Optical imaging device with soft X-ray radiation imaging capability and preparation method thereof

Abstract

The invention relates to an optical imaging device with soft X-ray radiation imaging capability and a preparation method thereof. The optical imaging device comprises an optical lens, a scintillation film layer and an imaging sensor, wherein the scintillation film layer is plated on the outer side of the incident surface of the optical lens and is used for converting incident soft X-rays into visible light in situ; the scintillation thin film layer comprises a doped yttrium aluminum garnet material; the optical lens is used for amplifying or reducing the visible light converted by the scintillation thin film layer for imaging; and the imaging sensor is used for receiving the visible light imaged by the optical lens so as to obtain a spatial distribution image of the soft X-ray. The invention has the beneficial effects that the scintillation film is directly plated at the foremost end of the lens, so that soft X-ray in-situ conversion is realized, optical signal spatial diffusion caused by an independent scintillation screen is thoroughly avoided, the imaging resolution is remarkably improved, the optical path is shortened, and the signal loss is reduced.

Description

Technical Field

[0001] This invention belongs to the field of optical detection technology, and particularly relates to an optical imaging device with soft X-ray radiation imaging capability and its preparation method. Background Technology

[0002] Soft X-ray radiation (typically in the 0-10 nm wavelength range) has irreplaceable application value in fields such as photolithography, light source diagnostics, plasma physics research, and material microstructure analysis. Its imaging technology is the core means of obtaining information on the spatial distribution and microscopic features of targets. Existing soft X-ray imaging schemes are mainly divided into two categories: one category uses dedicated soft X-ray detectors (such as CCD / CMOS back-illuminated devices), which requires concave mirrors or Fresnel zone plates to achieve light focusing, resulting in drawbacks such as complex imaging operations, high costs, low quantum efficiency, and the need for special vacuum packaging.

[0003] Another approach involves converting soft X-rays into visible light using a separate scintillation screen, which is then received by a visible light imaging system. However, this method faces serious physical limitations in practical applications: 1. Limitation of Isotropic Emission: The de-excitation process of a scintillator after absorbing soft X-ray energy is spatially random, and the resulting fluorescence is emitted isotropically throughout the 4π space, lacking the directionality of the incident rays. In an independent scintillator structure, this omnidirectional emission characteristic leads to severe geometric diffusion of a large amount of light signal before it reaches the subsequent optical lens.

[0004] 2. The contradiction between thickness and resolution: Although increasing the thickness of the scintillator can theoretically improve the absorption of high-energy rays, for soft X-rays with extremely weak penetrating power, effective excitation only occurs in the surface nanometer-scale layer. If the scintillator is too thick, the generated visible photons will produce severe lateral dispersion (crosstalk) when passing through the scintillator substrate, forming a "light cone" effect, which leads to a sharp broadening of the imaging point spread function (PSF), greatly limiting the spatial resolution of the system.

[0005] 3. Integration and loss issues: The free space between the independent scintillator and the imaging lens further amplifies the beam divergence angle, leading to difficulties in numerical aperture (NA) matching, low signal collection efficiency, and a loose system structure that is difficult to adapt to compact optical systems and precise magnification / reduction imaging requirements.

[0006] 4. Existing technologies exhibit significant technical bias: it is generally believed that the scintillator must be placed as an independent component at the front end of the imaging optical path to avoid affecting the lens's light transmittance, surface accuracy, and imaging control functions. Therefore, the technical approach of directly depositing the scintillator film at the very front of the lens has not been considered. Furthermore, conventional scintillator materials (such as gadolinium oxysulfide and cesium iodide) have poor conversion efficiency in the soft X-ray band, and are prone to cracking and insufficient adhesion during film preparation, making it difficult to meet the stringent requirements of high-precision imaging for film uniformity and stability. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide an optical imaging device with soft X-ray radiation imaging capability and its preparation method.

[0008] In the first aspect, an optical imaging device with soft X-ray radiation imaging capability is provided, including: an optical lens, a scintillation thin film layer and an imaging sensor; The scintillation film layer is deposited on the outer side of the incident surface of the optical lens to convert incident soft X-rays into visible light in situ; the scintillation film layer contains yttrium aluminum garnet material. The optical lens is used to magnify or reduce the visible light converted by the scintillating thin film layer for imaging; The imaging sensor is used to receive visible light after it has been imaged by the optical lens, in order to obtain a spatial distribution image of soft X-rays.

