Method, device and system for measuring transmissivity and computer readable storage medium

Abstract

The invention relates to the technical field of optics, in particular to a transmissivity measuring method, device and system and a computer readable storage medium. The method comprises the following steps: acquiring a first curve that the reflectivity of an optical cavity changes along with the frequency of light in a first state and a second curve that the reflectivity of the optical cavity changes along with the frequency of light in a second state; determining a first value of an optical power attenuation parameter of the optical cavity in the first state according to the half-peak width of the first curve; determining a second value of the optical power attenuation parameter of the optical cavity in the second state according to the half-peak width of the second curve; obtaining a correlation formula between the reflectivity of the optical cavity and the frequency of the light, the optical power attenuation parameter of the optical cavity, the coupling efficiency of the light and the optical cavity, and the transmissivity of the first reflector; and fitting according to a correlation formula, the first curve, the first value, the second curve and the second value to obtain the value of the transmissivity of the first reflector. According to the invention, the transmissivity of the reflector in the optical cavity can be measured more accurately.

Description

Technical Field

[0001] The present disclosure relates to the field of optical technology, and in particular to a transmittance measurement method, device, system and computer-readable storage medium. Background Art

[0002] Optical cavities are important components in modern optical engineering and modern basic scientific research. Optical cavities are composed of multi-faceted mirrors arranged according to optical design, so as to achieve the confinement of photons and the enhancement of the interaction between photons and quantum bits. The reflectivity and transmittance of the mirrors that constitute the optical cavity are very important parameters of the optical cavity.

[0003] In the related art, the transmittance of a single-sided reflector is measured before building an optical cavity. Summary of the invention

[0004] It is noted that measuring the transmittance of a single-sided mirror before building an optical cavity in the related art leads to several problems.

[0005] First, the reflector will inevitably change its transmittance during the construction of the optical cavity. For example, due to dust, chemical reactions on the mirror surface, or other reasons, the transmittance measured after the cavity is formed is different from the transmittance measured before the cavity is formed, and the accuracy of the measurement is affected. In particular, when the reflector has an extremely high reflectivity close to 1, the transmittance of the reflector is extremely low. At this time, a slight change in the transmittance value of the reflector during the construction of the optical cavity can have a significant impact on the accuracy of the measurement.

[0006] Secondly, accurately measuring the transmittance of a single-sided reflector before building an optical cavity also places high demands on the reflector itself. For example, for special small reflectors or spherical reflectors with a small radius of curvature, measuring the transmittance is technically difficult, and it is necessary to fully receive the transmitted light while well shielding the stray light in order to accurately measure the transmittance.

[0007] In view of this, the present disclosure proposes the following technical solution, which helps to more accurately measure the transmittance of the reflector in the optical cavity.

[0008] According to a first aspect of an embodiment of the present disclosure, a transmittance measurement method is proposed, and the transmittance measurement method includes: obtaining a first curve of how the reflectance of an optical cavity in a first state varies with the frequency of light, and a second curve of how the reflectance of the optical cavity in a second state varies with the frequency of light, wherein light enters the optical cavity from a first reflector of the optical cavity; determining a first value of an optical power attenuation parameter of the optical cavity in the first state according to the half-peak width of the first curve; determining a second value of the optical power attenuation parameter of the optical cavity in the second state according to the half-peak width of the second curve, the second value being different from the first value; obtaining a correlation formula between the reflectance of the optical cavity and the frequency of light, the optical power attenuation parameter of the optical cavity, the coupling efficiency of light and the optical cavity, and the transmittance of the first reflector; and fitting the transmittance value of the first reflector according to the correlation formula, the first curve, the first value, the second curve, and the second value.

[0009] According to some embodiments of the present disclosure, in the first state, there is a first light shielding object in the optical cavity; in the second state, there is no light shielding object in the optical cavity or there is a second light shielding object, and the spatial information of the second light shielding object is different from the spatial information of the first light shielding object, and the spatial information includes at least one of shape and position.

[0010] According to some embodiments of the present disclosure, obtaining the correlation formula includes: obtaining a first reflectivity R corresponding to a portion of the light that is not coupled to the optical cavity after the light is incident on the first reflector. 1 With the coupling efficiency C k A first correlation formula between: obtaining a second reflectivity R corresponding to the portion coupled to the optical cavity after the light is incident on the first reflector 2 The optical power attenuation parameter R of the optical cavity is ’ round , the coupling efficiency C k , and the transmittance t of the first reflector k a second association formula between; and determining the association formula according to the first association formula and the second association formula.

[0011] According to some embodiments of the present disclosure, the correlation formula is: R k (f) = R 1 +R 2 ; Among them, R k (f) is the reflectivity of the optical cavity.

[0012] According to some embodiments of the present disclosure, the first correlation formula is: 1 =1-C k .

[0013] According to some embodiments of the present disclosure, the second association formula is: ; where φ round is the phase change accumulated during one cycle of light propagation in the optical cavity, φ round =4πfl / c, l is the effective length of the optical cavity, c is the speed of light, R ’ round =R round (1-L), L is the value of the optical loss factor of the optical cavity in the first state or the second state, L<1, , is the product of the reflectivity of all the mirrors that sequentially reflect the light during one cycle of light propagation in the optical cavity, r j is the reflectivity of the reflector that reflects the light for the jth time during the process of light propagating in the optical cavity for one cycle, and N is the number of times the light is reflected by all the reflectors during the process of light propagating in the optical cavity for one cycle.

[0014] According to some embodiments of the present disclosure, the first value and the second value are obtained according to the following formula: ; Among them, R ’ round is the optical power attenuation parameter, f HWHM is the half-peak width, l is the effective length of the optical cavity, and c is the speed of light.

[0015] According to some embodiments of the present disclosure, fitting the transmittance value of the first reflector according to the association formula, the first curve, the first value, the second curve, and the second value includes: fitting a third value related to the transmittance of the first reflector and the coupling efficiency according to the association formula, the first curve and the first value; fitting a fourth value related to the transmittance of the first reflector and the coupling efficiency according to the association formula, the second curve and the second value; and determining the transmittance value of the first reflector according to the third value and the fourth value.

[0016] According to a second aspect of an embodiment of the present disclosure, a transmittance measuring device is proposed, the transmittance measuring device comprising: a first acquisition module, configured to acquire a first curve of a reflectance of an optical cavity in a first state varying with the frequency of light, and a second curve of a reflectance of the optical cavity in a second state varying with the frequency of light, wherein light enters the optical cavity from a first reflector of the optical cavity; a first determination module, configured to determine a first value of an optical power attenuation parameter of the optical cavity in the first state according to a half-peak width of the first curve; a second determination module, configured to determine a second value of an optical power attenuation parameter of the optical cavity in the second state according to a half-peak width of the second curve, the second value being different from the first value; a second acquisition module, configured to acquire an association formula between the reflectance of the optical cavity and the frequency of light, the optical power attenuation parameter of the optical cavity, the coupling efficiency of light and the optical cavity, and the transmittance of the first reflector; and a fitting module, configured to obtain a value of the transmittance of the first reflector by fitting according to the association formula, the first curve, the first value, the second curve, and the second value.

