Shielding measurement device for two-photon spectral absorption

Abstract

The utility model discloses a shielding measuring device for two-photon spectral absorption, which comprises a shading shell, a collecting port is arranged on the side wall of the shading shell, a target material cavity and a reflecting mirror are arranged in the shading shell, the target material cavity is positioned between the reflecting mirror and the collecting port, and the reflecting mirror is positioned between the collecting port and the target material cavity. A collecting pipeline communicated with the interior of the shading shell is further arranged on the top of the shading shell, a photomultiplier is installed at the upper end of the collecting pipeline, and the collecting pipeline is located over the target material cavity and is perpendicular to the target material cavity. According to the scheme, the influence of external stray light on a result is isolated through a large cavity, and the experimental measurement efficiency is greatly improved; a small cavity is made to cut off the influence of scattered photons of incident light on a result, a light insulation protection measure of a photomultiplier is taken, and meanwhile, the photomultiplier is mounted above a target material cavity, so that the signal-to-noise ratio of a two-photon absorption spectrum is greatly improved.

Description

Technical Field

[0001] The utility model relates to the technical field of optics, and particularly relates to a shielding measurement device for two-photon spectral absorption. Background Technique

[0002] Two-photon spectral absorption has become a new means of absorption spectrum measurement at the present stage. Mainly, on the laser light path emitted by a continuous spectrum laser, a focal point of ultra-strong laser is generated. Since the energy of the laser on the entire light path is not sufficient to excite two-photon absorption, and because the laser beam generated by the continuous spectrum laser has a relatively long wavelength and the photon energy is not sufficient to cause the outer electrons of the atomic nucleus to transition between specific energy levels, therefore, two-photon absorption spectroscopy is a very good absorption spectrum measurement method.

[0003] During the two-photon absorption process, it is necessary to heat and evaporate the target material cavity to form a stable vapor state inside. Then, the incident light emitted by the laser enters from one end face of the target material cavity, generating the first photon absorption. After passing through the target material cavity, the reflected photons enter the target material cavity after being reflected by a total reflection mirror at the back, performing secondary photon absorption, thereby generating two-photon absorption. Subsequently, a PMT (photomultiplier tube) can be used to measure the excited fluorescence photons.

[0004] During the entire measurement process, since the PMT is very sensitive to photon measurement, stray light in the environment has a very large impact on the measurement results. Summary of the Utility Model

[0005] Aiming at the above deficiencies existing in the prior art, the technical problem to be solved by the utility model is: how to provide a shielding measurement device for two-photon spectral absorption that can shield stray light in the environment and ensure the measurement effect of the photomultiplier tube on fluorescence photons.

[0006] To solve the above technical problems, the utility model adopts the following technical solutions:

[0007] A shielding measurement device for two-photon spectral absorption, including a light-shielding outer shell. A collection port is opened on the side wall of the light-shielding outer shell. A target material cavity and a mirror are arranged inside the light-shielding outer shell. The target material cavity is located between the mirror and the collection port. A collection pipeline communicating with the inside of the light-shielding outer shell is further arranged at the top of the light-shielding outer shell. A photomultiplier tube is installed at the upper end of the collection pipeline, and the collection pipeline is located directly above the target material cavity and is perpendicular to the target material cavity.

[0008] In this way, when the shielding measurement device of this solution is in use, the incident light generated by the laser enters the light-shielding outer shell through the collection port. The incident light that enters the light-shielding outer shell further enters the target material cavity. The incident light that enters the target material cavity is absorbed by the target material atomic vapor in the target material cavity and transitions to a metastable state structure. Then the incident light further passes through the target material cavity and exits from its rear end and hits the mirror. The mirror reflects the incident light to form reflected light and enters the target material cavity again. The reflected light that enters the target material cavity is secondarily absorbed by the target material atomic vapor, and the extranuclear electrons in the metastable state structure are excited to a better energy state. When the electrons in the excited state deexcite to the ground state, fluorescent photons of a specific wavelength are emitted. The fluorescent photons are collected in the target material cavity and converge into the collection pipeline. The fluorescent photons that converge into the collection pipeline are further absorbed by the photomultiplier tube, thereby achieving the purpose of experimentally measuring two-photon absorption.

