CN113514426A - Device and method for measuring refractive index of spherical element medium - Google Patents
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Abstract
The embodiment of the application discloses a device and a method for measuring the medium refractive index of a spherical element, wherein the measuring device comprises a spectrum confocal sensor, a spectrometer and a distance adjusting mechanism, and the spectrum confocal sensor comprises a white light point light source, a semi-transparent semi-reflecting mirror and a dispersion objective lens; the semi-transparent semi-reflecting mirror and the dispersion objective lens are sequentially arranged between the white light point light source and the detected spherical element medium along the optical axis; the distance adjusting mechanism drives the spectrum confocal sensor and the measured spherical element medium to be close to or far away from each other so that the distance between the dispersion objective lens and the measured spherical element medium changes 4 times along the optical axis; the spectrometer is opposite to the reflecting surface of the semi-transparent and semi-reflective mirror and is used for detecting the wavelengths of the upper surface and the lower surface focused and reflected on the detected spherical element medium; and calculating the refractive index curve of the detected spherical element medium according to the detected 5 different wavelengths. According to the invention, the method has the advantages of high detection efficiency and small error.
Description
Technical Field
The invention relates to the field of measurement of refractive index of transparent materials, in particular to a device and a method for measuring the refractive index of a spherical element medium.
Background
The refractive index is one of the basic parameters of optical materials, the refractive index of a medium decreases with the wavelength of incident light, and the difference in refractive index at different wavelengths is called dispersion. The research on the refractive index and the dispersion of the medium is significant for knowing the properties of the medium material and is an indispensable parameter in the design of an optical system, and the size of the medium directly influences the imaging quality of the system. The accurate obtaining of the refractive index of the optical material in the visible and near infrared bands is very important to the production, use and optical design of the optical material.
The high-precision refractive index measuring instrument adopts a precision angle measuring method, and utilizes a large-scale angle measuring instrument to realize the measurement of the refraction angle, thereby calculating the refractive index value. In general, the refractive index measurement method includes a minimum deviation angle method, an auto-collimation method, and the like. However, these methods require complicated operations and some require the material to be processed into a specific shape and size. However, in the actual optical system and optical lens, a large number of spherical elements are required, and these machined spherical elements sometimes need to be subjected to refractive index precision measurement for recheck before forming the lens or optical system, or the refractive index needs to be measured or calibrated when purchasing the spherical elements in stock. Therefore, the conventional detection method cannot effectively detect the target. Meanwhile, some conventional refractive index detection methods need to use more than 10 wavelength data, so that a large amount of measurement time is consumed, and the conventional method is a difficult problem in measuring the refractive index curve of the spherical element medium.
In view of the above, there is a need to develop a device and a method for measuring refractive index of spherical element medium, so as to solve the above problems.
Disclosure of Invention
The embodiment of the application provides a device and a method for measuring the refractive index of a spherical element medium, which can measure the refractive index of the spherical element medium with a certain thickness under different wavelengths, and have the advantages of high detection efficiency and small error.
In order to solve the above technical problem, an embodiment of the present application discloses the following technical solutions:
on one hand, the device for measuring the medium refractive index of the spherical element comprises a spectrum confocal sensor, a spectrometer and a distance adjusting mechanism, wherein the spectrum confocal sensor comprises a white light point light source, a semi-transparent semi-reflecting mirror and a dispersion objective lens; the semi-transparent semi-reflecting mirror and the dispersive objective lens are sequentially arranged between the white light point light source and the detected spherical element medium along the optical axis, the semi-transparent semi-reflecting mirror is close to the white light point light source, and the dispersive objective lens is close to the detected spherical element medium side; the distance adjusting mechanism drives the spectrum confocal sensor and the measured spherical element medium to be close to or far away from each other so that the distance between the dispersion objective lens and the measured spherical element medium changes 4 times along the optical axis; the spectrometer is opposite to the reflecting surface of the semi-transparent and semi-reflective mirror and is used for detecting the wavelength of the monochromatic light focused and reflected on the detected spherical element medium; if the upper and lower surfaces of the measured spherical element medium are spherical, substituting the detected 5 different wavelengths into a formula:
calculating the refractive index of the measured spherical element medium under 5 wavelengths; if the opposite side surface of the detected spherical element medium and the dispersive objective lens is a plane, 5 different detected wavelengths are substituted into the formula:
calculating the refractive index of the measured spherical element medium under 5 wavelengths; defining:
the central thickness of the spherical element medium is H;
the plurality of monochromatic lights decomposed by the dispersion objective lens are composed of at least one monochromatic light subset, and each monochromatic light subset comprises an upper monochromatic light and a lower monochromatic light; the upper monochromatic light in each monochromatic photon concentration is focused on the upper surface of the measured spherical element medium, and the lower monochromatic light in each monochromatic photon concentration is focused on the lower surface of the measured spherical element medium;
the wavelength of the lower monochromatic light in each monochromatic photon set is lambda;
the incident angle of the lower monochromatic light of each monochromatic photon concentration is
；
The focal distance between the upper monochromatic light and the lower monochromatic light in each monochromatic photon concentration is
；
Wherein the content of the first and second substances,
and
is a known parameter of a dispersive objective lens in a spectral confocal sensor;
is the curvature radius of the opposite side surface of the measured spherical element medium and the dispersive objective lens.
Optionally, defining:
when the distance between the dispersion objective lens and the measured spherical element medium is not changed, the wavelength of the upper monochromatic light is lambda1Wavelength of the lower monochromatic light is λ2；
When the distance between the dispersion objective lens and the measured spherical element medium is changed for the first time, the wavelength of the upper monochromatic light is lambda3Wavelength of the lower monochromatic light is λ4；
When the distance between the dispersion objective lens and the measured spherical element medium changes for the second time, the wavelength of the upper monochromatic light is lambda5Wavelength of the lower monochromatic light is λ6；
When the distance between the dispersion objective lens and the measured spherical element medium is changed for the third time, the wavelength of the upper monochromatic light is lambda7Wavelength of the lower monochromatic light is λ8；
When the distance between the dispersion objective lens and the measured spherical element medium is changed for the third time, the wavelength of the upper monochromatic light is lambda9Wavelength of the lower monochromatic light is λ10(ii) a Then the incident angle of each monochromatic light can be obtained
And has the following components:
according to refractive index
And combining the formulas
Calculating a refractive index curve of the detected spherical element medium;
wherein, X1、X2、X3、X4Is the wavelength term coefficient; A. b, C, D, E are constants to be solved.