[0017] According to the third aspect of an embodiment of the present disclosure, a transmittance measuring device is proposed, which includes: a memory; and a processor coupled to the memory, configured to execute the transmittance measuring method of any one of the above-mentioned embodiments based on instructions stored in the memory.

[0018] According to a fourth aspect of an embodiment of the present disclosure, a transmittance measurement system is proposed, which comprises: a transmittance measurement device of any one of the above embodiments; a signal generator configured to generate a swept frequency signal; a transmitter configured to transmit light with a changing frequency to the first reflector according to the swept frequency signal; and a detection device configured to detect a reflected light signal of the optical cavity, and determine correlation information between the power of the reflected light signal and the frequency of light according to the reflected light signal and the swept frequency signal; wherein the transmittance measurement device is configured to obtain the first curve and the second curve according to the correlation information.

[0019] According to a fifth aspect of the embodiments of the present disclosure, a computer-readable storage medium is provided, wherein the computer-readable storage medium includes computer program instructions, and when the computer program instructions are executed by a processor, the transmittance measurement method of any one of the above embodiments is implemented.

[0020] According to a sixth aspect of the embodiments of the present disclosure, a computer program product is proposed. The computer program product includes a computer program. When the computer program is executed by a processor, the transmittance measurement method of any one of the above embodiments is implemented.

[0021] In the disclosed embodiment, on the one hand, since the entire measurement process is based on the optical cavity having been constructed, the influence of the process of constructing the optical cavity on the transmittance value of the first reflector is eliminated, and the measured transmittance value of the first reflector is more accurate.

[0022] On the other hand, after the optical cavity is built, the measurement result of the above method is basically determined only by the structure of the optical cavity itself. The influence of factors outside the optical cavity (such as the construction and debugging of the optical path) on the measurement result becomes smaller, and the measurement operation error is also smaller, thus making the measured transmittance value of the first reflector more accurate.

[0023] On the other hand, since the transmittance of the reflector is related to the incident angle of light, when the incident angle of light changes, the measured transmittance will also change accordingly. According to the above transmittance measurement method, it is only necessary to determine the structure of the appropriate optical cavity so that light can be incident on the first reflector at a desired incident angle and coupled with the optical cavity, and the transmittance of the first reflector at the desired incident angle can be measured. That is, the transmittance measurement method of the embodiment of the present disclosure can accurately measure the transmittance of the reflector at any incident angle. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 It is a flowchart of a method for measuring transmittance according to some embodiments of the present disclosure.

[0026] Figure 2 A first curve, a second curve, and a third curve according to some embodiments of the present disclosure are shown.

[0027] Figure 3 It is a schematic diagram of a flow chart of fitting the transmittance value of the first reflector in the transmittance measurement method according to some embodiments of the present disclosure.

[0028] Figure 4 It is a flowchart of obtaining the correlation formula in the transmittance measurement method according to some embodiments of the present disclosure.

[0029] Figure 5 is a schematic diagram of light entering an optical cavity in a method for measuring transmittance according to some embodiments of the present disclosure.

[0030] Figure 6is a schematic diagram of light entering an optical cavity in a method for measuring transmittance according to yet other embodiments of the present disclosure.

[0031] Figure 7 It is a schematic diagram of the structure of a transmittance measuring device according to some embodiments of the present disclosure.

[0032] Figure 8 4 is a schematic diagram of the structure of a transmittance measuring device according to some other embodiments of the present disclosure.

[0033] Fig. 9 is a schematic diagram of the structure of a transmittance measurement system according to some embodiments of the present disclosure.

[0034] Fig.10 is a schematic structural diagram of a transmittance measurement system according to some other embodiments of the present disclosure. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present disclosure to clearly and completely describe the technical solutions in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present disclosure.

[0036] Unless specifically stated otherwise, the relative arrangement of components and steps, the numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present disclosure.

[0037] At the same time, it should be understood that for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

[0038] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0039] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0040] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0041] Figure 1 FIG. 1 is a flow chart of a method for measuring transmittance according to some embodiments of the present disclosure. Figure 1 As shown, the transmittance measurement method includes steps S10 to S50.

[0042] In step S10, a first curve showing that the reflectivity of the optical cavity in the first state varies with the frequency of light and a second curve showing that the reflectivity of the optical cavity in the second state varies with the frequency of light are obtained.

[0043] Here, the optical cavity has, for example, M reflective mirrors, M ≥ 2, and light (eg, laser light) enters the optical cavity from the kth reflective mirror (hereinafter referred to as the first reflective mirror) of the optical cavity, 1 ≤ k ≤ M. The reflective mirror has, for example, an extremely high reflectivity close to 1.

[0044] It can be understood that the two curves of the optical cavity in the two states are different, and the first curve and the second curve each include multiple sets of data. Each set of data in the first curve includes the reflectivity of the optical cavity in the first state and the corresponding frequency of light, and each set of data in the second curve includes the reflectivity of the optical cavity in the second state and the corresponding frequency of light.

[0045] For example, the reflectivity of an optical cavity is the power reflectivity.

[0046] In some embodiments, before step S10, an optical cavity is constructed and an optical path of light incident on the optical cavity is adjusted so that the light is incident from the first reflector and the coupling efficiency C between the light and the optical cavity is k Higher.

[0047] Figure 2 shows the coupling efficiency C of light into the optical cavity k When the reflectivity R of the optical cavity is low (e.g. close to 0), k (f) The third curve S3 that changes with the frequency f of the light. At this time, because the optical cavity has not been built or the optical path is not well adjusted, the light and the optical cavity are basically not coupled, so the light incident on the first reflector is basically all reflected back, and the reflectivity R of the optical cavity is k (f) is close to 1 and does not change with the frequency f of light.

[0048] In step S20, a first value of an optical power attenuation parameter of the optical cavity in a first state is determined according to the half-peak width of the first curve.

[0049] It should be understood that the optical power attenuation parameter can reflect the attenuation of the optical power during the propagation of light in the optical cavity. In some embodiments, the optical power attenuation parameter is related to the reflectivity of the reflector that reflects the light during the propagation of light in the optical cavity. In other embodiments, the optical power attenuation parameter is also related to the light loss caused by the light shielding object in the optical cavity to the propagation of light.

