An optical system and optical lens working in far-infrared wave band

Abstract

The application provides an optical system and an optical lens working in a far-infrared wave band, which sequentially comprises, along an optical axis, from an object side to an image side: a first chalcogenide refractive lens, a superlens, and a second chalcogenide refractive lens; the first chalcogenide refractive lens and the second chalcogenide refractive lens are both positive lenses; the superlens comprises a substrate and a superstructure unit, and the superstructure unit is provided with micro-nano structures; the optical system satisfies the following condition with a unit of 1 / mm: 0.25<=n*(|C1|+|C2|)<=2.01; wherein, when n is the refractive index of the first chalcogenide refractive lens, C1 is the curvature of the front surface of the first chalcogenide refractive lens, and C2 is the curvature of the back surface of the first chalcogenide refractive lens; when n is the refractive index of the second chalcogenide refractive lens, C1 is the curvature of the front surface of the second chalcogenide refractive lens, and C2 is the curvature of the back surface of the second chalcogenide refractive lens. The optical system provided by the application can simultaneously meet the requirements of good imaging quality, small size, sufficient athermalization, and high lens processability of the optical system.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of lenses, in particular to an optical system and an optical lens working in a far-infrared wave band. BACKGROUND

[0002] Since the optical system working in the far-infrared wave band can well adapt to working environments such as rain, night, fog and the like, it is widely applied in vehicle-mounted, security and other fields. However, the optical system working in the far-infrared wave band provided in the related art is difficult to simultaneously meet the requirements of the optical system for good imaging quality, small size, sufficient correction of aberration and high lens processability. SUMMARY

[0003] An object of the present application is to provide an optical system and an optical lens working in a far-infrared wave band, so as to meet the requirements of the optical system for good imaging quality, small size, sufficient correction of aberration and high lens processability.

[0004] According to an aspect of an embodiment of the present application, an optical system working in a far-infrared wave band is disclosed, which comprises, in sequence from an object side to an image side along an optical axis of the optical system: a first chalcogenide refractive lens, a superlens, and a second chalcogenide refractive lens; the first chalcogenide refractive lens and the second chalcogenide refractive lens are both positive lenses; the superlens comprises a substrate and a superstructure unit, and the superstructure unit is provided with micro-nano structures; the optical system satisfies the following conditions in units of 1 / mm:

[0005]

[0006] wherein, when n is the refractive index of the first chalcogenide refractive lens, is the curvature of a front surface of the first chalcogenide refractive lens towards the object side, is the curvature of a back surface of the first chalcogenide refractive lens towards the image side; when n is the refractive index of the second chalcogenide refractive lens, is the curvature of a front surface of the second chalcogenide refractive lens towards the object side, is the curvature of a back surface of the second chalcogenide refractive lens towards the image side.

[0007] In an exemplary embodiment of the present application, the optical system provided by the present application further satisfies the following condition in units of femtoseconds fs:

[0008]

[0009] wherein, GD is the group delay of the micro-nano structure, and V is the Abbe number of the first chalcogenide refractive lens or the Abbe number of the second chalcogenide refractive lens.

[0010] In an example embodiment of the present application, the first chalcogenide refractive lens and the second chalcogenide refractive lens are both spherical lenses; the optical system provided by the present application also satisfies the following condition: 2

[0011]

[0012] wherein M is the maximum value of the absolute value of the slope of the phase provided by the superlens, f1 is the effective focal length of the first chalcogenide refractive lens, f2 is the effective focal length of the second chalcogenide refractive lens.

[0013] In an example embodiment of the present application, the optical system provided by the present application also satisfies the following condition:

[0014]

[0015] wherein, D2 is the optical effective aperture of the second chalcogenide refractive lens, f is the back focal length of the optical system.

[0016] In an example embodiment of the present application, the micro-nano structure is a positive micro-nano structure, or a negative micro-nano structure.

[0017] In an example embodiment of the present application, the superlens comprises at least one layer of the superstructure unit.

[0018] In an example embodiment of the present application, the optical system is provided with a diaphragm adjacent to the superlens; the diaphragm is arranged on the surface of the superlens, or the diaphragm is arranged spaced apart from the superlens.

[0019] In an example embodiment of the present application, the front surface of the first chalcogenide refractive lens is convex, and the back surface of the first chalcogenide refractive lens is concave; the front surface of the second chalcogenide refractive lens is concave, and the back surface of the second chalcogenide refractive lens is convex.

[0020] According to an aspect of an embodiment of the present application, an optical lens working in a far-infrared wave band is disclosed, comprising: a lens barrel; a pressing ring, a first spacer ring, a second spacer ring and an optical system provided by any of the above embodiments arranged inside the lens barrel;

[0021] The pressing ring abuts against the front surface of the first chalcogenide refractive lens; the first spacer ring abuts against the front surface of the superlens towards the object side; and the second spacer ring abuts against the front surface of the second chalcogenide refractive lens.

[0022] ​In an example embodiment of the present application, the optical lens further comprises a window glass, and an imaging detector arranged at an image plane of the optical system; the window glass is arranged between the second chalcogenide refractive lens and the imaging detector.

[0023] In the optical system provided by the embodiments of the present application, along the optical axis of the optical system, from the object side of the optical system to the image side of the optical system, the optical system comprises in sequence: a first chalcogenide refractive lens, a superlens, and a second chalcogenide refractive lens. Through the cooperation of the first chalcogenide refractive lens, the superlens, and the second chalcogenide refractive lens, the optical system provided by the present application can have good imaging quality. Moreover, since the thickness of the superlens is much smaller than the thickness of the conventional lens, compared with the optical system in the related art which uses at least three conventional lenses, the volume of the optical system provided by the present application is greatly reduced. Further, the optical system provided by the present application satisfies the following condition: ; wherein n is the refractive index of the first chalcogenide refractive lens, is the curvature of the front surface of the first chalcogenide refractive lens towards the object side, is the curvature of the back surface of the first chalcogenide refractive lens towards the image side; n is the refractive index of the second chalcogenide refractive lens, is the curvature of the front surface of the second chalcogenide refractive lens towards the object side, is the curvature of the back surface of the second chalcogenide refractive lens towards the image side. Through the constraint of the condition, the optical system is sufficiently athermalized, the refractive lens has good machinability, the refractive lens can sufficiently focus light, and thus the optical system can have good imaging quality. In summary, the optical system provided by the present application meets the requirements of good imaging quality, small volume, sufficient athermalization, and high lens machinability of the optical system.

[0024] Other features and advantages of the present application will become apparent from the following detailed description, or will be learned by practice of the present application.

[0025] It should be understood that the general description above and the following detailed description are only exemplary and do not limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0026] The above and other objects, features and advantages of the present application will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

[0027] Figure 1 The architecture layout of the optical system working in the far-infrared wave band in an embodiment of the present application is shown.

[0028] Figure 2A layout diagram of an optical system operating in a far infrared waveband is shown in an embodiment of the present application.

[0029] Figure 3 A layout diagram of an optical system operating in a far infrared waveband is shown in an embodiment of the present application.

[0030] Figure 4 A curve diagram of MTF of an optical system in an embodiment of the present application under normal temperature environment is shown.

[0031] Figure 5 A curve diagram of MTF of an optical system in an embodiment of the present application under -40℃ environment is shown.

[0032] Figure 6 A curve diagram of MTF of an optical system in an embodiment of the present application under 80℃ environment is shown.

[0033] Figure 7 A field curvature diagram of an optical system in an embodiment of the present application is shown.

[0034] Figure 8 A distortion diagram of an optical system in an embodiment of the present application is shown.

[0035] Figure 9 A layout diagram of an optical system operating in a far infrared waveband is shown in an embodiment of the present application.

[0036] Figure 10 A curve diagram of MTF of an optical system in an embodiment of the present application under normal temperature environment is shown.

[0037] Figure 11 A curve diagram of MTF of an optical system in an embodiment of the present application under -40℃ environment is shown.

[0038] Figure 12 A curve diagram of MTF of an optical system in an embodiment of the present application under 80℃ environment is shown.

[0039] Figure 13 A field curvature diagram of an optical system in an embodiment of the present application is shown.