Optionally, X is more than or equal to 3.51≤4, 4.5≤X2≤5, 5.5≤X3≤6, 0.1≤X4≤0.5。
In another aspect, a method for measuring refractive index of spherical element medium is provided, which comprises the following steps:
providing a measuring device, wherein the measuring device comprises a spectrum confocal sensor, a spectrometer and a distance adjusting mechanism, wherein the spectrum confocal sensor comprises a white light point light source, a semi-transparent semi-reflecting mirror and a dispersion objective lens; the semi-transparent semi-reflecting mirror and the dispersive objective lens are sequentially arranged between the white light point light source and the detected spherical element medium along the optical axis, the semi-transparent semi-reflecting mirror is close to the white light point light source, and the dispersive objective lens is close to the detected spherical element medium side;
the distance adjusting mechanism drives the spectrum confocal sensor and the measured spherical element medium to be close to or far away from each other so that the distance between the dispersion objective lens and the measured spherical element medium changes 4 times along the optical axis;
the spectrometer is arranged opposite to the reflecting surface of the semi-permeable and semi-reflective mirror and is used for detecting the wavelength of monochromatic light which is focused and reflected on the medium of the spherical element to be detected;
if the upper and lower surfaces of the measured spherical element medium are spherical, substituting the detected 5 different wavelengths into a formula:
calculating the refractive index of the measured spherical element medium under 5 wavelengths; if the opposite side surface of the detected spherical element medium and the dispersive objective lens is a plane, 5 different detected wavelengths are substituted into the formula:
calculating the refractive index of the measured spherical element medium under 5 wavelengths; defining:
the central thickness of the spherical element medium is H;
the plurality of monochromatic lights decomposed by the dispersion objective lens are composed of at least one monochromatic light subset, and each monochromatic light subset comprises an upper monochromatic light and a lower monochromatic light; the upper monochromatic light in each monochromatic photon concentration is focused on the upper surface of the measured spherical element medium, and the lower monochromatic light in each monochromatic photon concentration is focused on the lower surface of the measured spherical element medium;
the wavelength of the lower monochromatic light in each monochromatic photon set is lambda;
the incident angle of the lower monochromatic light of each monochromatic photon concentration is
；
The focal distance between the upper monochromatic light and the lower monochromatic light in each monochromatic photon concentration is
；
Wherein the content of the first and second substances,
and
is a known parameter of a dispersive objective lens in a spectral confocal sensor;
is the curvature radius of the opposite side surface of the measured spherical element medium and the dispersive objective lens.
Optionally, defining:
when the distance between the dispersion objective lens and the measured spherical element medium is not changed, the wavelength of the upper monochromatic light is lambda1Wavelength of the lower monochromatic light is λ2；
When the distance between the dispersion objective lens and the measured spherical element medium is changed for the first time, the wavelength of the upper monochromatic light is lambda3Wavelength of the lower monochromatic light is λ4；
When the distance between the dispersion objective lens and the measured spherical element medium changes for the second time, the wavelength of the upper monochromatic light is lambda5Wavelength of the lower monochromatic light is λ6；
When the distance between the dispersion objective lens and the measured spherical element medium is changed for the third time, the wavelength of the upper monochromatic light is lambda7Wavelength of the lower monochromatic light is λ8；
When the distance between the dispersion objective lens and the measured spherical element medium is changed for the third time, the wavelength of the upper monochromatic light is lambda9Wavelength of the lower monochromatic light is λ10(ii) a Then the incident angle of each monochromatic light can be obtained
And has the following components:
according to refractive index
And combining the formulas
Calculating a refractive index curve of the detected spherical element medium;
wherein, X1、X2、X3、X4Is the wavelength term coefficient; A. b, C, D, E are constants to be solved.
Optionally, X is more than or equal to 3.51≤4, 4.5≤X2≤5, 5.5≤X3≤6, 0.1≤X4≤0.5。
One of the above technical solutions has the following advantages or beneficial effects: the refractive index of a spherical element medium with a certain thickness under different wavelengths can be measured, and the refractive index measurement under 5 different wavelengths can be rapidly realized only by changing the distance between the dispersion objective and the measured spherical element medium for 4 times along the optical axis, so that the problem that the refractive index curve of the spherical element is difficult to measure is solved.
One of the above technical solutions has the following advantages or beneficial effects: the refractive index curve of the detected spherical element medium can be calculated by only utilizing the refractive indexes obtained under 5 different wavelengths, and the method has the advantages of high detection efficiency and small error.
Drawings
In order to more clearly illustrate the technical solution of the embodiments of the present invention, the drawings of the embodiments will be briefly described below, and it is apparent that the drawings in the following description relate only to some embodiments of the present invention and are not limiting thereof, wherein:
FIG. 1 is a front view of a device for measuring the refractive index of a spherical element medium according to an embodiment of the present invention;
FIG. 2 is a schematic diagram and an optical path structure of a device for measuring a refractive index of a spherical element medium according to an embodiment of the present invention;
fig. 3 is a schematic diagram of the principle of dispersion of a spectral confocal sensor in a measuring device for refractive index of a spherical element medium according to an embodiment of the present invention;
FIG. 4 is a six type of spherical element;
fig. 5 is a schematic diagram of a spectral confocal sensor in a measuring apparatus for refractive index of spherical element medium according to an embodiment of the present invention for measuring refractive index of biconvex element medium at current wavelength;
fig. 6 is a schematic diagram of a spectral confocal sensor in a measuring apparatus for refractive index of spherical element medium according to an embodiment of the present invention for measuring refractive index of biconcave element medium at current wavelength;
fig. 7 is a schematic diagram of a spectral confocal sensor in a device for measuring the refractive index of a spherical element medium according to an embodiment of the present invention to measure the refractive index of a plano-convex element medium at a current wavelength;
FIG. 8 is a schematic diagram showing the change of the focal length of the dispersive objective lens L from 350-1100 nm;
FIG. 9 is a diagram comparing the exit angle of the dispersion lens light with the wavelength curve and the collected data calculated by using a formula;
FIG. 10 is a plot of chromatic dispersion lens back intercept position versus wavelength curve versus acquired data calculated using a formula;
FIG. 11 is a graph of refractive index profile error for BAM23 material calculated using the refractive index equation of the present invention;
FIG. 12 is a graph of the refractive index profile error for a PBH55 material calculated using the refractive index formula of the present invention;
fig. 13 is a flow chart illustrating a method for measuring the refractive index of a spherical element medium according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
In the drawings, the shape and size may be exaggerated for clarity, and the same reference numerals will be used throughout the drawings to designate the same or similar components.
Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. The use of "first," "second," and similar terms in the description and claims of the present application do not denote any order, quantity, or importance, but rather the terms are used to distinguish one element from another. Also, the use of the terms "a," "an," or "the" and similar referents do not denote a limitation of quantity, but rather denote the presence of at least one. The word "comprise" or "comprises", and the like, means that the element or item listed before "comprises" or "comprising" covers the element or item listed after "comprising" or "comprises" and its equivalents, and does not exclude other elements or items. "upper", "lower", "left", "right", and the like are used merely to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships may also be changed accordingly.
In the following description, terms such as center, thickness, height, length, front, back, rear, left, right, top, bottom, upper, lower, etc., are defined with respect to the configurations shown in the respective drawings, and in particular, "height" corresponds to a dimension from top to bottom, "width" corresponds to a dimension from left to right, "depth" corresponds to a dimension from front to rear, which are relative concepts, and thus may be varied accordingly depending on the position in which it is used, and thus these or other orientations should not be construed as limiting terms.
Terms concerning attachments, coupling and the like (e.g., "connected" and "attached") refer to a relationship wherein structures are secured or attached, either directly or indirectly, to one another through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise.
