阅读说明：本技术 具有标准具的白光干涉仪的量值测量方法 (Method for measuring value of white light interferometer with etalon ) 是由 张成悌 薛靓 张宝武 付天坤 汤江文 沈小燕 蔡东炎 龚柯安 李貌 于 2019-09-18 设计创作，主要内容包括：本发明公开了一种具有标准具的白光干涉仪的量值测量方法,其测量步骤为：在白光干涉仪的光路中分光光路前增加通光孔径相同平行光路系统,并在其中放置标准具；调整干涉仪的干涉条纹,将干涉仪两个相干光路调整到完全垂直；调整使两相干光自分光点至两参考镜的距离相等,出现白光零次干涉带；通过参考镜和量块工作台的调整,达到钢平晶上的干涉带平行于被测量块短边,并且被测量块上的零次干涉带通过被测量块中部的中点；测出钢平晶上的零次干涉带与被测量块中心点上零次干涉带的距离并修正。本发明方法提高了量块测量精度,不会产生粗大误差,提高测量效率,不磨损,寿命长,易于实现测量的自动化与半自动化,可以进行许多精密测量。(The invention discloses a method for measuring the quantity of a white light interferometer with an etalon, which comprises the following measuring steps: adding a parallel optical path system with the same clear aperture in front of a light splitting optical path in an optical path of the white light interferometer, and placing an etalon in the parallel optical path system; adjusting interference fringes of the interferometer, and adjusting two coherent light paths of the interferometer to be completely vertical; adjusting to make the distances from the light splitting points of the two coherent lights to the two reference mirrors equal, and generating a white light zero-order interference band; adjusting a reference mirror and a gauge block workbench to ensure that an interference band on a steel flat crystal is parallel to the short side of the measured block, and a zero-order interference band on the measured block passes through the middle point of the middle part of the measured block; and measuring and correcting the distance between the zero-order interference band on the steel flat crystal and the zero-order interference band on the central point of the measured block. The method improves the measuring accuracy of the gauge block, does not generate gross errors, improves the measuring efficiency, is free from abrasion, has long service life, is easy to realize the automation and semi-automation of measurement, and can carry out a plurality of precise measurements.)

1. A method for measuring the quantity of a white light interferometer with an etalon is characterized in that a parallel light path system is added in a light path of the white light interferometer, and the etalon is arranged in the parallel light path system; the measuring steps are as follows:

step 1: a parallel light system with the same clear aperture is added in front of a light splitting optical path of the white light interferometer, and a standard tool (6) is placed in the parallel light system;

step 2: adjusting a coherent light path of a white light interferometer;

two coherent light paths of a white light interferometer are adjusted to be completely vertical, namely the two coherent light paths are completely overlapped, and interference fringes can be seen when monochromatic light is adopted for illumination;

the interference system of the contact white light interferometer is complete and needs to be adjusted when leaving a factory; for a white light interferometer for detecting an equal measuring block, a measured block (8) and a lapped steel flat crystal (15) form a reference plane of one of coherent light paths, the measured block (8) is lapped on the steel flat crystal (15) and is placed on a measuring block workbench (14) to form a complete interference system when interference is adjusted, and then the coherent light path is adjusted;

and step 3: adjusting zero-order white light interference fringes;

monochromatic light interference fringes can be seen under monochromatic light illumination, white light illumination is added at the moment, the distance between two coherent light beams from the light splitting point to the two reference mirrors is adjusted to be equal, the monochromatic light interference fringes are clearer and clearer in the adjustment process, and finally a white light color interference band group appears in the monochromatic light interference fringes, and zero-order black interference bands are clearest in the color interference bands; adjusting the direction and the interval of the interference bands to be required;

the contact type white light interferometer is well adjusted when being delivered from a factory;

for an equal-mass white light interferometer, zero-order black interference fringes can be simultaneously seen on a steel flat crystal (15) and a measured block (8), firstly, a zero-order interference band on the steel flat crystal is adjusted to be parallel to the short side of the measured block (8) and a proper interval is set; then, adjusting the workbench up and down to enable zero-order black stripes on the measured block (8) to pass through the central point of the measured block (8), and checking whether an interference band on the flat crystal is still parallel to the short side of the measured block (8) or not, wherein the quality of the steel flat crystal (15) is ensured to ensure that the monochromatic light interference stripes can be seen when any steel flat crystal (15) is placed on the workbench;

