CN101614526B - Double-confocal method for measuring thickness and refractive index and measuring device - Google Patents
Double-confocal method for measuring thickness and refractive index and measuring device Download PDFInfo
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- CN101614526B CN101614526B CN200910100310XA CN200910100310A CN101614526B CN 101614526 B CN101614526 B CN 101614526B CN 200910100310X A CN200910100310X A CN 200910100310XA CN 200910100310 A CN200910100310 A CN 200910100310A CN 101614526 B CN101614526 B CN 101614526B
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Abstract
The invention relates to a double-confocal method and a device for measuring thickness and a refractive index. A double-confocal system comprises two coaxially and symmetrically arranged confocal wave-filtration optical groups which are provided with photoelectric detectors, and the two confocal wave-filtration optical groups can move relatively along a common axial line. When the anterior focal points of the two confocal wave-filtration optical groups are superposed, the response of each photoelectric detector is a maximum value, and during defocusing, the response value is rapidly lowered; an object to be measured is vertically arranged between the two confocal wave-filtration optical groups; when the anterior focal point of any optical group is adjusted to the surface of the object to be measured, the response of each photoelectric detector is also a maximum value; and during defocusing, the response value is sharply lowered. By utilizing the two characteristics, the anterior focal points of the two confocal wave-filtration optical groups can be accurately positioned, and the geometrical thickness of the object to be measured is measured; and the geometrical thickness and the refractive index of a transparent material can be simultaneously measured. The invention is suitable for measuring the thickness and the refractive index during the mechanics experiments of materials or on other occasions.
Description
Technical field
The present invention relates to measure the measuring method and the device of measured object geometric thickness, refractive index or optical thickness.
Background technology
In engineering and scientific research, the measurement of geometric thickness, refractive index or optical thickness there is demand very widely, and under many occasions, needs to use nondestructiving detecting means.For some analytic targets, also requirement can be measured geometric thickness and refractive index (or optical thickness) simultaneously.For example, on Material Testing Machine,, just need suitable non-contact measurement method, in the loading process by the mechanical property and the photodynamics character of stretching experiment test transparent polymer material, not only can measure the variation of sample lateral dimension, variation that again can measurement of materials refractive index.At present in the Experiments of Machanics technology, measuring methods such as speckle interferometry, image correlation method, mark line tracing have been arranged, can measure the transversely deforming of material, but as the surface deformation measuring technique, they are not suitable for measuring the variation in thickness of plate sample, can not measure refractive index (or optical thickness).Common interference technique can only be measured optical thickness, generally is not suitable for directly measuring geometric thickness, and interference system is subject to such environmental effects such as vibration.Dissimilar interference techniques according to the difference of measuring principle, all has specific requirement to the coherence of light source, causes interference technique to be subjected to many restrictions in practical application.Adopt low coherent chromatography method, though can realize the synchro measure of transparent layered material geometric thickness and refractive index (or optical thickness), this method can not be used for non-transparent material.Low coherent chromatography method also has characteristics, is exactly to use low-coherence light source, and can not uses high-coherence light source, therefore can't measure the refractive index under the single wavelength condition.For testing of materials, the non-contact measurement method that need all be suitable for transparent material and non-transparent material very can synchro measure geometric thickness and refractive index (or optical thickness), and can use the light source of different coherent lengths as required.
Summary of the invention
The objective of the invention is a kind of simple in structure, the easy to operate measurement thickness and the double-confocal method and the measurement mechanism of refractive index.
