodiments may be appropriately combined within a range that does not cause contradictions. For example, configurations disclosed in multiple different embodiments may be combined, or configurations disclosed in multiple different modified examples of the same embodiment may be combined.

[0079] <Application Example to Electronic Devices> The above-described terahertz wave detection device can be applied to various electronic devices, such as imaging devices such as digital still cameras and digital video cameras, mobile phones with imaging functions, and other devices with imaging functions. An example of an imaging system to which the optical package is applied will be described below.

[0080] Fig. 18 is a block diagram showing an example of the configuration of an imaging system. As shown in Fig. 18, the imaging system 1010 includes an optical system 1020, a photodetector 1030, and a DSP (Digital Signal Processor) 1040. The DSP 1040, a display device 1050, an operation system 1060, a memory 1080, a recording device 1090, and a power supply system 1100 are connected via a bus 1070, and the imaging system 1010 is capable of capturing still images and moving images.

[0081] The optical system 1020 is configured to have one or more lenses, and guides image light (incident light) from a subject to the photodetector 1030 , forming an image on the light-receiving surface (sensor portion) of the photodetector 1030 .

[0082] Any of the photodetector devices having the above-described configuration examples is applied as the photodetector 1030. Electrons are accumulated in the photodetector 1030 for a certain period of time in accordance with an image formed on the light-receiving surface via the optical system 1020. A signal corresponding to the electrons accumulated in the photodetector 1030 is then supplied to the DSP 1040.

[0083] The DSP 1040 performs various signal processing on the signal from the photodetector 1030 to acquire an image, and temporarily stores the image data in the memory 1080. The image data stored in the memory 1080 is recorded in the recording device 1090 or supplied to the display device 1050 to display the image. In addition, the operation system 1060 accepts various operations by the user and supplies operation signals to each block of the imaging system 1010, and the power supply system 1100 supplies power necessary to drive each block of the imaging system 1010.

[0084] <Application Example to Endoscopic Surgery System> The technology according to the present disclosure (the present technology) can be applied to various products. For example, the technology according to the present disclosure may be applied to an endoscopic surgery system.

[0085] Fig. 19 is a diagram showing an example of the schematic configuration of an endoscopic surgery system to which the technology according to the present disclosure (the present technology) can be applied. Fig. 19 shows a state in which an operator (doctor) 11131 is performing surgery on a patient 11132 on a patient bed 11133 using an endoscopic surgery system 11000. As shown in the figure, the endoscopic surgery system 11000 is composed of an endoscope 11100, other surgical tools 11110 such as an insufflation tube 11111 and an energy treatment tool 11112, a support arm device 11120 that supports the endoscope 11100, and a cart 11200 on which various devices for endoscopic surgery are mounted.

[0086] The endoscope 11100 is composed of a lens barrel 11101, a region of a predetermined length from the tip of which is inserted into a body cavity of a patient 11132, and a camera head 11102 connected to the base end of the lens barrel 11101. In the example shown, the endoscope 11100 is configured as a so-called rigid scope having a rigid lens barrel 11101, but the endoscope 11100 may also be configured as a so-called flexible scope having a flexible lens barrel.

[0087] An opening into which an objective lens is fitted is provided at the tip of the lens barrel 11101. A light source device 11203 is connected to the endoscope 11100, and light generated by the light source device 11203 is guided to the tip of the lens barrel by a light guide extending inside the lens barrel 11101, and is irradiated via the objective lens toward an object to be observed inside the body cavity of the patient 11132. The endoscope 11100 may be a direct-viewing endoscope, an oblique-viewing endoscope, or a side-viewing endoscope.

[0088] An optical system and an image sensor are provided inside the camera head 11102, and light reflected from the object of observation (observation light) is collected by the optical system onto the image sensor. The observation light is photoelectrically converted by the image sensor to generate an electrical signal corresponding to the observation light, i.e., an image signal corresponding to the observed image. The image signal is sent to a camera control unit (CCU) 11201 as RAW data.