and 4, step 4: carrying out a quantity measurement;

for a contact white light interferometer, a measuring head is contacted with a measuring ball or rib of a workbench to find a turning point, a zero-order interference band is adjusted to be a zero line in the middle of a view field, and a reading a is carried out₁(ii) a Then the measuring head is lifted and put into the measured block (8), the measuring head is contacted with the measured block (8) according to the grating reading on the interferometer body, and a second reading a of the measured block (8) is obtained₂The difference L ═ a between the dimensions of the block to be measured (8) and the etalon (6)₂-a₁；

For an equal-small-block white light interferometer, zero-order interference band of the central point of a measured block (8) to zero on a steel flat crystal (15) is measuredDistance L of sub-interference band under monochromatic light₁And measuring the distance L between N interference bands on the steel flat crystal (15) by monochromatic light₂Calculating the difference L between the gauge block and the etalon₁×N×λ/(2×L₂) λ is the wavelength of monochromatic light;

and (3) detecting the nanoscale sensor: the interferometer and the sensor are simultaneously contacted with the workbench, when the sensor is positioned at a zero position, the zero-order interference band is positioned at the center of the view field, and the reading of a zero reticle is a₀The reading of the interferometer by the sensor to the corresponding examined point is a_iThe difference L between the point of the sensor and the etalon (6)_i＝a_i-a₀；

And 5: determining the actual size to be measured;

the exact dimensions of the block (8) to be measured are obtained by adding the difference L between the dimensions of the etalon (6) and the dimensions thereof and correcting the environmental conditions.

2. The method of magnitude measurement of a white light interferometer with an etalon according to claim 1, wherein in step 1, air in the etalon is opened to the atmosphere; for a large-size measured object, the etalon (6) should be close to the measured object as much as possible, and the refractive indexes of the air in the etalon (6) and the air near the measured object are consistent.

3. The method as claimed in claim 1, wherein when measuring the high-grade gauge block, the whole measuring device is placed in the heat-insulating cover, and the temperature sensor, the humidity sensor and the air pressure sensor are used in the heat-insulating cover to collect the temperature, the humidity and the air pressure, respectively, and regulate and control the temperature, the humidity and the air pressure, so that various parameters of the air meet the requirements of the JJJG 146 and 2003 gauge block calibration procedures.

4. The method of claim 1, wherein in step 4, the distance between the zero-order interference band on the steel flat crystal (15) and the zero-order interference band on the central point of the measured block (8) is measured by the area array CCD (10); when the direction from the zero-order interference fringe of the measured block (8) to the zero-order interference fringe on the steel flat crystal (15) is consistent with the movement direction of the interference fringe when the workbench moves upwards, the optical path of the zero-order interference band on the measuring block is larger than that of the zero-order interference band on the steel flat crystal (15); i.e. indicating that the gauge block size is smaller than the etalon size; the difference takes a negative value and conversely takes a positive value.

5. The method of magnitude measurement of a white light interferometer with an etalon of claim 1 wherein in step 2, the white light interferometer uses a monochromatic light source, the monochromatic light source is generated by adding an interference filter to the white light or by switching the monochromatic light source.

6. The method for measuring the magnitude of a white light interferometer having an etalon according to claim 1, wherein the correction value of the measurement block (8) is obtained by correcting the length of the etalon (6) by the air pressure, temperature and humidity parameters measured by the sensor and converting the corrected value into the measurement result in the condition of the standard parameters in step 5.

7. The method of magnitude measurement of a white light interferometer with an etalon according to claim 1, wherein the etalon (6) has a standard size identical to the size of the block (8) to be measured, or is made to be identical to the size of the block (8) to be measured by a multiple of optical multiplication method, or is made to be identical to the size of the block (8) to be measured by a sum and difference method of the sizes of the etalon (6).

8. The method of magnitude measurement of a white light interferometer with an etalon according to claim 1 wherein the white light interferometer having a size of 100mm or less the etalon (6) and the measured mass (8) are in a vertical state; the white light interferometer with the size larger than 100mm is in a horizontal state.

Technical Field

The invention belongs to the technical field of length measurement, and particularly relates to a measurement method of a white light interferometer with an etalon.

