Vacuum ultraviolet band cryogenic radiometer system based on a synchrotron radiation source

Abstract

The application relates to the technical field of optical testing, and discloses a vacuum ultraviolet band cryogenic radiometer system based on a synchrotron radiation source, which comprises a windowless cryogenic radiometer, a synchrotron radiation source, a filter, a filter cell, a monochromatic spectrometer unit and a beam line valve, the cryogenic radiometer is directly connected with the end of a synchrotron radiation beam line of the synchrotron radiation source, receives light emitted by an extreme ultraviolet to vacuum ultraviolet light source, the beam line valve is located at the front end of the synchrotron radiation beam line, the absorption cavity of the cryogenic radiometer adopts an inclined bottom cylindrical cavity, when the beam line valve is opened, the light enters the absorption cavity of the cryogenic radiometer through the monochromatic spectrometer unit and the filter or through the monochromatic spectrometer unit and the filter cell, so that the temperature in the absorption cavity rises and is maintained at a first temperature, when the beam line valve is closed, the light is blocked, the heating unit of the cryogenic radiometer heats the absorption cavity, so that the temperature in the absorption cavity rises and is maintained at the first temperature, and thus the electric heating power of the heating unit which is heated and maintained at the first temperature is measured as the optical power.

Description

Technical Field

[0001] This invention relates to the field of optical testing technology, and in particular to a vacuum ultraviolet band cryogenic radiometer system based on a synchrotron radiation source. Background Technology

[0002] The application of vacuum ultraviolet (UV) technology is becoming increasingly widespread, but current power measurements in the vacuum UV band suffer from problems such as incomplete band coverage, weak light source energy, and significant measurement uncertainty. Therefore, to address the traceability requirements of vacuum UV measurements, it is urgent to conduct research on metrology techniques based on synchrotron radiation, develop methods for vacuum UV spectral responsivity based on synchrotron radiation, and establish a complete vacuum UV metrology system to meet the calibration requirements for vacuum UV wavelengths and spectral responsivity. This is of great significance and essential for promoting the rapid development of vacuum UV detection and quantitative measurement technologies.

[0003] The principle of electrosubstitution is the main approach to achieving accurate measurement of optical power. By replicating the temperature rise caused by optical radiation through electrical heating, the incident optical power can be calibrated by accurately measuring the electrical power, and the measurement results can be directly traced back to the current in the International System of Units (SI). To achieve high-precision measurement of optical power, technologies such as vacuum, cryogenics, and superconductivity are usually employed, using cryogenic electrosubstitution optical power radiometers to improve accuracy.

[0004] Common light sources in the vacuum ultraviolet band include deuterium lamps, gas discharge lamps, and synchrotron radiation sources. Among them, synchrotron radiation sources are currently the optimal light source for vacuum ultraviolet band metrology due to their relatively high optical power, good long-term stability, small spot size, and no heat generation. However, compared to laser sources (1μW~1mW) commonly used in the visible and infrared bands, the optical power of synchrotron radiation sources is still too low (1nW~100nW). Therefore, it is necessary to design a cryogenic radiometer measurement system to serve low-power synchrotron radiation sources. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a vacuum ultraviolet band cryogenic radiometer system based on a synchrotron radiation source, which can achieve high-precision measurement of optical power.

[0006] The technical solution of this invention: A vacuum ultraviolet band cryogenic radiometer system based on a synchrotron radiation source, wherein the system includes a windowless cryogenic radiometer, a synchrotron radiation source, a filter, a filter cell, a monochromatic beam splitter unit, and a beamline valve, wherein...

[0007] The cryogenic radiometer is directly connected to the end of the synchrotron radiation beamline of a synchrotron radiation source to receive light emitted from extreme ultraviolet to vacuum ultraviolet light sources. The beamline valve is located at the front end of the synchrotron radiation beamline and is used to control the on / off state of the light. The monochromatic beam splitter, the filter, and the filter cell are located sequentially between the front and end of the synchrotron radiation beamline. The absorption cavity of the cryogenic radiometer is a sloping-bottom cylindrical cavity. When the beamline valve is open, the light passes through the beamline valve, the monochromatic beam splitter, and the filter, or the monochromatic beam splitter and the filter cell, and then enters the absorption cavity of the cryogenic radiometer, causing the temperature inside the absorption cavity to rise and be maintained at a first temperature. When the beamline valve is closed, the light is blocked, and the heating unit of the cryogenic radiometer heats the absorption cavity, causing the temperature inside the absorption cavity to rise and be maintained at the first temperature. The electrical heating power of the heating unit in heating and maintaining the first temperature is measured as the optical power.

