CN214066925U

CN214066925U - Optical wedge device

Info

Publication number: CN214066925U
Application number: CN202023033822.XU
Authority: CN
Inventors: 赵羽; 徐海涛
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2020-12-16
Filing date: 2020-12-16
Publication date: 2021-08-27
Anticipated expiration: 2030-12-16

Abstract

The utility model belongs to the technical field of the optical measurement, a method that optical wedge device and measurement solution infrared absorption coefficient is related to. In the optical wedge device of the utility model, the upper layer glass is inserted into the groove of the upper plate, the lower layer glass is inserted into the groove of the lower plate, and the upper plate and the middle plate are fastened with each other through the spring; the middle plate and the lower plate are relatively fixed through bolts, and the upper layer of glass and the lower layer of glass form wedge through adjustment of the high-precision thread pair. In the process of measuring the infrared absorption coefficient of the solution, firstly, the angle theta of a wedge in an optical wedge device is determined, then the solution to be measured is injected into the wedge device, and the infrared absorption coefficient k of the solution to be measured under the set wavelength is measured_s. The optical wedge device is designed in a split type, and can conveniently carry out the processing of the upper layer glass and the lower layer glassThe assembling, adjusting and cleaning greatly improve the flexibility of the optical wedge device in actual use.

Description

Optical wedge device

Technical Field

The utility model belongs to the technical field of the optical measurement, especially, relate to an optics wedge device.

Background

The absorption coefficient of a substance to light is an important physical quantity, and the method is widely applied to various fields of substance concentration and temperature measurement based on absorption spectrum, signal transmission and attenuation control, directional energy transmission and the like. Specifically, when light of a certain wavelength propagates in a homogeneous substance, the intensity of the light is attenuated with the optical path length due to the absorption of the light by the substance, which follows the Beer-Lambert's law:

where λ is the wavelength of the light, L is the optical path length of the light in the substance, I₀And I_tThe light intensity of the incident light and the emergent light respectively, τ (λ) is the transmittance of the light after passing through the substance, and k (λ) is the absorption coefficient of the substance for the light with the wavelength. Most of the current applications based on absorption spectroscopy are for light waves with wavelengths in the infrared band, where k (λ) is referred to as the infrared absorption coefficient. The magnitude of the absorption coefficient of a substance depends on various factors such as the kind, concentration, temperature, pressure, and wavelength of the light to be absorbed of the substance. For the infrared absorption coefficient of a gas, under the condition that the gas density is low, a relevant theoretical formula exists, and relatively accurate calculation can be carried out. But for denser gases, the theoretical calculations become complex and less accurate. For liquid, because the liquid has small molecular distance and strong intermolecular interaction, accurate theoretical calculation of the infrared absorption coefficient of the liquid (especially a complex component solution) is not feasible at present, and therefore, an experimental method is generally required for measurement.

Fourier transform infrared spectroscopy (FTIR) is the most commonly used instrument for determining the infrared absorption coefficient of a substance at present, but fourier transform infrared spectroscopy usually gives only qualitative changes in the infrared absorption coefficient, not quantitative absorption coefficient values. If the infrared absorption coefficient of the liquid is to be measured quantitatively by a Fourier transform infrared spectrometer, a set of liquid sample cells with known and precise optical path lengths must be provided. As can be seen from the beer-lambert law, if the infrared absorption coefficient of the solution is to be accurately measured by the light intensity transmittance with high data quality (i.e., not very large or very small), the optical path length of the liquid pool needs to be matched with the infrared absorption coefficient at that time. Specifically, if the infrared absorption coefficient of the solution is small, the optical path length of the liquid pool needs to be large; if the infrared absorption coefficient of the solution is large at this time, the optical path length of the liquid pool needs to be small. When the infrared absorption coefficient of the solution to be measured at the infrared wavelength to be measured is very strong, even a liquid pool with a set of known precise optical path length in the micrometer scale (less than 10 micrometers) is required at this time, which is obviously very difficult to achieve. Therefore, the Fourier transform infrared spectrometer has difficulty in meeting the goal of accurately measuring the strong infrared absorption coefficient of the solution.

Disclosure of Invention

The utility model aims at providing an optics wedge device need possess the not enough of the known accurate optical path length liquid pool of a set of micron magnitude (being less than 10 microns) when measuring the strong infrared absorption coefficient of solution among the prior art and improve to the realization is only split the optical wedge who has the solution that awaits measuring to carry out the mode that infrared laser space scanned through annotating and alright measure the purpose of the infrared absorption coefficient of solution, is particularly useful for the measurement of the very strong wave band of infrared absorption coefficient.