The double-confocal method of measurement thickness of the present invention and refractive index is to adopt and construct two two confocal light path systems of confocal wave-filtration optical groups formation identical and coaxial, symmetric arrangement; Two confocal wave-filtration optical groups are installed in respectively on the base plate at two three-dimensional transfer table tops, can relatively move at the public horizontal axis x of the two confocal light path systems in the drive lower edge of separately three-dimensional transfer table;
Confocal wave-filtration optical group I comprises first detection object lens, the first's catoptron, the first smooth hurdle that blocks chief ray, the first confocal lens, first pinhole filter and first photodetector that sets gradually from right to left along common axis x, first's catoptron and axis x angle at 45, the light hole of first pinhole filter is positioned at the back focus place of the first confocal lens;
Confocal wave-filtration optical group II is by second detection object lens, the second portion catoptron that sets gradually from left to right along common axis x, the second smooth hurdle that blocks chief ray, the second confocal lens, second pinhole filter and second photodetector, second portion catoptron and axis x angle at 45, the light hole of second pinhole filter is positioned at the back focus place of the second confocal lens;
Light-source system is arranged on a side of two confocal light path systems; Light-source system comprises light source, beam splitter, first plane mirror, second plane mirror and the 3rd plane mirror, light source, beam splitter and second plane mirror are fixed on the base plate, wherein to be 45 tilting for beam splitter and horizontal direction, second plane mirror is between two confocal light path systems and beam splitter and vertical with beam splitter, first plane mirror and horizontal direction are that 45 is tilting to be fixed on first base plate, and the 3rd plane mirror and horizontal direction are that 45 is tilting to be fixed on second base plate; Light source produces the parallel beam perpendicular to the axis x of two confocal filtering systems, and this parallel beam is decomposed into reflected light R and transmitted light T with 45 incident beam splitter by beam splitter; Reflected light R is with 45 incident first plane mirror, by after the first plane reflection mirror reflection with 45 incident first catoptron, become the detecting light beam of confocal wave-filtration optical group I; Transmitted light T is with 45 incident second plane mirror, by after the second plane reflection mirror reflection with 45 incident the 3rd plane mirror, by after the 3rd plane reflection mirror reflection with 45 incident second portion catoptron, become the detecting light beam of confocal wave-filtration optical group II;
Measuring process is as follows:
1, setting measurement reference point: light path system is initially adjusted, with two three-dimensional transfer table mobile respectively confocal wave-filtration optical group I and confocal wave-filtration optical group II, as the response R of first photodetector
1Or the response R of second photodetector
2When reaching maximal value, the front focus O of confocal wave-filtration optical group I overlaps with the front focus O ' of confocal wave-filtration optical group II, and this coincide point is datum mark;
2, measure how much and move journey: measured object vertically is positioned between confocal wave-filtration optical group I and the confocal wave-filtration optical group II, and be fixed on the base plate, with two three-dimensional transfer tables confocal wave-filtration optical group I and confocal wave-filtration optical group II are moved respectively along axis x direction, the front focus O of confocal wave-filtration optical group I is shifted to the front surface q of measured object by reference point, as the response R of first photodetector
1When reaching maximum value, the front focus O of confocal wave-filtration optical group I just is on the front surface q of measured object, measures the displacement of confocal wave-filtration optical group I with the first three-dimensional transfer table, how much be moved journey d
1The front focus O ' of confocal wave-filtration optical group II is shifted to the rear surface h of measured object by reference point, as the response R of second photodetector
2When reaching maximum value, the front focus O ' of confocal wave-filtration optical group II just is on the rear surface h of measured object, measures the displacement of confocal wave-filtration optical group II with the second three-dimensional transfer table, how much be moved journey d
2Measure when moving journey how much, stipulate to move right confocal wave-filtration optical group I and confocal wave-filtration optical group II, the geometry that records moves journey d
1And d
2For on the occasion of, and be moved to the left confocal wave-filtration optical group I and confocal wave-filtration optical group II, the geometry that records moves journey d
1And d
2Be negative value;
3, measure optics and move journey: make confocal wave-filtration optical group I move to rear surface h by the front surface q of measured object along system axis x with the first three-dimensional transfer table, perhaps the rear surface h by measured object moves to front surface q, when the front focus O of confocal wave-filtration optical group I by measured object front surface q and during the h of rear surface, the response R of first photodetector
1Each occurs maximum value one time, with the first three-dimensional transfer table measure two secondary maximum responses before and after confocal wave-filtration optical group I and first photodetector corresponding displacement, optics move the journey Δ