[0089] The CCU 11201 is configured with a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc., and comprehensively controls the operations of the endoscope 11100 and the display device 11202. Furthermore, the CCU 11201 receives image signals from the camera head 11102 and performs various image processing on the image signals, such as development processing (demosaic processing), to display images based on the image signals. Under the control of the CCU 11201, the display device 11202 displays images based on the image signals that have been subjected to image processing by the CCU 11201.

[0090] The light source device 11203 is composed of a light source such as an LED (Light Emitting Diode) and supplies illumination light to the endoscope 11100 when photographing the surgical site, etc. The input device 11204 is an input interface for the endoscopic surgery system 11000. A user can input various information and instructions to the endoscopic surgery system 11000 via the input device 11204. For example, the user inputs an instruction to change the imaging conditions (type of illumination light, magnification, focal length, etc.) of the endoscope 11100.

[0091] The treatment tool control device 11205 controls the driving of the energy treatment tool 11112 for cauterizing tissue, incising, sealing blood vessels, etc. The insufflation device 11206 inflates the body cavity of the patient 11132 through the insufflation tube 11111 in order to ensure a clear field of view for the endoscope 11100 and a working space for the surgeon. The recorder 11207 is a device capable of recording various types of information related to the surgery. The printer 11208 is a device capable of printing various types of information related to the surgery in various formats such as text, images, or graphs.

[0092] The light source device 11203, which supplies illumination light to the endoscope 11100 when photographing the surgical site, can be configured from a white light source, such as an LED, a laser light source, or a combination of these. When the white light source is configured from a combination of RGB laser light sources, the output intensity and output timing of each color (each wavelength) can be controlled with high precision, allowing the light source device 11203 to adjust the white balance of the captured image. In this case, it is also possible to time-share images corresponding to each RGB by irradiating the object of observation with laser light from each RGB laser light source and controlling the drive of the image sensor of the camera head 11102 in synchronization with the irradiation timing. According to this method, color images can be obtained without providing a color filter to the image sensor.

[0093] Furthermore, the light source device 11203 may be controlled to change the intensity of light it outputs at predetermined time intervals. By controlling the driving of the image sensor of the camera head 11102 in synchronization with the timing of the change in light intensity to acquire images in a time-division manner and combining the images, it is possible to generate an image with a high dynamic range that is free from so-called blocked-up shadows and blown-out highlights.

[0094] The light source device 11203 may also be configured to supply light in a predetermined wavelength band corresponding to special light observation. Special light observation, for example, utilizes the wavelength dependence of light absorption in body tissues to irradiate light in a narrower band than the light irradiated during normal observation (i.e., white light) to capture high-contrast images of specific tissues, such as blood vessels on the surface of mucous membranes, in what is known as narrow band imaging. Alternatively, special light observation may involve fluorescence observation, in which images are obtained using fluorescence generated by irradiating excitation light. Fluorescence observation may involve irradiating excitation light onto body tissues and observing the fluorescence from the tissues (autofluorescence observation), or may involve locally injecting a reagent such as indocyanine green (ICG) into the body tissue and irradiating the tissues with excitation light corresponding to the fluorescent wavelength of the reagent to obtain a fluorescent image. The light source device 11203 may be configured to supply narrow band light and / or excitation light corresponding to such special light observation.

[0095] Fig. 20 is a block diagram showing an example of the functional configuration of the camera head 11102 and CCU 11201 shown in Fig. 19. The camera head 11102 has a lens unit 11401, an imaging unit 11402, a drive unit 11403, a communication unit 11404, and a camera head control unit 11405. The CCU 11201 has a communication unit 11411, an image processing unit 11412, and a control unit 11413. The camera head 11102 and the CCU 11201 are connected to each other via a transmission cable 11400 so as to be able to communicate with each other.

[0096] The lens unit 11401 is an optical system provided at the connection portion with the lens barrel 11101. Observation light taken in from the tip of the lens barrel 11101 is guided to the camera head 11102 and enters the lens unit 11401. The lens unit 11401 is composed of a combination of multiple lenses including a zoom lens and a focus lens.