[0040] Figure 14 A distortion diagram of an optical system in an embodiment of the present application is shown.

[0041] Figure 15 A layout diagram of an optical system operating in a far infrared waveband is shown in an embodiment of the present application.

[0042] Figure 16A curve diagram showing the MTF of the optical system in one embodiment of the application varying with field of view in a normal temperature environment is shown.

[0043] Figure 17 A curve diagram showing the MTF of the optical system in one embodiment of the application varying with field of view in a -40℃ environment is shown.

[0044] Figure 18 A curve diagram showing the MTF of the optical system in one embodiment of the application varying with field of view in an 80℃ environment is shown.

[0045] Figure 19 A field curvature diagram of the optical system in one embodiment of the application is shown.

[0046] Figure 20 A distortion diagram of the optical system in one embodiment of the application is shown.

[0047] Figure 21 A layout diagram of the optical system working in a far infrared waveband in one embodiment of the application is shown.

[0048] Figure 22 A curve diagram showing the MTF of the optical system in one embodiment of the application varying with field of view in a normal temperature environment is shown.

[0049] Figure 23 A curve diagram showing the MTF of the optical system in one embodiment of the application varying with field of view in a -40℃ environment is shown.

[0050] Figure 24 A curve diagram showing the MTF of the optical system in one embodiment of the application varying with field of view in an 80℃ environment is shown.

[0051] Figure 25 A field curvature diagram of the optical system in one embodiment of the application is shown.

[0052] Figure 26 A distortion diagram of the optical system in one embodiment of the application is shown.

[0053] Figure 27 A layout diagram of the optical system working in a far infrared waveband in one embodiment of the application is shown.

[0054] Figure 28 A curve diagram showing the MTF of the optical system in one embodiment of the application varying with field of view in a normal temperature environment is shown.

[0055] Figure 29 A curve diagram showing the MTF of the optical system in one embodiment of the application varying with field of view in a -40℃ environment is shown.

[0056] Figure 30 A graph showing the MTF of the optical system in one embodiment of the present application as a function of field of view at 80°C.

[0057] Figure 31 A graph showing the field curvature of the optical system in one embodiment of the present application.

[0058] Figure 32 A graph showing the distortion of the optical system in one embodiment of the present application.

[0059] Figure 33 A layout diagram showing the architecture of the optical system operating in the far infrared band in one embodiment of the present application.

[0060] Figure 34 A graph showing the MTF of the optical system in one embodiment of the present application as a function of field of view at room temperature.

[0061] Figure 35 A graph showing the MTF of the optical system in one embodiment of the present application as a function of field of view at -40°C.

[0062] Figure 36 A graph showing the MTF of the optical system in one embodiment of the present application as a function of field of view at 80°C.

[0063] Figure 37 A graph showing the field curvature of the optical system in one embodiment of the present application.

[0064] Figure 38 A graph showing the distortion of the optical system in one embodiment of the present application.

[0065] Reference Signs:

[0066] 1 - first chalcogenide refractive lens; 2 - superlens; 3 - second chalcogenide refractive lens; 4 - window glass; 5 - image plane; 6 - lens barrel; 7 - compression ring; 8 - first spacer ring; 9 - second spacer ring. DETAILED DESCRIPTION

[0067] Example implementations will now be described more fully with reference to the accompanying drawings. Example implementations can be implemented in any number of ways, and example implementations can be implemented using digital electronic circuitry, analog electronic circuitry, or digital components or analog components consisting of one or more transistors, logic gates, resistors, capacitors, inductors, and / or the like, combined with any number of other components, as would be recognized by one skilled in the relevant art(s). Example implementations can be implemented using both object-oriented and non-object-oriented programming techniques, among others. The example implementations can be implemented using digital electronic components, analog electronic components, or combinations thereof, such as one or more computer(s) including both general and special purpose computers. Example implementations can also be implemented using computers having one or more central processing units (CPU), digital signal processors (DSPs), application-specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or combinations thereof.

[0068] Moreover, the described features, structures, or characteristics can be combined in any suitable manner in one or more example embodiments. In the following description, numerous specific details are provided to give a thorough understanding of example embodiments. One skilled in the relevant art will recognize, however, that the technology can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, methods, implementations, or operations are not shown or described in detail to avoid obscuring aspects of the disclosure.

[0069] In order to overcome the above-mentioned defects of the related art, the present application provides an optical system and an optical lens working in a far-infrared wave band, which can simultaneously meet the requirements of good imaging quality, small size, sufficient correction of aberration, and high lens processability.

[0070] Figure 1 The architecture layout of the optical system working in the far-infrared wave band provided by the present application is shown. Figure 1 The left-to-right direction in the figure is the direction from the object side of the optical system to the image side of the optical system. Referring to Figure 1 The optical system provided by the present application comprises, in order from the object side to the image side along the optical axis of the optical system, a first chalcogenide refractive lens 1, a superlens 2, and a second chalcogenide refractive lens 3.

[0071] The first chalcogenide refractive lens 1 and the second chalcogenide refractive lens 3 are both positive lenses. The superlens 2 comprises a substrate and a superstructure unit, which is arranged on the front surface of the substrate towards the object side and / or on the rear surface of the substrate towards the image side. The vertex and / or center of the superstructure unit is provided with a micro-nano structure. The filling material between the micro-nano structures is air or other material transparent in the working wave band.

[0072] In the optical system provided by the present application, the first chalcogenide refractive lens 1 is mainly used to correct the primary spherical aberration in the system, and the second chalcogenide refractive lens 3 is mainly used to collect light. In the process of collecting light, the second chalcogenide refractive lens 3 will generate higher-order spherical aberration and chromatic aberration. The superlens 2 is mainly used to correct the higher-order spherical aberration and chromatic aberration introduced by the second chalcogenide refractive lens 3, and the off-axis aberration that is difficult to correct by only the first chalcogenide refractive lens 1 and the second chalcogenide refractive lens 3. The off-axis aberration in the present application mainly includes coma, distortion, and off-axis spherical aberration.

[0073] Therefore, by the cooperation of the first chalcogenide refractive lens 1, the superlens 2 and the second chalcogenide refractive lens 3, the optical system provided by the present application can have good imaging quality. Moreover, since the thickness of the superlens 2 is much smaller than that of the conventional lens, compared with the optical system in the related art which uses at least three conventional lenses, the volume of the optical system provided by the present application is greatly reduced.

[0074] Further, since the first chalcogenide refractive lens 1 and the second chalcogenide refractive lens 3 are both made of chalcogenide glass material, and the refractive index temperature coefficient of the chalcogenide glass material is lower than that of other materials, the use of the chalcogenide glass material can help the optical system to be athermalized. Further, the optical system provided by the present application satisfies the following conditions in units of 1 / mm:

[0075]

[0076] wherein n is the refractive index of the first chalcogenide refractive lens 1, is the curvature of the front surface of the first chalcogenide refractive lens 1 towards the object side, is the curvature of the back surface of the first chalcogenide refractive lens 1 towards the image side; n is the refractive index of the second chalcogenide refractive lens 3, is the curvature of the front surface of the second chalcogenide refractive lens 3 towards the object side, is the curvature of the back surface of the second chalcogenide refractive lens 3 towards the image side. n is a dimensionless parameter; and all have units of 1 / mm.

[0077] In detail, the condition composed of n, and constrains the first chalcogenide refractive lens 1 and the second chalcogenide refractive lens 3 at the same time. By setting the lower limit value of the condition to 0.25, the curvature of the refractive lens (including the first chalcogenide refractive lens 1 and the second chalcogenide refractive lens 3) is prevented from being too small, so that even if the refractive index of the refractive lens is small, the refractive lens can still provide sufficient optical power, thereby enabling the refractive lens to sufficiently focus light, and further enabling the optical system to have good imaging quality.

[0078] It should be noted that the greater the refractive index of the refractive lens, the greater the proportion of the role it plays in the optical system, so the greater the influence of the temperature change on the optical system. Moreover, the greater the curvature of the refractive lens, the more susceptible it is to temperature changes, so the greater the influence on the optical system. Therefore, by setting the upper limit value of the condition to 2.01, the refractive index of the refractive lens is prevented from being too large, while the curvature of the refractive lens is prevented from being too large, and thus the performance of the refractive lens under high or low temperature conditions is prevented from being poor, thereby fully correcting the optical system for chromatic aberration, while also ensuring that the refractive lens has good machinability.