[0009] Preferably, the doped yttrium aluminum garnet material is cerium-doped yttrium aluminum garnet or terbium-doped yttrium aluminum garnet; the doping atom concentration of the cerium-doped yttrium aluminum garnet ranges from 0.1% to 1.5%; and the doping atom concentration of the terbium-doped yttrium aluminum garnet ranges from 0.5% to 10%.

[0010] Preferably, the thickness of the scintillation film layer is 100 nm to 2 μm.

[0011] Preferably, it further includes a refractive index matching layer disposed between the incident surface of the optical lens and the scintillation film layer.

[0012] Preferably, the refractive index matching layer is made of hafnium oxide, titanium dioxide, or optical-grade polyimide; the refractive index of the refractive index matching layer is in the range of 1.60-1.75; and the thickness of the refractive index matching layer is 100 nm – 2 μm.

[0013] Preferably, the optical lens is a zoom lens or a fixed focal length lens group, which can achieve magnification or reduction imaging in the range of 1-100 times for visible light by adjusting the focal length or combining optical paths.

[0014] Preferably, the imaging sensor is a CMOS image sensor or a CCD image sensor.

[0015] In a second aspect, a method is provided for an optical imaging apparatus having soft X-ray radiation imaging capability as described in any of the first aspects, comprising: S1. Provide optical lenses; S2. A scintillation film layer is deposited on the outer side of the incident surface of the optical lens, the scintillation film layer comprising doped yttrium aluminum garnet material; S3. Assemble the optical lens with the scintillation thin film layer, along with the matching optical path components and imaging sensor, according to the magnification / reduction imaging requirements. Adjust the optical path focal length and coupling accuracy to complete the construction of the optical imaging device.

[0016] Preferably, before S2, the method further includes: depositing a refractive index matching layer on the incident surface of the optical lens; S2 specifically involves depositing the scintillation film layer on the refractive index matching layer.

[0017] Preferably, in S2, the scintillation thin film layer is deposited by magnetron sputtering followed by high-temperature atmosphere annealing or pulsed laser in-situ growth.

[0018] The beneficial effects of this invention are: 1. The scintillation film of this invention is directly deposited on the front end of the lens, realizing in-situ soft X-ray conversion, completely avoiding spatial diffusion of light signals caused by a separate scintillation screen, significantly improving imaging resolution, while shortening the optical path and reducing signal loss. Furthermore, the soft X-ray conversion and visible light magnification / reduction imaging share the same optical lens and core optical path, simplifying the system structure, increasing integration, significantly reducing device size and cost, and eliminating the need for a dedicated soft X-ray detector.

[0019] 2. This invention utilizes yttrium aluminum garnet (YAG) doped material, which exhibits high absorption and conversion efficiency in the soft X-ray band. The thin film structure is stable, has strong adhesion, and good compatibility with the lens surface, ensuring it does not affect the lens's magnification / reduction imaging function, thus improving the imaging stability and lifespan of the device. Furthermore, the optical lens supports visible light magnification or reduction adjustment (1-100x), adapting to different observation scenarios (such as magnified imaging of microstructures and reduced overview imaging of large-scale targets), broadening application scenarios and lowering the barrier to entry.

[0020] 3. By setting a refractive index matching layer, this invention further improves the visible light coupling efficiency, ensuring clear images with minimal distortion after magnification / reduction, and guaranteeing imaging quality. Attached Figure Description

[0021] Figure 1 A schematic diagram of the optical lens structure for the integrated scintillation film provided by the present invention; Figure 2 This is a schematic diagram of the soft X-ray imaging principle provided by the present invention; Figure 3 This is a schematic diagram of the scintillation thin film preparation process provided by the present invention; Figure labeling: 1. Scintillation thin film layer; 2. Refractive index matching layer; 3. Optical lens; 4. Lens; 5. Visible light; 6. Chip; 7. Soft X-ray; 8. Silicon wafer. Detailed Implementation

[0022] The present invention will be further described below with reference to embodiments. The description of the embodiments below is only for the purpose of helping to understand the present invention. It should be noted that those skilled in the art can make several modifications to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0023] Example 1: To address the technical problems of existing soft X-ray imaging devices, such as high cost, low integration, imaging resolution limited by independent scintillation screens, poor compatibility of conventional scintillation materials, and inability to achieve precise imaging by magnifying or reducing visible light, Embodiment 1 of this application provides a soft X-ray integrated optical imaging device with a compact structure, high resolution, strong stability, and the ability to control the magnification or reduction of converted visible light.