[0097] The imaging unit 11402 is composed of an imaging element. The imaging element constituting the imaging unit 11402 may be a single (so-called single-chip type) or multiple (so-called multi-chip type). When the imaging unit 11402 is composed of a multi-chip type, for example, each imaging element may generate an image signal corresponding to each of RGB, and a color image may be obtained by combining these signals. Alternatively, the imaging unit 11402 may be configured to have a pair of imaging elements for acquiring image signals for the right eye and the left eye corresponding to 3D (dimensional) display. The 3D display allows the surgeon 11131 to more accurately grasp the depth of the biological tissue at the surgical site. Note that when the imaging unit 11402 is composed of a multi-chip type, multiple lens units 11401 may be provided corresponding to each imaging element.

[0098] Furthermore, the imaging unit 11402 does not necessarily have to be provided in the camera head 11102. For example, the imaging unit 11402 may be provided inside the lens barrel 11101, immediately behind the objective lens. The driving unit 11403 is composed of an actuator, and moves the zoom lens and focus lens of the lens unit 11401 a predetermined distance along the optical axis under the control of the camera head control unit 11405. This allows the magnification and focus of the image captured by the imaging unit 11402 to be adjusted as appropriate.

[0099] The communication unit 11404 is configured by a communication device for transmitting and receiving various types of information to and from the CCU 11201. The communication unit 11404 transmits the image signal obtained from the imaging unit 11402 to the CCU 11201 via the transmission cable 11400 as RAW data.

[0100] Furthermore, the communication unit 11404 receives a control signal for controlling the driving of the camera head 11102 from the CCU 11201 and supplies the control signal to the camera head control unit 11405. The control signal includes information on the imaging conditions, such as information specifying the frame rate of the captured image, information specifying the exposure value at the time of imaging, and / or information specifying the magnification and focus of the captured image.

[0101] The image capturing conditions such as the frame rate, exposure value, magnification, and focus may be appropriately specified by the user, or may be automatically set by the control unit 11413 of the CCU 11201 based on the acquired image signal. In the latter case, the endoscope 11100 is equipped with a so-called AE (Auto Exposure) function, AF (Auto Focus) function, and AWB (Auto White Balance) function.

[0102] The camera head control unit 11405 controls the driving of the camera head 11102 based on a control signal received from the CCU 11201 via the communication unit 11404. The communication unit 11411 is configured by a communication device for transmitting and receiving various information to and from the camera head 11102. The communication unit 11411 receives an image signal transmitted from the camera head 11102 via the transmission cable 11400.

[0103] The communication unit 11411 also transmits to the camera head 11102 a control signal for controlling the driving of the camera head 11102. The image signal and the control signal can be transmitted by electrical communication, optical communication, etc. The image processing unit 11412 performs various types of image processing on the image signal, which is RAW data transmitted from the camera head 11102.

[0104] The control unit 11413 performs various controls related to the imaging of the surgical site, etc. by the endoscope 11100 and the display of the captured image obtained by imaging the surgical site, etc. For example, the control unit 11413 generates a control signal for controlling the driving of the camera head 11102.

[0105] Furthermore, the control unit 11413 displays the captured image showing the surgical site, etc., on the display device 11202 based on the image signal subjected to image processing by the image processing unit 11412. At this time, the control unit 11413 may recognize various objects in the captured image using various image recognition technologies. For example, the control unit 11413 can recognize surgical tools such as forceps, specific biological parts, bleeding, mist generated when using the energy treatment tool 11112, etc., by detecting the shape and color of the edges of objects included in the captured image. When displaying the captured image on the display device 11202, the control unit 11413 may use the recognition results to superimpose various surgical support information on the image of the surgical site. By superimposing the surgical support information and presenting it to the surgeon 11131, the burden on the surgeon 11131 can be reduced and the surgeon 11131 can proceed with the surgery reliably.

[0106] The transmission cable 11400 connecting the camera head 11102 and the CCU 11201 is an electrical signal cable for electrical signal communication, an optical fiber for optical communication, or a composite cable of these. In the illustrated example, communication is performed by wire using the transmission cable 11400, but communication between the camera head 11102 and the CCU 11201 may also be performed wirelessly.

