CN114518087A - Device and method for non-contact measurement of thickness and rise in lens - Google Patents

Abstract

The invention relates to a device and a method for non-contact measurement of thickness and rise in lens, the device comprises an xy translation stage (1), a first z translation stage (2,3), a second z translation stage (4), a switching stage (5), an object carrying plate (6) and a displacement meter (7), wherein the displacement meter (7) comprises a first probe (8) and a second probe (9) which are coaxially arranged, the object carrying plate (6) is positioned between the two probes, and the device also comprises a micrometer (10). The invention can simultaneously measure the thickness and the rise of the lens, thereby avoiding the measurement error caused by separate measurement.

Description

Device and method for non-contact measurement of thickness and rise in lens

Technical Field

The invention relates to a device and a method for measuring the thickness and the rise of a lens in a non-contact manner.

Background

In the prior art, the methods for measuring the thickness (i.e. center thickness) and saggital height of a lens are: firstly, flatly placing a lens on a marble base of a dial indicator, contacting the bottom surface of the lens with a marble platform, and using the dial indicator to contact the vertex (visual vertex) of the convex surface of the lens for measurement to obtain the total thickness of the lens; then, the lens is inversely placed on the marble base, the vertex of the upper convex surface of the lens is contacted with the marble platform, and a dial gauge is used for contacting the vertex (visual vertex) of the lower concave surface of the lens for measurement to obtain the medium thickness of the lens; the rise is given by the total thickness minus the median thickness. This method has the following problems or disadvantages: 1. the positions measured twice are visual vertexes, accuracy is lacked, data obtained by measurement of different personnel have large difference, measurement is unstable, and influence of the personnel is large; 2. the contact measurement (the dial gauge contacts the upper and lower vertexes of the lens) and the lens inversion (the upper convex surface contacts the marble table top) have the risk of scratching the surface of the lens; 3. the operation is inconvenient and the efficiency is low.

There are devices on the market using white light confocal principle, such as the measuring device disclosed in patent CN104613881A, which can perform non-contact measurement on the thickness of the lens by using a spectrometer, but the device cannot measure the lens rise simultaneously, and the rise measurement needs to be performed by other devices separately. The way of such separate measurements lacks accuracy.

Disclosure of Invention

The invention aims to provide a device and a method for measuring the thickness and the rise of a lens in a non-contact mode, wherein the device and the method can be used for simultaneously measuring the thickness and the rise of the lens in a non-contact mode.

In order to achieve the purpose, the invention provides a device and a method for non-contact measurement of the thickness and the rise of a lens.

According to one aspect of the invention, the object carrying plate is arranged on the adapting platform, and the adapting platform is arranged on the xy translation stage;

the xy translation stage is arranged on the pitch platform, and the pitch platform is arranged on the second z translation stage;

a first probe is disposed on the first z-translation stage.

According to one aspect of the invention, the displacement meter is a white light confocal displacement meter, wherein each probe head further comprises a respective adjustment module.

According to one aspect of the invention, the device further comprises a centering tool which is arranged on the carrying plate.

According to one aspect of the invention, further comprising a support column to which the first and second z-translation stages, the second probe and the micrometer are affixed.

A method of non-contact measurement of thickness and saggital height in a lens comprising the steps of:

a. placing a standard sheet on the object carrying plate, and carrying out zero calibration on the micrometer, the first probe and the second probe;

b. replacing the standard wafer with a measured lens, moving the object carrying plate to the reading zero position of the second probe, and recording the moving distance y of the object carrying plate;

c. translating the carrier plate until the vertex of the convex surface and the concave surface of the lens are positioned on the axes of the first probe and the second probe, and recording the readings y1 and y2 of the first probe and the second probe;

d. calculating the thickness of the lens by using the thickness d of the standard plate and the readings y1 and y2 of the first probe and the second probe;

e. the lens rise is calculated using the distance y traveled by the carrier plate and the reading y2 from the second probe.

According to one aspect of the invention, in step (a), the carrier plate and the first probe are moved successively to the calibration position, the probe of the micrometer is abutted against the carrier plate, and then the readings of the micrometer and the first and second probes are cleared.

According to one aspect of the invention, the formula for calculating the thickness a of the lens in step (d) is: a ═ d + y1+ y 2;

the formula for calculating the lens rise B in the step (e) is as follows: b ═ y + y 2.