dPerhaps make confocal wave-filtration optical group II move to rear surface h by the front surface q of measured object along system axis x with the second three-dimensional transfer table, perhaps the rear surface h by measured object moves to front surface q, when the front focus O ' of confocal wave-filtration optical group II by measured object front surface q and during the h of rear surface, the response R of second photodetector
2Each occurs maximum value one time, with the second three-dimensional transfer table measure two secondary maximum responses before and after confocal wave-filtration optical group II and second photodetector corresponding displacement, obtain optics and move the journey Δ
d
4, by formula (1) calculates the geometric thickness δ of measured object,
δ＝d
2-d
1(1)；
5, by formula (2) calculate the refractive index n of measured object,
Be used to realize the measurement mechanism of the double-confocal method of above-mentioned measurement thickness and refractive index, comprise that structure is identical and coaxial, two confocal wave-filtration optical group I of symmetric arrangement and II; Two confocal wave-filtration optical groups are installed in respectively on the base plate at two three-dimensional transfer table tops, and the public horizontal axis x of the two confocal light path systems in edge relatively moves; Two three-dimensional transfer tables are installed on the base plate;
Confocal wave-filtration optical group I comprises first detection object lens, the first's catoptron, the first smooth hurdle that blocks chief ray, the first confocal lens, first pinhole filter and first photodetector that sets gradually from right to left along common axis x, first's catoptron and axis x angle at 45, the first smooth hurdle is partly the round screen of a diameter less than beam size, the light hole of first pinhole filter is positioned at the back focus place of the first confocal lens, and its light hole diameter is less than or equal to 5 millimeters;
Confocal wave-filtration optical group II is by second detection object lens, the second portion catoptron that sets gradually from left to right along common axis x, the second smooth hurdle that blocks chief ray, the second confocal lens, second pinhole filter and second photodetector, second portion catoptron and axis x angle at 45, the second smooth hurdle is partly the round screen of a diameter less than beam size, the light hole of second pinhole filter is positioned at the back focus place of the second confocal lens, and its light hole diameter is less than or equal to 5 millimeters;
Light-source system is arranged on a side of two confocal light path systems; Light-source system comprises light source, beam splitter, first plane mirror, second plane mirror and the 3rd plane mirror, light source, the beam splitter and second plane mirror are fixed on the base plate, wherein to be 45 tilting for beam splitter and horizontal direction, second plane mirror is between two confocal light path systems and beam splitter and vertical with beam splitter, first plane mirror and horizontal direction are that 45 is tilting to be fixed on first base plate, the 3rd plane mirror and horizontal direction are that 45 is tilting to be fixed on second base plate, light source produces the parallel beam perpendicular to the axis x of two confocal filtering systems, this parallel beam is decomposed into reflected light R and transmitted light T with 45 incident beam splitter by beam splitter; Reflected light R is with 45 incident first plane mirror, by after the first plane reflection mirror reflection with 45 incident first catoptron, become the detecting light beam of confocal wave-filtration optical group I; Transmitted light T is with 45 incident second plane mirror, by after the second plane reflection mirror reflection with 45 incident the 3rd plane mirror, by after the 3rd plane reflection mirror reflection with 45 incident second portion catoptron, become the detecting light beam of confocal wave-filtration optical group II.
Among the present invention, said light source can be high-coherence light source, low-coherence light source or quasi coherent source.
Measured object is generally nontransparent or transparent board-like material, and for example steel plate, aluminium sheet, polycarbonate plate etc. also can the tabular objects of right and wrong.
Beneficial effect of the present invention is:
The first, can measure the geometric thickness and the refractive index of measured object simultaneously.
The second, utilize the focus positioning principle of confocal filtering, can reach higher measuring accuracy with non-interference mode; Round screen light hurdle is set in the confocal wave-filtration optical group blocks chief ray, can improve the location sensitivity of confocal wave-filtration optical group front focus, thereby make system can obtain higher resolution and measuring accuracy.
The 3rd, broad quantum.This is because the front focus spacing of two groups of confocal worry wave system systems can be adjusted in centimetre-sized (even meter level) scope zero, and the conventional bearing accuracy of double-confocal method is the micron number magnitude,, arrive centimetre-sized or higher greatly so but the Thickness Measurement by Microwave wide ranges is little of micron order.
The 4th, thickness evenness and surface reflection characteristic to measured object are not strict with, and therefore are suitable for measuring the geometric thickness of material in uneven thickness, measure refractive index materials for needs, thickness evenness requires also not harsh, as long as material has enough big transmittance to measure.
The 5th, the mutual alignment relation of measuring system and measured object is more flexible, and measured object can be located in the scope of the one section broad in confocal some both sides of light path system.Utilize closed-loop control system, can measure in real time, therefore be suitable for the measurement in the material loading deformation process the geometric thickness and the refractive index of measured object.