[0107] The above describes an example of an endoscopic surgery system to which the technology according to the present disclosure can be applied. The technology according to the present disclosure can be applied to, for example, the endoscope 11100, the imaging unit 11402 of the camera head 11102, the image processing unit 11412 of the CCU 11201, and the like, among the above-described configurations. Specifically, the technology according to the present disclosure can be applied to the terahertz imaging device 1A of FIG. 1 , the terahertz imaging device 1B of FIG. 6 , the terahertz imaging device 1C of FIG. 8 , the terahertz imaging device 1D of FIG. 9 , the terahertz imaging device 1E of FIG. 10 , and the terahertz imaging device 1I of FIG. 15 . Note that, although an endoscopic surgery system has been described as an example here, the technology according to the present disclosure may also be applied to other systems, such as a microsurgical system.

[0108] <Application to a Mobile Body> The technology according to the present disclosure (the present technology) can be applied to various products. For example, the technology according to the present disclosure may be realized as a device mounted on any type of mobile body, such as an automobile, an electric vehicle, a hybrid electric vehicle, a motorcycle, a bicycle, personal mobility, an airplane, a drone, a ship, or a robot.

[0109] Fig. 21 is a block diagram showing a schematic configuration example of a vehicle control system, which is an example of a mobile object control system to which the technology according to the present disclosure can be applied. The vehicle control system 12000 includes a plurality of electronic control units connected via a communication network 12001. In the example shown in Fig. 21, the vehicle control system 12000 includes a drive system control unit 12010, a body system control unit 12020, an outside-vehicle information detection unit 12030, an inside-vehicle information detection unit 12040, and an integrated control unit 12050. The functional configuration of the integrated control unit 12050 also includes a microcomputer 12051, an audio / video output unit 12052, and an in-vehicle network I / F (interface) 12053.

[0110] The drivetrain control unit 12010 controls the operation of devices related to the drivetrain of the vehicle in accordance with various programs. For example, the drivetrain control unit 12010 functions as a control device for a drive force generating device for generating a drive force of the vehicle, such as an internal combustion engine or a drive motor, a drive force transmission mechanism for transmitting the drive force to the wheels, a steering mechanism for adjusting the steering angle of the vehicle, and a braking device for generating a braking force of the vehicle.

[0111] The body system control unit 12020 controls the operation of various devices equipped in the vehicle body according to various programs. For example, the body system control unit 12020 functions as a control device for a keyless entry system, a smart key system, a power window device, or various lamps such as headlamps, backup lamps, brake lamps, turn signals, and fog lamps. In this case, radio waves transmitted from a portable device that serves as a key or signals from various switches can be input to the body system control unit 12020. The body system control unit 12020 receives these radio waves or signals and controls the vehicle's door lock device, power window device, lamps, etc.

[0112] The outside-vehicle information detection unit 12030 detects information outside the vehicle equipped with the vehicle control system 12000. For example, an imaging unit 12031 is connected to the outside-vehicle information detection unit 12030. The outside-vehicle information detection unit 12030 causes the imaging unit 12031 to capture images outside the vehicle and receives the captured images. The outside-vehicle information detection unit 12030 may perform object detection processing or distance detection processing for people, cars, obstacles, signs, characters on the road surface, etc. based on the received images.

[0113] The imaging unit 12031 is an optical sensor that receives light and outputs an electrical signal corresponding to the amount of light received. The imaging unit 12031 can output the electrical signal as an image or as distance measurement information. The light received by the imaging unit 12031 may be visible light or invisible light such as infrared light.

[0114] The in-vehicle information detection unit 12040 detects information inside the vehicle. For example, a driver state detection unit 12041 that detects the state of the driver is connected to the in-vehicle information detection unit 12040. The driver state detection unit 12041 includes, for example, a camera that captures an image of the driver, and the in-vehicle information detection unit 12040 may calculate the degree of fatigue or concentration of the driver based on the detection information input from the driver state detection unit 12041, or may determine whether the driver is dozing off.