[0050] In step S30, a second value of the optical power attenuation parameter of the optical cavity in the second state is determined according to the half-peak width of the second curve. Here, the second value is different from the first value, that is, the values ​​reflecting different attenuation conditions of the optical power during the propagation of light in the optical cavity are determined according to the two curves.

[0051] There is no restriction on the execution order of step S20 and step S30. For example, step S20 may be executed before step S30, after step S30, or simultaneously with step S30.

[0052] In some embodiments, the first value and the second value of the optical power attenuation parameter may be determined according to the following formula:

[0053] Among them, R ’ round is the optical power attenuation parameter, f HWHM is the half-peak width, l is the effective length of the optical cavity, and c is the speed of light.

[0054] According to formula (1), when the value of the optical power attenuation parameter of the optical cavity changes, the half-peak width of the curve of the reflectivity of the optical cavity changing with the frequency of light will change accordingly. Conversely, based on the first curve and the second curve with different half-peak widths, the first value of the optical power attenuation parameter of the optical cavity in the first state and the second value in the second state can be determined. The detailed derivation of formula (1) will be given below.

[0055] In some embodiments, the optical power attenuation parameter can be defined as the ratio of the power of light after one cycle of propagation in the optical cavity (i.e., the light is incident on a certain reflector from a certain initial position along a certain initial propagation direction until it is reflected at least once by each of the M reflectors and then returns to the initial position in the initial propagation direction) to the current power. By changing the propagation state of light in the optical cavity, the value of the optical power attenuation parameter of the optical cavity can be changed.

[0056] For example, the optical power attenuation parameter R ’ round Can be:

[0057] Wherein, L is the value of the optical loss factor of the optical cavity in a certain state (such as the first state or the second state), L<1, , It is the product of the reflectivity of all the mirrors that reflect the light in sequence during one cycle of light propagation in the optical cavity, r jis the reflectivity of the mirror that reflects the light for the jth time during the propagation of the light in the optical cavity for one cycle, and N is the number of times all the mirrors reflect the light during the propagation of the light in the optical cavity for one cycle. Since each of the M mirrors in the optical cavity reflects the light at least once, N ≥ M.

[0058] According to equation (2), during the propagation of light in the optical cavity for one cycle, the power attenuation includes the attenuation caused by the reflection of each mirror (R round ) and the attenuation (1-L) caused by other factors (such as partial obstruction of the beam, etc.).

[0059] In some embodiments, the value of the optical loss factor (L) of the optical cavity can be changed by placing a light shield in the optical cavity, or by changing the spatial information of the light shield when the light shield already exists in the optical cavity, thereby changing the value of the optical power attenuation parameter. Here, the spatial information includes at least one of shape and position.

[0060] For example, in the first state, there is a first light shielding object in the optical cavity; and in the second state, there is no light shielding object in the optical cavity.

[0061] For another example, in the first state, there is a first light shielding object in the optical cavity; in the second state, there is a second light shielding object in the optical cavity, and the spatial information of the second light shielding object is different from the spatial information of the first light shielding object.

[0062] In this way, the optical loss magnification of the optical cavity in the first state and the second state can have different values, thereby making the first value of the optical power attenuation parameter of the optical cavity in the first state different from the second value of the optical power attenuation parameter of the optical cavity in the second state.

[0063] In some embodiments, when there is no light shielding object in the optical cavity in the second state, L=0. In this case, the product of the reflectivity of all the mirrors that sequentially reflect the light during one cycle of light propagation in the optical cavity can be determined according to the half-peak width of the second curve through equation (1).

[0064] According to equations (1) and (2), when the spatial information of the light shielding object in the optical cavity is changed (for example, the light shielding object is brought closer to the optical axis) so that L increases, the reflectivity R of the optical cavity is k (f) The half-peak width of the curve changes with the frequency f of the light. When the spatial information of the light shielding object in the optical cavity is changed (for example, the light shielding object is moved further away from the optical axis) so that L decreases, the reflectivity R of the optical cavity decreases. k (f) The half-peak width of the curve decreases as the frequency f of light changes.

[0065] Figure 2The first curve and the second curve according to some embodiments of the present disclosure are shown. The value of the optical loss magnification of the optical cavity corresponding to the second curve S2 on the right is greater than the value of the optical loss magnification of the optical cavity corresponding to the first curve S1 on the left. It can be seen that due to the increase, the half-peak width of the curve increases accordingly.

[0066] In addition, from Figure 2 It can also be seen that as L increases, the lowest point of the curve moves upward and the depth of the valley of the curve decreases.

[0067] In some embodiments, the approximate value of L can be calculated based on the electromagnetic field equation according to the spatial information of the light shielding object (such as shape and position) and the structure of the optical cavity (such as shape). This is beneficial to the execution of the transmittance measurement method.

[0068] In step S40, a correlation formula between the reflectivity of the optical cavity and the frequency of light, the optical power attenuation parameter of the optical cavity, the coupling efficiency between light and the optical cavity, and the transmittance of the first reflector is obtained.

[0069] The coupling efficiency between light and the optical cavity is the ratio of the power of the portion of light incident on the first reflector that is coupled with the optical cavity to the power of the light incident on the first reflector.

[0070] In some embodiments, the reflected light of the optical cavity is divided into two parts, the first part of the light is the part of the light incident on the first reflector that is not coupled with the optical cavity and is directly reflected by the first reflector, and the second part of the light is the part of the light incident on the first reflector that is coupled with the optical cavity and is reflected by the optical cavity (including being directly reflected by the first reflector and being transmitted from the first reflector after entering the optical cavity). The reflectivity of the optical cavity can be determined based on the first part of the light and the second part of the light, so that the correlation formula between the reflectivity of the optical cavity and the frequency of light, the optical power attenuation parameter of the optical cavity, the coupling efficiency of light and the optical cavity, and the transmittance of the first reflector can be obtained.

[0071] In some embodiments, the reflectivity R of the optical cavity k (f) is related to the frequency f of the light and the optical power attenuation parameter R of the optical cavity. ’ round , the coupling efficiency between light and the optical cavity C k , and the transmittance of the first reflector t k The correlation formula between them is:

[0072] Among them, φ round is the phase change accumulated during one cycle of light propagation in the optical cavity, φ round =4πfl / c, l is the effective length of the optical cavity, c is the speed of light, R ’ round=R round (1-L), R round The meanings of and L are the same as above. The detailed derivation of formula (3) is given below.

[0073] It should be noted that formula (3) is only an exemplary form of the correlation formula. In other forms, depending on different factors considered (such as whether to consider two parts of light, whether to perform approximate processing, etc.), the correlation formula may also be a formula in other forms.