The 6th, as a kind of " geometrical optics " measuring method, the coherence of light source there are not special requirement, therefore can select the different light source of coherence flexibly according to different measurement requirement.
Description of drawings
Fig. 1 is two confocal measuring apparatus synoptic diagram of measurement thickness of the present invention and refractive index;
Fig. 2 is the focus positioning principle synoptic diagram of two confocal measurements;
Fig. 3 is that the measured object geometric thickness moves the synoptic diagram that concerns of journey with how much,
Fig. 4 is the synoptic diagram that concerns that optics moves journey and measured object geometric thickness and photodetector response.
Embodiment
With reference to Fig. 1, the measurement mechanism of the double-confocal method of measurement thickness of the present invention and refractive index comprises two the confocal wave-filtration optical group I and the II of identical and coaxial, the symmetric arrangement of structure; Two confocal wave-filtration optical groups are installed in respectively on the base plate 19,20 at two three-dimensional transfer table 22,23 tops, and the public horizontal axis x of the two confocal light path systems in edge relatively moves; Two three-dimensional transfer tables 22,23 are installed on the base plate 21;
Confocal wave-filtration optical group I comprises the first detection object lens 10, first's catoptron 9, first smooth hurdle 17, first confocal lens 8, first pinhole filter 7 and first photodetector 6 that sets gradually from right to left along common axis x, first's catoptron 9 and axis x angle at 45, the first smooth hurdle 17 is partly the round screen of a diameter less than beam size, be used for blocking chief ray, measure sensitivity and precision to improve, the light hole of first pinhole filter 7 is positioned at the back focus place of the first confocal lens 8, and its light hole diameter is less than or equal to 5 millimeters;
Confocal wave-filtration optical group II is by the second detection object lens 12, second portion catoptron 13, the second smooth hurdle 18, the second confocal lens 14, second pinhole filter 15 and second photodetector 16 that set gradually from left to right along common axis x, second portion catoptron 13 and axis x angle at 45, the second smooth hurdle 18 is partly the round screen of a diameter less than beam size, be used for blocking chief ray, measure sensitivity and precision to improve, the light hole of second pinhole filter 15 is positioned at the back focus place of the second confocal lens 14, and its light hole diameter is less than or equal to 5 millimeters;
Light-source system is arranged on a side of two confocal light path systems, two shared same light-source systems of confocal wave-filtration optical group; Light-source system comprises light source 1, beam splitter 2, first plane mirror 3, second plane mirror 4 and the 3rd plane mirror 5, light source 1, the beam splitter 2 and second plane mirror 4 are fixed on the base plate 21, wherein to be 45 tilting for beam splitter 2 and horizontal direction, second plane mirror 4 is between two confocal light path systems and beam splitter 2 and vertical with beam splitter 2, first plane mirror 3 is with horizontal direction that 45 is tilting to be fixed on first base plate 19, the 3rd plane mirror 5 is with horizontal direction that 45 is tilting to be fixed on second base plate 20, the parallel beam that light source 1 produces perpendicular to the axis x of two confocal filtering systems, this parallel beam is decomposed into reflected light R and transmitted light T with 45 incident beam splitter 2 by beam splitter 2; Reflected light R with 45 incident first catoptron 9, is become the detecting light beam of confocal wave-filtration optical group I by first plane mirror, 3 reflection backs with 45 incident first plane mirror 3; Transmitted light T is with 45 incident second plane mirror 4, reflected the back with 45 incident the 3rd plane mirror 5 by second plane mirror 4, with 45 incident second portion catoptron 13, become the detecting light beam of confocal wave-filtration optical group II by the 3rd plane mirror 5 reflection backs.
Light source 1 can be a high-coherence light source, and for example helium-neon laser also can be low-coherence light source and quasi coherent source.Adopt which kind of light source, should determine according to measurement requirement.
Measuring principle of the present invention, being the very big characteristic of focus signal of utilizing confocal filtering system positions the front focus of confocal wave-filtration optical group, locate by front focus, at first determine datum mark, mobile then front focus, bench mark to the geometry on measured object surface moves journey, for transparent measured object, that also can measure its front and rear surfaces moves journey (optics moves journey) relatively, utilizes the geometry that records to move journey, can calculate the geometric thickness of measured object; The optics that utilization records moves journey and geometric thickness, in conjunction with refraction law, can calculate the refractive index and the optical thickness of measured object.