Background

At present, the development of related instruments for measuring the central length of the gauge block is endless, and the following instruments are summarized so far: 1) the measurement range of the optical wave interferometer based on the decimal coincidence method principle is divided into 0.5-100mm and 125-1000mm, and the uncertainty of measurement reaches U₉₉＝(0.02μm+0.2×10^-6L), the measurement requirements of 1 equal measuring block are met; 2) the contact type laser gage block length measuring instrument has the measuring range of 0.5-100mm, and can only measure 2, 3 and other gage blocks; 3) the automatic comparator based on the principles of an inductance micrometer, a camera, a grating type and the like has the main functions of replacing the traditional subjective interpretation of naked eyes, replacing a computer with the automatic interpretation of the difference value between a standard gauge block and a measured block and realizing the automatic processing of measured data. These instruments have been successful, and some have improved resolution and performance compared with the original contact interferometer.

The establishment of the technical specification of the gauge block and the development of a gauge block measuring instrument are greatly developed so far, but the improvement of the measuring accuracy of the gauge block is always the research subject and the continuous pursuit of a gauge block measuring technician. The research subjects of the related art of the gauge block measurement include: meticulous design and debugging of each part of the gauge block laser interferometer; researching the phase correction of the gauge block interferometry; the measurement of the linear expansion coefficient of the gauge block, the measurement technology of the non-steel mass block, the measurement of the fractional part of the interference fringe, the refractive index of air, the temperature of the gauge block, the linear expansion coefficient of the gauge block and the like. In addition, the traditional instrument must use the reference gauge block to realize the traceability of the measured block when the length is transmitted. This inevitably causes wear of the reference gauge block, reduces its accuracy, and reduces its life. Secondly, the automatic verification of the gauge blocks, particularly the batch automatic sorting grade of a gauge block production factory, urgently needs the research and development of related technologies.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a method for measuring the quantity of the white light interferometer with the etalon, which improves the precision of precision measurement, does not generate a coarse error and is easy to realize automation and semi-automation of measurement.

In order to solve the technical problems, the invention adopts the technical scheme that:

a method for measuring the quantity of a white light interferometer with an etalon comprises the steps of adding a parallel light path system in a light path of the white light interferometer, and placing the etalon in the parallel light path system; the measuring steps are as follows:

step 1: adding a parallel light system with the same clear aperture in front of a light splitting path of the white light interferometer, and placing a standard tool in the parallel light system;

step 2: adjusting a coherent light path of a white light interferometer;

two coherent light paths of a white light interferometer are adjusted to be completely vertical, namely the two coherent light paths are completely overlapped, and interference fringes can be seen when monochromatic light is adopted for illumination;

the interference system of the contact white light interferometer is complete and needs to be adjusted when leaving a factory; for a white light interferometer for detecting an equal-mass block, a measured block and a lapped steel flat crystal form a reference plane of one of coherent light paths, the measured block is lapped on the steel flat crystal firstly when interference is adjusted, the steel flat crystal is placed on a measuring block workbench to form a complete interference system, and then the coherent light path is adjusted;

and step 3: adjusting zero-order white light interference fringes;

monochromatic light interference fringes can be seen under monochromatic light illumination, white light illumination is added at the moment, the distance between two coherent light beams from the light splitting point to the two reference mirrors is adjusted to be equal, the monochromatic light interference fringes are clearer and clearer in the adjustment process, and finally a white light color interference band group appears in the monochromatic light interference fringes, and zero-order black interference bands are clearest in the color interference bands; adjusting the direction and the interval of the interference bands to be required;

the contact type white light interferometer is well adjusted when being delivered from a factory;

for an equal-mass white light interferometer, zero-order black interference fringes can be simultaneously seen on a steel flat crystal and a measured block, firstly, a zero-order interference band on the steel flat crystal is adjusted to be parallel to the short edge of the measured block and a proper interval is set; then adjusting the workbench up and down to enable zero-order black stripes on the measured block to pass through the central point of the measured block, and checking whether an interference band on the flat crystal is still parallel to the short edge of the measured block again, wherein the quality of the steel flat crystal is ensured to ensure that the monochromatic light interference stripes can be seen when any steel flat crystal is placed on the workbench;

and 4, step 4: carrying out a quantity measurement;

for a contact white light interferometer, a measuring head is contacted with a measuring ball or rib of a workbench to find a turning point, a zero-order interference band is adjusted to be a zero line in the middle of a view field, and a reading a is carried out₁(ii) a Then the measuring head is lifted and put into the measured block, the measuring head is contacted with the measured block according to the grating reading on the interferometer main body, and a second reading a of the measured block is obtained₂The difference L ═ a between the size of the measured block and the size of the etalon₂-a₁；