[0074] In step S50, the transmittance value of the first reflector is obtained by fitting according to the correlation formula, the first curve, the first value of the optical power attenuation parameter, the second curve, and the second value of the optical power attenuation parameter.

[0075] According to the correlation formula, the reflectivity of the optical cavity is related to the optical power attenuation parameter, and is related to the frequency of light, the transmittance of the first reflector, and the coupling efficiency. In addition, both the first curve and the second curve include multiple sets of data that have been acquired, and each set of data includes the reflectivity of the optical cavity and the frequency of light. Therefore, based on the known multiple sets of data in the first curve, the multiple sets of data in the second curve, the first value, and the second value, the unknown transmittance value of the first reflector in the correlation formula can be fitted.

[0076] In some embodiments, step S50 can also obtain the value of the coupling efficiency between the light and the optical cavity which is unknown in the correlation formula. That is, when the transmittance of the first reflector is measured, the coupling efficiency between the light and the optical cavity can also be measured.

[0077] Through steps S10 to S50 , the transmittance of the reflector to be measured, ie, the first reflector, is measured.

[0078] On the one hand, since the entire measurement process is based on the optical cavity having been constructed, the influence of the process of constructing the optical cavity on the transmittance value of the first reflector is eliminated, and the measured transmittance value of the first reflector is more accurate.

[0079] On the other hand, after the optical cavity is built, the measurement result of the above method is basically determined only by the structure of the optical cavity itself. The influence of factors outside the optical cavity (such as the construction and debugging of the optical path) on the measurement result becomes smaller, and the measurement operation error is also smaller, thus making the measured transmittance value of the first reflector more accurate.

[0080] On the other hand, since the transmittance of the reflector is related to the incident angle of light, when the incident angle of light changes, the measured transmittance will also change accordingly. According to the above transmittance measurement method, it is only necessary to determine the structure of the appropriate optical cavity so that light can be incident on the first reflector at a desired incident angle and couple with the optical cavity, and the transmittance of the first reflector at the desired incident angle can be measured. That is, the above transmittance measurement method can accurately measure the transmittance of the reflector at any incident angle.

[0081] Figure 3 It is a schematic diagram of a flow chart of fitting the transmittance value of the first reflector in the transmittance measurement method according to some embodiments of the present disclosure.

[0082] In some embodiments, Figure 3 As shown, step S50 includes steps S501-S503.

[0083] In step S501, a third value related to the transmittance and coupling efficiency of the first reflector is obtained by fitting according to the correlation formula, the first curve and the first value.

[0084] For example, after substituting the first value into the correlation formula, the first formula of the correlation formula between the reflectivity of the optical cavity and the frequency of light, the coupling efficiency, and the transmittance of the first reflector can be obtained. Furthermore, according to the first formula of the correlation formula and the first curve, a third value related to the transmittance and coupling efficiency of the first reflector can be fitted.

[0085] In the first formula of the correlation formula, the unknown quantities include the transmittance and coupling efficiency of the first reflector. Using multiple sets of data in the first curve, each set of data includes the reflectance of the optical cavity and the frequency of light, and the first formula of the correlation formula, a third value related to the transmittance and coupling efficiency of the first reflector can be fitted. When fitting, some or all sets of data in the first curve can be used.

[0086] In step S502, a fourth value related to the transmittance and coupling efficiency of the first reflector is obtained by fitting according to the correlation formula, the second curve and the second value.

[0087] Similarly, after substituting the second value into the correlation formula, the second formula of the correlation formula between the reflectivity of the optical cavity and the frequency of light, the coupling efficiency, and the transmittance of the first reflector can be obtained. Furthermore, according to the second formula of the correlation formula and the second curve, a fourth value related to the transmittance and coupling efficiency of the first reflector can be fitted.

[0088] In the second formula of the correlation formula, the unknown quantity also includes the transmittance and coupling efficiency of the first reflector. Using multiple sets of data in the second curve, each set of data includes the reflectance of the optical cavity and the frequency of light, and the second formula of the correlation formula, a fourth value related to the transmittance and coupling efficiency of the first reflector can be fitted. Similarly, during fitting, some or all sets of data in the second curve can be used.

[0089] In step S503, the transmittance value of the first reflector is determined according to the third value and the fourth value.

[0090] In some embodiments, the value of the coupling efficiency may also be determined according to the third value and the fourth value.

[0091] In the above steps S501-S503, since the second curve is different from the first curve, and the second value is different from the first value, the fourth value obtained by fitting is also different from the third value. In this way, two different sets of relationships satisfied by the transmittance and coupling efficiency of the first reflector are obtained, and then the transmittance value of the first reflector can be determined according to the two different sets of relationships.

[0092] Figure 4 It is a flowchart of obtaining the correlation formula in the transmittance measurement method according to some embodiments of the present disclosure.

[0093] In some embodiments, Figure 4 As shown, step S40 of obtaining the association formula includes steps S401-S403.

[0094] In step S401, a first reflectivity R corresponding to a portion of the light that is incident on the first reflector and is not coupled to the optical cavity is obtained. 1 and coupling efficiency C k Here, the first reflectivity R 1 It is the contribution of the part of light that is not coupled with the optical cavity after entering the first reflector to the reflectivity of the optical cavity.

[0095] In step S402, a second reflectivity R corresponding to the portion of the light incident on the first reflector and coupled with the optical cavity is obtained. 2 The frequency f of the light and the optical power attenuation parameter R of the optical cavity ’ round , coupling efficiency C k , and the transmittance of the first reflector t k Here, the second reflectivity R 2 It is the contribution of the part of light that is coupled with the optical cavity after entering the first reflector to the reflectivity of the optical cavity.

[0096] In step S403, a correlation formula is determined according to the first correlation formula and the second correlation formula.

[0097] As some implementations, the associated formula is:

[0098] Among them, R k (f) is the reflectivity of the optical cavity.

[0099] In the above steps S401-S403, the reflected light from the optical cavity is divided into two parts: the reflected light of the part of the light not coupled with the optical cavity after being directly reflected by the first reflector, and the reflected light of the part of the light coupled with the optical cavity after being reflected by the entire optical cavity. At this time, the light intensity of the reflected light of the optical cavity is equal to the sum of the light intensities of the two parts of the reflected light, and thus the reflectivity of the optical cavity is equal to the sum of the ratios of the light intensities or powers of the two parts of the reflected light to the light intensity or power of the light incident on the first reflector.

[0100] Figure 5 is a schematic diagram of light entering an optical cavity in a method for measuring transmittance according to some embodiments of the present disclosure.