Measuring process is as follows:
1, setting measurement reference point: light path system is initially adjusted, referring to Fig. 1, inject first's catoptron 9 of confocal wave-filtration optical group I with 45 from the parallel beam R of light-source system, be decomposed into reflected light and transmitted light, wherein reflected light is propagated to the right along primary optical axis x, by the first detection object lens 10, converge at the back focus O (O also is the front focus of confocal wave-filtration optical group I simultaneously) of the first detection object lens 10; Inject the second portion catoptron 13 of confocal wave-filtration optical group II with 45 from the parallel beam T of light-source system, be decomposed into reflected light and transmitted light, wherein reflected light is propagated left along primary optical axis x, by the second detection object lens 12, converge at the back focus O ' (O ' while also is the front focus of confocal wave-filtration optical group II) of the second detection object lens 12.With mobile respectively confocal wave-filtration optical group I of two three-dimensional transfer tables (22,23) and confocal wave-filtration optical group II, adjust the spacing of confocal wave-filtration optical group I and confocal wave-filtration optical group II, then the response R of first photodetector 6
1Response R with first photodetector 16
2The capital changes continuously.When the front focus O of two confocal wave-filtration optical groups overlaps with O ', this moment is whole light holes by second pinhole filter 15 by the right mutually cone-shaped beam that sends of confocal some O (O '), the energy that second photodetector 16 receives reaches maximal value, equally, fail to agree the cone-shaped beam that sends all by the light hole of first pinhole filter 7 by confocal some O (O '), and the energy that first photodetector 6 receives also reaches maximal value.Therefore the response R that works as first photodetector (6)
1Response R with second photodetector (16)
2When reaching maximal value, the front focus O of confocal wave-filtration optical group I overlaps with the front focus O ' of confocal wave-filtration optical group II, and this coincide point is datum mark;
2, measure how much and move journey: measured object 11 vertically is positioned over (see figure 2) between confocal wave-filtration optical group I and the confocal wave-filtration optical group II, and be fixed on the base plate 21, the light that penetrates from confocal wave-filtration optical group I and confocal wave-filtration optical group II reflects at the front surface q and the rear surface h of measured object 11 respectively.As shown in Figure 3, with two three-dimensional transfer tables 22,23 confocal wave-filtration optical group I and confocal wave-filtration optical group II are moved respectively along axis x direction, the front focus O of confocal wave-filtration optical group I is shifted to the front surface q of measured object 11 by reference point, as the response R of first photodetector 6
1When reaching maximum value, the front focus O of confocal wave-filtration optical group I just is on the front surface q of measured object 11, measures the displacement of confocal wave-filtration optical group I with the first three-dimensional transfer table 22, how much be moved journey d
1The front focus O ' of confocal wave-filtration optical group II is shifted to the rear surface h of measured object 11 by reference point, as the response R of second photodetector 16
2When reaching maximum value, the front focus O ' of confocal wave-filtration optical group II just is on the rear surface h of measured object 11, measures the displacement of confocal wave-filtration optical group II with the second three-dimensional transfer table 23, how much be moved journey d
2Measure when moving journey how much, stipulate to move right confocal wave-filtration optical group I and confocal wave-filtration optical group II, the geometry that records moves journey d
1And d
2For on the occasion of, and be moved to the left confocal wave-filtration optical group I and confocal wave-filtration optical group II, the geometry that records moves journey d
1And d
2Be negative value;
3, measure optics and move journey:
If confocal wave-filtration optical group I or confocal wave-filtration optical group II are moved, then the response R of first photodetector 6 along system axis x
1Or the response R of second photodetector 16
2Change continuously.When the front focus O of confocal wave-filtration optical group I just in time arrives the front surface q (or rear surface h) of measured object 11, the response R of first photodetector 6
1Maximum value appears one time; Equally, when the front focus O ' of confocal wave-filtration optical group II just in time arrives the front surface q (or rear surface h) of measured object 11, the response R of second photodetector 16
2Maximum value appears one time.The front focus O that makes confocal wave-filtration optical group I moves to rear surface h along system axis x by the front surface q of measured object 11, perhaps the rear surface h by measured object 11 moves to front surface q, two greatly responses that can utilize 6 pairs of measured objects of first photodetector, 11 front surface q and rear surface h to produce in succession, measure the distance that confocal wave-filtration optical group I moves by the first three-dimensional transfer table 22, use Δ
dExpression (referring to Fig. 4); Equally, the front focus O ' that makes confocal wave-filtration optical group II moves to rear surface h along system axis x by the front surface q of measured object 11, perhaps the rear surface h by measured object 11 moves to front surface q, two greatly responses that can utilize 16 pairs of measured objects of second photodetector, 11 front surface q and rear surface h to produce in succession, measure the distance that confocal wave-filtration optical group II moves by the second three-dimensional transfer table 23, also use Δ
dExpression.In order to move journey d with geometry
1And d
2Distinguish, with Δ
dBe defined as optics and move journey.