[0079] Therefore, the optical system provided by the present application, by the constraint of the condition composed of n, and together, fully corrects the optical system for chromatic aberration while ensuring that the refractive lens has good machinability, and also enables the refractive lens to fully focus light, thereby enabling the optical system to have good imaging quality.

[0080] In summary, the optical system provided by the present application has good imaging quality while reducing the volume, fully correcting for chromatic aberration, and also ensuring that the refractive lens has good machinability; thereby, the requirements of the optical system for good imaging quality, small volume, full chromatic aberration correction, and high lens machinability are met.

[0081] Preferably, in an embodiment, the optical system provided by the present application satisfies the following condition in units of 1 / mm:

[0082]

[0083] In an embodiment, the front surface of the first chalcogenide refractive lens 1 is convex, and the back surface of the first chalcogenide refractive lens 1 is concave; the front surface of the second chalcogenide refractive lens 3 is concave, and the back surface of the second chalcogenide refractive lens 3 is convex. In this embodiment, the first chalcogenide refractive lens 1 as a whole is crescent-shaped towards the object side, and the second chalcogenide refractive lens 3 as a whole is crescent-shaped towards the image side.

[0084] In an embodiment, the optical system provided by the present application also satisfies the following condition in units of femtoseconds fs:

[0085]

[0086] wherein GD (Group Delay) is the group delay of the micro-nano structure, and V is the Abbe number of the first chalcogenide refractive lens 1 or the Abbe number of the second chalcogenide refractive lens 3. The unit of GD is femtosecond, and V is a dimensionless parameter.

[0087] In detail, the following can be used The micro-nano structure at a radial position r in the superlens 2 provides a phase at an angular frequency The first-order expansion term obtained after Taylor expansion of is the group delay GD. It should be noted that the same micro-nano structure usually provides different phases for different wavelengths, and thus there is a certain phase difference in the phases provided by the same micro-nano structure for different wavelengths. If the group delay GD of the micro-nano structure at a certain position is greater, it indicates that the phase difference in the phases provided by the micro-nano structure at the position for different wavelengths is greater. Therefore, the group delay GD can be regarded as the dispersion coefficient of the micro-nano structure, and thus can be used to describe the dispersion introduced by the micro-nano structure.

[0088] It should be noted that the dispersion introduced by the micro-nano structure in the superlens 2 is negative dispersion, that is, the longer the wavelength of the light, the greater the deflection angle of the light. This is contrary to the traditional refractive lens. The dispersion introduced by the traditional refractive lens is positive dispersion, that is, the longer the wavelength of the light, the smaller the deflection angle of the light. Moreover, the positive dispersion introduced by the traditional refractive lens can be described by the Abbe number: the greater the Abbe number, the smaller the positive dispersion introduced by the corresponding refractive lens; on the contrary, the smaller the Abbe number, the greater the positive dispersion introduced by the corresponding refractive lens. Therefore, in combination with the group delay GD corresponding to the micro-nano structure and the Abbe number V corresponding to the refractive lens, the negative dispersion introduced by the superlens 2 and the positive dispersion introduced by the refractive lens can be balanced, thereby correcting the chromatic aberration.

[0089] Therefore, by configuring the lower limit of the condition composed of GD and V to be 5.31, it is possible to prevent the refractive lens (including the first chalcogenide refractive lens 1 and the second chalcogenide refractive lens 3) from introducing too much positive dispersion; by configuring the upper limit of this condition to be 17.90, it is possible to prevent the superlens 2 from introducing too much negative dispersion. Therefore, under the constraint of this condition, the negative dispersion introduced by the superlens 2 and the positive dispersion introduced by the refractive lens are mutually compensated and balanced, thereby fully correcting the chromatic aberration of the optical system.

[0090] Preferably, in an embodiment, the optical system provided by the present application satisfies the following condition in femtoseconds fs:

[0091]

[0092] In an embodiment, since the comprehensive performance of the aspheric lens is better than that of the spherical lens, in this example, the first chalcogenide refractive lens 1 and the second chalcogenide refractive lens 3 are both aspheric lenses, thereby providing a better foundation for the optical system to have good imaging quality.

[0093] In an embodiment, for the purpose of reducing cost, the first chalcogenide refractive lens 1 and the second chalcogenide refractive lens 3 are both spherical lenses. In this case, in order to ensure that the optical system still has good imaging quality, the optical system provided by the present application also satisfies the following condition: 2

[0094]

[0095] wherein M is the maximum value of the absolute value of the slope of the phase provided by the superlens 2, f1 is the effective focal length of the first chalcogenide refractive lens 1, f3 is the effective focal length of the second chalcogenide refractive lens 3. The unit of M is rad / mm, and all in mm.

[0096] In detail, M can be used to represent the optical power provided by the superlens 2 in the off-axis field of view: the larger M is, the greater the optical power provided by the superlens 2 in the off-axis field of view, and the greater the light deflection ability of the superlens 2 in the off-axis field of view; conversely, the smaller M is, the smaller the optical power provided by the superlens 2 in the off-axis field of view, and the smaller the light deflection ability of the superlens 2 in the off-axis field of view.

[0097] Therefore, in the present embodiment, by configuring the lower limit of the condition constituted by M, and as 0.48, it is ensured that the superlens 2 has sufficient light deflection ability in the off-axis field of view, and thus can fully correct the off-axis aberrations, especially the coma, distortion and off-axis spherical aberration, which are difficult to correct by the first chalcogenide refractive lens 1 and the second chalcogenide refractive lens 3 which are set as spherical lenses; by configuring the upper limit of this condition as 1.34, it is avoided that the superlens 2 has too large light deflection ability in the off-axis field of view, thereby avoiding that the superlens 2 introduces excessive chromatic aberration.

[0098] Preferably, in an embodiment, the optical system provided by the present application satisfies the following condition: 2

[0099]

[0100] In an embodiment, the optical system provided by the present application satisfies the following condition:

[0101]

[0102] wherein D3 is the optical effective aperture of the second chalcogenide refractive lens 3, ​​(Back Focal Length) is the back focal length of the optical system. and Same unit (e.g., all in mm).

[0103] In this embodiment, by as well as This condition, as a whole, can be used to characterize the light refraction capability of the second chalcogenide refractive lens 3 in an optical system. The larger the value of this condition, the stronger the light refraction capability of the second chalcogenide refractive lens 3, the faster the light converges, and the smaller the system volume, but at the same time, the greater the chromatic aberration introduced by the second chalcogenide refractive lens 3; conversely, the smaller the value of this condition, the weaker the light refraction capability of the second chalcogenide refractive lens 3, the slower the light converges, and the larger the system volume, but at the same time, the smaller the chromatic aberration introduced by the second chalcogenide refractive lens 3.

[0104] Therefore, by setting the lower limit of this condition to 0.54, the system size is avoided from being too large; by setting the upper limit of this condition to 1.52, excessive chromatic aberration is avoided from being introduced by the second chalcogenide refractive lens 3.

[0105] Preferably, in one embodiment, the optical system provided in this application satisfies the following conditions:

[0106]

[0107] In one embodiment, the micro / nano structure is either a positive micro / nano structure or a negative micro / nano structure. When assembling the superlens 2 with other structural components, the negative micro / nano structure is less susceptible to damage compared to the positive micro / nano structure.

[0108] Furthermore, to further improve the transmittance of the superlens in the far-infrared band, in this embodiment, an antireflective coating can be applied to one side of the substrate with the micro / nano structure of the superlens. Specifically, when the micro / nano structure is a positive micro / nano structure, the antireflective coating covers the area on one side of the substrate where the micro / nano structure is located; when the micro / nano structure is a negative micro / nano structure, the antireflective coating covers the area on one side of the substrate where the micro / nano structure is not located.

[0109] In one embodiment, the superlens 2 includes at least one layer of superstructure unit.

[0110] In this embodiment, the superlens 2 may include a single superstructure unit or multiple superstructure units. Compared to a superlens 2 with a single superstructure unit, a superlens 2 with multiple superstructure units has a higher degree of freedom in modulating light.