[0009] In this solution, the target material cavity and the mirror are placed in the light-shielding outer shell. The light-shielding outer shell can block the influence of external stray light on the experimental results, greatly improving the measurement efficiency. At the same time, the fluorescent photons are converged to the photomultiplier tube through the collection pipeline, and the signal-to-noise ratio of the measurement results is also greatly increased. Therefore, this solution can shield the stray light in the environment and ensure the measurement effect of the photomultiplier tube on the fluorescent photons.

[0010] Preferably, a notch filter is movably connected to the entrance of the collection pipeline near the light-shielding outer shell.

[0011] In this way, the notch filter can only allow fluorescent photons of a specific wavelength to pass through, while photons of other wavelengths are reflected. Since in addition to the fluorescent photons converging to the collection pipeline, there are also scattered light of part of the incident light, by setting the notch filter, as many fluorescent photons as possible that need to be collected can pass through the notch filter and reach the photomultiplier tube to be absorbed, while the scattered light of the incident light can be reflected as much as possible, thereby further improving the signal-to-noise ratio of the two-photon absorption spectrum.

[0012] Preferably, an absorbing layer made of an absorbing material is provided on the inner side wall of the light-shielding outer shell.

[0013] In this way, the absorbing layer made of the absorbing material can effectively absorb the stray light that enters the light-shielding outer shell, further reducing the influence of the stray light on the measurement results of the photomultiplier tube.

[0014] Preferably, a heating device for heating the target material cavity is further provided in the light-shielding outer shell.

[0015] In this way, the heating device is used to heat the target material cavity to keep it at a constant temperature, so that the target material in the target material cavity is in a stable saturated atomic density vapor state to ensure the absorption effect on the incident light and the reflected light.

[0016] Preferably, the heating device is an electric heating wire and a temperature control component.

[0017] In this way, the electric heating wire is used to heat the target chamber, and the temperature control component is used to ensure that the target chamber is in a constant temperature state.

[0018] Preferably, the target chamber is a fully sealed target chamber made of glass material.

[0019] In this way, the fully sealed target chamber can ensure the absorption effect of incident light and reflected light, and further ensure the measurement effect of the photomultiplier tube.

[0020] Preferably, the central line of the collection port, the axis of the target chamber, and the axis of the mirror are on the same horizontal line.

[0021] In this way, the central line of the collection port, the axis of the target chamber, and the axis of the mirror are on the same horizontal line, which can make the incident light and the reflected light keep on the same axis as much as possible, ensure the output rate of the two-photon absorption process of the target atomic vapor in the target chamber, and further ensure the number of fluorescent photons received by the photomultiplier tube.

[0022] Preferably, the mirror is a total reflection mirror with silver plating on the back.

[0023] In this way, the total reflection mirror with silver plating on the back can ensure the reflection effect of the incident laser beam.

[0024] Compared with the prior art, in this solution, a large chamber, that is, a light-shielding outer shell, is used to block the influence of external stray light on the result. At the same time, the inside of the light-shielding outer shell is painted with a light-absorbing material, and the experimental measurement efficiency is greatly increased. By making a small chamber, that is, a collection pipe, to block the influence of scattered photons of incident light on the result, and taking good light isolation protection measures for the photomultiplier tube. At the same time, by installing the photomultiplier tube above the target chamber, the signal-to-noise ratio of the two-photon absorption spectrum is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic structural diagram of the shielding measurement device for two-photon spectrum absorption of the present invention.

[0026] Description of the reference numerals in the drawings: laser 1, aperture 2, beam splitter 3, power meter 4, first mirror 5, target chamber 6, mirror 7, light-shielding outer shell 8, collection pipe 9, photomultiplier tube 10. DETAILED DESCRIPTION OF THE INVENTION

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present utility model clearer, the technical solutions of the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are some but not all of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present utility model without creative efforts shall fall within the scope of protection of the present utility model. Unless otherwise defined, the technical terms or scientific terms used herein shall have the ordinary meanings understood by those of ordinary skill in the art to which the present utility model pertains.