The utility model provides an optical wedge device, which comprises an upper plate, a middle plate, a lower plate, an upper layer of glass and a lower layer of glass; one side of the upper plate is provided with a groove, the upper layer of glass is inserted into the groove of the upper plate, the same side of the lower plate as the upper plate is provided with a groove, and the lower layer of glass is inserted into the groove of the lower plate; the upper plate, the middle plate and the lower plate are mutually arranged from top to bottom, and the upper plate and the middle plate are mutually fastened through a fastening spring; the middle plate and the lower plate are relatively fixed through fastening bolts, and the distance between the upper plate and the middle plate is adjusted through the three groups of high-precision thread pairs so that the upper layer glass of the upper plate and the lower layer glass of the lower plate form wedge points.

The utility model provides an optics wedge device, its advantage:

utilize the utility model discloses an optics wedge device carries out the mode that infrared laser space scans through the optics wedge to annotating the solution that awaits measuring, measures the infrared absorption coefficient of the solution that awaits measuring, is particularly useful for the measurement of the very strong wave band of infrared absorption coefficient. The utility model overcomes utilize Fourier transform infrared spectroscopy (FTIR) to possess the difficult point and not enough of the known accurate optical path length liquid cell of a set of micron magnitude (being less than 10 microns) when measuring the strong infrared absorption coefficient of solution in the tradition, needn't know infrared laser and pass the absolute thickness of wedge liquid film in the optical wedge, and then improved and carried out measuring ease of operation nature and accuracy to the strong infrared absorption coefficient of solution. The utility model discloses in the operation process of method, all need not to confirm absolute thickness size of wedge liquid film in the absolute space coordinate of the accurate position of this optics wedge extreme point, this optics wedge and this optics wedge, the utility model discloses only need concern the relative coordinate of this optics wedge, can accomplish the demarcation of optics wedge angle and the measurement of the infrared absorption coefficient of solution that awaits measuring. The utility model provides an optics wedge device is split type design, can conveniently carry out loading, adjustment and washing of upper glass and lower floor's glass, so can greatly improve the flexibility of optics wedge device in-service use.

Drawings

Fig. 1 is a schematic structural diagram of an optical wedge device according to the present invention.

FIG. 2 is a cross-sectional view of the optical cleaving apparatus shown in FIG. 1.

FIG. 3 is a top view of the midplane of the optical cleaving device shown in FIG. 1.

FIG. 4 is a schematic diagram of the structure of the lower plate of the optical cleaving device shown in FIG. 1, wherein (a) is a top view of the lower plate and (b) is a cross-sectional view A-A of (a).

Fig. 5 is a schematic view illustrating angle calibration in the testing process of the optical wedge device of the present invention.

Fig. 6 is a schematic diagram of the testing process of the optical wedge device of the present invention.

Fig. 7 is a schematic diagram illustrating the testing principle of the optical wedge device of the present invention.

In fig. 1 to 7, 1 is an upper plate, 2 is a high-precision screw pair, 3 is an intermediate plate, 4 is a lower plate, 5 is an upper glass, 6 is a lower glass, 7 is an upper plate spring mounting hole, 8 is a fastening bolt, 9 is a liquid injection groove, 10 is an intermediate plate spring mounting hole, 11 is a fastening spring, 12 is a lower plate screw hole, 13 is a visible laser, 14 is a visible laser, 15 is a concave lens, 16 is a convex lens, 17 is a reflector, 18 is ground glass, 19 is a camera, 20 is an infrared laser, 21 is an infrared laser, 22 is a reflector, 23 is a reflector, 24 is an infrared detector, and 25 is a solution to be measured.

Detailed Description

The structure of the optical wedge device provided by the utility model is shown in fig. 1, and comprises an upper plate 1, a middle plate 3, a lower plate 4, an upper layer of glass 5 and a lower layer of glass 6; one side of the upper plate 1 is provided with a groove, the upper layer glass 5 is inserted into the groove of the upper plate 1, the same side of the lower plate 4 as the upper plate 1 is provided with a groove, and the lower layer glass 6 is inserted into the groove of the lower plate 4; the upper plate 1, the middle plate 3 and the lower plate 4 are mutually arranged from top to bottom, and the upper plate 1 and the middle plate 3 are mutually fastened through a fastening spring 11; the middle plate 3 and the lower plate 4 are relatively fixed through a fastening bolt 8, and the distance between the upper plate 1 and the middle plate 3 is adjusted through the three groups of high-precision thread pairs 2 by the upper plate 1 and the middle plate 3, so that the upper layer glass 5 of the upper plate and the lower layer glass 6 of the lower plate form wedge.