[0008] Preferably, the cryogenic radiometer further includes an aperture assembly and a cooling device. The aperture assembly includes a main aperture, a stray-removing aperture, and a field aperture. The cooling device includes a primary auxiliary cooling screen, a secondary auxiliary cooling screen, and a heat sink auxiliary cooling screen. The field aperture is located in the housing of the cryogenic radiometer at the position closest to the light source and is installed on the primary auxiliary cooling screen. There are five stray-removing apertures, of which three stray-removing apertures are installed on the secondary auxiliary cooling screen, and the remaining two stray-removing apertures and the main aperture are installed on the heat sink auxiliary cooling screen.

[0009] Preferably, the cryogenic radiometer further includes a temperature sensor for detecting the temperature inside the absorption cavity.

[0010] Preferably, the cryogenic radiometer further includes a temperature measurement and control electronics device, which includes multiple digital multimeters connected in parallel.

[0011] Preferably, the number of digital multimeters is 6, including 2 34420A digital multimeters with 7.5-digit precision, 2 34401A digital multimeters with 6.5-digit precision, and 2 multi-channel scanning cards 2700 and 7700.

[0012] Preferably, the heating unit is a heating resistor.

[0013] Preferably, the bottom surface of the inclined cylindrical cavity has an inclination angle of 30°.

[0014] The above technical solution can be used to set up a cryogenic radiometer, a synchrotron radiation source, a filter, a filter cell, a monochromatic beam splitter, and a beamline valve. The absorption cavity of the cryogenic radiometer adopts a sloping-bottom cylindrical cavity. When the beamline valve is open, light enters the absorption cavity of the cryogenic radiometer through the beamline valve, the monochromatic beam splitter, and the filter, or through the monochromatic beam splitter and the filter cell, causing the temperature inside the absorption cavity to rise and be maintained at a first temperature. When the beamline valve is closed, the light is blocked. The heating unit of the cryogenic radiometer heats the absorption cavity, causing the temperature inside the absorption cavity to rise and be maintained at the first temperature. The electric heating power of the heating unit to heat and maintain the first temperature is measured as the optical power, so as to achieve high-precision measurement of optical power. Attached Figure Description

[0015] The accompanying drawings, which form part of this specification, are provided to further illustrate embodiments of the invention and, together with the textual description, explain the principles of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0016] Figure 1 A schematic diagram of a vacuum ultraviolet band cryogenic radiometer system based on a synchrotron radiation source provided in an embodiment of the present invention;

[0017] Figure 2 This is a detailed internal structure diagram of the cryogenic radiometer in an embodiment of the present invention. Detailed Implementation

[0018] Specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In the following description, specific details are set forth for purposes of explanation and not limitation, in order to aid in a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced in other embodiments departing from these specific details.

[0019] It should be noted that, in order to avoid obscuring the invention with unnecessary details, only the device structure and / or processing steps closely related to the solution according to the invention are shown in the accompanying drawings, while other details that are not closely related to the invention are omitted.

[0020] Figure 1 This is a schematic diagram of a vacuum ultraviolet band cryogenic radiometer system based on a synchrotron radiation source, provided as an embodiment of the present invention.

[0021] like Figure 1-2As shown, this embodiment of the invention provides a vacuum ultraviolet band cryogenic radiometer system based on a synchrotron radiation source. The system includes a windowless cryogenic radiometer, a synchrotron radiation source, a filter, a filter cell, a monochromatic beam splitter, and a beamline valve.