[0028] The terms "first", "second", and similar terms used in the specification and claims of the patent application of the present utility model do not denote any order, quantity, or importance, but are merely used to distinguish different components. Similarly, unless the context clearly indicates otherwise, singular forms such as "a", "an", or "the" do not denote a limitation on quantity, but rather indicate the presence of at least one. The terms "including" or "comprising" and the like mean that the elements or items appearing before "including" or "comprising" cover the features, wholes, steps, operations, elements, and / or components listed after "including" or "comprising", and do not exclude the existence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations. The terms "upper", "lower", "left", "right", etc. are only used to indicate relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0029] As shown in the Figure 1 accompanying drawings, a shielding measurement device for two-photon spectral absorption includes a laser 1, a diaphragm 2, a beam splitter 3, a power meter 4, a first mirror 5, a light-shielding housing 8, a target material cavity 6, a mirror 7, a collection pipe 9, a photomultiplier tube 10, and a computer. A collection port is provided on the side wall of the light-shielding housing 8, and the size of the collection port is preferably such that the incident light can just pass through, so as to reduce the entry of external stray light into the light-shielding housing 8. An absorption layer made of an absorbent material is provided on the inner side wall of the light-shielding housing 8. The absorption layer made of the absorbent material can effectively absorb the stray light entering the light-shielding housing 8, and further reduce the influence of the stray light on the measurement result of the photomultiplier tube 10.

[0030] The target chamber 6 and the mirror 7 are arranged inside the light-shielding outer shell 8, and the target chamber 6 is located between the mirror 7 and the collection port. The center line of the collection port, the axis of the target chamber 6, and the axis of the mirror 7 are on the same horizontal line, which can make the incident light and the reflected light maintain the same axis as much as possible, thus ensuring the production rate of the two-photon absorption process of the target atomic vapor in the target chamber 6, and further ensuring the number of fluorescent photons received by the photomultiplier tube 10. The target chamber 6 is a fully sealed target chamber 6 made of glass material; the fully sealed target chamber 6 can ensure the absorption effect of the incident light and the reflected light, and further ensure the measurement effect of the photomultiplier tube 10. The mirror 7 is a total reflection mirror 7 with silver plating on the back; the total reflection mirror 7 with silver plating on the back can ensure the reflection effect of the incident laser beam. A heating device (not shown in the figure) for heating the target chamber 6 is also provided inside the light-shielding outer shell 8; the target chamber 6 is heated by the heating device to keep it at a constant temperature, so that the target in the target chamber 6 is in a stable saturated atomic density vapor state to ensure the absorption effect of the incident light and the reflected light. The heating device is an electric heating wire and a temperature control component; the electric heating wire is used to heat the target chamber 6, and the temperature control component is used to ensure that the target chamber 6 is in a constant temperature state.

[0031] A collection pipe 9 communicating with the inside of the light-shielding outer shell 8 is also provided at the top of the light-shielding outer shell 8. A photomultiplier tube 10 is installed at the upper end of the collection pipe 9, and the collection pipe 9 is located directly above the target chamber 6 and is arranged perpendicular to the target chamber 6. A notch filter is movably connected to the entrance of the collection pipe 9 near the light-shielding outer shell 8. The notch filter can only allow fluorescent photons of a specific wavelength to pass through, while photons of other wavelengths are reflected. Since in addition to fluorescent photons, part of the scattered light of the incident light also converges at the collection pipe 9, by setting the notch filter, as many fluorescent photons as possible that need to be collected can pass through the notch filter and reach the photomultiplier tube 10 to be absorbed, while the scattered light of the incident light can be reflected as much as possible, thereby further improving the signal-to-noise ratio of the two-photon absorption spectrum.