In the optical wedge device, the upper layer glass 5 and the lower layer glass 6 can adopt calcium fluoride crystal glass. The fastening bolts 8 on the middle plate are used for connecting the middle plate and the lower plate through bolts, and the threaded holes 12 on the lower plate are used for being matched with the fastening bolts 8, so that the middle plate and the lower plate are connected through bolts.

Utilize the utility model provides an optics wedge device measures the method of the infrared absorption coefficient of solution, including following step:

(1) placing a piece of ground glass 18 directly above the optical wedge device, the ground glass 18 being parallel to the lower glass 6, as shown in fig. 5;

(2) after a beam of visible light laser is expanded, the beam is perpendicular to the lower layer glass 6 from the lower part of the lower layer glass 6 and enters an optical wedge device;

(3) adjusting the angle of an optical wedge formed by the upper layer glass 5 and the lower layer glass 6 by using three groups of high-precision thread pairs 2 on the optical wedge device until light and dark interference fringes arranged in parallel along the opening direction of the optical wedge are observed from the optical wedge, and calculating the angle theta of the optical wedge by using the following formula:

wherein λ is₀The wavelength of the visible laser, i and j are the reference numerals of the interference fringes, x_iAnd x_jIs the position of the interference fringes;

the optical cleave angle θ was kept constant in the following solution infrared absorption coefficient measurement step.

(4) To pour into solution to be measured into the wedge formed by upper glass 5 and lower floor glass 6, in one embodiment of the utility model, the solution to be measured is poured into from the liquid injection groove 9 processed on the upper plate 1, so that a very thin wedge solution film is formed between the upper glass 5 and the lower floor glass 6;

(5) measuring the infrared absorption coefficient of the solution under a set wavelength, and enabling a beam of infrared laser with the same wavelength as the set wavelength to be vertical to the lower calcium fluoride crystal glass 6 and incident to the optical wedge device in the step (5), so that the infrared laser sequentially passes through the upper calcium fluoride crystal glass 5, the middle solution film 25 and the lower calcium fluoride crystal glass 6 of the optical wedge device;

(6) enabling infrared laser to scan the optical wedge device, enabling an infrared detector to receive the infrared laser at different positions after the infrared laser passes through the optical wedge device in the step (6) in real time to obtain emergent light intensity of the infrared laser after the infrared laser passes through the optical wedge device from different positions, and calculating to obtain an infrared absorption coefficient k of the solution to be measured under the set wavelength by utilizing the following formula_s：

Wherein m and n are respectively the number of the scanning position of the infrared laser on the optical wedge device, y'_nAnd y'_mRespectively, the position of the infrared laser beam emitted from the optical wedge device, I_t,mAnd I_t,nDevice for respectively passing infrared laser from different positions through optical wedgeThe post-positioned emergent light intensity theta is an optical wedge angle, subscript t represents emergent infrared laser, and ln (·) is a natural logarithm operator.

The following describes the present invention in detail with reference to the attached drawings:

the utility model provides an optics wedge device and utilize the method of the infrared absorption coefficient of measurement solution that this optics wedge device realized as shown in figure 1, figure 2, the device contains upper plate 1,

medium plate

3 and 4 triplexes of hypoplastron. Wherein the upper glass 5 and the lower glass 6 of the optical wedge are made of a material which is not absorptive to infrared light and visible light of the wave band to be measured, in one embodiment of the utility model, the upper glass 5 and the lower glass 6 are calcium fluoride (CaF)₂) A crystalline glass. One side of the upper plate 1 is provided with a groove, the upper layer glass 5 is inserted into the groove of the upper plate 1, and the upper plate 1 is provided with a fastening spring mounting hole 7. As shown in fig. 3, the middle plate 3 has a 7-shaped structure, and the middle plate 3 is provided with fastening bolts 8 for fastening the middle plate 3 and the lower plate 4 by bolts, and fastening spring mounting holes 10. As shown in fig. 4, the lower plate 4 is recessed on the same side as the upper plate 1, the lower glass 6 is inserted into the recess of the lower plate 4, and the lower plate 4 is provided with screw holes 12 for bolt-coupling with the middle plate 3. The upper plate 1, the middle plate 3 and the lower plate 4 are mutually arranged from top to bottom, the upper plate 1 and the middle plate 3 are mutually fastened through a fastening spring 11, the middle plate 3 and the lower plate 4 are relatively fixed through a fastening bolt 8, the upper plate 1 and the middle plate 3 adjust the distance between the upper plate 1 and the middle plate 3 through three groups of high-precision thread pairs 2, so that the upper layer glass 5 of the upper plate 1 and the lower layer glass 6 of the lower plate 4 form an optical wedge, and the angle of the optical wedge is adjustable. Simultaneously, processing has annotate liquid groove 9 on the upper plate 1 the utility model discloses an in the embodiment, process out from upper plate 1 annotate liquid groove 9 to pour into the solution that awaits measuring in the optics wedge for form extremely thin wedge solution film 25 between upper glass 5 and lower floor's glass 6. The utility model discloses a split type design of optics wedge device can make things convenient for loading, adjustment and washing of upper glass 5 and lower floor's glass 6, can greatly improve the flexibility of this optics wedge device in-service use.