[0115] The microcomputer 12051 can calculate control target values ​​for the driving force generating device, steering mechanism, or braking device based on the information inside and outside the vehicle acquired by the outside-vehicle information detection unit 12030 or the inside-vehicle information detection unit 12040, and output control commands to the drive system control unit 12010. For example, the microcomputer 12051 can perform cooperative control aimed at realizing the functions of an ADAS (Advanced Driver Assistance System), including vehicle collision avoidance or impact mitigation, following driving based on the inter-vehicle distance, vehicle speed maintenance driving, vehicle collision warning, vehicle lane departure warning, etc.

[0116] In addition, the microcomputer 12051 can perform cooperative control for the purpose of autonomous driving, which allows the vehicle to travel autonomously without relying on driver operation, by controlling the driving force generating device, steering mechanism, braking device, etc. based on information about the surroundings of the vehicle obtained by the outside vehicle information detection unit 12030 or the inside vehicle information detection unit 12040.

[0117] Furthermore, the microcomputer 12051 can output a control command to the body system control unit 12020 based on the information outside the vehicle acquired by the outside information detection unit 12030. For example, the microcomputer 12051 can control the headlamps according to the position of a preceding vehicle or an oncoming vehicle detected by the outside information detection unit 12030, and perform cooperative control aimed at preventing glare, such as switching from high beams to low beams.

[0118] The audio / video output unit 12052 transmits at least one of audio and video output signals to an output device capable of visually or audibly notifying information to vehicle occupants or the outside of the vehicle. In the example of Fig. 21, the output devices are exemplified by an audio speaker 12061, a display unit 12062, and an instrument panel 12063. The display unit 12062 may include, for example, at least one of an on-board display and a head-up display.

[0119] Fig. 22 is a diagram showing an example of the installation position of the image capturing unit 12031. In Fig. 22, a vehicle 12100 has image capturing units 12101, 12102, 12103, 12104, and 12105 as the image capturing unit 12031.

[0120] The imaging units 12101, 12102, 12103, 12104, and 12105 are provided, for example, at positions such as the front nose, side mirrors, rear bumper, back door, and the top of the windshield inside the vehicle cabin of the vehicle 12100. The imaging unit 12101 provided on the front nose and the imaging unit 12105 provided on the top of the windshield inside the vehicle cabin mainly acquire images of the front of the vehicle 12100. The imaging units 12102 and 12103 provided on the side mirrors mainly acquire images of the sides of the vehicle 12100. The imaging unit 12104 provided on the rear bumper or back door mainly acquires images of the rear of the vehicle 12100. The forward images acquired by the imaging units 12101 and 12105 are mainly used to detect preceding vehicles, pedestrians, obstacles, traffic lights, traffic signs, lanes, etc.

[0121] 22 shows an example of the imaging ranges of the imaging units 12101 to 12104. Imaging range 12111 indicates the imaging range of the imaging unit 12101 provided on the front nose, imaging ranges 12112 and 12113 indicate the imaging ranges of the imaging units 12102 and 12103 provided on the side mirrors, respectively, and imaging range 12114 indicates the imaging range of the imaging unit 12104 provided on the rear bumper or back door. For example, by overlaying the image data captured by the imaging units 12101 to 12104, an overhead image of the vehicle 12100 viewed from above can be obtained.

[0122] At least one of the image capturing units 12101 to 12104 may have a function of acquiring distance information. For example, at least one of the image capturing units 12101 to 12104 may be a stereo camera made up of multiple image capturing elements, or may be an image capturing element having pixels for phase difference detection.

[0123] For example, based on the distance information obtained from the imaging units 12101 to 12104, the microcomputer 12051 can calculate the distance to each three-dimensional object within the imaging ranges 12111 to 12114 and the change in this distance over time (relative speed with respect to the vehicle 12100), thereby extracting as a preceding vehicle, in particular, the three-dimensional object that is the closest three-dimensional object on the path of the vehicle 12100 and traveling in approximately the same direction as the vehicle 12100 at a predetermined speed (e.g., 0 km / h or higher). Furthermore, the microcomputer 12051 can set a vehicle-to-vehicle distance to be maintained in advance in front of the preceding vehicle, and perform automatic braking control (including follow-up stop control), automatic acceleration control (including follow-up start control), etc. In this way, cooperative control can be performed for the purpose of autonomous driving, which runs autonomously without relying on driver operation.