[0022] The cryogenic radiometer is directly connected to the end of the synchrotron radiation beamline of the synchrotron radiation source to receive light emitted from extreme ultraviolet to vacuum ultraviolet light sources. The beamline valve is located at the front end of the synchrotron radiation beamline (i.e., the end of the synchrotron radiation beamline furthest from the cryogenic radiometer) and is used to control the on / off state of the light. The monochromatic beam splitter, the filter, and the filter cell are sequentially located between the front and rear ends of the synchrotron radiation beamline (i.e., arranged sequentially between the front and rear ends of the synchrotron radiation beamline). The absorption cavity of the cryogenic radiometer is a sloping-bottom cylindrical cavity. When the beamline valve is open, the light passes through the beamline valve and then through the monochromatic beam splitter and the filter, or through the monochromatic beam splitter and the filter cell, into the absorption cavity of the cryogenic radiometer, causing the temperature T inside the absorption cavity to rise. A The light is raised and maintained at a first temperature. When the beam valve is closed, the light is blocked, and the heating unit of the cryogenic radiometer heats the absorption chamber, causing the temperature inside the absorption chamber to reach T. A The temperature is raised and maintained at a first temperature, thereby measuring the electrical heating power P of the heating unit that heats and maintains the first temperature. el As optical power P ph (That is, the temperature T inside the absorption chamber after the heating unit is heated) A When the temperature is stable and constant and equal to the first temperature, the incident light power P ph =Electric heating power P el ).

[0023] The monochromatic beam splitting unit is used to separate composite light into monochromatic light. For example, the filter can be a magnesium fluoride filter, and the filter cell can be a gas filter cell. Figure 2 In the middle, Q R The power of the heat sink in the absorption cavity to absorb heat leakage.

[0024] The above technical solution can be used to set up a cryogenic radiometer, a synchrotron radiation source, a filter, a filter cell, a monochromatic beam splitter, and a beamline valve. The absorption cavity of the cryogenic radiometer adopts a sloping-bottom cylindrical cavity. When the beamline valve is open, light enters the absorption cavity of the cryogenic radiometer through the beamline valve, the monochromatic beam splitter, and the filter, or through the monochromatic beam splitter and the filter cell, causing the temperature inside the absorption cavity to rise and be maintained at a first temperature. When the beamline valve is closed, the light is blocked. The heating unit of the cryogenic radiometer heats the absorption cavity, causing the temperature inside the absorption cavity to rise and be maintained at the first temperature. The electric heating power of the heating unit to heat and maintain the first temperature is measured as the optical power, so as to achieve high-precision measurement of optical power.

[0025] According to one embodiment of the present invention, the cryogenic radiometer further includes an aperture assembly and a cooling device. The aperture assembly includes a main aperture, a stray-removing aperture, and a field aperture. The cooling device includes a primary auxiliary cooling screen, a secondary auxiliary cooling screen, and a heat sink auxiliary cooling screen. The field aperture is located in the housing of the cryogenic radiometer at the position closest to the light source and is mounted on the primary auxiliary cooling screen. The number of stray-removing apertures is five, of which three stray-removing apertures are mounted on the secondary auxiliary cooling screen, and the remaining two stray-removing apertures and the main aperture are mounted on the heat sink auxiliary cooling screen.

[0026] The field of view of the cryogenic radiometer can be determined by the size and spacing of the main aperture and the field aperture. The stray aperture can be used to suppress stray light outside the field of view. Another function of the stray aperture is to suppress background radiation noise, thereby improving the signal-to-noise ratio of the probe cavity.

[0027] According to one embodiment of the present invention, the cryogenic radiometer further includes a temperature sensor for detecting the temperature inside the absorption cavity.

[0028] According to one embodiment of the present invention, the cryogenic radiometer further includes a temperature measurement and control electronics device, which includes multiple digital multimeters connected in parallel.

[0029] According to one embodiment of the present invention, the number of digital multimeters is 6, including 2 34420A digital multimeters with 7.5-digit precision, 2 34401A digital multimeters with 6.5-digit precision, and 2 multi-channel scanning cards 2700 and 7700.

[0030] According to one embodiment of the present invention, the heating unit is a heating resistor.

[0031] According to one embodiment of the present invention, the bottom surface of the inclined cylindrical cavity has an inclination angle of 30°.

[0032] The vacuum ultraviolet band cryogenic radiometer system based on a synchrotron radiation source described in this invention is described below with reference to examples.