4. calculate the geometric thickness of measured object.Referring to Fig. 3, be true origin with reference point O (O '), be coordinate axis with the axis x of confocal wave-filtration optical road system, find out that easily the geometric thickness δ of measured object 11 moves journey d with how much
1And d
2Between relation following three kinds of situations are arranged:
Shown in Fig. 3 (a), when reference point O (O ') is positioned at 11 of measured objects,
δ＝d
1+d
2(a)；
Shown in Fig. 3 (b), when reference point O (O ') is positioned at the left side of measured object 11,
δ＝d
2-d
1(b)；
Shown in Fig. 3 (c), when reference point O (O ') is positioned at the right side of measured object 11,
δ＝d
1-d
2(c)。
Confocal wave-filtration optical group I and confocal wave-filtration optical group II if regulation moves right, the geometry that records moves journey d
1And d
2For on the occasion of, be moved to the left confocal wave-filtration optical group I and confocal wave-filtration optical group II, the geometry that records moves journey d
1And d
2Be negative value, then above-mentioned three kinds of situations can be unified to be write as
δ＝d
2-d
1(1)。
Formula (1) is exactly the computing formula of measured object 11 geometric thicknesses.
5. calculate the refractive index of measured object.According to refraction law, the refractive index of optical material equals its geometric thickness moves the journey gained divided by optics merchant.Therefore, geometric thickness δ and the optics that records measured object 11 moves the journey Δ
dAfter, can calculate its refractive index n by following formula:
N and δ are multiplied each other, can also obtain the optical thickness n δ of measured object 11.
Claims (3)
1. measure the double-confocal method of thickness and refractive index, it is characterized in that, adopt that structure is identical and coaxial, two confocal wave-filtration optical group I of symmetric arrangement and II constitute two confocal light path systems; Two confocal wave-filtration optical groups are installed in respectively on the base plate (19,20) at two three-dimensional transfer tables (22,23) top, and the public horizontal axis x of the two confocal light path systems in edge relatively moves;
Confocal wave-filtration optical group I comprises first detection object lens (10), the first's catoptron (9), the first smooth hurdle (17) that blocks chief ray, the first confocal lens (8), first pinhole filter (7) and first photodetector (6) that sets gradually from right to left along common axis x, first's catoptron (9) and axis x angle at 45, the light hole of first pinhole filter (7) is positioned at the back focus place of the first confocal lens (8);
Confocal wave-filtration optical group II is made up of second detection object lens (12), the second portion catoptron (13) that sets gradually from left to right along common axis x, the second smooth hurdle (18) that blocks chief ray, the second confocal lens (14), second pinhole filter (15) and second photodetector (16), second portion catoptron (13) and axis x angle at 45, the light hole of second pinhole filter (15) is positioned at the back focus place of the second confocal lens (14);
Light-source system is arranged on a side of two confocal light path systems; Light-source system comprises light source (1), beam splitter (2), first plane mirror (3), second plane mirror (4) and the 3rd plane mirror (5), light source (1), beam splitter (2) and second plane mirror (4) are fixed on the base plate (21), wherein to be 45 tilting for beam splitter (2) and horizontal direction, second plane mirror (4) is positioned between two confocal light path systems and the beam splitter (2) and is vertical with beam splitter (2), first plane mirror (3) and horizontal direction are that 45 is tilting to be fixed on first base plate (19), and the 3rd plane mirror (5) is with horizontal direction that 45 is tilting to be fixed on second base plate (20); Light source (1) produces the parallel beam perpendicular to the axis x of two confocal filtering systems, and this parallel beam is decomposed into reflected light R and transmitted light T with 45 incident beam splitter (2) by beam splitter (2); Reflected light R with 45 incident first catoptron (9), is become the detecting light beam of confocal wave-filtration optical group I by first plane mirror (3) reflection back with 45 incident first plane mirror (3); Transmitted light T is with 45 incident second plane mirror (4), reflected the back with 45 incident the 3rd plane mirror (5) by second plane mirror (4), with 45 incident second portion catoptron (13), become the detecting light beam of confocal wave-filtration optical group II by the 3rd plane mirror (5) reflection back;