[0101] like Figure 5 As shown, the optical cavity is, for example, a Fabry-Perot (FP) resonant cavity composed of two mutually parallel plane mirrors. The reflectivity and transmittance of the first mirror M1 are r 1 and t 1 The reflectivity and transmittance of the other reflector (called the second reflector) M2 are r 2 and t 2 , the amplitude of the light incident on the first reflector is A 0 , the phase is 0, the frequency is f, and the effective length of the optical cavity (the distance between the first reflector M1 and the second reflector M2) is l.

[0102] Figure 5 Also shown in FIG. 1 are the light incident on the first reflector M1 and the amplitudes of the partially reflected light and the transmitted light.

[0103] The following is based on Figure 5 The derivation process of the correlation formula (3) is introduced.

[0104] For light that matches the mode of the optical cavity and can be coupled to the optical cavity (the coupling efficiency between the light and the optical cavity can be considered to be C k equal to 1), the reflected light directly reflected by the first reflector M1, and the transmitted light after the light enters the optical cavity from the first reflector M1 and then is transmitted from the first reflector M1 (including the transmitted light reflected once by the second reflector M2 in the cavity, and then reflected by the first reflector M1 and the second reflector M2 0, 1, 2, 3... infinitely many times and then transmitted from the first reflector M1) can be coherently superimposed.

[0105] In some embodiments, the complex number representations of the amplitudes of the various parts of light included in the reflected light of the optical cavity are respectively: ….

[0106] The first item represents the reflected light directly reflected by the first reflector M1, and the subsequent items represent the light entering the optical cavity from the first reflector M1, being reflected once by the second reflector M2, and then being reflected 0, 1, 2, 3... infinitely many times by the first reflector M1 and the second reflector M2, and then being transmitted from the first reflector M1, φ r is the phase change accumulated during one cycle of light propagation in the optical cavity, φ r =4πfl / c, c is the speed of light.

[0107] Since the reflection of light occurs at the interface between the film and the mirror body (such as glass) of the reflector, the different refractive indices of the film and the mirror body will cause the vibration direction of the light to suddenly change to the opposite direction of the vibration direction before reflection when the light is emitted from the film or the mirror body with a lower refractive index to the other with a higher refractive index. That is, the phase also undergoes a sudden change of π at the same time as the amplitude changes, which is called "half-wave loss". In the above embodiment, the case where the refractive index of the film of the reflector is lower than that of the mirror body is considered. Therefore, only when the light is directly reflected by the first reflector M1 can the half-wave loss condition be met. In the complex representation of the amplitude of each part of the light, only the first term exists e iπ .

[0108] Therefore, the complex number of the amplitude of the reflected light of the optical cavity is expressed as A r for:

[0109] In some other embodiments, the complex number representations of the amplitudes of the various parts of light included in the reflected light of the optical cavity are respectively: ….

[0110] In the above embodiment, the refractive index of the film of the reflector is higher than that of the mirror body. In this case, except for the direct reflection by the first reflector M1, each reflection of the light in the optical cavity after entering the optical cavity satisfies the half-wave loss condition, and only the first term does not exist in the complex representation of the amplitude of each part of the light. iπ Therefore, the complex number of the amplitude of the reflected light from the optical cavity is A r is A in formula (5) r Multiply by -1.

[0111] For either of the above two cases, the reflectivity R of the optical cavity c (f) are:

[0112] Similarly, the transmitted light transmitted from the second reflector M2 of the optical cavity includes the transmitted light that enters the optical cavity from the first reflector M1 and is reflected by the second reflector M2 and the first reflector M1 0, 1, 2, 3...infinitely times, and then transmitted from the second reflector M2, and these transmitted lights can be coherently superimposed.

[0113] In some embodiments, the complex number representations of the amplitudes of the various parts of light contained in the transmitted light of the optical cavity are respectively: ….

[0114] Among them, each item represents the transmitted light that enters the optical cavity from the first reflector M1, is reflected by the second reflector M2 and the first reflector M1 0, 1, 2, 3...infinitely times, and then is transmitted from the second reflector M2.

[0115] In the above embodiment, the refractive index of the film of the reflector is lower than the refractive index of the mirror body, so before the light is transmitted from the second reflector M2, no half-wave loss occurs when the light is reflected by the second reflector M2 and the first reflector M1 in the optical cavity.

[0116] In some other embodiments, the complex number representations of the amplitudes of the various parts of light contained in the transmitted light of the optical cavity are respectively: ….

[0117] In the above embodiment, the refractive index of the film of the reflector is higher than the refractive index of the mirror body. Therefore, before the light is transmitted from the second reflector M2, two additional half-wave losses occur each time the light is reflected once by the second reflector M2 and the first reflector M1 in the optical cavity.

[0118] For either of the above two cases, the complex number of the amplitude of the transmitted light of the optical cavity is expressed as A t for:

[0119] The transmittance T of the optical cavity c (f) is:

[0120] In general, part of the light does not match the mode of the optical cavity and cannot couple with the optical cavity. At this time, the coupling efficiency C k Less than 1. The first reflectivity R corresponding to the part of the light that is not coupled with the optical cavity after it enters the first reflector 1 for:

[0121] This formula shows that the proportion of light incident on the first reflector M1 is (1-C k) is not coupled with the optical cavity and is directly reflected by the first reflector M1.

[0122] When the coupling efficiency between light and the optical cavity is C k When it is less than 1, according to formula (6), the second reflectivity R corresponding to the part of the light incident on the first reflector and coupled with the optical cavity is 2 for:

[0123] This formula shows that the proportion of light incident on the first reflector M1 is C k The part of the light is coupled with the optical cavity, a part of the light is directly reflected by the first reflector M1, and the other part enters the optical cavity and is transmitted from the first reflector M1, and the part of the light directly reflected by the first reflector M1 and the part of the light entering the optical cavity and being transmitted from the first reflector M1 can be coherently superimposed.

[0124] Combining equations (9), (10) and (4), the reflectivity R of the optical cavity is k (f) may be:

[0125] After extending the optical cavity from the case of the Fabry-Perot resonant cavity to the general case of an optical cavity composed of M-surface mirrors, Equation (11) can be rewritten as:

[0126] Among them, the reflectivity of the first reflector changes from r 1 Rewrite as r k , the transmittance from t 1 Rewrite as t k , the accumulated phase change of light propagating in the optical cavity for one cycle changes from φ r Rewritten as φ round φ round =4πfl / c, l is the effective length of the optical cavity, c is the speed of light. 1 r 2 Rewrite as , which represents the attenuation of the amplitude of light after one more cycle of propagation in the optical cavity. 2 Rewrite as , which represents the attenuation of the amplitude of the light after it enters the optical cavity from the first reflector and does not propagate a complete cycle in the optical cavity, that is, when it is transmitted from the first reflector.