[0033] The cryogenic radiometer system for measuring low-power light sources described in this invention includes a cryogenic radiometer, a synchrotron radiation source, a filter, a filter cell, a monochromatic beam splitter unit, and a beamline valve.

[0034] The cryogenic radiometer employs a windowless design, allowing direct connection to a synchrotron radiation beamline to receive extreme ultraviolet to vacuum ultraviolet light sources. Its structure includes an absorption cavity, an aperture assembly, a cooling device, a vacuum device (to provide a vacuum environment), and temperature control electronics. The cryogenic radiometer is docked at the end of the synchrotron radiation beamline, and optical path alignment ensures that all light from the synchrotron radiation source enters the cryogenic radiometer's absorption cavity.

[0035] To achieve highly sensitive detection of light across the entire wavelength range, the instrument must have a sufficiently high absorptivity for the incident light, which depends on the design of the absorption cavity. The absorptivity of the absorption cavity affects the temperature change of the cavity when heated by optical radiation power, and also affects the reaction time constant of the absorption cavity. In this invention, the absorption cavity is a sloping-bottom cylindrical cavity, with a preferred bottom sloping angle of 30°, and the inner surface is coated with a blackened coating to absorb broad-spectrum incident light. After multiple reflections and absorptions within the cavity, the total absorptivity can reach 0.9968.

[0036] To eliminate the influence of stray light on measurements, an aperture assembly is used for stray radiation suppression. The aperture assembly includes a main aperture, a stray-suppressing aperture, and a field aperture. The size and spacing of the main and field apertures determine the field of view of the cryoradiometer, while the stray-suppressing aperture is used to suppress stray light outside the field of view. Another major function of the stray-suppressing aperture is to suppress background radiation noise and improve the signal-to-noise ratio of the probe cavity. The field aperture is located at the front of the cryoradiometer and is mounted on the primary auxiliary cooling screen. There are five stray-suppressing apertures: three are mounted on the secondary auxiliary cooling screen, and the other two, along with the main aperture, are mounted on the heat sink auxiliary cooling screen.

[0037] According to one embodiment of the present invention, a Cx-1070 thin-film temperature sensor (Cernox thin-film temperature sensor) can be used as the temperature sensor for the absorption cavity. The Cernox thin-film temperature sensor uses sapphire as a substrate, with a platinum-molybdenum composite film deposited on the substrate as a resistor. It exhibits excellent performance; the Cx-1070 has a sensitivity of -1.1 at 10K and a temperature response time of 15ms, making it ideal for improving temperature control accuracy.

[0038] To ensure the absolute measurement accuracy of the cryogenic radiometer, this invention employs a high-precision digital multimeter as the high-precision measurement system. Multiple high-precision digital multimeters are connected in parallel via a GPIB bus, including two 7.5-digit precision 34420A multimeters, two 6.5-digit precision 34401A multimeters, and two multi-channel scanning cards 2700 and 7700. Based on the GPIB standard 488 protocol, the measurement modes of the temperature control electronics are configured through computer software system control, achieving automated measurement. The measurement timing and frequency of the temperature control electronics are controlled by various external trigger modes. Key parameters of the cryogenic radiometer are measured synchronously, while temperature field changes in the 50K and 5K temperature zones are monitored simultaneously.

[0039] Common cryogenic radiometers typically use a shutter to control the on / off state of light. However, this method introduces significant fluctuations in background infrared radiation, resulting in a certain noise floor. This noise is negligible when measuring high-power light sources such as visible / infrared lasers, but it has a significant impact on synchrotron radiation sources. Therefore, this invention uses a valve on the beamline of the synchrotron radiation source instead of a shutter. The beamline valve is located at the farthest end of the synchrotron radiation source beamline. The device directly facing the cryogenic radiometer within its field of view is either a magnesium fluoride filter (vacuum ultraviolet band) or a gas filter cell (extreme ultraviolet band), depending on the wavelength range. The opening and closing of the beamline valve does not affect the background infrared radiation received by the cryogenic radiometer, effectively eliminating this source of noise. The magnesium fluoride filter and the gas filter cell operate selectively depending on the type of monochromatic light obtained from the filter.