[0111] In one embodiment, the optical system has an aperture stop adjacent to the superlens 2; the aperture stop is disposed on the surface of the superlens 2, or the aperture stop is spaced apart from the superlens 2.

[0112] In this embodiment, the optical system is provided with a diaphragm to control the amount of light entering the optical system. The diaphragm is adjacent to the superlens 2; specifically, the diaphragm can be provided on the front surface of the substrate of the superlens 2 facing the object side, or on the rear surface of the substrate of the superlens 2 facing the image side, or can be provided separately from the superlens 2 without other optical elements between them, but other non-optical elements (for example, a spacer for maintaining the spacing between them) can be provided.

[0113] Figure 2 The architectural layout of the optical lens provided by the present application working in the far-infrared waveband is shown. Referring to Figure 2 The present application also provides an optical lens working in the far-infrared waveband, which comprises a lens barrel 6; a pressing ring 7, a first spacer ring 8, a second spacer ring 9 provided inside the lens barrel, and an optical system (a first chalcogenide refractive lens 1, a superlens 2, and a second chalcogenide refractive lens 3) provided by any of the above embodiments.

[0114] In the optical lens, the pressing ring 7 abuts against the front surface of the first chalcogenide refractive lens facing the object side, the first spacer ring 8 abuts against the front surface of the superlens facing the object side, and the second spacer ring 9 abuts against the front surface of the second chalcogenide refractive lens facing the object side.

[0115] In an embodiment, the optical lens provided by the present application further comprises a window glass 4 and an imaging detector provided on the image plane 5. The window glass 4 is provided between the second chalcogenide refractive lens 3 and the imaging detector to protect the second chalcogenide refractive lens 3 and the imaging detector.

[0116] Table 1. Target requirements for various system parameters of the optical system

[0117] System Parameters Data Total Optical Length (TTL) ≤ 20 mm Field of View (2ω) ≥31° F Number ≤1.05 MTF ≥0.2 Operating Waveband 8-12 μm

[0118] Table 1 shows the target requirements for various system parameters of the optical system to be provided in an embodiment. Specifically, in an embodiment, the optical system to be provided is targeted to work in the far-infrared waveband, i.e., the 8-12 μm waveband; the total optical length TTL (Total Track Length) is targeted to be less than or equal to 20 mm; the field of view angle is targeted to be greater than or equal to 31°; and the F number is targeted to be less than or equal to 1.05. Moreover, in this embodiment, the MTF target requirement for each spatial frequency in the full field of view range is greater than or equal to 0.2. Wherein, MTF (Modulation Transfer Function), also known as modulation transfer function, is an important indicator for describing the imaging quality of an optical system. The closer the MTF value is to the diffraction limit, the better the imaging quality.

[0119] With the target requirements shown in Table 1 as the target, the present application exemplarily provides six optical systems satisfying the target requirements shown in Table 1 in six embodiments. Next, the six optical systems provided by the present application are introduced in detail.

[0120] Example 1

[0121] Figure 3 The layout architecture diagram of the optical system provided by Embodiment 1 working in the far-infrared waveband is shown. Referring to Figure 3 The optical system provided by the present embodiment comprises, in order from the object side to the image side along the optical axis: a first chalcogenide refractive lens, an aperture stop, a superlens, and a second chalcogenide refractive lens; wherein the aperture stop is arranged on the front surface of the superlens. On the basis of the optical system, a window glass can be further arranged between the second chalcogenide refractive glass and the image plane.

[0122] Table 2. System parameters of the optical system provided by Embodiment 1

[0123] System Parameters Data Total Optical Length (TTL) 13.75 mm Field of View (2ω) 31.1° F Number 1.0 Effective Focal Length 7.05 mm Operating Waveband 8-12 μm

[0124] As can be seen from Table 2, the optical system provided by the present embodiment works in the 8-12 μm waveband, and the total optical length is 13.75 mm, which fully meets the demand of the optical system for miniaturization; the field of view is 31.1°, which fully meets the demand of the optical system for the field of view; and the F number is 1.0, which fully meets the demand of the optical system for the amount of light.

[0125] In the direction from the object side to the image side, each surface contained from the first chalcogenide refractive lens to the image plane in the present embodiment is numbered, and the parameters of each surface are summarized to obtain Table 3 as shown below.

[0126] Table 3. Parameters of each surface contained from the first chalcogenide refractive lens to the image plane in Embodiment 1

[0127]

[0128] Wherein, Table 1 is an object plane (which is not shown in the drawings), and Table 2 is an image plane (which is not shown in the drawings). Figure 3Surface 1 is a plane, which is located at the left side of the first chalcogenide refractive lens. Surface 2 is the front surface of the first chalcogenide refractive lens. Surface 3 is the back surface of the first chalcogenide refractive lens. Surface 4 is the front surface of the superlens substrate. Since the aperture is located at the front surface of the superlens in this embodiment, the surface type of surface 4 is recorded as aperture. Surface 5 is the back surface of the superlens. Since the micro-nano structure is located at the back surface of the superlens in this embodiment, the surface type of surface 5 is recorded as super surface. Surface 6 is the front surface of the second chalcogenide refractive lens. Surface 7 is the back surface of the second chalcogenide refractive lens. Surface 8 is the front surface of the window glass towards the object side. Surface 9 is the back surface of the window glass towards the image side. Surface 10 is the image plane.

[0129] As can be seen from Table 3, the curvature radius of surface 1 is infinite (i.e., it is a plane), the distance between surface 1 and surface 2 is indefinite, and the material between surface 1 and surface 2 is air. Surface 2 is a spherical surface with a curvature radius of 5.41 mm, the distance between surface 2 and surface 3 is 1.11 mm, and the material between surface 2 and surface 3 is IRG204 chalcogenide glass. Surface 3 is a spherical surface with a curvature radius of 5.06 mm, the distance between surface 3 and surface 4 is 1.03 mm, and the material between surface 3 and surface 4 is air. Surface 4 is a plane, the distance between surface 4 and surface 5 is 0.375 mm, and the material between surface 4 and surface 5 is silicon, including but not limited to intrinsic silicon, optical silicon, crystalline silicon, amorphous silicon, extrinsic silicon. Surface 5 is a plane, the distance between surface 5 and surface 6 is 1.81 mm, and the material between surface 5 and surface 6 is air. Surface 6 is an even aspheric surface with a curvature radius of -33.42 mm, the distance between surface 6 and surface 7 is 4.00 mm, and the material between surface 6 and surface 7 is IRG204 chalcogenide glass. Surface 7 is an even aspheric surface with a curvature radius of -10.09 mm, the distance between surface 7 and surface 8 is 4.80 mm, and the material between surface 7 and surface 8 is air. Surface 8 is a plane, the distance between surface 8 and surface 9 is 0.5 mm, and the material between surface 8 and surface 9 is silicon, including but not limited to intrinsic silicon, optical silicon, crystalline silicon, amorphous silicon, extrinsic silicon. Surface 9 is a plane, the distance between surface 9 and surface 10 is 0.13 mm, and the material between surface 9 and surface 10 is air.

[0130] Figure 4 A curve graph showing the MTF of the optical system provided in Embodiment 1 changing with the field of view in a normal temperature environment is shown; in general, the normal temperature environment refers to a 25℃ environment. Figure 5 A curve graph showing the MTF of the optical system provided in Embodiment 1 changing with the field of view in a -40℃ environment is shown. Figure 6 A curve graph showing the MTF of the optical system provided in Embodiment 1 changing with the field of view in a 80℃ environment is shown.

[0131] In Figures 4-6In any of the accompanying drawings, the horizontal axis represents the field of view on the Y axis, in degrees; the vertical axis represents the MTF value; and T represents the meridional curve and S represents the sagittal curve. Specifically, the meridional curve T1 and the sagittal curve S1 correspond to a spatial frequency of 5.00 cycles per millimeter (cyc / mm); the meridional curve T2 and the sagittal curve S2 correspond to a spatial frequency of 10.00 cyc / mm; the meridional curve T3 and the sagittal curve S3 correspond to a spatial frequency of 15.00 cyc / mm; the meridional curve T4 and the sagittal curve S4 correspond to a spatial frequency of 20.00 cyc / mm; the meridional curve T5 and the sagittal curve S5 correspond to a spatial frequency of 40.00 cyc / mm; and the meridional curve T6 and the sagittal curve S6 correspond to a spatial frequency of 42.00 cyc / mm.