Example 1
Fig. 1 to 13 show embodiment 1 of the present invention, and with reference to fig. 1 to 8, it can be seen that the device 1 for measuring the refractive index of a spherical element medium includes a spectral confocal sensor 11, a spectrometer 14 and a distance adjustment mechanism, where the spectral confocal sensor 11 includes a white light point light source S, a semi-transparent half-mirror X and a dispersive objective lens L; the semi-transparent semi-reflecting mirror X and the dispersive objective lens L are sequentially arranged between the white light point light source S and the spherical element medium 13 to be measured along the optical axis, the semi-transparent semi-reflecting mirror X is close to the white light point light source S, and the dispersive objective lens L is close to the spherical element medium 13 side to be measured; the distance adjusting mechanism drives the spectral confocal sensor 11 and the measured spherical element medium 13 to be close to or far away from each other so that the distance between the dispersive objective lens L and the measured spherical element medium 13 changes 4 times along the optical axis; the spectrometer 14 is opposite to the reflecting surface of the semi-permeable and semi-reflective mirror X and is used for detecting the wavelength of the monochromatic light focused and reflected on the detected spherical element medium 13; and calculating the refractive index curve of the detected spherical element medium 13 according to the detected 5 different wavelengths. In the present embodiment, the spherical element medium 13 to be measured is placed on the platform 12 below the dispersive objective lens L, and the distance between the dispersive objective lens L and the spherical element medium 13 to be measured can be adjusted by lifting the platform 12 or the spectral confocal sensor 11. Referring to fig. 2, fig. 2 shows a light path schematic diagram of a spectral confocal sensor 11, which is an optical system that produces an image S' of a point source S on the surface of a medium, the backscattered light being collected by the same optical system that is imaged at a pinhole S ″.
The pinhole S "is placed in front of the spectrometer 14 so that light of a particular wavelength reflected back by the surface of the medium can pass through and light of wavelengths elsewhere is blocked, so it is also referred to as a" spatial filter ". The spectral confocal sensor is characterized by a special signal-to-noise ratio. According to the principle of spectral confocal, the optical system is a dispersive lens. The spectrometer signal exhibits a spectral peak corresponding to the spectral redistribution of the collected light. The spectral peak on the spectrometer changes as the medium is displaced within the measurement range. The detected spherical element medium 13 in this embodiment may be a glass material, a crystal material, a transparent film material, a liquid crystal material, a transparent liquid material, or a transparent plastic material with this characteristic.
Referring again to fig. 4, the spherical elements may be divided into 6 types in total, which are planoconvex, planoconcave, biconvex, positive meniscus, negative meniscus, and biconcave, respectively.
Referring again to fig. 5-6, if the spherical element medium under test is bi-convex, positive meniscus, negative meniscus and bi-concave, define:
the central thickness of the spherical element medium is H;
the plurality of monochromatic lights decomposed by the dispersion objective lens L are composed of at least one monochromatic light subset, and each monochromatic light subset comprises an upper monochromatic light and a lower monochromatic light; the upper monochromatic light in each monochromatic photon concentration is focused on the upper surface of the measured spherical element medium 13, and the lower monochromatic light in each monochromatic photon concentration is focused on the lower surface of the measured spherical element medium 13;
the wavelength of the lower monochromatic light in each monochromatic photon set is lambda;
the incident angle of the lower monochromatic light of each monochromatic photon concentration is
；
The focal distance between the upper monochromatic light and the lower monochromatic light in each monochromatic photon concentration is
(ii) a The refractive index of the measured spherical element medium 13 at the wavelength λ
Is derived from the following formula:
wherein the content of the first and second substances,
and
is a known parameter of the dispersive objective lens L in the spectroscopic confocal sensor 11;
is the curvature radius of the opposite side surface of the measured spherical element medium and the dispersive objective lens.
In the formula only
Is unknown, and the other quantities are known or measured, so that it is possible to calculate
。
Referring again to FIG. 7, if the measured spherical element medium is planoconvex and planoconcave, the refractive index of the measured spherical element medium 13 at the wavelength λ
Is derived from the following formula:
the dispersive objective lens L in the spectral confocal sensor is a core optical component, an important index in the dispersive objective lens is the degree of dispersion, namely, the distance between focuses with different wavelengths, the step that the usable wavelength of the dispersive objective lens designed in the embodiment is 350-1100 nm needs to be carried out by matching with a spectrometer, and the dispersive distance of the dispersive objective lens L designed in the embodiment in the wave band of 350-1100 nm is 108 mm. FIG. 9 shows a schematic diagram of the variation of the focal length of the dispersive objective lens L from 350 to 1100nm, in which the focal length at the leftmost end is 350nm and the focal length at the rightmost end is 1100 nm. Specific parameters of the dispersive objective lens are given in table 1, and the relationship data between the wavelength of the dispersive objective lens L and the position of the rear intercept, which is the distance from the last surface of the lens to the focal point, is given in table 2:
table 1 dispersive objective lens parameters
| -369.618 | 15 | SF5 |
| 797.370 | 7 | |
| -488.393 | 18 | LASFN31 |
| -149.540 | 1.5 | |
| 286.893 | 20 | LASFN31 |
| -312.027 | 2 | |
| 173.887 | 18 | SF5 |
| 612.929 | 10 | |
| -2516.018 | 12 | LASFN31 |
| 215.297 | 11.23 | |
| 81.443 | 16 | SF5 |
| 72.519 | 201.089 |
TABLE 2 wavelength and rear intercept position (unit: mm) of dispersive objective
| Wavelength (nm) | 350 | 400 | 500 | 600 | 700 | 800 | 900 | 1000 | 1100 |
| Rear intercept (mm) | 201.09 | 225 | 255.64 | 273.85 | 285.67 | 293.94 | 300.12 | 305 | 309.07 |
Further, the dispersive objective lens L is a lens with large dispersion and large NA, and since the focal positions are different for different wavelengths, the corresponding angles are different, but it can be expressed by apochromatic property formula (ACF formula). The formula of the exit angle and the wavelength of the marginal ray of the dispersive objective lens L is given as follows:
in the present embodiment, there is defined:
Aθ=5.80125181；
Bθ=259436.175；
Cθ=2482754578937；
Dθ=-0.0001707953；
substituting equation (1) yields:
fig. 9 is a light exit angle curve of the dispersion lens, in which a circle is collected data, a solid line is a curve calculated by solving the formula (1) using 500nm, 600nm, 700nm, and 800nm, and the collected data and the calculated curve have a good fit, which indicates that the light exit angle at any wavelength within 350 to 1100nm can be calculated by using an ACF formula
。
The same reasoning gives the formula of the back intercept and the wavelength:
given in this example:
Al=305.31355503；
Bl=-14679661.111；
Cl=60295422216018.2；
Dl=0.0142284985130074；
further, it is found that:
similarly, fig. 10 is a back intercept position and wavelength curve, where a circle is acquired data, a solid line is a curve calculated by solving an ACF formula using 500nm, 600nm, 700nm, and 800nm, and the acquired data and the calculated curve have a good fit, which indicates that the back intercept position at any wavelength within 350 to 1100nm can be calculated by using the ACF formula
。
The distance between any two wavelengths in the return-spectrum confocal system can be obtained by the following equation:
when the center thickness H of the spherical element medium is larger, the first surface has a spherical radius r1When known, is according to
Calculated by the formula (3)
。
Or the central thickness H of the spherical element medium, and the first face being a plane, according to
Calculated by the formula (4)
。
Specifically, referring to fig. 5 to 7, there are defined:
when the distance between the dispersion objective lens L and the measured spherical element medium 13 is not changed, the wavelength of the upper monochromatic light is lambda1Wavelength of the lower monochromatic light is λ2；
When the distance between the dispersion objective lens L and the measured spherical element medium 13 is changed for the first time, the wavelength of the upper monochromatic light is lambda3Wavelength of the lower monochromatic light is λ4；
When the distance between the dispersion objective lens L and the measured spherical element medium 13 changes for the second time, the wavelength of the upper monochromatic light is lambda5Wavelength of the lower monochromatic light is λ6；
When the distance between the dispersion objective lens L and the measured spherical element medium 13 changes for the third time, the wavelength of the upper monochromatic light is lambda7Wavelength of the lower monochromatic light is λ8(ii) a When the distance between the dispersion objective lens and the measured spherical element medium is changed for the third time, the wavelength of the upper monochromatic light is lambda9Wavelength of the lower monochromatic light is λ10(ii) a Then the incident angle of each monochromatic light can be obtained
And has the following components:
according to refractive index
Is calculated by the formula (2)
And in combination with the formula:
calculating the refractive index curve of the measured spherical element medium 13, wherein X is more than or equal to 3.51≤4, 4.5≤X2≤5, 5.5≤X3≤6, 0.1≤X4≤0.5。
Further, the error of OHARA glass library material was verified using equation (5), where X1=4, X2=5, X3=6, X4=0.2, maximum and minimum error data in the wavelength range of 400-1100 nm are shown in table 3 by solving curves at wavelengths of 400nm, 560nm, 680nm, 800nm and 1100nm, and fig. 11 and 12 are error graphs (corresponding to table 3) of refractive index curves of BAM23 and PBH55 calculated by using formula (5).