[0024] Specifically, by directly depositing a yttrium aluminum garnet scintillation film onto the front edge of the lens, in-situ efficient conversion of soft X-rays is achieved. Utilizing the lens's own optical structure and matching optical path design, the converted visible light is magnified or reduced for imaging. At the same time, key issues such as the compatibility between the scintillation film and the lens, the stability of the film structure, the soft X-ray to visible light conversion efficiency, and the precision of visible light control are addressed.

[0025] like Figure 2 As shown, an optical imaging device with soft X-ray radiation imaging capability includes: an optical lens, a scintillation thin film layer, and an imaging sensor.

[0026] The scintillation film layer is deposited on the outer side of the incident surface of the optical lens, without affecting the optical surface accuracy and light transmission performance of the lens, and is used to convert incident soft X-rays into visible light in situ. The scintillation film layer contains doped yttrium aluminum garnet material. The doped yttrium aluminum garnet material is cerium-doped yttrium aluminum garnet or terbium-doped yttrium aluminum garnet. The doped yttrium aluminum garnet material is selected from cerium-doped yttrium aluminum garnet (Ce:YAG, doping atom concentration range of 0.1%~1.5%) or terbium-doped yttrium aluminum garnet (Tb:YAG, doping atom concentration range of 0.5%~10%). This type of material has extremely low gas exudation rate and non-hygroscopicity, ensuring its stability in a vacuum environment, while exhibiting high absorption efficiency and high visible light conversion efficiency in the soft X-ray band. Furthermore, the scintillation film layer emits fluorescence in the visible light band (400-760 nm) under soft X-ray excitation, and the fluorescence spectrum matches the response band of the optical lens and imaging sensor.

[0027] The optical lens is used to magnify or reduce the visible light converted by the scintillation thin film layer for imaging. The soft X-ray to visible light conversion process and the visible light magnification / reduction imaging process share the same optical lens and core optical path, simplifying the system structure.

[0028] The imaging sensor is used to receive visible light after it has been imaged by the optical lens, in order to obtain a spatial distribution image of soft X-rays.

[0029] Example 2: Based on Embodiment 1, Embodiment 2 of this application provides a specific optical imaging device with soft X-ray radiation imaging capability, such as... Figure 1 As shown, it includes: an optical lens, a scintillation thin film layer, and an imaging sensor.

[0030] The scintillation film layer is deposited on the outer side of the incident surface of the optical lens to convert incident soft X-rays into visible light in situ; the scintillation film layer contains yttrium aluminum garnet material.

[0031] The optical lens is used to magnify or reduce the visible light converted by the scintillation film layer to form an image.

[0032] The thickness of the scintillation film layer is between 100 nm and 2 μm. This thickness is chosen because: the attenuation length of soft X-rays in YAG materials is typically on the order of hundreds of nanometers to micrometers, and this thickness is sufficient to achieve a quantum absorption efficiency of >80%; limiting the thickness effectively suppresses the lateral diffusion of visible photons within the film, ensuring that the transfer function (MTF) of the imaging system meets the high-resolution requirements; this thickness is much greater than the wavelength of soft X-rays, and combined with the amorphous / nanocrystalline structure, it can eliminate thin-film interference effects in the visible light band, ensuring the uniformity of image plane irradiance. Furthermore, the scintillation film layer is an amorphous or nanocrystalline structure, possessing good structural stability and adhesion to the lens surface.

[0033] In addition, it also includes: a refractive index matching layer disposed between the incident surface of the optical lens and the scintillating thin film layer, the material of which is preferably hafnium oxide (HfO2), titanium dioxide (TiO2) or optical grade polyimide, and the refractive index range is set between 1.60 and 1.75, which is the middle value between the scintillator (1.83) and the lens substrate (1.50), thereby improving the coupling efficiency of visible light by reducing the interface reflection coefficient; its thickness is preferably 100 nm – 2 μm, which can be prepared by atomic layer deposition (ALD) or spin coating process. This thickness can meet the requirements of single-layer or multi-layer anti-reflection interference, and can also use its chemical stability to ensure a low gas outflow rate in a vacuum environment, avoiding contamination of the back-end optical system.