[0132] From Figure 4 It can be seen that the optical system provided in this embodiment has an MTF of each spatial frequency in the full field of view range greater than 0.2 at room temperature, which indicates that the imaging quality of the optical system is excellent at room temperature. From Figure 5 It can be seen that the optical system provided in this embodiment has an MTF of each spatial frequency in the full field of view range greater than 0.2 at -40°C, which indicates that the imaging quality of the optical system is excellent at -40°C. From Figure 5 It can be seen that the optical system provided in this embodiment has an MTF of each spatial frequency in the full field of view range greater than 0.2 at 80°C, which indicates that the imaging quality of the optical system is excellent at 80°C.

[0133] In summary Figures 4-6 It can be seen that the optical system provided in this embodiment can maintain good imaging quality in the temperature range of -40°C to 80°C, which indicates that the optical system fully realizes the athermalization.

[0134] Figure 7 A field curvature diagram of the optical system provided in Example 1 is shown. Figure 7 The horizontal axis represents the distance deviation between the actual focal point of the optical system and the image plane, in millimeters; and the vertical axis represents the field of view in the positive direction of the Y axis, in degrees. Figure 7 In the diagram, T represents the meridional curve and S represents the sagittal curve; specifically, the meridional curve T8 and the sagittal curve S8 correspond to a working wavelength of 8 μm; the meridional curve T 10 and the sagittal curve S 10 correspond to a working wavelength of 10 μm; the meridional curve T 12 and the sagittal curve S 12 correspond to a working wavelength of 12 μm.

[0135] From Figure 7As can be seen, in this embodiment, the field curvature corresponding to each wavelength in the 8-12μm band is less than 0.05 mm, which indicates that the field curvature of the optical system is very small.

[0136] Figure 8 The distortion diagram of the optical system provided in Embodiment 1 is shown. Figure 8 The horizontal axis represents the degree of image distortion, expressed as a percentage; the vertical axis represents the field of view along the positive Y-axis, expressed as degrees. Figure 8 The actual figure shows three curves: the distortion curve corresponding to the 8μm wavelength, the distortion curve corresponding to the 10μm wavelength, and the distortion curve corresponding to the 12μm wavelength. However, these three curves almost completely overlap.

[0137] Depend on Figure 8 As can be seen, in this embodiment, the distortion corresponding to each wavelength in the 8-12μm band is less than 2.0%, which indicates that the distortion of the optical system is very small.

[0138] Example 2

[0139] Figure 9 A layout diagram of the optical system operating in the far-infrared band provided in Embodiment 2 is shown. See also Figure 9 The optical system provided in this embodiment includes, in sequence along the optical axis from the object side to the image side: a first chalcogenide refractive lens, an aperture stop, a superlens, and a second chalcogenide refractive lens; wherein the aperture stop is disposed between the first chalcogenide refractive lens and the superlens. Based on this optical system, a window glass may be further provided, disposed between the second chalcogenide refractive glass and the image plane.

[0140] Table 4. System parameters of the optical system provided in Example 2

[0141] System Parameters Data Total Optical Length (TTL) 11.82 mm Field of View (2ω) 31° F Number 1.0 Effective Focal Length 7.02 mm Operating Waveband 8-12 μm

[0142] As shown in Table 4, the optical system provided in this embodiment operates in the 8-12μm band, with a total optical length of 11.82mm, which fully meets the requirements for miniaturization of the optical system; its field of view is 31°, which fully meets the requirements for the field of view of the optical system; and its F-number is 1.0, which fully meets the requirements for the amount of light entering the optical system.

[0143] Along the direction from the object side to the image side, each surface included from the first chalcogenide refractive lens to the image plane in this embodiment is labeled, and the parameters of each surface are summarized to obtain the following Table 5.

[0144] Table 5. Parameters of each surface included from the first chalcogenide refractive lens to the image plane in Example 2.

[0145]

[0146] Table 5 is not described again here.

[0147] Figure 10 A curve diagram showing the MTF of the optical system provided in Embodiment 2 varying with the field of view in a normal temperature environment is shown. Figure 11 A curve diagram showing the MTF of the optical system provided in Embodiment 2 varying with the field of view in a -40℃ environment is shown. Figure 12 A curve diagram showing the MTF of the optical system provided in Embodiment 2 varying with the field of view in an 80℃ environment is shown.

[0148] In any of the accompanying drawings, the horizontal axis represents the field of view on the Y axis, in degrees; the vertical axis represents the MTF value. Meridional curve T1 and sagittal curve S1 correspond to a spatial frequency of 5.00 cyc / mm; meridional curve T2 and sagittal curve S2 correspond to a spatial frequency of 10.00 cyc / mm; meridional curve T3 and sagittal curve S3 correspond to a spatial frequency of 15.00 cyc / mm; meridional curve T4 and sagittal curve S4 correspond to a spatial frequency of 20.00 cyc / mm; meridional curve T5 and sagittal curve S5 correspond to a spatial frequency of 40.00 cyc / mm; meridional curve T6 and sagittal curve S6 correspond to a spatial frequency of 42.00 cyc / mm. Figures 10-12

[0149] It can be seen that the MTF of the optical system provided in the embodiment is always greater than 0.32 at each spatial frequency in the full field of view in a normal temperature environment, thereby indicating that the imaging quality of the optical system in a normal temperature environment is excellent. It can be seen that the MTF of the optical system provided in the embodiment is always greater than 0.28 at each spatial frequency in the full field of view in a -40℃ environment, thereby indicating that the imaging quality of the optical system in a -40℃ environment is excellent. It can be seen that the MTF of the optical system provided in the embodiment is always greater than 0.34 at each spatial frequency in the full field of view in an 80℃ environment, thereby indicating that the imaging quality of the optical system in an 80℃ environment is excellent. Figure 10 Figure 11 Figure 12

[0150] In summary Figures 10-12 It can be seen that the optical system provided in the embodiment can always maintain excellent imaging quality in a temperature range of -40℃ to 80℃, thereby indicating that the optical system fully realizes athermalization.

[0151] Figure 13 A field curvature diagram of the optical system provided in Embodiment 2 is shown. Figure 13 The horizontal axis represents the distance deviation between the actual focal point of the optical system and the image plane, in millimeters; the vertical axis represents the field of view in the positive direction along the Y axis, in degrees. Figure 13 ​​​​In the diagram, the meridional curve T8 and the sagittal curve S8 correspond to the 8μm operating wavelength; the meridional curve T... 10 With the sagittal curve S 10 Corresponding to a 10μm operating wavelength; Meridian curve T 12 With the sagittal curve S 12 Corresponding to a 12μm operating wavelength.

[0152] Depend on Figure 13 As can be seen, in this embodiment, the field curvature corresponding to each wavelength in the 8-12μm band is less than 0.02 mm, which indicates that the field curvature of the optical system is very small.

[0153] Figure 14 The distortion diagram of the optical system provided in Embodiment 2 is shown. Figure 14 The horizontal axis represents the degree of image distortion, expressed as a percentage; the vertical axis represents the field of view along the positive Y-axis, expressed as degrees. Figure 14 The actual figure shows three curves: the distortion curve corresponding to the 8μm wavelength, the distortion curve corresponding to the 10μm wavelength, and the distortion curve corresponding to the 12μm wavelength. However, these three curves almost completely overlap.

[0154] Depend on Figure 14 As can be seen, in this embodiment, the distortion corresponding to each wavelength in the 8-12μm band is less than 1.0%, which indicates that the distortion of the optical system is very small.

[0155] Example 3

[0156] Figure 15 The layout architecture diagram of the optical system operating in the far-infrared band provided in Embodiment 3 is shown. See also Figure 15 The optical system provided in this embodiment includes, in sequence along the optical axis from the object side to the image side: a first chalcogenide refractive lens, a superlens, an aperture stop, and a second chalcogenide refractive lens; wherein the aperture stop is disposed on the rear surface of the superlens, and the micro / nano structure is also disposed on the rear surface of the superlens. Based on this optical system, a window glass may be further provided, disposed between the second chalcogenide refractive glass and the image plane.