TABLE 3 calculation of 400-1100 nm refractive index error using equation (5)
TABLE 3 calculation of 400-1100 nm refractive index error using equation (5)
| Material | Maximum error (%) | Minimum error (%) |
| APL1 | 0.001626 | -0.00879 |
| BAH13 | 0.000809 | -0.00077 |
| BAH22 | 0.002685 | -3.4E-05 |
| BAH26 | 0.000839 | -6.3E-05 |
| BAH30 | 0.001901 | -3.6E-05 |
| BAH32 | 0.002246 | -4.1E-05 |
| BAH54 | 0.000898 | -0.00071 |
| BAH71 | 0.001069 | -5.7E-05 |
| BAH77 | 0.00073 | -0.00011 |
| BAH78 | 0.000939 | -6.7E-05 |
| BAL15 | 0.001358 | -0.00606 |
| BAL15Y | 0.001318 | -0.00493 |
| BAL35Y | 0.001495 | -0.00622 |
| BAL42 | 0.001338 | -0.00585 |
| BAL5 | 0.001068 | -0.00342 |
| BAL50 | 0.001481 | -0.00704 |
| BAL7 | 0.000924 | -0.00261 |
| BAM21 | 0.000738 | -0.0003 |
| BAM23 | 0.000827 | -6.8E-05 |
| BAM3 | 0.000815 | -0.0009 |
| BAM5 | 0.000908 | -0.00193 |
| BAM8 | 0.000986 | -0.00242 |
| BAM9 | 0.000835 | -0.00107 |
| BPH35 | 0.001413 | -0.00457 |
| BPH40 | 0.00127 | -0.00342 |
| BPH45 | 0.001397 | -7.5E-05 |
| BPH5 | 0.001441 | -0.00403 |
| BPH50 | 0.002192 | -4.7E-05 |
| BPH8 | 0.001014 | -0.0005 |
| BPM4 | 0.001601 | -0.00646 |
| BPM51 | 0.001653 | -0.00607 |
| BSL1 | 0.001437 | -0.0066 |
| BSL21 | 0.001629 | -0.0084 |
| BSL22 | 0.001264 | -0.00463 |
| BSL3 | 0.001807 | -0.00971 |
| BSL7 | 0.001486 | -0.00688 |
| BSL7Y | 0.001758 | -0.00855 |
| BSM16C | 0.001515 | -0.00707 |
| BSM18 | 0.001295 | -0.00514 |
| BSM22 | 0.000926 | -0.00187 |
| BSM23 | 0.001091 | -0.00371 |
| BSM24 | 0.000791 | -0.00091 |
| BSM36 | 0.001683 | -0.00795 |
| BSM51Y | 0.001447 | -0.0059 |
| BSM6 | 0.00105 | -0.00331 |
| BSM7 | 0.001289 | -0.00545 |
| BSM71 | 0.000822 | -0.00098 |
| BSM81 | 0.002055 | -0.01077 |
| BSM9 | 0.000994 | -0.00247 |
| FPL51 | 0.00086 | -0.00349 |
| FPL52 | 0.000909 | -0.00461 |
| FPL53 | 0.000637 | -0.00215 |
| FSL3 | 0.001559 | -0.00788 |
| FSL5 | 0.001804 | -0.01033 |
| FTL8 | 0.001667 | -0.00937 |
| FTM16 | 0.001118 | -0.00371 |
| FTM8 | 0.001234 | -0.00495 |
| LAH51 | 0.001205 | -0.00282 |
| LAH52 | 0.001278 | -0.00281 |
| LAH53 | 0.001111 | -0.00172 |
| LAH54 | 0.001219 | -0.00259 |
| LAH55 | 0.001102 | -0.00155 |
| LAH58 | 0.001795 | -6.3E-05 |
| LAH59 | 0.001098 | -0.00202 |
| LAH60 | 0.001024 | -0.00094 |
| LAH63 | 0.001069 | -0.0013 |
| LAH64 | 0.00133 | -0.00355 |
| LAH65 | 0.001306 | -0.00343 |
| LAH66 | 0.001419 | -0.00456 |
| LAH67 | 0.001361 | -0.00376 |
| LAH71 | 0.002044 | -4.8E-05 |
| LAH75 | 0.000913 | -0.00032 |
| LAH78 | 0.003223 | -3.8E-05 |
| LAL10 | 0.001148 | -0.00318 |
| LAL11 | 0.001418 | -0.00607 |
| LAL12 | 0.002351 | -4.3E-05 |
| LAL13 | 0.001557 | -0.00642 |
| LAL14 | 0.001722 | -0.00746 |
| LAL18 | 0.001723 | -0.00742 |
| LAL52 | 0.001559 | -0.00703 |
| LAL54 | 0.001281 | -0.00486 |
| LAL56 | 0.001051 | -0.0031 |
| LAL58 | 0.000912 | -0.00126 |
| LAL59 | 0.001598 | -0.0065 |
| LAL60 | 0.001717 | -0.00725 |
| LAL61 | 0.001579 | -0.00592 |
| LAL7 | 0.001541 | -0.00682 |
| LAL8 | 0.001682 | -0.00728 |
| LAL9 | 0.00144 | -0.00507 |
| LAM2 | 0.000787 | -0.00031 |
| LAM3 | 0.000807 | -0.00061 |
| LAM54 | 0.001647 | -0.00664 |
| LAM55 | 0.000854 | -0.00056 |
| LAM58 | 0.002684 | -3E-05 |
| LAM59 | 0.000904 | -0.00105 |
| LAM60 | 0.001539 | -0.00589 |
| LAM61 | 0.001526 | -5.1E-05 |
| LAM66 | 0.001184 | -0.00243 |
| LAM7 | 0.005136 | -0.00015 |
| L-BAL35 | 0.001676 | -0.00766 |
| L-BAL35P | 0.001678 | -0.00761 |
| L-BAL42 | 0.001341 | -0.00527 |
| L-BAL42P | 0.001321 | -0.00506 |
| L-BAL43 | 0.001376 | -0.00549 |
| L-BBH1 | 0.004225 | -0.00162 |
| L-BBH2 | 0.008222 | -0.001 |
| L-BSL7 | 0.001734 | -0.00852 |
| L-LAH53 | 0.000942 | -0.00035 |
| L-LAH81 | 0.000886 | -0.00017 |
| L-LAH83 | 0.002582 | -5E-05 |
| L-LAH84 | 0.00148 | -7.3E-05 |
| L-LAH84P | 0.00177 | -6.2E-05 |
| L-LAH85 | 0.001466 | -7.9E-05 |