[0127] For example, Figure 6 As shown, the optical cavity is a triangular optical cavity with M=3, and the optical cavity includes a first reflector M1 (with a reflectivity of r 1 )、The second reflector M2 (reflectivity is r2 ) and the third reflector M3 (reflectivity r 3 ). The light is incident on the first reflector M1 along the first direction P1 and is transmitted from the first reflector M1 along the second direction P2. The effective length l of the optical cavity is the first distance l 1 The second distance l 2 The sum of the first distance l 1 is the distance between the first reflector M1 and the second reflector M2, and the second distance l 2 is the distance between the first reflector M1 and the third reflector M3.

[0128] In this case, the light needs to be reflected once at the first reflector M1, the second reflector M2, the first reflector M1 and the third reflector M3 in sequence for each propagation cycle in the optical cavity. It can be specifically written as r 1 ·r 2 ·r 1 ·r 3 .

[0129] In addition, after the light enters the optical cavity from the first reflector M1, it has not propagated a complete cycle in the optical cavity, that is, it needs to be reflected once at the second reflector M2, the first reflector M1, and the third reflector M3 in sequence before it is transmitted out from the first reflector M1. It can be specifically written as r 2 ·r 1 ·r 3 .

[0130] The denominator on the right side of “+” in formula (12) Recorded as , R round It indicates the power attenuation of light after one more cycle of propagation in the optical cavity. At the same time, all the reflectors in the optical cavity are reflectors with extremely high reflectivity (close to 1) or t k The relative measurement accuracy requirement is much smaller than In the case of , all reflectivities except the denominator on the right side of “+” in equation (12) are replaced by 1. Equation (12) can be further rewritten as:

[0131] In the above derivation process, the attenuation of the amplitude of light after one cycle of propagation in the optical cavity only considers the attenuation caused by the reflection of each mirror ( ), so the power attenuation also only includes the attenuation caused by the reflection of each mirror.

[0132] After further considering the power attenuation caused by other factors (such as the light beam being partially blocked by a light shielding object, etc.), the light loss factor L is introduced, and R in the denominator on the right side of equation (12) is replaced by round Rewrite as R ’ round (1-L), denoted as R ’ round , represents the power attenuation after the light propagates one more cycle in the optical cavity after considering other factors. At this time, equation (13) can be further rewritten as:

[0133] At this point, the correlation formula (3) is obtained.

[0134] Based on the above derivation, the first reflectivity R corresponding to the part of the light that is not coupled with the optical cavity after it enters the first reflector is 1 and coupling efficiency C k The first correlation formula between can be written as:

[0135] The second reflectivity R corresponding to the part of the light incident on the first reflector and coupled with the optical cavity 2 The frequency f of the light and the optical power attenuation parameter R of the optical cavity ’ round , coupling efficiency C k , and the transmittance of the first reflector t k The second correlation formula between can be written as:

[0136] Next, the derivation of equation (1) for determining the first value (or second value) of the optical power attenuation parameter of the optical cavity in the first state (or second state) according to the half-peak width of the first curve (or second curve) is introduced.

[0137] First, according to the above derivation, consider the coupling efficiency C between light and the optical cavity k When it is less than 1, the transmittance T of an optical cavity (such as a Fabry-Perot resonant cavity) k (f) is:

[0138] This formula shows that the proportion of light incident on the first reflector M1 is C k The part of light coupled with the optical cavity is coupled with the optical cavity, and the light of the part coupled with the optical cavity becomes the transmitted light of the optical cavity after being transmitted from the optical cavity.

[0139] Secondly, according to the law of energy conservation, the reflectivity R of the optical cavity is k (f) and transmittance T kThe sum of (f) is 1, so:

[0140] It can be seen from formula (17) that no matter the coupling efficiency C k What is the reflectivity R of the optical cavity? k (f) and the transmittance T of the optical cavity c Therefore, the half-peak width f derived from equation (8) is HWHM With r 1 r 2 The relationship between 1 r 2 Expanded to R ’ round ).

[0141] According to formula (8), when φ r is φ 0 =2nπ, when n is an integer, the value of formula (8) is the smallest. For formula (8), when φ r As T c (f) is the independent variable, φ r The half-peak width Δφ r satisfy:

[0142] Due to Δφ r Approaching 0, we can get:

[0143] According to formula (8), the half-peak width f HWHM With r 1 r 2 The relationship is:

[0144] Therefore, for the correlation formula (3), the half-peak width f HWHM With R ’ round The relationship is:

[0145] Thus, the formula (1) based on which the first value (or second value) of the optical power attenuation parameter of the optical cavity in the first state (or second state) is determined according to the half-peak width of the first curve (or second curve) is obtained.

[0146] At the same time, it can be seen from formula (17) that the reflectivity R of the optical cavity k (f) The half-peak width of a curve (such as the first curve or the second curve) that varies with the frequency of light satisfies:

[0147] Among them, f res To make the reflectivity R of the optical cavity k (f) The value of the frequency of light (i.e., the resonant frequency) when it reaches the minimum value.

[0148] In summary, before determining the first value of the optical power attenuation parameter of the optical cavity in the first state or the second value of the optical power attenuation parameter of the optical cavity in the second state according to formula (1), the half-peak width of the first curve or the second curve can be obtained according to formula (21) and the data included in the first curve or the second curve.

[0149] The present disclosure also proposes a transmittance measurement device, which is configured to implement the method of any one of the above embodiments.

[0150] Figure 7 It is a schematic diagram of the structure of a transmittance measuring device according to some embodiments of the present disclosure.

[0151] like Figure 7 As shown, the transmittance measuring device includes a first acquisition module 701 , a first determination module 702 , a second determination module 703 , a second acquisition module 704 and a fitting module 705 .

[0152] The first acquisition module 701 is configured to acquire a first curve of the reflectivity of the optical cavity in the first state varying with the frequency of light, and a second curve of the reflectivity of the optical cavity in the second state varying with the frequency of light. Here, light enters the optical cavity from the first reflector of the optical cavity.

[0153] The first determination module 702 is configured to determine a first value of an optical power attenuation parameter of the optical cavity in a first state according to a half-peak width of the first curve.

[0154] The second determination module 703 is configured to determine a second value of the optical power attenuation parameter of the optical cavity in the second state according to the half-peak width of the second curve. Here, the second value is different from the first value.

[0155] The second acquisition module 704 is configured to obtain a correlation formula between the reflectivity of the optical cavity and the frequency of light, the optical power attenuation parameter of the optical cavity, the coupling efficiency between light and the optical cavity, and the transmittance of the first reflector.