[0032] In this way, when the shielding measurement device of this solution is in use, the incident light generated by the laser 1 sequentially passes through the aperture 2, the beam splitter 3, and the first mirror 5, and then enters the light-shielding housing 8 through the collection port. The incident light entering the light-shielding housing 8 further enters the target chamber 6. The incident light entering the target chamber 6 is absorbed by the target atomic vapor in the target chamber 6 and transitions to a metastable state structure. Then, the incident light further exits from the rear end of the target chamber 6 and hits the mirror 7. The mirror 7 reflects the incident light to form reflected light and enters the target chamber 6 again. The reflected light entering the target chamber 6 is secondarily absorbed by the target atomic vapor, and the outer electrons of the atomic nucleus in the metastable state structure are excited to a better energy state. When the electrons in the excited state deexcite to the ground state, fluorescent photons of a specific wavelength are emitted. The fluorescent photons and the scattered light of the incident light are jointly collected and converged into the collection pipe 9 in the target chamber 6. A movable notch filter is inserted at the entrance of the collection pipe 9, allowing only fluorescent photons of a specific wavelength to pass through the notch filter, and photons of other wavelengths are reflected. The PMT (photomultiplier tube 10) collects as many fluorescent photons of the specific wavelength passing through the notch filter as possible, thereby achieving the purpose of experimentally measuring two-photon absorption.

[0033] In this solution, the target chamber 6 and the mirror 7 are placed in the light-shielding housing 8. The light-shielding housing 8 can block the influence of external stray light on the experimental results, greatly improving the measurement efficiency. At the same time, the fluorescent photons are converged to the photomultiplier tube 10 through the collection pipe 9, and the signal-to-noise ratio of the measurement results is also greatly increased. Therefore, this solution can shield the stray light in the environment and ensure the measurement effect of the photomultiplier tube 10 on the fluorescent photons.

[0034] Compared with the prior art, this solution uses a large cavity, namely the light-shielding housing 8, to block the influence of external stray light on the results. At the same time, the interior of the light-shielding housing 8 is painted with an absorbent material, greatly increasing the experimental measurement efficiency. By making a small cavity, namely the collection pipe 9, to block the influence of the scattered photons of the incident light on the results, and taking good light isolation protection measures for the photomultiplier tube 10. At the same time, by installing the photomultiplier tube 10 above the target chamber 6, the signal-to-noise ratio of the two-photon absorption spectrum is greatly improved.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and do not limit the technical solutions. Those of ordinary skill in the art should understand that any modifications or equivalent replacements of the technical solutions of the present invention, without departing from the purpose and scope of the present technical solution, should be covered by the scope of the claims of the present invention.

Claims

1. A shielding measurement device for two-photon spectral absorption, characterized in that: It includes a light-shielding shell, a collecting port is opened on the side wall of the light-shielding shell, a target material cavity and a reflector are arranged in the light-shielding shell, the target material cavity is located between the reflector and the collecting port, and a collecting pipe communicating with the interior of the light-shielding shell is also arranged on the top of the light-shielding shell, a photomultiplier tube is installed on the upper end of the collecting pipe, and the collecting pipe is located directly above the target material cavity and is arranged perpendicular to the target material cavity.

2. The shielding measurement device of two-photon spectral absorption according to claim 1, characterized in that: A notch filter is movably connected to the inlet of the collecting pipe close to one end of the light-shielding housing.

3. The shielding measurement device of two-photon spectral absorption according to claim 1, characterized in that: A light absorbing layer made of light absorbing material is arranged on the inner side wall of the light shading shell.

4. The shielding measurement device of two-photon spectral absorption according to claim 1, characterized in that: A heating device for heating the target cavity is also provided in the light-shielding housing.

5. The shielding measurement device of two-photon spectral absorption according to claim 4, characterized in that: The heating device comprises a heating wire and a temperature control component.

6. The shielding measurement device of two-photon spectral absorption according to claim 1, characterized in that: The target cavity is a fully sealed target cavity made of glass material.

7. The shielding measurement device of two-photon spectral absorption according to claim 1, characterized in that: The center line of the collecting port, the axis of the target cavity and the axis of the reflector are located on the same horizontal line.

8. The shielding measurement device of two-photon spectral absorption according to claim 1, characterized in that: The reflector is a total reflector with silver plated on the back.

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