| L-LAH86 | 0.004278 | -9E-05 |
| L-LAH87 | 0.000848 | -0.00034 |
| L-LAH90 | 0.001335 | -7.6E-05 |
| L-LAH91 | 0.001226 | -0.00278 |
| L-LAL12 | 0.001432 | -0.00511 |
| L-LAL13 | 0.001345 | -0.00427 |
| L-LAL15 | 0.001634 | -0.00623 |
| L-LAM60 | 0.001194 | -0.00271 |
| L-LAM69 | 0.001101 | -0.00165 |
| L-LAM72 | 0.001358 | -0.00381 |
| L-NBH54 | 0.006268 | -0.00021 |
| L-PHL1 | 0.000939 | -0.00261 |
| L-PHL2 | 0.001055 | -0.00353 |
| NSL33 | 0.001026 | -0.00333 |
| NSL7 | 0.001265 | -0.00533 |
| PBH1 | 0.007143 | -0.00025 |
| PBH10 | 0.004774 | -0.00013 |
| PBH11 | 0.005801 | -0.0002 |
| PBH11W | 0.005801 | -0.0002 |
| PBH13 | 0.005002 | -0.00015 |
| PBH13W | 0.005002 | -0.00015 |
| PBH14 | 0.00121 | -4.2E-05 |
| PBH14W | 0.00121 | -4.2E-05 |
| PBH18 | 0.003724 | -9.1E-05 |
| PBH23 | 0.004669 | -0.00015 |
| PBH23W | 0.004669 | -0.00015 |
| PBH25 | 0.0046 | -0.00014 |
| PBH3 | 0.008126 | -0.0003 |
| PBH3W | 0.004738 | -0.00014 |
| PBH4 | 0.006539 | -0.00022 |
| PBH4W | 0.006539 | -0.00022 |
| PBH53 | 0.009512 | -0.00037 |
| PBH53W | 0.009512 | -0.00037 |
| PBH55 | 0.012253 | -0.00064 |
| PBH56 | 0.011837 | -0.00057 |
| PBH6 | 0.004783 | -0.00015 |
| PBH6W | 0.004783 | -0.00015 |
| PBH71 | 0.01459 | -0.00104 |
| PBH72 | 0.010948 | -0.00058 |
| PBL1 | 0.000653 | -0.00015 |
| PBL1Y | 0.000956 | -0.00177 |
| PBL2 | 0.000995 | -0.0029 |
| PBL21 | 0.001108 | -0.00383 |
| PBL22 | 0.002637 | -3E-05 |
| PBL25 | 0.001072 | -0.00316 |
| PBL25Y | 0.000865 | -0.0005 |
| PBL26 | 0.000785 | -0.00064 |
| PBL26Y | 0.000925 | -0.00109 |
| PBL27 | 0.000906 | -0.00192 |
| PBL35Y | 0.000817 | -0.0003 |
| PBL6 | 0.000793 | -0.00119 |
| PBL6Y | 0.001127 | -0.0032 |
| PBL7 | 0.001069 | -0.00355 |
| PBM1 | 0.00086 | -0.00124 |
| PBM11 | 0.001336 | -0.0052 |
| PBM18Y | 0.000813 | -0.00015 |
| PBM2 | 0.000816 | -0.00095 |
| PBM22 | 0.002805 | -4E-05 |
| PBM25 | 0.003361 | -6.6E-05 |
| PBM27 | 0.00326 | -5.8E-05 |
| PBM28 | 0.005886 | -0.00018 |
| PBM28W | 0.005886 | -0.00018 |
| PBM2Y | 0.002237 | -4.1E-05 |
| PBM3 | 0.002131 | -4E-05 |
| PBM35 | 0.000942 | -0.00229 |
| PBM39 | 0.001174 | -5.7E-05 |
| PBM4 | 0.000733 | -0.00029 |
| PBM5 | 0.000707 | -0.00025 |
| PBM6 | 0.002122 | -3.5E-05 |
| PBM8 | 0.001425 | -4.9E-05 |
| PBM8Y | 0.00089 | -0.00032 |
| PBM9 | 0.000765 | -0.00039 |
| PHM51 | 0.001338 | -0.00557 |
| PHM52 | 0.001013 | -0.00331 |
| PHM53 | 0.001208 | -0.005 |
| S-APL1 | 0.001626 | -0.00879 |
| S-BAH10 | 0.000951 | -0.00137 |
| S-BAH11 | 0.000886 | -0.00108 |
| S-BAH27 | 0.000903 | -0.00083 |
| S-BAH32 | 0.000909 | -0.00091 |
| S-BAH54 | 0.000898 | -0.00071 |
| S-BAL11 | 0.001247 | -0.00456 |
| S-BAL12 | 0.001191 | -0.00445 |
| S-BAL14 | 0.001182 | -0.00405 |
| S-BAL2 | 0.00095 | -0.00212 |
| S-BAL22 | 0.001612 | -0.00737 |
| S-BAL3 | 0.000932 | -0.00215 |
| S-BAL35 | 0.001425 | -0.00587 |
| S-BAL41 | 0.001403 | -0.00581 |
| S-BAL42 | 0.001254 | -0.00467 |
| S-BAL50 | 0.001481 | -0.00704 |
| S-BAM12 | 0.000988 | -0.00171 |
| S-BAM3 | 0.000957 | -0.00202 |
| S-BAM4 | 0.0008 | -0.0007 |
| S-BSL7 | 0.001623 | -0.00784 |
| S-BSM10 | 0.001145 | -0.00355 |
| S-BSM14 | 0.001407 | -0.00567 |
| S-BSM15 | 0.001279 | -0.00461 |
| S-BSM16 | 0.001406 | -0.00562 |
| S-BSM18 | 0.001065 | -0.00283 |
| S-BSM2 | 0.001022 | -0.00284 |
| S-BSM21 | 0.001096 | -0.00307 |
| S-BSM22 | 0.001059 | -0.0028 |
| S-BSM25 | 0.00094 | -0.00158 |
| S-BSM28 | 0.000982 | -0.00207 |
| S-BSM4 | 0.001168 | -0.00387 |
| S-BSM71 | 0.001065 | -0.00275 |
| S-BSM81 | 0.001977 | -0.00941 |
| S-BSM9 | 0.001091 | -0.00312 |
| S-BSM93 | 0.001424 | -0.00608 |
| S-FPL51 | 0.00075 | -0.00254 |
| S-FPL51Y | 0.000692 | -0.0021 |
| S-FPL52 | 0.000763 | -0.00299 |
| S-FPL53 | 0.000645 | -0.0024 |
| S-FPL55 | 0.000675 | -0.00261 |
| S-FPM2 | 0.0007 | -0.00126 |
| S-FPM3 | 0.000839 | -0.00272 |
| S-FSL5 | 0.001664 | -0.00851 |