For an equal-small-quantity block white light interferometer, measuring the distance L from the zero-order interference band at the central point of the measured block to the zero-order interference band on the steel flat crystal under monochromatic light₁And measuring the distance L between N interference bands on the steel plate with monochromatic light₂Calculating the difference L between the gauge block and the etalon₁×N×λ/(2×L₂) λ is the wavelength of monochromatic light;

and (3) detecting the nanoscale sensor: the interferometer and the sensor are simultaneously contacted with the workbench, and the sensor is positioned at zero timeThe interference zone is positioned in the center of the visual field, and the reading of a zero reticle is a₀The reading of the interferometer by the sensor to the corresponding examined point is a_iThe difference L between the point of the sensor and the etalon_i＝a_i-a₀；

And 5: determining the actual size to be measured; the etalon size plus the difference L from the etalon size plus the correction of the environmental conditions, the accurate size of the measured block is obtained.

Further, in step 1, the air in the etalon should be communicated with the atmosphere; for a measurement object with a larger size, the etalon should be close to the measurement object as much as possible, so that the refractive indexes of the air in the etalon and the air near the measurement object are consistent.

Furthermore, when measuring a high-grade gauge block, the whole measuring device is arranged in the heat-insulating cover, the temperature sensor, the humidity sensor and the air pressure sensor are adopted in the heat-insulating cover to respectively collect temperature, humidity and air pressure, and the temperature, the humidity and the air pressure are regulated and controlled, so that various parameters of the air meet the requirements of the JJG 146-doped 2003 gauge block verification rules.

Further, in step 4, measuring the distance between a zero-order interference band on the steel flat crystal and a zero-order interference band on the central point of the measured block through an area array CCD; when the direction from the zero-order interference fringe of the measured block to the zero-order interference fringe on the steel flat crystal is consistent with the movement direction of the interference fringe when the working table moves upwards, the optical path of the zero-order interference band on the measuring block is larger than that of the zero-order interference band on the steel flat crystal; i.e. indicating that the gauge block size is smaller than the etalon size; the difference takes a negative value and conversely takes a positive value.

Further, in step 2, the white light interferometer uses a monochromatic light source, and the monochromatic light source is generated by adding an interference filter on the basis of white light or by switching the monochromatic light source.

Further, in step 5, the correction value of the measured block is obtained by correcting the length of the etalon by using the air pressure, temperature and humidity parameters of the air measured by the sensor, and converting the corrected value into the measurement result under the standard parameter condition.

Further, the standard size of the etalon is the same as the size of the measured block, or the standard size of the etalon is consistent with the size of the measured block by adopting a certain multiple of optical multiplication method, or the standard size of the etalon is consistent with the size of the measured block by adopting a sum and difference method of the etalon sizes.

Further, the etalon and the measured block of the white light interferometer with the size less than or equal to 100mm are in a vertical state; the white light interferometer with the size larger than 100mm is in a horizontal state.

Compared with the prior art, the invention has the beneficial effects that:

1) the present invention uses non-contact etalon to replace the reference gauge block used for detecting 2-5 equivalent blocks and needing contact measurement, and uses etalon to directly measure gauge block, so that it is high in efficiency and has no wear, and uses reference gauge block to firstly calibrate on the reference gauge block, then measures the measured block. This is inefficient and wears out the reference gauge block.

2) The different grades of gauge blocks can be calibrated by one set of etalon without the need for a large number of reference gauge blocks.

3) The zero-order interference band is measured by using a white light interferometer, compared with the existing method, the image of the monochromatic light interference band with larger path difference is much clearer, and the electric signal is also many times stronger; therefore, the measurement by the white light interferometer is not only high in efficiency, but also accurate, and avoids the occurrence of gross errors.