[0157] Table 6. System parameters of the optical system provided in Example 3

[0158] System Parameters Data Total Optical Length (TTL) 10.92 mm Field of View (2ω) 34° F Number 1.0 Effective Focal Length 6.87 mm Operating Waveband 8-12 μm

[0159] As shown in Table 6, the optical system provided in this embodiment operates in the 8-12μm band, with a total optical length of 10.92mm, which fully meets the requirements for miniaturization of the optical system; its field of view is 34°, which fully meets the requirements for the field of view of the optical system; and its F-number is 1.0, which fully meets the requirements for the amount of light entering the optical system.

[0160] Along the direction from the object side to the image side, each surface included from the first chalcogenide refractive lens to the image plane in this embodiment is labeled, and the parameters of each surface are summarized to obtain the following Table 7.

[0161] Table 7. Parameters of each surface included from the first chalcogenide refractive lens to the image plane in Example 3.

[0162]

[0163] See the explanation for Table 3; Table 7 will not be repeated here.

[0164] Figure 16 The graph shows the MTF of the optical system provided in Example 3 as a function of the field of view under normal temperature conditions. Figure 17 The graph shows the MTF of the optical system provided in Example 3 as a function of the field of view at -40°C. Figure 18 The graph shows the MTF of the optical system provided in Example 3 as a function of the field of view at an 80°C environment.

[0165] exist Figures 16-18 In any of the attached figures, the horizontal axis represents the field of view on the Y-axis, in degrees; the vertical axis represents the MTF value. Meridian curve T1 and sagittal curve S1 correspond to a spatial frequency of 5.00 cyc / mm; meridian curve T2 and sagittal curve S2 correspond to a spatial frequency of 10.00 cyc / mm; meridian curve T3 and sagittal curve S3 correspond to a spatial frequency of 15.00 cyc / mm; meridian curve T4 and sagittal curve S4 correspond to a spatial frequency of 20.00 cyc / mm; meridian curve T5 and sagittal curve S5 correspond to a spatial frequency of 40.00 cyc / mm; and meridian curve T6 and sagittal curve S6 correspond to a spatial frequency of 42.00 cyc / mm.

[0166] Depend on Figure 16 As can be seen, the optical system provided in this embodiment maintains an MTF greater than 0.3 at all spatial frequencies across the entire field of view under normal temperature conditions, demonstrating excellent imaging quality at room temperature. Figure 17 As can be seen, the optical system provided in this embodiment maintains an MTF greater than 0.25 at all spatial frequencies across the entire field of view at -40℃, demonstrating excellent imaging quality at this temperature. Figure 18 As can be seen, the optical system provided in this embodiment has an MTF greater than 0.3 for all spatial frequencies in the entire field of view at 80°C, which indicates that the optical system has excellent imaging quality at 80°C.

[0167] comprehensive Figures 16-18As can be seen, the optical system provided in this embodiment can maintain excellent imaging quality within a temperature range of -40℃ to 80℃, which shows that the optical system has fully achieved thermal differential reduction.

[0168] Figure 19 The field curve diagram of the optical system provided in Example 3 is shown. Figure 19 The horizontal axis represents the distance deviation between the actual focal point of the optics and the image plane, in millimeters; the vertical axis represents the field of view along the positive Y-axis, in degrees. Figure 19 In the diagram, the meridional curve T8 and the sagittal curve S8 correspond to the 8μm operating wavelength; the meridional curve T... 10 With the sagittal curve S 10 Corresponding to a 10μm operating wavelength; Meridian curve T 12 With the sagittal curve S 12 Corresponding to a 12μm operating wavelength.

[0169] Depend on Figure 19 As can be seen, in this embodiment, the field curvature corresponding to each wavelength in the 8-12μm band is less than 0.09 mm, which indicates that the field curvature of the optical system is very small.

[0170] Figure 20 The distortion diagram of the optical system provided in Example 3 is shown. Figure 20 The horizontal axis represents the degree of image distortion, expressed as a percentage; the vertical axis represents the field of view along the positive Y-axis, expressed as degrees. Figure 20 The actual figure shows three curves: the distortion curve corresponding to the 8μm wavelength, the distortion curve corresponding to the 10μm wavelength, and the distortion curve corresponding to the 12μm wavelength. However, these three curves almost completely overlap.

[0171] Depend on Figure 20 As can be seen, in this embodiment, the distortion corresponding to each wavelength in the 8-12μm band is less than 1.2%, which indicates that the distortion of the optical system is very small.

[0172] Example 4

[0173] Figure 21 A layout diagram of the optical system operating in the far-infrared band, as provided in Embodiment 4, is shown. See also... Figure 21 The optical system provided in this embodiment includes, in sequence along the optical axis from the object side to the image side: a first chalcogenide refractive lens, a superlens, an aperture stop, and a second chalcogenide refractive lens; wherein the aperture stop is disposed on the rear surface of the superlens, and the micro / nano structure is also disposed on the rear surface of the superlens. Based on this optical system, a window glass may be further provided, disposed between the second chalcogenide refractive glass and the image plane.

[0174] Table 8. System parameters of the optical system provided in Example 4

[0175] System Parameters Data Total Optical Length (TTL) 11.32 mm Field of View (2ω) 34° F Number 1.0 Effective Focal Length 6.89 mm Operating Waveband 8-12 μm

[0176] As shown in Table 8, the optical system provided in this embodiment operates in the 8-12μm band, with a total optical length of 11.32mm, which fully meets the requirements for miniaturization of the optical system; its field of view is 34°, which fully meets the requirements for the field of view of the optical system; and its F-number is 1.0, which fully meets the requirements for the amount of light entering the optical system.

[0177] Along the direction from the object side to the image side, each surface included from the first chalcogenide refractive lens to the image plane in this embodiment is labeled, and the parameters of each surface are summarized to obtain Table 9 as shown below.

[0178] Table 9. Parameters of each surface included from the first chalcogenide refractive lens to the image plane in Example 4

[0179]

[0180] See the explanation for Table 3; Table 9 will not be repeated here.

[0181] Figure 22 The graph shows the MTF of the optical system provided in Example 4 as a function of the field of view under normal temperature conditions. Figure 23 The graph shows the MTF of the optical system provided in Example 4 as a function of the field of view at -40°C. Figure 24 The graph shows the MTF of the optical system provided in Example 4 as a function of the field of view at an 80°C environment.

[0182] exist Figures 22-24 In any of the attached figures, the horizontal axis represents the field of view on the Y-axis, in degrees; the vertical axis represents the MTF value. Meridian curve T1 and sagittal curve S1 correspond to a spatial frequency of 5.00 cyc / mm; meridian curve T2 and sagittal curve S2 correspond to a spatial frequency of 10.00 cyc / mm; meridian curve T3 and sagittal curve S3 correspond to a spatial frequency of 15.00 cyc / mm; meridian curve T4 and sagittal curve S4 correspond to a spatial frequency of 20.00 cyc / mm; meridian curve T5 and sagittal curve S5 correspond to a spatial frequency of 40.00 cyc / mm; and meridian curve T6 and sagittal curve S6 correspond to a spatial frequency of 42.00 cyc / mm.

[0183] Depend on Figure 22 As can be seen, the optical system provided in this embodiment maintains an MTF (Mean Transmission Frequency) greater than 0.19 at almost all spatial frequencies across the entire field of view under normal temperature conditions, indicating that the optical system exhibits good imaging quality at normal temperature. Figure 23As can be seen, the optical system provided in this embodiment maintains an MTF (Mean Transmission Frequency) greater than 0.15 at almost all spatial frequencies across the entire field of view at -40℃, indicating that the optical system exhibits good imaging quality at -40℃. Figure 24 As can be seen, the optical system provided in this embodiment has an MTF greater than 0.2 for all spatial frequencies in the entire field of view at 80°C, which indicates that the optical system has excellent imaging quality at 80°C.

[0184] comprehensive Figures 22-24 As can be seen, the optical system provided in this embodiment can maintain good imaging quality within a temperature range of -40℃ to 80℃, which shows that the optical system has fully achieved thermal differential reduction.