| S-FSL5Y | 0.001642 | -0.00834 |
| S-FTL10 | 0.001282 | -0.0052 |
| S-FTM16 | 0.000855 | -0.00086 |
| S-LAH51 | 0.001108 | -0.00152 |
| S-LAH52 | 0.001017 | -0.00083 |
| S-LAH52Q | 0.001349 | -6.9E-05 |
| S-LAH53 | 0.000992 | -0.00055 |
| S-LAH53V | 0.001054 | -7.6E-05 |
| S-LAH54 | 0.001219 | -0.00259 |
| S-LAH55 | 0.001102 | -0.00112 |
| S-LAH55V | 0.001021 | -0.00072 |
| S-LAH55VS | 0.000936 | -0.00032 |
| S-LAH58 | 0.002698 | -4.8E-05 |
| S-LAH59 | 0.001013 | -0.00097 |
| S-LAH60 | 0.001227 | -8E-05 |
| S-LAH60MQ | 0.003991 | -7.7E-05 |
| S-LAH60V | 0.001884 | -6.1E-05 |
| S-LAH63 | 0.00099 | -0.00054 |
| S-LAH63Q | 0.001988 | -5.4E-05 |
| S-LAH64 | 0.00133 | -0.0033 |
| S-LAH65 | 0.001293 | -0.00289 |
| S-LAH65V | 0.001282 | -0.00275 |
| S-LAH65VS | 0.001106 | -0.00159 |
| S-LAH66 | 0.001443 | -0.0043 |
| S-LAH67 | 0.001361 | -0.00376 |
| S-LAH71 | 0.006339 | -0.0002 |
| S-LAH96 | 0.000967 | -0.00111 |
| S-LAH97 | 0.001535 | -0.00527 |
| S-LAL10 | 0.001303 | -0.00362 |
| S-LAL11 | 0.001418 | -0.00607 |
| S-LAL12 | 0.001246 | -0.00385 |
| S-LAL13 | 0.001517 | -0.00548 |
| S-LAL14 | 0.001766 | -0.00741 |
| S-LAL18 | 0.001697 | -0.00667 |
| S-LAL19 | 0.00168 | -0.0065 |
| S-LAL20 | 0.001376 | -5.2E-05 |
| S-LAL21 | 0.000917 | -0.00132 |
| S-LAL52 | 0.001559 | -0.00703 |
| S-LAL54 | 0.001209 | -0.00386 |
| S-LAL54Q | 0.001667 | -0.00696 |
| S-LAL56 | 0.00102 | -0.00202 |
| S-LAL58 | 0.000892 | -0.00108 |
| S-LAL59 | 0.00151 | -0.00507 |
| S-LAL60 | 0.001717 | -0.00725 |
| S-LAL61 | 0.001631 | -0.00602 |
| S-LAL7 | 0.00145 | -0.00562 |
| S-LAL7Q | 0.001876 | -0.00848 |
| S-LAL8 | 0.001611 | -0.00608 |
| S-LAL9 | 0.001636 | -0.00644 |
| S-LAM2 | 0.00077 | -0.00012 |
| S-LAM3 | 0.000855 | -0.00062 |
| S-LAM51 | 0.000933 | -0.0012 |
| S-LAM52 | 0.000741 | -0.00011 |
| S-LAM54 | 0.001503 | -0.00468 |
| S-LAM55 | 0.001057 | -7.2E-05 |
| S-LAM58 | 0.001105 | -6.7E-05 |
| S-LAM59 | 0.000954 | -0.00131 |
| S-LAM60 | 0.001499 | -0.00479 |
| S-LAM61 | 0.000931 | -0.00096 |
| S-LAM66 | 0.000953 | -0.00032 |
| S-NBH5 | 0.001194 | -0.00256 |
| S-NBH51 | 0.000943 | -0.00029 |
| S-NBH52 | 0.000918 | -0.0005 |
| S-NBH52V | 0.001119 | -0.00175 |
| S-NBH53 | 0.00164 | -6.4E-05 |
| S-NBH53V | 0.00145 | -7.2E-05 |
| S-NBH8 | 0.000865 | -0.0001 |
| S-NBM51 | 0.001388 | -0.00447 |
| S-NSL2 | 0.001211 | -0.00468 |
| S-NSL3 | 0.001166 | -0.00439 |
| S-NSL36 | 0.001194 | -0.00429 |
| S-NSL5 | 0.001335 | -0.00557 |
| S-PHM51 | 0.001338 | -0.00557 |
| S-PHM52 | 0.001012 | -0.00306 |
| S-PHM53 | 0.001194 | -0.00448 |
| SSL2 | 0.001349 | -0.00514 |
| SSL5 | 0.00169 | -0.00856 |
| S-TIH20 | 0.002353 | -3.5E-05 |
| S-TIL1 | 0.001045 | -0.00281 |
| S-TIL2 | 0.001085 | -0.00316 |
| S-TIL25 | 0.001022 | -0.00212 |
| S-TIL26 | 0.001033 | -0.00241 |
| S-TIL27 | 0.001038 | -0.00236 |
| S-TIL6 | 0.001141 | -0.00361 |
| S-TIM1 | 0.000818 | -0.00042 |
| S-TIM2 | 0.000846 | -0.00061 |
| S-TIM3 | 0.000889 | -0.00096 |
| S-TIM5 | 0.000898 | -0.001 |
| S-TIM6 | 0.000757 | -0.00011 |
| S-TIM8 | 0.000895 | -0.00111 |
| S-YGH51 | 0.001578 | -0.00551 |
| S-YGH52 | 0.001494 | -0.00531 |
| TIH11 | 0.002217 | -3.6E-05 |
| TIH14 | 0.001503 | -5.5E-05 |
| TIH23 | 0.001595 | -4.9E-05 |
| TIH53 | 0.00325 | -6.9E-05 |
| TIH6 | 0.004877 | -0.00014 |
| TIM11 | 0.001336 | -0.0052 |
| TPH55 | 0.000799 | -0.00019 |
| YGH51 | 0.001603 | -0.00624 |
| YGH52 | 0.001494 | -0.00531 |
As can be seen from Table 3, the maximum absolute error is not more than 0.015%, the maximum average error is 0.001806% (the average value of the maximum errors of all glass materials in Table 3), and the minimum average error is-0.00282%, which shows that the refractive index of OHARA glass measured by using the formula (5) in the range of 400-1100 nm has smaller errors, and can better meet the requirements of engineering practice.