Utilize the utility model discloses an infrared absorption coefficient of solution is measured to optics wedge device specifically includes two following steps:

the first step is to determine the angle θ of the wedge in the optical wedge device:

as shown in fig. 5, the utility model discloses a visible light laser 14 is launched to a visible light laser 13, the utility model discloses an embodiment to the green laser of 532nm wavelength to utilize concave lens 15 and convex lens 16 to expand this bundle of visible light laser 14, then incide the visible light laser after will expanding from the below perpendicular to lower floor's glass 6 of lower floor's glass 6 through speculum 17 in the optics wedge device. In order to observe and shoot clear interference fringes from the optical wedge, a piece of ground glass 18 is placed right above the optical wedge device, and the ground glass 18 is parallel to the lower layer glass 6.

The utility model discloses utilize three high accuracy thread pairs 2 of group on the optics wedge device adjust the angle of the optics wedge that upper glass 5 and lower floor's glass 6 formed, until following observe the edge on the optics wedge the alternate interference fringe of light and shade of optics wedge opening direction parallel arrangement. The camera 19 is used for shooting the interference fringes on the optical wedge, and the optical wedge angle θ can be calculated by combining the following formula:

wherein λ is₀I and j are the wavelength of the visible laser, and x is the index of interference fringe_iAnd x_jIs the position of the interference fringes; in the measuring link that follows, the utility model discloses a tighten the lock nut on the vice 2 of three high accuracy screw threads of group will optics wedge angle theta is fixed down.

The second step is to measure the infrared absorption coefficient k of the solution to be measured at the set wavelength_s：

Through measure link 1 and confirmed after the angle theta of optics wedge, the utility model discloses pour into the solution that awaits measuring into in the optics wedge that is formed by upper glass 5 and lower floor's glass 6, the utility model discloses an in the embodiment, the liquid groove 9 that annotates that processes out from upper plate 1 pours into the solution that awaits measuring into in the optics wedge for form extremely thin wedge solution film 25 (thickness generally is less than 10 microns) between upper glass 5 and the lower floor's glass 6.

The utility model discloses measure the infrared absorption coefficient of solution under setting for the wavelength, as shown in fig. 6, the utility model discloses an infrared laser 20 launches a branch of wavelength and should set for the infrared laser 21 that the wavelength is the same to utilize speculum 22 to make infrared laser 21 perpendicular to lower floor calcium fluoride crystal glass 6 incides to optics wedge, infrared laser passes calcium fluoride crystal glass 5, middle solution film 25 and the calcium fluoride crystal glass 6 of lower floor on the upper strata of optics wedge device in proper order. Therefore, the loss of light intensity of the infrared laser light 21 passing through the optical chopping device can be divided into three parts in total: reflection losses through the upper glass 5, reflection losses through the lower glass 6 and absorption losses through the wedge-shaped solution film 25 in the optical wedge. The emergent light intensity of the infrared laser 21 after passing through the optical wedge is measured in real time by an infrared detector 24.

As shown in fig. 6, the optical cleave tip is scanned by an infrared laser 21. As shown in FIG. 7, the optical path diagram of the optical wedge injected with the solution 25 to be measured in the measurement link 2 is an infrared laser spatial scanning optical path diagram, and the total transmittance T of the infrared laser passing through the optical wedge from different positions_mComprises the following steps:

wherein m is the number of the scanning position of the infrared laser 21 on the optical wedge, I_t,mFor the intensity of the infrared laser 21 after passing through the optical wedge from different positions, the subscript t represents the intensity of the emitted infrared laser, |_mIs the thickness of the wedge-shaped solution film 25 through which the infrared laser 21 passes from different positions through the optical wedge₀Is the initial intensity of the infrared laser light 21 before it passes through the optical wedge, T_rFor infrared laser 21 throughTransmittance when passing through the upper glass 5 or the lower glass 6 (taking into account reflection loss when the infrared laser light 21 passes through the upper glass 5 or the lower glass 6), k_sExp (-) is an exponential function operator with a natural constant e as the base, for the infrared absorption coefficient of the solution to be measured at a set wavelength.