According to one aspect of the invention, the formula for calculating the thickness a of the lens in step (d) is: a-d-y 1-y 2;

the formula for calculating the lens rise B in the step (e) is as follows: b-y 2.

According to the concept of the present invention, a micrometer capable of measuring a moving distance of the carrier plate is provided. So, after changing the standard film for the lens, carry the thing board and move down when seeking the second probe zero point, the micrometer can survey the distance of carrying the thing board. The distance is the height of the lower limit of the lens lower than the calibration zero point, so that the lens vector height can be calculated by matching the distance with the reading of the second probe after the second probe finds the vertex of the concave surface of the lens. Therefore, the sagitta height can be calculated by combining the parameters measured by the additionally arranged micrometer and the parameters required by measuring the thickness of the lens, so that the aim of simultaneously measuring the thickness and the sagitta height is fulfilled, and errors caused by respective measurement are eliminated.

According to one scheme of the invention, the axis of the whole device is inclined or vertical to the vertical direction, so that the lens or the standard plate can be positioned on the object carrying plate by means of self gravity by matching with the design of the centering tool, thereby avoiding measurement errors caused by manual placement and improving the efficiency and the measurement accuracy.

Drawings

FIG. 1 is a schematic representation of a block diagram of an apparatus for non-contact measurement of thickness and rise in a lens according to one embodiment of the present invention;

FIG. 2 schematically illustrates an installation of a centering tool according to an embodiment of the present invention;

FIG. 3 is a schematic representation of a process for calibration using the apparatus of one embodiment of the present invention;

FIG. 4 is a schematic representation of a flow chart for measurements made using the apparatus of one embodiment of the present invention;

fig. 5 is a schematic view showing measurement parameters in measurement by the apparatus according to the embodiment of the present invention.

Detailed Description

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments will be briefly described below. It is obvious that the drawings in the following description are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.

In describing embodiments of the present invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in an orientation or positional relationship that is based on the orientation or positional relationship shown in the associated drawings, which is for convenience and simplicity of description only, and does not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus, the above-described terms should not be construed as limiting the present invention.

The present invention is described in detail below with reference to the drawings and the specific embodiments, which are not repeated herein, but the embodiments of the present invention are not limited to the following embodiments.

Referring to fig. 1, the device for non-contact measurement of the thickness and the rise of the lens comprises an xy translation stage 1, a first z translation stage 2, a second z translation stage 3, a pitching stage 4, a transfer stage 5, a carrying plate 6 and a displacement meter 7. The displacement gauge 7 comprises a first probe 8 and a second probe 9 arranged coaxially with the carrier plate 6 between them, so that the lens to be measured can also be positioned between them. According to the concept of the present invention, a micrometer 10 for measuring the movement parameters of the carrier plate 6 along the axis (i.e. z-axis direction) of the first probe 8 and the second probe 9 is further included. In this embodiment, the parameter is the distance y of the object plate 6, so that the lens vector height can be calculated according to the definition of the lens vector height and the detection result of the second z translation stage 3. The invention can simultaneously measure the thickness and the rise of the lens, thereby improving the accuracy and the efficiency of measurement and the convenience degree of operation.

With continued reference to fig. 1, in the present invention, the displacement meter 7 is a white light confocal displacement meter which can perform the measurement without contacting the lens. As can be seen from the figure, the micrometer 10 measures the distance traveled by the carrier plate 6 by bringing its probe into contact with the carrier plate 6, and therefore, it does not contact the lens. Therefore, the invention realizes non-contact measurement, thereby avoiding scratching the lens. In the device, a switching platform 5 is used for connecting an object carrying plate 6 with an xy translation table 1. Thus, the object plate 6 is fixedly arranged on the relay platform 5, and the relay platform 5 is arranged on the xy translation stage 1. The carrier plate 6 may be a glass plate. The pitching platform 4 is used for adjusting the posture of the carrier plate 6 to be perpendicular to the two probe axes of the displacement meter 7. Specifically, the xy translation stage 1 is provided on the pitch platform 4. And the pitching platform 4 is laterally connected to the second z translation stage 3, which also enables the movement of the second z translation stage 3 to move the carrier plate 6 along the two probe axes. The first probe 8 of the displacement meter 7 is arranged on the first z translation stage 2 so as to be driven in motion along its own axis by the z translation stage. Thus, the above arrangement allows the slide 6 to be adjusted in 5 dimensions X, Y, Z, pitch and roll, to achieve alignment with the two probes and movement during measurement. In order to accurately place the object on the object carrying plate 6, as shown in fig. 2, the present invention further provides a centering tool 14 on the object carrying plate 6, so that the object can be automatically centered after being placed on the object carrying plate 6. The centering tool 14 is a substantially rectangular flat plate, a long side of one side of the centering tool is provided with a positioning notch 14a, and a lens can be clamped in the positioning notch to complete positioning. Based on the use mode of the device, the centering tool 14 not only needs to complete the centering of the lens, but also needs to complete the centering of the standard piece used for calibration. The standard plate and the lens are different in shape, the standard plate is generally rectangular, and the lens is generally circular. Based on this, the positioning notch 14a of the centering tool 14 is rectangular as a whole and is used for positioning the standard sheet; and the outer edges of the two sides of the notch incline towards opposite directions to form inclined planes for positioning the lens.