Mixing X1, X2, X3, X4The average maximum error and average minimum error of the refractive index of OHARA glass library material are calculated by formula (5) using other coefficients and using 400, 560, 680, 800 and 1100nm as well (X in this case) as shown in Table 41, X2, X3, X4Only some of the values are listed, but do not affect the understanding of the present solution):
table 4 calculation of refractive index error of 400-1100 nm using different coefficients
| X1 | X1 | X1 | X1 | Mean maximum error (%) | Mean minimum error (%) |
| 4 | 5 | 6 | 0.1 | 0.001652 | -0.00387 |
| 4 | 5 | 5.1 | 0.9 | 0.00432 | -0.00028 |
| 4 | 4.9 | 5.8 | 0.4 | 0.002133 | -0.00145 |
| 3.9 | 5 | 5.7 | 0.3 | 0.001579 | -0.00228 |
| 3.5 | 4.7 | 6 | 1 | 0.003741 | -0.00026 |
| 3.5 | 4.3 | 6 | 1.7 | 0.007642 | -0.00087 |
| 3.4 | 4.8 | 5.8 | 1.4 | 0.006155 | -0.00051 |
| 3.3 | 4.9 | 5.7 | 1.7 | 0.006155 | -0.00051 |
And (4) conclusion: in the embodiment, a spectrum confocal system is used, the refractive index of a certain spherical element medium material can be measured without complicated steps according to the characteristics of a dispersion lens, and then the whole refractive index curve can be rapidly calculated through a formula (5) according to the measured 5 refractive index data with any wavelength, wherein the refractive index for measuring a single wavelength is faster than that of the conventional method, and the refractive index curve is calculated by using less refractive index data (other formulas need more data), so the detection process is very rapid.
Example 2
Fig. 1 to 13 also show embodiment 2 of the present invention, and embodiment 2 differs from embodiment 1 in that:
a method for measuring the refractive index of a spherical element medium is provided, which comprises the following steps:
providing a measuring device, wherein the measuring device comprises a spectrum confocal sensor, a spectrometer and a distance adjusting mechanism, wherein the spectrum confocal sensor comprises a white light point light source, a semi-transparent semi-reflecting mirror and a dispersion objective lens; the semi-transparent and semi-reflective mirror (X) and the dispersive objective lens are sequentially arranged between the white light point light source and the detected spherical element medium along an optical axis, the semi-transparent and semi-reflective mirror (X) is close to the white light point light source, and the dispersive objective lens is close to the detected spherical element medium side;
the distance adjusting mechanism drives the spectrum confocal sensor and the measured spherical element medium to be close to or far away from each other so that the distance between the dispersion objective lens and the measured spherical element medium changes 4 times along the optical axis;
the spectrometer is arranged opposite to the reflecting surface of the semi-permeable and semi-reflective mirror and is used for detecting the wavelength of monochromatic light which is focused and reflected on the medium of the spherical element to be detected;
the detected 5 different wavelengths are used according to the formula:
calculating the refractive index of the measured spherical element medium at 5 wavelengths, and defining:
the central thickness of the spherical element medium is H;
the plurality of monochromatic lights decomposed by the dispersion objective lens are composed of at least one monochromatic light subset, and each monochromatic light subset comprises an upper monochromatic light and a lower monochromatic light; the upper monochromatic light in each monochromatic photon concentration is focused on the upper surface of the measured spherical element medium, and the lower monochromatic light in each monochromatic photon concentration is focused on the lower surface of the measured spherical element medium;
the wavelength of the lower monochromatic light in each monochromatic photon set is lambda;
the incident angle of the lower monochromatic light of each monochromatic photon concentration is
；
The focal distance between the upper monochromatic light and the lower monochromatic light in each monochromatic photon concentration is
；
Wherein the content of the first and second substances,
and
is a known parameter of a dispersive objective lens in a spectral confocal sensor;
is the curvature radius of the opposite side surface of the measured spherical element medium and the dispersive objective lens.
If the surface of the spherical element medium to be measured opposite to the dispersion objective lens is a plane, the refractive index of the spherical element medium to be measured 13 at the wavelength λ is set to be a refractive index
Is derived from the following formula:
further, defining:
when the distance between the dispersion objective lens L and the measured spherical element medium 13 is not changed, the wavelength of the upper monochromatic light is lambda1Wavelength of the lower monochromatic light is λ2；
When the distance between the dispersion objective lens L and the measured spherical element medium 13 is changed for the first time, the wavelength of the upper monochromatic light is lambda3Wavelength of the lower monochromatic light is λ4；
When the distance between the dispersion objective lens L and the measured spherical element medium 13 changes for the second time, the wavelength of the upper monochromatic light is lambda5Wavelength of the lower monochromatic light is λ6；
When the distance between the dispersion objective lens L and the measured spherical element medium 13 changes for the third time, the wavelength of the upper monochromatic light is lambda7Wavelength of the lower monochromatic light is λ8；
When the distance between the dispersion objective lens L and the measured spherical element medium 13 changes for the third time, the wavelength of the upper monochromatic light is lambda9Wavelength of the lower monochromatic light is λ10(ii) a Then the incident angle of each monochromatic light can be obtained
And has the following components:
according to refractive index
And combining the formulas
The refractive index curve of the measured spherical element medium 13 is calculated.
Further, X is not less than 3.51≤4, 4.5≤X2≤5, 5.5≤X3≤6, 0.1≤X4≤0.5。
Fig. 13 shows a flowchart of this embodiment, and the method for measuring the refractive index of the spherical element medium provided in this embodiment corresponds to the function implemented in embodiment 1, so for other functions of this embodiment, reference may be made to the contents in embodiment one, and details are not repeated here.
The number of apparatuses and the scale of the process described herein are intended to simplify the description of the present invention. Applications, modifications and variations of the present invention will be apparent to those skilled in the art.
The features of the different implementations described herein may be combined to form other embodiments not specifically set forth above. The components may be omitted from the structures described herein without adversely affecting their operation. Further, various individual components may be combined into one or more individual components to perform the functions described herein.
Furthermore, while embodiments of the invention have been described above, it is not limited to the applications set forth in the description and the embodiments, which are fully applicable in a variety of fields of endeavor to which the invention pertains, and further modifications may readily be made by those skilled in the art, it being understood that the invention is not limited to the details shown and described herein without departing from the general concept defined by the appended claims and their equivalents.