[0185] Figure 25 The field curve diagram of the optical system provided in Example 4 is shown. Figure 25 The horizontal axis represents the distance deviation between the actual focal point of the optics and the image plane, in millimeters; the vertical axis represents the field of view along the positive Y-axis, in degrees. Figure 25 In the diagram, the meridional curve T8 and the sagittal curve S8 correspond to the 8μm operating wavelength; the meridional curve T... 10 With the sagittal curve S 10 Corresponding to a 10μm operating wavelength; Meridian curve T 12 With the sagittal curve S 12 Corresponding to a 12μm operating wavelength.

[0186] Depend on Figure 25 As can be seen, in this embodiment, the field curvature corresponding to each wavelength in the 8-12μm band is less than 0.08 mm, which indicates that the field curvature of the optical system is very small.

[0187] Figure 26 The distortion diagram of the optical system provided in Example 4 is shown. Figure 26 The horizontal axis represents the degree of image distortion, expressed as a percentage; the vertical axis represents the field of view along the positive Y-axis, expressed as degrees. Figure 26 The actual figure shows three curves: the distortion curve corresponding to the 8μm wavelength, the distortion curve corresponding to the 10μm wavelength, and the distortion curve corresponding to the 12μm wavelength. However, these three curves almost completely overlap.

[0188] Depend on Figure 26 As can be seen, in this embodiment, the distortion corresponding to each wavelength in the 8-12μm band is less than 0.8%, which indicates that the distortion of the optical system is very small.

[0189] Example 5

[0190] Figure 27A layout architecture diagram of the optical system operating in the far-infrared wave band provided in Embodiment 5 is shown. Referring to Figure 27 The optical system provided in the embodiment comprises, in order from the object side to the image side along the optical axis, a first chalcogenide refractive lens, a superlens, an aperture, and a second chalcogenide refractive lens. The aperture is arranged on the rear surface of the superlens. On the basis of the optical system, a window glass can be further arranged between the second chalcogenide refractive glass and the image plane.

[0191] Table 10. System parameters of the optical system provided in Embodiment 5

[0192] System Parameters Data Total Optical Length (TTL) 11.70 mm Field of View (2ω) 34° F Number 0.99 Effective Focal Length 6.98 mm Operating Waveband 8-12 μm

[0193] As shown in Table 10, the optical system provided in the embodiment operates in the 8-12 μm wave band, has an optical total length of 11.70 mm, fully meets the demand of the optical system for miniaturization, has a field of view of 34°, fully meets the demand of the optical system for the field of view, and has an F number of 0.99, fully meets the demand of the optical system for the amount of light.

[0194] The surfaces comprised from the first chalcogenide refractive lens to the image plane in the embodiment are numbered in order from the object side to the image side, and the parameters of the surfaces are summarized to obtain Table 11 as shown below.

[0195] Table 11. Parameters of the surfaces comprised from the first chalcogenide refractive lens to the image plane in Embodiment 5

[0196]

[0197] For the explanation of Table 3, Table 11 is not described here again.

[0198] Figure 28 A curve diagram of the MTF of the optical system provided in Embodiment 5 varying with the field of view in a normal temperature environment is shown. Figure 29 A curve diagram of the MTF of the optical system provided in Embodiment 5 varying with the field of view in a -40℃ environment is shown. Figure 30 A curve diagram of the MTF of the optical system provided in Embodiment 5 varying with the field of view in an 80℃ environment is shown.

[0199] In Figures 28-30In any of the attached figures, the horizontal axis represents the field of view on the Y-axis, in degrees; the vertical axis represents the MTF value. Meridian curve T1 and sagittal curve S1 correspond to a spatial frequency of 5.00 cyc / mm; meridian curve T2 and sagittal curve S2 correspond to a spatial frequency of 10.00 cyc / mm; meridian curve T3 and sagittal curve S3 correspond to a spatial frequency of 15.00 cyc / mm; meridian curve T4 and sagittal curve S4 correspond to a spatial frequency of 20.00 cyc / mm; meridian curve T5 and sagittal curve S5 correspond to a spatial frequency of 40.00 cyc / mm; and meridian curve T6 and sagittal curve S6 correspond to a spatial frequency of 42.00 cyc / mm.

[0200] Depend on Figure 28 As can be seen, the optical system provided in this embodiment maintains an MTF greater than 0.2 at all spatial frequencies across the entire field of view under normal temperature conditions, demonstrating excellent imaging quality at room temperature. Figure 29 As can be seen, the optical system provided in this embodiment maintains an MTF (Mean Transmission Frequency) greater than 0.18 at almost all spatial frequencies across the entire field of view at -40℃, indicating that the optical system exhibits good imaging quality at -40℃. Figure 30 As can be seen, the optical system provided in this embodiment has an MTF greater than 0.23 for all spatial frequencies in the entire field of view at 80°C, which indicates that the optical system has excellent imaging quality at 80°C.

[0201] comprehensive Figures 28-30 As can be seen, the optical system provided in this embodiment can maintain good imaging quality within a temperature range of -40℃ to 80℃, which shows that the optical system has fully achieved thermal differential reduction.

[0202] Figure 31 The field curve diagram of the optical system provided in Example 5 is shown. Figure 31 The horizontal axis represents the distance deviation between the actual focal point of the optics and the image plane, in millimeters; the vertical axis represents the field of view along the positive Y-axis, in degrees. Figure 31 In the diagram, the meridional curve T8 and the sagittal curve S8 correspond to the 8μm operating wavelength; the meridional curve T... 10 With the sagittal curve S 10 Corresponding to a 10μm operating wavelength; Meridian curve T 12 With the sagittal curve S 12 Corresponding to a 12μm operating wavelength.

[0203] Depend on Figure 31 As can be seen, in this embodiment, the field curvature corresponding to each wavelength in the 8-12μm band is less than 0.04 mm, which indicates that the field curvature of the optical system is very small.

[0204] Figure 32The distortion diagram of the optical system provided in Embodiment 5 is shown. Figure 32 The horizontal axis represents the degree of image distortion, expressed as a percentage; the vertical axis represents the field of view along the positive Y-axis, expressed as degrees. Figure 32 The actual figure shows three curves: the distortion curve corresponding to the 8μm wavelength, the distortion curve corresponding to the 10μm wavelength, and the distortion curve corresponding to the 12μm wavelength. However, these three curves almost completely overlap.

[0205] Depend on Figure 32 As can be seen, in this embodiment, the distortion corresponding to each wavelength in the 8-12μm band is less than 0.45%, which indicates that the distortion of the optical system is very small.

[0206] Example 6

[0207] Figure 33 A layout diagram of the optical system operating in the far-infrared band provided in Embodiment 6 is shown. See also Figure 33 The optical system provided in this embodiment includes, in sequence along the optical axis from the object side to the image side: a first chalcogenide refractive lens, a superlens, an aperture stop, and a second chalcogenide refractive lens; wherein the aperture stop is disposed on the rear surface of the superlens, and the micro / nano structure is also disposed on the rear surface of the superlens. Based on this optical system, a window glass may be further provided, disposed between the second chalcogenide refractive glass and the image plane.

[0208] Table 12. System parameters of the optical system provided in Example 6

[0209] System Parameters Data Total Optical Length (TTL) 11.43 mm Field of View (2ω) 30.9° F Number 1.0 Effective Focal Length 6.90 mm Operating Waveband 8-12 μm

[0210] As shown in Table 12, the optical system provided in this embodiment operates in the 8-12μm band, with a total optical length of 11.43mm, which fully meets the requirements for miniaturization of the optical system; its field of view is 30.9°, which fully meets the requirements for the field of view of the optical system; and its F-number is 1.0, which fully meets the requirements for the amount of light received by the optical system.

[0211] Along the direction from the object side to the image side, each surface included from the first chalcogenide refractive lens to the image plane in this embodiment is labeled, and the parameters of each surface are summarized to obtain Table 13 as shown below.

[0212] Table 13. Parameters of each surface included from the first chalcogenide refractive lens to the image plane in Example 6

[0213]

[0214] See the explanation for Table 3; Table 13 will not be repeated here.