As shown in fig. 1, the apparatus of the present invention further comprises a support column 11, and the first z translation stage 2, the second z translation stage 3, the second probe 9 and the micrometer 10 are fixed on the support column 11. The support column 11 thus constitutes the main body support structure of the device of the invention. In the invention, the lens is positioned by utilizing the self gravity of the lens, thereby avoiding the measurement error caused by artificial placement. In the present embodiment, the axes of the first probe 8 and the second probe 9 are at an angle (e.g., 15 °) to the vertical direction. In this way, the remaining components, both arranged according to the axes of the two probes, are also globally inclined, so that the lens (or reticle) on the objective plate 6 can be positioned by its own weight. In the present embodiment, the surface of the support column 11 on which the respective components are mounted is made to be an inclined surface, so that the entire structure is naturally inclined after the respective components are mounted thereon. Of course, in other embodiments, the two probe axes may be vertical, and the lens (or the standard plate) may be pushed to a designated position when placed. In addition, the displacement meter 7 further includes a first adjustment module 12 and a second adjustment module 13 for adjusting the attitude and position of the two probes so that the axes of the two probes are aligned. In the invention, the adjusting module can drive the probe to adjust 4 dimensions such as pitching, rolling and xy translation. Due to the arrangement of the adjustment module, the probe itself is not directly connected to the z-translation stage or the support column 11.

Referring to fig. 3, in the method of measuring the thickness and the rise in the lens, which is performed using the apparatus set up as described above, the zero point calibration of the two probes in the displacement meter 7 and the side micrometer 10 is first performed using a master. Specifically, a standard sheet is placed on the object carrying plate 6, then the object carrying plate 6 and the first probe 8 are sequentially moved to the calibration position, so that the probe of the micrometer 10 is abutted on the object carrying plate 6 (the object carrying plate 6 is not arranged and can be abutted on the transfer platform 5), and at this time, the readings of the micrometer 10, the first probe 8 and the second probe 9 are cleared, and zero calibration is completed.

Referring to fig. 4, after the zero point calibration is completed according to the above steps, the standard wafer can be replaced with the measured lens, and the measurement of the lens is started. Since the structure of the lens is different from that of the standard sheet, the standard sheet of the invention is a standard cubic structure, so the bottom surface is a plane, and the bottom of the lens is a concave surface. Therefore, after the lens is replaced, the reading of the lower second probe 9 is not zero, and the carrier plate 6 needs to be vertically moved down to the position where the reading of the second probe 9 is zero. The vertical downward movement referred to above in the present invention is only for the direction shown in fig. 4, and in practice this step would be to move the carrier plate 6 along the axis of both probes towards the second probe 9. Since the probe of the micrometer 10 is always abutted against the carrier plate 6 during the movement of the carrier plate 6, the downward movement of the carrier plate 6 causes the probe of the micrometer to follow the elongation of the carrier plate, and the elongation of the probe is the downward movement distance of the carrier plate 6, and at this time, the movement distance should be recorded. Of course, the micrometer 10 readings do not distinguish between directions, so y is always a scalar (positive).