[0040] The computer software system can also be used to synchronously control the temperature control electronics of the cryogenic radiometer and the beamline valve of the synchrotron radiation source. By synchronously switching the opening and closing of the beamline valve and the heating power of the temperature control electronics, the purpose of measuring optical power using the principle of electrical substitution can be achieved.

[0041] The features described and / or illustrated above with respect to one embodiment may be used in the same or similar manner in one or more other embodiments, and / or in combination with or in lieu of features in other embodiments.

[0042] It should be emphasized that the term "including / comprises" as used herein refers to the presence of a feature, whole, step, or component, but does not exclude the presence or addition of one or more other features, wholes, steps, components, or combinations thereof.

[0043] The apparatus and methods described above can be implemented in hardware or in combination with software. This invention relates to computer-readable programs that, when executed by a logic component, enable that logic component to implement the apparatus or constituent parts described above, or to implement the various methods or steps described above. This invention also relates to storage media for storing the above programs, such as hard disks, magnetic disks, optical disks, DVDs, flash memory, etc.

[0044] Many features and advantages of these embodiments are apparent from this detailed description, and therefore the appended claims are intended to cover all such features and advantages of these embodiments that fall within their true spirit and scope. Furthermore, since many modifications and alterations will readily occur to those skilled in the art, the embodiments of the invention are not intended to be limited to the precise structures and operations illustrated and described, but rather to encompass all suitable modifications and equivalents falling within their scope.

[0045] The parts of this invention not described in detail are techniques known to those skilled in the art.

Claims

1. A vacuum ultraviolet band cryogenic radiometer system based on a synchrotron radiation source, characterized in that, The system includes a windowless cryogenic radiometer, a synchrotron radiation source, filters, a filter cell, a monochromatic beam splitter, and beamline valves. The cryogenic radiometer is directly connected to the end of the synchrotron radiation beamline of a synchrotron radiation source to receive light emitted from extreme ultraviolet to vacuum ultraviolet light sources. The beamline valve is located at the front end of the synchrotron radiation beamline and is used to control the on / off state of the light. The monochromatic beam splitter, the filter, and the filter cell are located sequentially between the front and end of the synchrotron radiation beamline. The absorption cavity of the cryogenic radiometer is a sloping-bottom cylindrical cavity. When the beamline valve is open, the light passes through the beamline valve, the monochromatic beam splitter, and the filter, or the monochromatic beam splitter and the filter cell, and then enters the absorption cavity of the cryogenic radiometer, causing the temperature inside the absorption cavity to rise and be maintained at a first temperature. When the beamline valve is closed, the light is blocked, and the heating unit of the cryogenic radiometer heats the absorption cavity, causing the temperature inside the absorption cavity to rise and be maintained at the first temperature. The electrical heating power of the heating unit in heating and maintaining the first temperature is measured as the optical power.

2. The system according to claim 1, characterized in that, The cryogenic radiometer also includes an aperture assembly and a cooling device. The aperture assembly includes a main aperture, a stray aperture, and a field aperture. The cooling device includes a primary auxiliary cooling screen, a secondary auxiliary cooling screen, and a heat sink auxiliary cooling screen. The field aperture is located in the housing of the cryogenic radiometer at the position closest to the light source and is installed on the primary auxiliary cooling screen. There are five stray apertures, three of which are installed on the secondary auxiliary cooling screen, and the remaining two stray apertures and the main aperture are installed on the heat sink auxiliary cooling screen.

3. The system according to claim 2, characterized in that, The cryogenic radiometer also includes a temperature sensor for detecting the temperature inside the absorption cavity.

4. The system according to claim 3, characterized in that, The cryogenic radiometer also includes a temperature measurement and control electronics device, which comprises multiple digital multimeters connected in parallel.

5. The system according to claim 4, characterized in that, The number of digital multimeters is 6, including 2 34420A digital multimeters with 7.5 digit precision, 2 34401A digital multimeters with 6.5 digit precision, and 2 multi-channel scanning cards 2700 and 7700.

6. The system according to any one of claims 1-5, characterized in that, The heating unit is a heating resistor.

7. The system according to any one of claims 1-5, characterized in that, The bottom face of the inclined cylindrical cavity has an angle of 30°.

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