[0124] For example, the microcomputer 12051 classifies and extracts three-dimensional object data regarding three-dimensional objects into two-wheeled vehicles, ordinary vehicles, large vehicles, pedestrians, utility poles, and other three-dimensional objects based on distance information obtained from the imaging units 12101 to 12104, and can use the data for automatic obstacle avoidance. For example, the microcomputer 12051 distinguishes obstacles around the vehicle 12100 into obstacles that are visible to the driver of the vehicle 12100 and obstacles that are difficult to see. The microcomputer 12051 then determines a collision risk that indicates the risk of collision with each obstacle, and when the collision risk is equal to or greater than a set value and a collision is possible, the microcomputer 12051 can provide driving assistance for collision avoidance by outputting an alarm to the driver via the audio speaker 12061 or the display unit 12062, or by performing forced deceleration or avoidance steering via the drive system control unit 12010.

[0125] At least one of the image capturing units 12101 to 12104 may be an infrared camera that detects infrared rays. For example, the microcomputer 12051 can recognize a pedestrian by determining whether a pedestrian is present in the images captured by the image capturing units 12101 to 12104. Such pedestrian recognition is performed, for example, by extracting feature points from the images captured by the image capturing units 12101 to 12104 as infrared cameras and performing pattern matching on a series of feature points that indicate the outline of an object to determine whether the object is a pedestrian. When the microcomputer 12051 determines that a pedestrian is present in the images captured by the image capturing units 12101 to 12104 and recognizes the pedestrian, the audio / image output unit 12052 controls the display unit 12062 to superimpose a rectangular outline on the recognized pedestrian for emphasis. The audio / image output unit 12052 may also control the display unit 12062 to display an icon or the like indicating the pedestrian at a desired position.

[0126] The above describes an example of a vehicle control system to which the technology according to the present disclosure can be applied. The technology according to the present disclosure can be applied to, for example, the image capturing unit 12031 of the above-described configuration. Specifically, the technology can be applied to the terahertz image capturing device 1A of FIG. 1 , the terahertz image capturing device 1B of FIG. 6 , the terahertz image capturing device 1C of FIG. 8 , the terahertz image capturing device 1D of FIG. 9 , the terahertz image capturing device 1E of FIG. 10 , and the terahertz image capturing device 1I of FIG. 15 .