4) Since the etalon is non-contact and free from abrasion in measurement, the service life of the etalon is long, the verification cycle time is longer than that of the reference gauge block, and the management cost of submission and the cost of material consumption can be reduced.

5) The etalon adopts an optical multiplication and sum-difference processing method, so that the number of the etalons can be greatly reduced. Thereby reducing the cost of etalons; very small dimensions can be measured using the differential method, avoiding the difficulty of making small-dimension etalons.

6) When the etalon is used for calibrating the low-grade measuring block by using the set of etalon, the requirement of the environmental condition can be properly relaxed due to the high precision of the etalon, and the cost of the environmental condition can also be saved.

7) Because the precision of the precision measurement is improved, no gross error is generated, the automation and the semi-automation of the measurement are easy to realize; especially, the automatic measurement effect is more apparent when a batch of gauge blocks with the same size are sorted by a gauge block production factory.

8) The etalon and white light interferometer can not only test the measuring blocks of all levels, but also test the measurement of the indentation size of a standard ring gauge and a standard hardness tester, the calibration of a precision instrument (such as an electron microscope and the like), the calibration of a nano-scale sensor and the like.

Drawings

FIG. 1 is a schematic diagram of the optical path of the present invention for measuring gauge block using a white light interferometer.

FIG. 2 is a view of the field of view of a white light interferometer for calibrating high-grade gauge blocks in the present invention.

FIG. 1: the device comprises a 1-light source, a 2-diaphragm, a 3-lens, a 4-first reflector, a 5-etalon station platform, a 6-etalon, a 7-second reflector, an 8-measured block, a 9-imaging lens, a 10-area array CCD, an 11-beam splitter, 12-compensation glass, a 13-reference mirror, a 14-measuring block station platform and a 15-steel flat crystal.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

The invention uses 6 measurement values of the etalon to measure by using a white light interferometer, and the measurement values are transmitted to the measured length dimension. And (3) adopting a white light interferometer, additionally arranging an etalon 6 in a light path of the white light interferometer, and comparing the measured length dimension with the standard length dimension of the etalon 6 to obtain the actual dimension of the measured dimension. In order to achieve the accuracy of measurement, the white light interferometer should use a monochromatic light source for the calibration. The monochromatic light source can be an interference filter on the basis of white light or switched by adopting the monochromatic light source. The structure and principle of the white light interferometer are not limited at all. The measuring block quantity value is obtained by measuring parameters such as air pressure, temperature and humidity of air through a sensor to correct the length of the special etalon, and then converting the parameters into a measuring result under the condition of standard parameters.

As shown in FIG. 1, the whole optical path of the measuring instrument and its corresponding components are covered by a good heat-insulating cover. The light source consists of white light and monochromatic light and is arranged outside the heat-insulating cover; the monochromatic light is composed of general sodium lamp, potassium lamp, mercury lamp or white light plus interference filter, and the white light and monochromatic light can be automatically generated by program control. And (3) detecting the light path clear aperture of the white light interferometer of the equal-mass block not to be smaller than 40mm, and the clear aperture of the contact white light interferometer is not limited. The usual instruments for testing blocks of 100mm and below are vertical, so the etalon 6 should also be vertical in the light path and during testing. The apparatus for testing the gauge block of more than 100mm is horizontal, and the etalon 6 should also be horizontal in the light path and during testing.

In order to ensure that the refractive indexes of the air in the etalon 6 and the air in the light path of the white light interferometer are consistent, the positions of the etalon 6 and the measured block 8 are close to each other as much as possible, and the space of the etalon 6 is communicated with the atmosphere. In order to control various parameters of air in the heat-insulating cover to meet the requirements of the JJG 146-.

Because the measured blocks 8 are calibrated for a long isothermal time and a short calibration time, in order to improve efficiency, a plurality of stations for placing the etalon 6 and the measured blocks 8 on the etalon station table 5 and the measuring block table 14 are required to perform isothermal and preparation measurement, and a plurality of measured blocks 8 can be calibrated for one isothermal.