[0034] The optical lens is a zoom lens or a fixed focal length lens group, which can achieve magnification or reduction imaging in the range of 1-100 times in visible light by adjusting the focal length or combining optical paths, adapting to different observation distances and resolution requirements.

[0035] The imaging sensor is a CMOS image sensor or a CCD image sensor, which is precisely matched with the magnified / reduced visible light optical path to ensure image acquisition quality.

[0036] The imaging sensor is used to receive visible light after it has been imaged by the optical lens, in order to obtain a spatial distribution image of soft X-rays.

[0037] Furthermore, the above-mentioned device is suitable for soft X-ray radiation imaging in vacuum, low-pressure or normal-pressure environments.

[0038] It should be noted that the parts in this embodiment that are the same as or similar to those in Embodiment 1 can be referred to each other, and will not be repeated in this application.

[0039] Example 3: Based on Example 2, Example 3 of this application provides a method for an optical imaging device with soft X-ray radiation imaging capability, comprising: S1. Provides optical lenses.

[0040] The optical lens is a single lens or lens group with magnification or reduction imaging function. S1 also includes pretreatment of the frontmost surface of the optical lens, such as removing surface contaminants and impurities.

[0041] For example, a fused silica lens was used as a substrate and pretreated. The substrate was then subjected to ultrasonic cleaning with acetone and isopropanol for 15 minutes to thoroughly remove any attached organic contaminants; followed by a 5-minute surface treatment using oxygen plasma.

[0042] In addition, for soft X-ray imaging scenarios with higher energy spectra, sapphire or silicon carbide (SiC) lenses can be used instead of fused silica lens groups.

[0043] Before S2, the method further includes: depositing a refractive index matching layer on the incident surface of the optical lens; S2 specifically involves depositing the scintillation thin film layer on the refractive index matching layer.

[0044] For example, a 10 nm thick layer of SiO2 was deposited on a substrate using magnetron sputtering, with the base vacuum reduced to 5 × 10⁻⁶. -7 Torr is introduced with high-purity Ar and O2 at a flow rate of 2%-5% as the reaction gas. The operating pressure is set to 3×10⁻⁶. -3 Torr was used with a high-purity SiO2 ceramic target and a 120W RF power supply. After 5 minutes of pre-sputtering to clean the target surface, the baffle was turned on to form a 10 nm thick SiO2 film on the substrate surface.

[0045] S2. A scintillation film layer is deposited on the outer side of the incident surface of the optical lens, the scintillation film layer comprising yttrium aluminum garnet material.

[0046] In S2, the scintillation thin film layer is deposited by magnetron sputtering and supplemented by high-temperature atmosphere annealing or pulsed laser in-situ growth. During the deposition process, the process parameters are strictly controlled to avoid affecting the surface accuracy and optical performance of the lens.

[0047] For example, a substrate with a matching layer is placed in the cavity, and a high-purity Ce:YAG ceramic target is used, with the base vacuum evacuated to 5 × 10⁻⁶. -7 Torr. High-purity Ar was introduced at a flow rate of 40 sccm, and the working pressure was maintained at 5 × 10⁻⁶. -3 Torr was used, with the RF power set to 150W. After 10 minutes of pre-sputtering stabilization, the baffle was turned on to deposit a 100 nm amorphous thin film. After deposition, the sample was placed in a high-temperature annealing furnace and heated to 1050°C at a rate of 5°C per minute under an oxygen atmosphere, and held at that temperature for 2 hours.

[0048] In addition, regarding scintillation materials, Tb:YAG can be used instead of Ce:YAG, which can emit fluorescence in the green light band (about 543nm), making it suitable for CCD image sensors with higher green light quantum efficiency and improving the imaging effect of specific sensors; or LuAG:Ce material can be used to further enhance the conversion efficiency by utilizing its higher soft X-ray absorption cross section.