Measuring process is as follows:
(1), setting measurement reference point: light path system is initially adjusted, with mobile respectively confocal wave-filtration optical group I of two three-dimensional transfer tables (22,23) and confocal wave-filtration optical group II, response R when first photodetector (6)
1Response R with second photodetector (16)
2When reaching maximal value, the front focus O of confocal wave-filtration optical group I overlaps with the front focus O ' of confocal wave-filtration optical group II, and this coincide point is datum mark;
(2), measure how much and move journey: measured object (11) vertically is positioned between confocal wave-filtration optical group I and the confocal wave-filtration optical group II, and be fixed on the base plate (21), with two three-dimensional transfer tables (22,23) confocal wave-filtration optical group I and confocal wave-filtration optical group II are moved respectively along axis x direction, the front focus O of confocal wave-filtration optical group I is shifted to the front surface q of measured object (11) by reference point, as the response R of first photodetector (6)
1When reaching maximum value, the front focus O of confocal wave-filtration optical group I just is on the front surface q of measured object (11), measures the displacement of confocal wave-filtration optical group I with the first three-dimensional transfer table (22), how much be moved journey d
1The front focus O ' of confocal wave-filtration optical group II is shifted to the rear surface h of measured object (11) by reference point, as the response R of second photodetector (16)
2When reaching maximum value, the front focus O ' of confocal wave-filtration optical group II just is on the rear surface h of measured object (11), measures the displacement of confocal wave-filtration optical group II with the second three-dimensional transfer table (23), how much be moved journey d
2Measure when moving journey how much, stipulate to move right confocal wave-filtration optical group I and confocal wave-filtration optical group II, the geometry that records moves journey d
1And d
2For on the occasion of, and be moved to the left confocal wave-filtration optical group I and confocal wave-filtration optical group II, the geometry that records moves journey d
1And d
2Be negative value;
(3), measure optics and move journey: make confocal wave-filtration optical group I move to rear surface h by the front surface q of measured object (11) along system axis x with the first three-dimensional transfer table (22), perhaps the rear surface h by measured object (11) moves to front surface q, when the front focus O of confocal wave-filtration optical group I by measured object (11) front surface q and during the h of rear surface, the response R of first photodetector (6)
1Each occurs maximum value one time, with the first three-dimensional transfer table (22) measure two secondary maximum responses before and after confocal wave-filtration optical group I and first photodetector (6) corresponding displacement, optics move the journey Δ
dPerhaps use the second three-dimensional transfer table (23) to make confocal wave-filtration optical group II move to rear surface h by the front surface q of measured object (11) along system axis x, perhaps the rear surface h by measured object (11) moves to front surface q, when the front focus O ' of confocal wave-filtration optical group II by measured object (11) front surface q and during the h of rear surface, the response R of second photodetector (16)
2Each occurs maximum value one time, with the second three-dimensional transfer table (23) measure two secondary maximum responses before and after confocal wave-filtration optical group II and second photodetector (16) corresponding displacement, obtain optics and move the journey Δ
d
(4), by formula (1) calculate the geometric thickness δ of measured object (11),
δ＝d
2-d
1 (1)；
(5), by formula (2) calculate the refractive index n of measured objects (11),
2. the double-confocal method of measurement thickness according to claim 1 and refractive index is characterized in that light source (1) is high-coherence light source, low-coherence light source or quasi coherent source.