Claims (6)
1. The device for measuring the refractive index of the spherical element medium comprises a spectrum confocal sensor (11), a spectrometer (14) and a distance adjusting mechanism, wherein the spectrum confocal sensor (11) comprises a white light point light source (S), a semi-transparent semi-reflecting mirror (X) and a dispersion objective lens (L); the semi-transparent and semi-reflective mirror (X) and the dispersion objective lens (L) are sequentially arranged between the white light point light source (S) and the spherical element medium (13) to be measured along the optical axis, the semi-transparent and semi-reflective mirror (X) is close to the white light point light source (S), and the dispersion objective lens (L) is close to the spherical element medium (13) to be measured; the distance adjustment mechanism drives the spectrum confocal sensor (11) and the measured spherical element medium (13) to be close to or far away from each other so that the distance between the dispersion objective lens (L) and the measured spherical element medium (13) changes 4 times along the optical axis; the spectrometer (14) is opposite to the reflecting surface of the semi-transparent semi-reflecting mirror (X) and is used for detecting the wavelength of the monochromatic light which is focused and reflected on the detected spherical element medium (13); if the upper surface and the lower surface of the measured spherical element medium (13) are both spherical surfaces, 5 different detected wavelengths are substituted into the formula:
calculating the refractive index of the measured spherical element medium (13) at 5 wavelengths; if the surface of the spherical element medium (13) to be detected, which is opposite to the dispersive objective lens (L), is a plane, the detected 5 different wavelengths are substituted into the formula:
calculating the refractive index of the measured spherical element medium (13) at 5 wavelengths; defining:
the central thickness of the spherical element medium is H;
the plurality of monochromatic lights decomposed by the dispersion objective lens (L) are composed of at least one monochromatic light subset, and each monochromatic light subset comprises an upper monochromatic light and a lower monochromatic light; the upper monochromatic light in each monochromatic photon concentration is focused on the upper surface of the measured spherical element medium (13), and the lower monochromatic light in each monochromatic photon concentration is focused on the lower surface of the measured spherical element medium (13);
the wavelength of the lower monochromatic light in each monochromatic photon set is lambda;
the incident angle of the lower monochromatic light of each monochromatic photon concentration is
；
The focal distance between the upper monochromatic light and the lower monochromatic light in each monochromatic photon concentration is
；
Wherein the content of the first and second substances,
and
is a known parameter of a dispersive objective lens (L) in a spectral confocal sensor (11);
is the curvature radius of the opposite side surface of the measured spherical element medium (13) and the dispersive objective lens (L).
2. A spherical element medium refractive index measuring device according to claim 1, characterized by defining:
when the distance between the dispersion objective lens (L) and the measured spherical element medium (13) is not changed, the wavelength of the upper monochromatic light is lambda1Wavelength of the lower monochromatic light is λ2；
When the distance between the dispersion objective lens (L) and the measured spherical element medium (13) is changed for the first time, the wavelength of the upper monochromatic light is lambda3Wavelength of the lower monochromatic light is λ4；
The distance between the dispersive objective lens (L) and the measured spherical element medium (13) is secondAt the time of secondary change, the wavelength of the upper monochromatic light is lambda5Wavelength of the lower monochromatic light is λ6；
When the distance between the dispersion objective lens (L) and the measured spherical element medium (13) is changed for the third time, the wavelength of the upper monochromatic light is lambda7Wavelength of the lower monochromatic light is λ8；
When the distance between the dispersion objective lens (L) and the measured spherical element medium (13) is changed for the third time, the wavelength of the upper monochromatic light is lambda9Wavelength of the lower monochromatic light is λ10(ii) a Then the incident angle of each monochromatic light can be obtained
And has the following components:
according to refractive index
And combining the formulas
Calculating a refractive index curve of the detected spherical element medium (13);
wherein, X1、X2、X3、X4Is the wavelength term coefficient; A. b, C, D, E are constants to be solved.
3. The apparatus for measuring the refractive index of a spherical element medium as set forth in claim 2, wherein X is 3.5. ltoreq.X1≤4, 4.5≤X2≤5, 5.5≤X3≤6, 0.1≤X4≤0.5。
4. A method for measuring the refractive index of a spherical element medium is characterized by comprising the following steps:
providing a measuring device, wherein the measuring device comprises a spectrum confocal sensor (11), a spectrometer (14) and a distance adjusting mechanism, wherein the spectrum confocal sensor (11) comprises a white light point light source (S), a semi-transparent semi-reflecting mirror (X) and a dispersion objective lens (L); the semi-transparent and semi-reflective mirror (X) and the dispersion objective lens (L) are sequentially arranged between the white light point light source (S) and the spherical element medium (13) to be measured along the optical axis, the semi-transparent and semi-reflective mirror (X) is close to the white light point light source (S), and the dispersion objective lens (L) is close to the spherical element medium (13) to be measured;
the distance adjustment mechanism drives the spectrum confocal sensor (11) and the measured spherical element medium (13) to be close to or far away from each other so that the distance between the dispersion objective lens (L) and the measured spherical element medium (13) changes 4 times along the optical axis;
the spectrometer (14) is arranged opposite to the reflecting surface of the semi-transparent and semi-reflective mirror (X), and the spectrometer (14) is used for detecting the wavelength of monochromatic light which is focused and reflected on the detected spherical element medium (13);
if the upper surface and the lower surface of the measured spherical element medium (13) are both spherical surfaces, 5 different detected wavelengths are substituted into the formula:
calculating the refractive index of the measured spherical element medium (13) at 5 wavelengths;
if the surface of the spherical element medium (13) to be detected, which is opposite to the dispersive objective lens (L), is a plane, the detected 5 different wavelengths are substituted into the formula:
calculating the refractive index of the measured spherical element medium (13) at 5 wavelengths; defining:
the central thickness of the spherical element medium is H;
the plurality of monochromatic lights decomposed by the dispersion objective lens (L) are composed of at least one monochromatic light subset, and each monochromatic light subset comprises an upper monochromatic light and a lower monochromatic light; the upper monochromatic light in each monochromatic photon concentration is focused on the upper surface of the measured spherical element medium (13), and the lower monochromatic light in each monochromatic photon concentration is focused on the lower surface of the measured spherical element medium (13);
the wavelength of the lower monochromatic light in each monochromatic photon set is lambda;
the incident angle of the lower monochromatic light of each monochromatic photon concentration is
；
The focal distance between the upper monochromatic light and the lower monochromatic light in each monochromatic photon concentration is
；
Wherein the content of the first and second substances,
and
is a known parameter of a dispersive objective lens (L) in a spectral confocal sensor (11);
is the curvature radius of the opposite side surface of the measured spherical element medium (13) and the dispersive objective lens (L).
5. The measurement method according to claim 4, characterized by defining:
when the distance between the dispersion objective lens (L) and the measured spherical element medium (13) is not changed, the wavelength of the upper monochromatic light is lambda1Wavelength of the lower monochromatic light is λ2；
When the distance between the dispersive objective lens (L) and the measured spherical element medium (13) is changed for the first time, the chromatic dispersion objective lens is monochromaticWavelength of light is lambda3Wavelength of the lower monochromatic light is λ4；
When the distance between the dispersion objective lens (L) and the measured spherical element medium (13) changes for the second time, the wavelength of the upper monochromatic light is lambda5Wavelength of the lower monochromatic light is λ6；
When the distance between the dispersion objective lens (L) and the measured spherical element medium (13) is changed for the third time, the wavelength of the upper monochromatic light is lambda7Wavelength of the lower monochromatic light is λ8；
When the distance between the dispersion objective lens (L) and the measured spherical element medium (13) is changed for the third time, the wavelength of the upper monochromatic light is lambda9Wavelength of the lower monochromatic light is λ10(ii) a Then the incident angle of each monochromatic light can be obtained
And has the following components:
according to refractive index
And combining the formulas
Calculating a refractive index curve of the detected spherical element medium (13);
wherein, X1、X2、X3、X4Is the wavelength term coefficient; A. b, C, D, E are constants to be solved.
6. The measurement method according to claim 5, wherein 3.5. ltoreq.X1≤4, 4.5≤X2≤5, 5.5≤X3≤6, 0.1≤X4≤0.5。
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