[0215] Figure 34Fig. 6 shows a curve of the MTF of the optical system provided in Embodiment 6 varying with the field of view in a normal temperature environment. Figure 35 Fig. 7 shows a curve of the MTF of the optical system provided in Embodiment 6 varying with the field of view in an environment of -40°C. Figure 36 Fig. 8 shows a curve of the MTF of the optical system provided in Embodiment 6 varying with the field of view in an environment of 80°C.

[0216] In any of the accompanying drawings, the horizontal axis represents the field of view on the Y axis, in degrees; and the vertical axis represents the MTF value. Figures 34-36 In any of the accompanying drawings, the horizontal axis represents the field of view on the Y axis, in degrees; and the vertical axis represents the MTF value.

[0217] It can be seen that the MTF of the optical system provided in this embodiment is always greater than 0.25 at each spatial frequency in the full field of view in a normal temperature environment, which indicates that the imaging quality of the optical system in a normal temperature environment is excellent. Figure 34 It can be seen that the MTF of the optical system provided in this embodiment is always greater than 0.23 at each spatial frequency in the full field of view in an environment of -40°C, which indicates that the imaging quality of the optical system in an environment of -40°C is excellent. Figure 35 It can be seen that the MTF of the optical system provided in this embodiment is always greater than 0.27 at each spatial frequency in the full field of view in an environment of 80°C, which indicates that the imaging quality of the optical system in an environment of 80°C is excellent. Figure 36 In summary,

[0218] It can be seen that the optical system provided in this embodiment can always maintain excellent imaging quality in a temperature range of -40°C to 80°C, which indicates that the optical system fully realizes athermalization. Figures 34-36

[0219] Fig. 9 shows a field curvature diagram of the optical system provided in Embodiment 6. Figure 37 In the accompanying drawings, the horizontal axis represents the distance deviation between the actual focal point of the optical system and the image plane, in millimeters; and the vertical axis represents the field of view in the positive direction of the Y axis, in degrees. Figure 37 In the accompanying drawings, the horizontal axis represents the distance deviation between the actual focal point of the optical system and the image plane, in millimeters; and the vertical axis represents the field of view in the positive direction of the Y axis, in degrees. Figure 37 In the accompanying drawings, the horizontal axis represents the distance deviation between the actual focal point of the optical system and the image plane, in millimeters; and the vertical axis represents the field of view in the positive direction of the Y axis, in degrees. 10 In the accompanying drawings, the horizontal axis represents the distance deviation between the actual focal point of the optical system and the image plane, in millimeters; and the vertical axis represents the field of view in the positive direction of the Y axis, in degrees. 10 In the accompanying drawings, the horizontal axis represents the distance deviation between the actual focal point of the optical system and the image plane, in millimeters; and the vertical axis represents the field of view in the positive direction of the Y axis, in degrees.12 sagittal curve S 12 corresponding to 12 pm working wavelength. Meridional curve T8 and meridional curve T 12 Almost completely overlap at the maximum field of view.

[0220] By Figure 37 It can be seen that in this embodiment, the field curvature corresponding to each wavelength in the 8-12 pm waveband is less than 0.06 mm, thus illustrating that the field curvature of the optical system is very small.

[0221] Figure 38 The distortion figure of the optical system provided in embodiment 6 is shown. Figure 38 The horizontal axis represents the distortion degree of imaging, in percentage; the vertical axis represents the field of view along the positive direction of the Y axis, in degrees. Figure 38 The distortion curve I corresponding to 8 pm wavelength, the distortion curve II corresponding to 10 pm wavelength, and the distortion curve III corresponding to 12 pm wavelength are shown.

[0222] By Figure 38 It can be seen that in this embodiment, the distortion corresponding to each wavelength in the 8-12 pm waveband is less than 0.09%, thus illustrating that the distortion of the optical system is very small.

[0223] After summarizing the parameters of the optical systems provided in the above six embodiments, Table 14 shown below is obtained. The display of Table 14 is mainly used to illustrate that the conditions met by the optical systems provided in the present application are all verified and supported by experiments.

[0224] It should be noted that since n represents the refractive index of the first chalcogenide refractive lens or the refractive index of the second chalcogenide refractive lens, n in each embodiment in Table 14 has two values; specifically, in the same embodiment, the first value represents the refractive index of the first chalcogenide refractive lens, and the second value represents the refractive index of the second chalcogenide refractive lens. Similarly, the specific cases of , V and will not be described in detail.

[0225] It should also be noted that since a superlens contains numerous micro-nano structures, the group delay of different micro-nano structures is usually different, therefore, for the micro-nano structures of the superlens in each embodiment, the group delay GD thereof is not listed in discrete specific values, and in the following table, a numerical range is used to represent the group delay GD thereof; for the same reason, in the following table, a numerical range is used to represent the group delay GD of the micro-nano structures of the superlens. This condition is represented.

[0226] Table 14. Parameters of the optical systems provided in each embodiment

[0227] ​

[0228] Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the application being indicated by the following claims.

Claims

1. An optical system operating in the far-infrared band, characterized in that, Along the optical axis of the optical system, from the object side to the image side, the system comprises, in sequence: a first chalcogenide refractive lens, a superlens, and a second chalcogenide refractive lens, with a total of three lenses having optical power. Both the first and second chalcogenide refractive lenses are positive lenses. The front surface of the second chalcogenide refractive lens facing the object side is convex towards the image side, and the radius of curvature of its front surface facing the object side is negative. The superlens includes a substrate and a superstructure unit, the superstructure unit containing micro / nano structures. The optical system satisfies the following condition in units of 1 / mm: Where n is the refractive index of the first chalcogenide refractive lens, Let be the curvature of the front surface of the first chalcogenide refractive lens facing the object side. Let n be the curvature of the rear surface of the first chalcogenide refractive lens facing the image side; when n is the refractive index of the second chalcogenide refractive lens, Let be the curvature of the front surface of the second chalcogenide refractive lens facing the object side. The curvature of the rear surface of the second chalcogenide refractive lens facing the image side is denoted as .

2. The optical system according to claim 1, characterized in that, The optical system also satisfies the following condition in femtoseconds (fs): Wherein, GD is the group delay of the micro / nano structure, and V is the Abbe number of the first chalcogenide refractive lens or the Abbe number of the second chalcogenide refractive lens.

3. The optical system according to claim 1, characterized in that, Both the first and second chalcogenide refractive lenses are spherical lenses; the optical system also satisfies the following (in rad / mm) 2 Conditions for being a unit: Where M is the maximum absolute value of the slope of the phase provided by the superlens. The effective focal length of the first chalcogenide refractive lens is given. This is the effective focal length of the second chalcogenide refractive lens.

4. The optical system according to claim 1, characterized in that, The optical system also satisfies the following conditions: in, This is the effective optical aperture of the second chalcogenide refractive lens. The back focal length of the optical system is given.

5. The optical system according to claim 1, characterized in that, The micro / nano structure is either a positive micro / nano structure or a negative micro / nano structure.

6. The optical system according to claim 1, characterized in that, The superlens includes at least one layer of the superstructure unit.

7. The optical system according to claim 1, characterized in that, The optical system is provided with an aperture stop adjacent to the superlens; the aperture stop is disposed on the surface of the superlens, or the aperture stop is disposed at an interval from the superlens.

8. The optical system according to claim 1, characterized in that, The front surface of the first chalcogenide refractive lens is convex, and the rear surface of the first chalcogenide refractive lens is concave; the front surface of the second chalcogenide refractive lens is concave, and the rear surface of the second chalcogenide refractive lens is convex.

9. An optical lens operating in the far-infrared band, characterized in that, The optical lens includes: a lens barrel; a pressure ring, a first spacer, a second spacer disposed inside the lens barrel; and an optical system as described in any one of claims 1-8. The pressure ring abuts against the front surface of the first chalcogenide refractive lens; the first spacer abuts against the front surface of the superlens facing the object side; the second spacer abuts against the front surface of the second chalcogenide refractive lens.

10. The optical lens according to claim 9, characterized in that, The optical lens further includes: a window glass and an imaging detector disposed on the image plane of the optical system; the window glass is disposed between the second chalcogenide refractive lens and the imaging detector.

Images