3. be used to realize the measurement mechanism of the double-confocal method of described measurement thickness of claim 1 and refractive index, it is characterized in that comprising that structure is identical and coaxial, two confocal wave-filtration optical group I of symmetric arrangement and II; Two confocal wave-filtration optical groups are installed in respectively on the base plate (19,20) at two three-dimensional transfer tables (22,23) top, and the public horizontal axis x of the two confocal light path systems in edge relatively moves; Two three-dimensional transfer tables (22,23) are installed on the base plate (21);
Confocal wave-filtration optical group I comprises first detection object lens (10), the first's catoptron (9), the first smooth hurdle (17) that blocks chief ray, the first confocal lens (8), first pinhole filter (7) and first photodetector (6) that sets gradually from right to left along common axis x, first's catoptron (9) and axis x angle at 45, the first smooth hurdle (17) is partly the round screen of a diameter less than beam size, the light hole of first pinhole filter (7) is positioned at the back focus place of the first confocal lens (8), and its light hole diameter is less than or equal to 5 millimeters;
Confocal wave-filtration optical group II is made up of second detection object lens (12), the second portion catoptron (13) that sets gradually from left to right along common axis x, the second smooth hurdle (18) that blocks chief ray, the second confocal lens (14), second pinhole filter (15) and second photodetector (16), second portion catoptron (13) and axis x angle at 45, the second smooth hurdle (18) is partly the round screen of a diameter less than beam size, the light hole of second pinhole filter (15) is positioned at the back focus place of the second confocal lens (14), and its light hole diameter is less than or equal to 5 millimeters;
Light-source system is arranged on a side of two confocal light path systems; Light-source system comprises light source (1), beam splitter (2), first plane mirror (3), second plane mirror (4) and the 3rd plane mirror (5), light source (1), beam splitter (2) and second plane mirror (4) are fixed on the base plate (21), wherein to be 45 tilting for beam splitter (2) and horizontal direction, second plane mirror (4) is positioned between two confocal light path systems and the beam splitter (2) and is vertical with beam splitter (2), first plane mirror (3) and horizontal direction are that 45 is tilting to be fixed on first base plate (19), the 3rd plane mirror (5) and horizontal direction are that 45 is tilting to be fixed on second base plate (20), light source (1) produces the parallel beam perpendicular to the axis x of two confocal filtering systems, this parallel beam is decomposed into reflected light R and transmitted light T with 45 incident beam splitter (2) by beam splitter (2); Reflected light R with 45 incident first catoptron (9), is become the detecting light beam of confocal wave-filtration optical group I by first plane mirror (3) reflection back with 45 incident first plane mirror (3); Transmitted light T is with 45 incident second plane mirror (4), reflected the back with 45 incident the 3rd plane mirror (5) by second plane mirror (4), with 45 incident second portion catoptron (13), become the detecting light beam of confocal wave-filtration optical group II by the 3rd plane mirror (5) reflection back.
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| CN102175644A (en) * | 2010-12-30 | 2011-09-07 | 长春理工大学 | Device and method for detecting refractive index of optical flat based on displacement sensor |
| CN104568390B (en) * | 2015-01-12 | 2017-07-28 | 北京理工大学 | Bilateral dislocation differential confocal measurement method |
| CN105203036B (en) * | 2015-10-22 | 2018-08-28 | 茂莱（南京）仪器有限公司 | The device and method that eyes with non-contact method measures lens centre thickness |
| CN109991190B (en) * | 2019-04-19 | 2020-08-11 | 北京理工大学 | Transverse subtraction differential confocal lens refractive index measuring method |
| CN109991191B (en) * | 2019-04-19 | 2020-12-11 | 北京理工大学 | Refractive index measuring method for bilateral dislocation differential confocal lens |
| CN112229338B (en) * | 2020-11-27 | 2022-05-17 | 中国计量科学研究院 | Double-spectrum confocal thickness measuring method without standard sheet zero alignment |
| CN116045824B (en) * | 2023-01-04 | 2023-08-15 | 深圳市华众自动化工程有限公司 | High-precision detection device and method based on white light confocal principle |
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| CN101071101A (en) * | 2007-06-07 | 2007-11-14 | 浙江大学 | Side shaft matter light cofoca filtering method for optical coherence tomography and detecting lens |
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