[0156] The fitting module 705 is configured to obtain the value of the transmittance of the first reflector by fitting according to the correlation formula, the first curve, the first value, the second curve, and the second value.

[0157] Figure 8 4 is a schematic diagram of the structure of a transmittance measuring device according to some other embodiments of the present disclosure.

[0158] like Figure 8 As shown, the transmittance measuring device includes a memory 801 and a processor 802 coupled to the memory 801 , and the processor 802 is configured to execute the method of any one of the aforementioned embodiments based on the instructions stored in the memory 801 .

[0159] The memory 801 may include, for example, a system memory, a fixed non-volatile storage medium, etc. The system memory may store, for example, an operating system, an application program, a boot loader, and other programs.

[0160] In some embodiments, the transmittance measuring device may further include an input / output interface 803, a network interface 804, a storage interface 805, etc. These interfaces 803, 804, 805, and the memory 801 and the processor 802 may be connected, for example, via a bus 806. The input / output interface 803 provides a connection interface for input / output devices such as a display, a mouse, a keyboard, and a touch screen. The network interface 804 provides a connection interface for various networked devices. The storage interface 805 provides a connection interface for external storage devices such as SD cards and USB flash drives.

[0161] The present disclosure also proposes a transmittance measurement system.

[0162] Fig. 9 is a schematic diagram of the structure of a transmittance measurement system according to some embodiments of the present disclosure.

[0163] like Fig. 9 As shown, the transmittance measurement system includes a transmittance measurement device 900 according to any one of the above embodiments, a signal generator 901 , a transmitter 902 , and a detection device 903 .

[0164] The transmittance measuring device 900 may be, for example, Figure 7 The transmittance measurement device shown, or Figure 8 The transmittance measurement setup is shown.

[0165] The signal generator 901 is configured to generate a swept frequency signal.

[0166] The transmitter 902 is configured to transmit light with a changing frequency toward the first reflector according to the swept frequency signal.

[0167] The detection device 903 is configured to detect the reflected light signal of the optical cavity, and determine the correlation information between the power of the reflected light signal and the frequency of the light according to the reflected light signal and the swept frequency signal generated by the signal generator 901 .

[0168] In some embodiments, Fig. 9As shown, the detection device 903 includes a detector 904 and an oscilloscope 905. The detector 904 is configured to detect the reflected light signal of the optical cavity. The oscilloscope 905 is configured to determine the correlation information between the power of the reflected light signal and the frequency of the light according to the reflected light signal detected by the detector 904 and the swept frequency signal generated by the signal generator 901. The detector 904 can be, for example, a photodetector (PD).

[0169] The transmittance measuring device 900 is configured to obtain a first curve and a second curve of how the reflectance of the optical cavity changes with the frequency of light according to the associated information determined by the detection device 903. For example, the measuring device can calculate the reflectance of the optical cavity according to the power of the reflected light signal in the associated information, and then obtain the first curve and the second curve of how the reflectance of the optical cavity changes with the frequency of light.

[0170] Fig.10 is a schematic structural diagram of a transmittance measurement system according to some other embodiments of the present disclosure.

[0171] like Fig.10 As shown, the transmittance measurement system can measure the transmittance of the first reflector M1 of the Fabry-Perot resonant cavity. In this case, since the transmitted light transmitted from the first reflector M1 and the light vertically incident on the first reflector M1 are in the same straight line and are difficult to detect, a lens assembly can be arranged between the transmitter 902 and the first reflector M1, so as to deflect the propagation direction of the reflected light by 90° without changing the propagation direction of the light vertically incident on the first reflector M1, so as to facilitate detection by the detection device 903. For example, the lens assembly includes a polarization beam splitter (PBS) 906 and a quarter wave plate 907, and the quarter wave plate 907 is arranged between the polarization beam splitter 906 and the first reflector M1.

[0172] In some embodiments, Fig.10 As shown, the transmittance measurement system may further include another detector 904'. The detector 904' is configured to receive a transmission light signal of light transmitted from the optical cavity (i.e., transmitted from the second reflector M2), so that the detection device 903 may also determine the correlation information between the power of the transmission light signal of the optical cavity and the frequency of the light based on the transmission light signal.

[0173] In other embodiments, the transmittance measurement system is used to measure the transmittance of the reflector to different components of light at different incident angles. For example, the transmittance measurement system can also measure other optical cavities (such as butterfly optical cavities with M=4, ring optical cavities or Figure 6The transmittance of the first reflector M1 of the optical cavity (such as the triangular optical cavity shown in the figure) is measured. In this case, since the light is not incident vertically on the first reflector M1, the transmittance of the first reflector M1 to the component of the light whose polarization direction is perpendicular to the incident plane (S component) and the component of the light whose polarization direction is parallel to the incident plane (P component) are different. Before the light is incident on the first reflector M1, it can first pass through a polarizer (such as a polarizing plate) to retain only the S component or the P component of the light, so as to measure the transmittance of the first reflector M1 to the S component or the P component of the light incident at the current incident angle.

[0174] The following briefly introduces a measurement scheme for measuring transmittance using the transmittance measurement system disclosed in the present invention.

[0175] First, the optical cavity is built and the optical path is adjusted so that the light is incident from the kth reflector, i.e., the first reflector, and the coupling efficiency is as high as possible. Figure 2 As shown in the third curve S3, no change in reflectivity is observed when the frequency of the scanning light is scanned. At this time, the structure of the optical path and the optical cavity is continuously adjusted.

[0176] Subsequently, when the light and the optical cavity are well coupled, the frequency of the light is scanned, the reflected light power signal is observed, and the resonant frequency is found. The change of reflectivity with frequency can be observed near the resonant frequency.

[0177] Then, a light shield is placed in the optical cavity, the spatial information of the light shield is adjusted, and the curve of reflectivity changing with frequency is observed and recorded. It can be seen that as the light shield blocks part of the light, the valley depth of the reflectivity curve seen by the frequency sweep decreases, while the width increases.

[0178] Then, the position of the shading object is changed and the previous step is repeated. It can be seen that as the effective shading area increases, that is, the laser loss increases, the depth of the reflectivity valley will further decrease, while the width will further increase.

[0179] Then, according to the recorded reflectivity curve, the minimum reflectivity when the shading object has different spatial information is obtained, and then the R of the optical cavity is obtained. ’ round .

[0180] Finally, according to the recorded reflectivity curves, the different R ’ round The value of and equation (3) are fitted to obtain t k 2 .

[0181] The embodiments of the present disclosure further provide a computer-readable storage medium, comprising computer program instructions, which implement the method of any one of the above embodiments when executed by a processor.