[0049] In terms of deposition methods, pulsed laser deposition (PLD) can be used instead of magnetron sputtering. A 248 nm KrF excimer laser was used to bombard a rotating Ce:YAG single-crystal ceramic target, with an energy density set to 1.8 J / cm². 2 The repetition frequency is 10 Hz. When the pressure reaches 10- 7 After Torr, high-purity oxygen at 150 mTorr is introduced. The molten quartz substrate is heated in situ to 850°C using a heating stage, and then a scintillator film is deposited. After deposition, it is cooled in situ in an oxygen atmosphere.

[0050] S3. Assemble the optical lens with the scintillation thin film layer, along with the matching optical path components and imaging sensor, according to the magnification / reduction imaging requirements. Adjust the optical path focal length and coupling accuracy to complete the construction of the optical imaging device.

[0051] For example, the zoom lens integrating the above-mentioned scintillation film, refractive index matching layer and light filter protection layer is assembled into a vacuum-compatible lens barrel and optically coupled to the back-end CMOS image sensor.

[0052] It should be noted that the method provided in this embodiment is the corresponding preparation method of the product provided in Embodiment 2. Therefore, the parts that are the same as or similar to those in Embodiment 2 in this embodiment can be referred to each other, and will not be repeated in this application.

Claims

1. An optical imaging device with soft X-ray radiation imaging capability, characterized in that, include: Optical lenses, scintillation thin films, and imaging sensors; The scintillation film layer is deposited on the outer side of the incident surface of the optical lens to convert incident soft X-rays into visible light in situ; the scintillation film layer contains yttrium aluminum garnet material. The optical lens is used to magnify or reduce the visible light converted by the scintillating thin film layer for imaging; The imaging sensor is used to receive visible light after it has been imaged by the optical lens, in order to obtain a spatial distribution image of soft X-rays.

2. The optical imaging device with soft X-ray radiation imaging capability according to claim 1, characterized in that, The doped yttrium aluminum garnet material is cerium-doped yttrium aluminum garnet or terbium-doped yttrium aluminum garnet; the doping atom concentration of the cerium-doped yttrium aluminum garnet ranges from 0.1% to 1.5%; the doping atom concentration of the terbium-doped yttrium aluminum garnet ranges from 0.5% to 10%.

3. The optical imaging device with soft X-ray radiation imaging capability according to claim 2, characterized in that, The thickness of the scintillation film layer is 100 nm to 2 μm.

4. The optical imaging device with soft X-ray radiation imaging capability according to claim 3, characterized in that, Also includes: A refractive index matching layer is disposed between the incident surface of the optical lens and the scintillation film layer.

5. The optical imaging device with soft X-ray radiation imaging capability according to claim 4, characterized in that, The refractive index matching layer is made of hafnium oxide, titanium dioxide, or optical-grade polyimide; the refractive index of the refractive index matching layer is between 1.60 and 1.75; and the thickness of the refractive index matching layer is 100 nm – 2 μm.

6. The optical imaging device with soft X-ray radiation imaging capability according to claim 5, characterized in that, The optical lens is a zoom lens or a fixed focal length lens group, which can achieve magnification or reduction imaging in the range of 1-100 times for visible light by adjusting the focal length or combining optical paths.

7. The optical imaging device with soft X-ray radiation imaging capability according to claim 6, characterized in that, The imaging sensor is a CMOS image sensor or a CCD image sensor.

8. A method for preparing an optical imaging device with soft X-ray radiation imaging capability as described in any one of claims 1 to 7, characterized in that, include: S1. Provide optical lenses; S2. A scintillation film layer is deposited on the outer side of the incident surface of the optical lens, the scintillation film layer comprising doped yttrium aluminum garnet material; S3. Assemble the optical lens with the scintillation thin film layer, along with the matching optical path components and imaging sensor, according to the magnification / reduction imaging requirements. Adjust the optical path focal length and coupling accuracy to complete the construction of the optical imaging device.

9. The method of the optical imaging device with soft X-ray radiation imaging capability according to claim 8, characterized in that, Before S2, the method further includes: depositing a refractive index matching layer on the incident surface of the optical lens; S2 specifically involves depositing the scintillation thin film layer on the refractive index matching layer.

10. The method of the optical imaging device with soft X-ray radiation imaging capability according to claim 9, characterized in that, In S2, the scintillation thin film layer is deposited by magnetron sputtering and supplemented by high-temperature atmosphere annealing or pulsed laser in-situ growth.

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