[0127] The present disclosure may also be configured as follows: (1) A terahertz wave detection device comprising: an imaging lens facing a subject; a detection element that detects THz (terahertz) waves generated from the subject out of light incident through the imaging lens; a silicon substrate that is arranged on the subject side of the detection element and absorbs visible light and near-infrared light; and a filter unit that transmits the THz waves incident on the structures, the filter unit including a plurality of structures periodically arranged on the silicon substrate, the structures preventing reflection of light in a range from a wavelength of far-infrared light to a predetermined wavelength that includes the wavelength of the THz waves. (2) The terahertz wave detection device according to (1), wherein the predetermined wavelength is 1 mm. (3) The terahertz wave detection device according to (1), wherein the silicon substrate has the plurality of structures periodically arranged on a surface on which the light is incident and on a surface opposite to the light incident surface. (4) The terahertz wave detection device according to (1), wherein the structures prevent reflection of wavelengths in the vicinity of the THz waves. (5) The terahertz wave detecting device according to (1) above, wherein the filter section is configured by stacking two or more of the silicon substrates. (6) The terahertz wave detecting device according to (1) above, wherein the structure has a convex shape. (7) The terahertz wave detecting device according to (6) above, wherein the convex shape is a cylinder or a cone. (8) The terahertz wave detecting device according to (6) above, wherein the convex shape is a prism or a pyramid. (9) The terahertz wave detecting device according to (1) above, wherein the structure has a concave shape. (10) The terahertz wave detecting device according to (9) above, wherein the concave shape is a cylinder or a cone. (11) The terahertz wave detecting device according to (9) above, wherein the concave shape is a prism or a pyramid. (12) The terahertz wave detecting device according to (1), wherein the structure satisfies 0.2<p / λm<0.8, where p is the period of the structure and λm is the central wavelength for antireflection. (13) The terahertz wave detecting device according to (1), wherein the structure satisfies 0.01<h / λm<0.4, where h is the height of the structure and λm is the central wavelength for antireflection. (14) The terahertz wave detecting device according to (1), wherein the structure satisfies 0.4<l / p<0.9, where p is the period of the structure and 1 is the diameter of the structure.(15) The terahertz wave detection device according to (1) above, wherein the filter section cuts out unnecessary wavelengths by combining the silicon substrate and crystal quartz. (16) The terahertz wave detection device according to (1) above, wherein the imaging lens has an Fno (F number) brighter than 0.8. (17) The terahertz wave detection device according to (1) above, wherein the silicon substrate is placed in air on the subject side of the imaging lens. (18) The terahertz wave detection device according to (1) above, wherein the silicon substrate is placed in air near an aperture in the imaging lens. (19) The terahertz wave detection device according to (1) above, wherein the silicon substrate is placed in place of or near a sealing glass of a package that houses the detection element inside. (20) A terahertz wave detection device comprising: a silicon lens that faces a subject and absorbs visible light and near-infrared light; and a detection element that detects THz (terahertz) waves generated from the subject among the light incident through the silicon lens, wherein the silicon lens includes a plurality of structures periodically arranged on a light incident surface and on the surface opposite thereto, and transmits the THz waves incident on the structures and prevents reflection of light between the wavelength of far-infrared light and a predetermined wavelength including the wavelength of the THz waves. (21) An electronic device comprising a terahertz wave detection device, comprising: an imaging lens facing a subject; a detection element that detects THz (terahertz) waves generated from the subject among light incident through the imaging lens; a silicon substrate that is arranged on the subject side of the detection element and absorbs visible light and near-infrared light; and a filter unit that includes a plurality of structures periodically arranged on the silicon substrate and transmits the THz waves incident on the structures, wherein the structures prevent reflection of light between wavelengths of far-infrared light and predetermined wavelengths including the wavelength of the THz waves.

[0128] 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1I Terahertz imaging device 11 Imaging lens 12, 42, 51 Sensor 13, 20, 31, 40, 52, 61, 71, 81 Band-pass filter 14, 131, 211, 311, 611, 711, 811, 921 Silicon substrate 15 Photoresist 16 Mask 17 Engraved portion 43 Crystal quartz 91 Silicon lens 111 Upper lens 112 Lower lens 121, 421, 511 Imaging element 122, 422, 512 Case 123 Cover glass 132, 133, 212, 213, 312, 313, 412, 413, 522, 523, 612, 712, 812, 922, 923 Structure 151 Convex portion 152 Concave portion 1010 Imaging system 1020 Optical system 1030 Light detection device 1050 Display device 1060 Operation system 1070 Bus 1080 Memory 1090 Recording device 1100 Power supply system 10402 Imaging unit 11000 Endoscopic surgery system 11100 Endoscope 11101 Optical tube 11102 Camera head 11110 Surgical tool 11111 Insufflation tube 11112 Energy treatment tool 11120 Support arm device 11131 Surgeon (doctor) 11132 Patient 11133 Patient bed 11200 Cart 11201 Camera control unit (CCU) 11202 Display device 11203 Light source device 11204 Input device 11205 Treatment tool control device 11206 Insufflation device 11207 Recorder 11208 Printer 11400 Transmission cable 11401 Lens unit 11402, 12031 Imaging unit 11403 Driving unit 11404,11411 Communication unit 11405 Camera head control unit 11412 Image processing unit 11413 Control unit 12000 Vehicle control system 12001 Communication network 12010 Drive system control unit 12020 Body system control unit 12030 Outside vehicle information detection unit 12040 Inside vehicle information detection unit 12041 Driver state detection unit 12050 Integrated control unit 12051 Microcomputer 12052 Audio and image output unit 12061 Audio speaker 12062 Display unit 12063 Instrument panel 12100 Vehicle 12101, 12102, 12103, 12104, 12105 Imaging unit 12111, 12112, 12113, 12114 Imaging range,