The infrared detector 24 receives the infrared laser beams passing through the optical wedge from different positions in real time to obtain the emergent light intensity of the infrared laser beams 21 passing through the optical wedge from different positions. By using the following formula, the infrared absorption coefficient k of the solution to be measured under the set wavelength can be calculated_s：

Wherein m and n are respectively the number of the scanning position of the infrared laser 21 on the optical wedge, y'_mAnd y'_nRespectively, the position of the infrared laser 21 emitted from the optical wedge, I_t,mAnd I_t,nThe light intensities of the infrared laser 21 after passing through the optical wedge from different positions are respectively shown, subscript t represents the emergent infrared laser, theta is the angle of the optical wedge, and ln (·) is a natural logarithm operator.

In one embodiment of the present invention, the infrared detector used is manufactured by the company Poland VIGO, with the product model number PVI-4 TE-4T 08-1X 1.

Utilize the utility model provides an optics wedge device measures the infrared absorption coefficient of solution, is particularly useful for the measurement to the absorption coefficient that has the spectral line section of stronger absorption. The utility model discloses can be through carrying out the mode that infrared laser space scans to the optics wedge that is annotated with the solution that awaits measuring, measure the infrared absorption coefficient of the solution that awaits measuring.

Fourier transform infrared spectroscopy (FTIR), which is a prior art technique for measuring the infrared absorption coefficient of a solution, has a problem in that a liquid cell having a set of known precise optical path lengths on the order of micrometers (less than 10 micrometers) is required to measure the strong infrared absorption coefficient of a solution using the fourier transform infrared spectroscopy (FTIR). The utility model provides an optical wedge device can overcome the above-mentioned not enough of prior art, can realize the accurate measurement to solution infrared absorption coefficient (especially strong infrared absorption coefficient) through simple and convenient operation link.

It is worth emphasizing that, no matter the angle of the optical wedge is determined by analyzing the interference fringes in the measuring link 1, or the absorption coefficient of the solution to be measured under the set infrared wavelength is determined by the spatial scanning of the infrared laser in the measuring link 2, the utility model discloses the accurate position of the optical wedge endpoint, the absolute spatial coordinate of the optical wedge and the absolute thickness of the wedge solution film 25 passed by the infrared laser 21 when passing through the optical wedge from different positions are not required to be determined. The utility model discloses only need pay attention to the relative coordinate of optics wedge can begin the space scanning of analysis interference fringe and the infrared laser 21 of beginning from arbitrary position to accomplish the demarcation of optics wedge angle and the measurement of the infrared absorption coefficient of solution that awaits measuring. This advantage is derived from the theoretical design of the method and the ease of operation of the measurement process and the accuracy of the measurement results can be greatly improved.

Furthermore, the utility model discloses when carrying out the infrared absorption coefficient measurement of solution, need not to know the refractive index of infrared laser under the settlement wavelength in each optical medium (air, wedge glass, solution to be measured) or the reflection loss coefficient of interface department. And in the whole implementation process of the utility model, the initial light intensity I of the infrared laser 21 before passing through the optical wedge is not required to be measured₀Because these physical quantities can not influence the utility model discloses to the measuring result of solution infrared absorption coefficient, this easy operability and the accuracy of measuring result that can further improve this measurement process.

And simultaneously, the utility model discloses a split type design of optics wedge device can make things convenient for loading, adjustment and washing of upper glass 5 and lower floor's glass 6, can greatly improve the flexibility of this optics wedge device in the in-service use.

The utility model discloses can bring the help for a plurality of fields such as the absorption spectrum of solution and application, can to a great extent help to the infrared absorption spectroscopy of physical quantities such as thickness, temperature, concentration to micron order of magnitude solution liquid film measure.

Claims

1. An optical wedge device is characterized in that the optical wedge device comprises an upper plate, a middle plate, a lower plate, an upper layer of glass and a lower layer of glass; one side of the upper plate is provided with a groove, the upper layer of glass is inserted into the groove of the upper plate, the same side of the lower plate as the upper plate is provided with a groove, and the lower layer of glass is inserted into the groove of the lower plate; the upper plate, the middle plate and the lower plate are mutually arranged from top to bottom, and the upper plate and the middle plate are mutually fastened through a fastening spring; the middle plate and the lower plate are relatively fixed through fastening bolts, and the distance between the upper plate and the middle plate is adjusted through the three groups of high-precision thread pairs so that the upper layer glass of the upper plate and the lower layer glass of the lower plate form wedge points.