[0182] The embodiments of the present disclosure further provide a computer program product, including a computer program, which implements the method of any one of the above embodiments when executed by a processor.

[0183] So far, various embodiments of the present disclosure have been described in detail. In order to avoid obscuring the concept of the present disclosure, some details known in the art are not described. Based on the above description, those skilled in the art can fully understand how to implement the technical solution disclosed here.

[0184] Those skilled in the art will appreciate that the embodiments of the present disclosure may be provided as methods, systems, or computer program products. Therefore, the present disclosure may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present disclosure may take the form of a computer program product implemented on one or more computer-usable non-transient storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0185] The present disclosure is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present disclosure. It should be understood that the functions specified in one or more processes in the flowchart and / or one or more blocks in the block diagram can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the functions specified in the flowchart. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0186] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0187] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0188] Although some specific embodiments of the present disclosure have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present disclosure. It should be understood by those skilled in the art that the above embodiments may be modified or some technical features may be replaced by equivalents without departing from the scope and spirit of the present disclosure. The scope of the present disclosure is defined by the appended claims.

Claims

1. A method for measuring transmittance, characterized in that: include: Acquire a first curve of a reflectivity of an optical cavity in a first state varying with the frequency of light, and a second curve of a reflectivity of the optical cavity in a second state varying with the frequency of light, wherein light enters the optical cavity from a first reflector of the optical cavity; Determining a first value of an optical power attenuation parameter of the optical cavity in the first state according to the half-peak width of the first curve; determining a second value of the optical power attenuation parameter of the optical cavity in the second state according to the half-peak width of the second curve, wherein the second value is different from the first value; Obtaining a correlation formula between the reflectivity of the optical cavity and the frequency of light, the optical power attenuation parameter of the optical cavity, the coupling efficiency between light and the optical cavity, and the transmittance of the first reflector; and The transmittance value of the first reflector is obtained by fitting according to the correlation formula, the first curve, the first value, the second curve, and the second value.

2. The method for measuring transmittance according to claim 1, characterized in that: In the first state, a first light shielding object exists in the optical cavity; In the second state, there is no light shielding object or there is a second light shielding object in the optical cavity, the spatial information of the second light shielding object is different from the spatial information of the first light shielding object, and the spatial information includes at least one of shape and position.

3. The method for measuring transmittance according to claim 1, characterized in that: Obtaining the association formula includes: The first reflectivity R1 and the coupling efficiency C corresponding to the portion not coupled with the optical cavity after the light is incident on the first reflector are obtained. k The first correlation formula between After the light is incident on the first reflector, the second reflectivity R2 corresponding to the part coupled with the optical cavity and the frequency f of the light, the optical power attenuation parameter R of the optical cavity are obtained. ’ round , the coupling efficiency C k , and the transmittance t of the first reflector k A second correlation formula between ; and The association formula is determined according to the first association formula and the second association formula.

4. The method for measuring transmittance according to claim 3, characterized in that: The association formula is: R k (f)=R1+R2; Among them, R k (f) is the reflectivity of the optical cavity.

5. The method for measuring transmittance according to claim 4, characterized in that: The first correlation formula is: R1=1-C k 。 6. The method for measuring transmittance according to claim 4 or 5, characterized in that: The second association formula is: ； Among them, φ round is the phase change accumulated during one cycle of light propagation in the optical cavity, φ round =4πfl / c, l is the effective length of the optical cavity, c is the speed of light, R ’ round =R round (1-L), L is the value of the optical loss factor of the optical cavity in the first state or the second state, L<1, , is the product of the reflectivity of all the mirrors that sequentially reflect the light during one cycle of light propagation in the optical cavity, r j is the reflectivity of the reflector that reflects the light for the jth time during the process of light propagating in the optical cavity for one cycle, and N is the number of times the light is reflected by all the reflectors during the process of light propagating in the optical cavity for one cycle.

7. The method for measuring transmittance according to any one of claims 1 to 5, characterized in that: The first value and the second value are obtained according to the following formula: ； Among them, R ’ round is the optical power attenuation parameter, f HWHM is the half-peak width, l is the effective length of the optical cavity, and c is the speed of light.

8. The method for measuring transmittance according to any one of claims 1 to 5, characterized in that: According to the correlation formula, the first curve, the first value, the second curve, and the second value, the value of the transmittance of the first reflector obtained by fitting includes: According to the correlation formula, the first curve and the first value, fitting is performed to obtain a third value related to the transmittance of the first reflector and the coupling efficiency; According to the correlation formula, the second curve and the second value, a fourth value related to the transmittance of the first reflector and the coupling efficiency is obtained by fitting; and A value of the transmittance of the first reflector is determined according to the third value and the fourth value.

9. A transmittance measuring device, characterized in that: include: A first acquisition module is configured to acquire a first curve of a reflectivity of an optical cavity in a first state varying with the frequency of light, and a second curve of a reflectivity of the optical cavity in a second state varying with the frequency of light, wherein light enters the optical cavity from a first reflector of the optical cavity; A first determining module is configured to determine a first value of an optical power attenuation parameter of the optical cavity in the first state according to a half-peak width of the first curve; A second determining module is configured to determine a second value of the optical power attenuation parameter of the optical cavity in the second state according to the half-peak width of the second curve, wherein the second value is different from the first value; A second acquisition module is configured to acquire a correlation formula between the reflectivity of the optical cavity and the frequency of light, the optical power attenuation parameter of the optical cavity, the coupling efficiency of light and the optical cavity, and the transmittance of the first reflector; and The fitting module is configured to obtain the transmittance value of the first reflector by fitting according to the correlation formula, the first curve, the first value, the second curve, and the second value.

10. A transmittance measuring device, characterized in that: include: Memory; as well as A processor coupled to the memory is configured to execute the transmittance measurement method according to any one of claims 1 to 8 based on instructions stored in the memory.

11. A transmittance measurement system, characterized in that: include: The transmittance measuring device according to claim 9 or 10; a signal generator configured to generate a swept frequency signal; A transmitter, configured to transmit light with a changing frequency to the first reflector according to the frequency sweep signal; as well as a detection device configured to detect a reflected light signal of the optical cavity, and determine correlation information between the power of the reflected light signal and the frequency of light according to the reflected light signal and the frequency sweep signal; The transmittance measuring device is configured to obtain the first curve and the second curve according to the associated information.

12. A computer-readable storage medium, characterized in that: The invention comprises computer program instructions, which, when executed by a processor, implement the transmittance measurement method according to any one of claims 1 to 8.

13. A computer program product, characterized in that The invention comprises a computer program, which, when executed by a processor, implements the transmittance measurement method according to any one of claims 1 to 8.

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