The measured mass 8 is ground on a steel flat 15 and placed on a measuring mass table 14. The block lapping technique requires training to achieve lapping film thickness variation of less than 5 nm. Since the dimensional tolerance of the steel plate 15 and the etalon 6 is controlled and the device is adjusted in advance, the monochromatic light interference band can be seen when the etalon 6 and the block 8 to be measured are placed on the worktable. Through the adjustment of the reference mirror 13 and the gauge block workbench 14, the interference band on the steel flat crystal 15 is parallel to the short side of the measured block 8, the distance of interference band fringes is proper, and the zero-order interference band on the measured block 8 passes through the middle point of the middle part of the measured block 8, the zero-order interference band can be seen on the steel flat crystal 15 as shown in fig. 2, for a large gauge block of 1000mmK grade, the zero-order interference band can not be seen on the steel flat crystal 15 due to large deviation, and accurate measurement can still be carried out by adopting proper measures; these operations can also be automatically adjusted by the piezoelectric ceramics.

The zero order interference band on the steel plate 15 should be determined during the tuning process to be above the midpoint position of the measured mass 8, indicating that the measured mass 8 is larger than the etalon 6 size or smaller than the etalon 6 size. When the table is raised, the direction of movement of the interference band on the steel plate 15 is seen and determined. The distance between the zero-order interference band on the steel flat crystal 15 and the zero-order interference band on the central point of the measured block 8 is measured by an area array CCD (charge coupled device image sensor), so that the difference value between the measured block 8 and the etalon 6 can be known, and the actual size of the central length of the measured block 8 can be obtained by adding various correction values.

The measuring objects of the invention comprise measuring blocks with various precision grades including an equal measuring block, a smooth gauge, a smooth ring gauge, a three-line diameter size, a standard indentation size of a hardness block, the verification of a nano-scale sensor, the field of view accuracy of an electron microscope, the precision measurement of gravity acceleration, the accuracy of the displacement of an ultra-precision workbench and the like.

In order to reduce the number of etalons 6 and reduce the cost, the standard size of the etalon 6 can be identical to the size of the block 8 to be measured by adopting a certain multiple of optical multiplication method besides the same size as the block 8 to be measured, and the size of the etalon 6 can be identical to the size of the block 8 to be measured by adopting a sum and difference method. For high precision measurements, the optical multiplication should be no more than 4 times, so that the etalon 6, which measures dimensions no more than 1000mm, is up to 300mm in size. Under the condition of measurement uncertainty, the optical multiplication factor can reach 6-8 times. The sum and difference method of the 6-dimension etalon can solve a plurality of special dimensions, such as the special measuring block sizes of a calibration micrometer and a caliper; the small size measurement problem can also be solved because the small size etalon 6 is not easily manufactured, especially in a size smaller than 1mm, thereby reducing the instrument cost. The space of the etalon 6 for transferring the magnitude is communicated with the atmosphere; the etalon 6 is made of a material which is the same as that of the object to be measured. For the high-precision measuring etalon 6 to be close to the measured object as much as possible, the placing mode of the etalon 6 should be consistent with the placing mode (vertical or horizontal) of the measured object, and the requirement on the measuring environment should be consistent with the requirement on the environment by the uncertainty of the measurement of the measured object.

For high-precision measurement, the reading of interference fringes must be measured by a CCD device; allowing measurements at the scale position with zero interference fringes observed for low precision measurements. When the difference between the size of the measured block 8 and the size of the etalon 6 exceeds 10 interference fringes, the distance between the interference fringes can be increased to enable the zero-order interference fringes to fall within the field range, so that initial measurement is facilitated, and then the interference band interval is widened and the precise measurement of the fringe decimal is carried out by using monochromatic light; for example, large size K-order proof blocks may differ by more than 10 fringes from etalon size.

The etalon 6 can also meet the requirement of uncertainty when measuring a first-class gauge block by using a contact white light interferometer, and cannot be used for detecting the first-class gauge block by the national metrological department because the etalon does not conform to the international meter definition. But may be used for the verification of other grade gauge blocks. For non-national metrology departments, a quality block within the country may be certified upon passing the national certification permit. And for the gauge block production plant, the factory verification can be carried out on the 0-level and K-level gauge blocks produced by the national verification permission. When an equal-volume block is detected, the main error of the equal-volume block is given to the etalon 6, the measuring block is detected through comparison measurement, the etalon and the measuring block are made of the same material and have no main error, and the main error is counted in the form of the reference error of the etalon, so that the total error is not greatly influenced.