Claims

1. A terahertz wave detection device comprising: an imaging lens facing a subject; a detection element that detects THz (terahertz) waves generated from the subject out of light incident through said imaging lens; a silicon substrate that is positioned closer to the subject than said detection element and absorbs visible light and near-infrared light; and a filter section that includes a plurality of structures periodically arranged on said silicon substrate and transmits the THz waves that have entered said structures, wherein said structures prevent reflection of light in the range from the wavelength of far-infrared light to a predetermined wavelength that includes the wavelength of said THz waves.

2. The terahertz wave detection device according to claim 1, wherein the predetermined wavelength is 1 mm.

3. The terahertz wave detection device according to claim 1, wherein the silicon substrate has the plurality of structures periodically arranged on the light incident surface and on the surface opposite to the light incident surface.

4. A terahertz wave detection device according to claim 1, wherein the structure prevents reflection of wavelengths in the vicinity of the THz wave.

5. The terahertz wave detection device according to claim 1, wherein the filter section is constructed by stacking two or more of the silicon substrates.

6. The terahertz wave detection device according to claim 1, wherein the structure has a convex shape.

7. The terahertz wave detection device according to claim 6, wherein the convex shape is a cylindrical or conical shape.

8. The terahertz wave detection device according to claim 6, wherein the convex shape is a prism or pyramid shape.

9. The terahertz wave detection device according to claim 1, wherein the structure has a concave shape.

10. The terahertz wave detection device according to claim 9, wherein the concave shape is a cylindrical or conical shape.

11. The terahertz wave detection device according to claim 9, wherein the concave shape is a prism or pyramid shape.

12. The terahertz wave detection device according to claim 1, wherein the structure satisfies 0.2<p / λm<0.8, where p is the period of the structure and λm is the central wavelength for antireflection.

13. The terahertz wave detection device according to claim 1, wherein the structure satisfies 0.01<h / λm<0.4, where h is the height of the structure and λm is the center wavelength for antireflection.

14. The terahertz wave detection device according to claim 1, wherein the structure satisfies 0.4<l / p<0.9, where p is the period of the structure and l is the diameter of the structure.

15. The terahertz wave detection device according to claim 1, wherein the filter section cuts out unnecessary wavelengths by combining the silicon substrate with crystal quartz.

16. The terahertz wave detection device according to claim 1, wherein the imaging lens has an F number of 0.8 or brighter.

17. The terahertz wave detection device according to claim 1, wherein the silicon substrate is placed in the air on the subject side of the imaging lens.

18. The terahertz wave detection device according to claim 1, wherein the silicon substrate is placed in the air near an aperture in the imaging lens.

19. The terahertz wave detection device according to claim 1, wherein the silicon substrate is disposed in place of or near the sealing glass of a package that houses the detection element inside.

20. A terahertz wave detection device comprising: a silicon lens that faces a subject and absorbs visible light and near-infrared light; and a detection element that detects THz (terahertz) waves generated from the subject among the light incident through said silicon lens, wherein said silicon lens includes a plurality of structures periodically arranged on the light incident surface and the surface opposite thereto, and transmits THz waves incident on said structures and prevents reflection of light between the wavelength of far-infrared light and a predetermined wavelength including the wavelength of said THz waves.

21. Electronic equipment comprising an imaging lens facing a subject; a detection element that detects THz (terahertz) waves generated from the subject among light incident through said imaging lens; a silicon substrate that is arranged on the subject side of said detection element and absorbs visible light and near-infrared light; and a filter unit that includes a plurality of structures periodically arranged on said silicon substrate and transmits THz waves that have entered said structures, said structures comprising a terahertz wave detection device that prevents reflection of light between wavelengths of far-infrared light and a predetermined wavelength that includes the wavelength of said THz waves.

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