With continued reference to fig. 4, since the difference in shape between the lens and the standard results in the lens not being centered on the probe axis after being placed on the stage plate 6, the xy translation stage 1 is operated to move the stage plate 6 horizontally in fig. 4 so that the lens convex and concave vertices lie on the axis of both probes. Specifically, since the reading of the probe represents the distance between the object to be measured and the vertex of the convex surface and the vertex of the concave surface of the lens are both the limit of the reading, the objective plate 6 can be moved by the reading of the two probes. This way of visualization has largely eliminated the effect of human visual error. After finding the two vertices of the lens, readings y1 and y2 of the first probe 8 and the second probe 9 at that time may be recorded. Since both probes are the probes of the displacement meter 7, their readings contain the direction, i.e. this direction is also distinguished by sign in subsequent calculations. It is generally considered that movement away from the probe is negative in sign and vice versa (or it is also understood that away from the nominal position is positive, close to the nominal position is negative and the nominal position is 0). When the method is applied to the invention, the two vertexes of the lens at the calibration position are positioned at the inner sides of the upper limit and the lower limit of the standard plate, and the two vertexes are negative, otherwise, the two vertexes are positive.

With reference to fig. 5, the above measurements have obtained all the parameters for calculating the thickness and the rise in the lens, and then corresponding operations can be performed to obtain the two target values. Specifically, calculating the thickness of the lens requires the use of the thickness of the standard plate and the readings from the two probes. The standard piece is a standard piece selected in advance, and thus the thickness d thereof is known. In the invention, the absolute reading value of the two probes is actually the distance between two vertexes of the lens and the reading zero point of the corresponding probe. The distance between the two vertices is the lens thickness, and the reading of the two probes is the difference between the lens thickness and the standard sheet thickness. Therefore, the thickness of the lens is calculated based on the thickness of the standard plate, and the formula for calculating the thickness A is as follows: a ═ d + y1+ y 2. From the above description, if the vertex of the lens is located within the zero point line of the two probes as shown in fig. 5, y1 or y2 should be negative, otherwise positive. It will also be appreciated that the gauge plate should be of a thickness similar to the thickness of the lens so as to avoid interference with the lens under test due to the nominal position of the first probe 8 being too low. From the above analysis, it can be seen that the absolute value of the reading of the second probe 9 is actually the distance between the vertex of the concave surface of the lens and the zero point of the second probe 9. Therefore, the vector height of the lens can be obtained by summing the distance and the downward moving distance of the object carrying plate 6, and the calculation formula of the vector height B of the lens is as follows: b ═ y + y 2. Thus, the lens rise can be obtained by matching the moving distance of the loading plate 6 measured by the micrometer 10 additionally arranged in the device with the reading measured by the second probe 9 when the thickness is measured. Since y1 and y2 both use signs to distinguish directions, the above formula may be changed to a-d-y 1-y2 and B-y 2. Therefore, the invention can be used for simultaneously measuring the thickness and the rise, thereby avoiding the inaccuracy caused by separate measurement.

The above description is only one embodiment of the present invention, and is not intended to limit the present invention, and it is apparent to those skilled in the art that various modifications and variations can be made in the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (9)

1. The device for measuring the thickness and the rise of the lens in a non-contact mode comprises an xy translation table (1), a first z translation table (2,3), a second z translation table (4), a pitching platform (5), a switching platform (5), an object carrying plate (6) and a displacement meter (7), wherein the displacement meter (7) comprises a first probe (8) and a second probe (9) which are coaxially arranged, the object carrying plate (6) is located between the two probes, and the device is characterized by further comprising a micrometer (10).

2. The device according to claim 1, characterized in that the stage plate (6) is arranged on the transfer platform (5), the transfer platform (5) being arranged on the xy translation stage (1);

the xy translation stage (1) is arranged on the pitching platform (4), and the pitching platform (4) is arranged on the second z translation stage (3);

a first probe (8) is arranged on the first z translation stage (2).

3. The device according to claim 1, characterized in that the displacement meter (7) is a white light confocal displacement meter, wherein each probe head further comprises a respective adjustment module.

4. The device according to claim 1, characterized in that it further comprises a centering fixture (14) arranged on the carrier plate (6).

5. The device according to any one of claims 1 to 4, further comprising a support column (11), the first and second z-translation stages (2,3), the second probe (9) and the micrometer (10) being fixed on the support column (11).

6. A method of using the apparatus of any of claims 1-4 for non-contact measurement of thickness and saggital height in a lens, comprising the steps of:

a. a standard sheet is placed on the object carrying plate (6), and zero calibration is carried out on the micrometer (10) and the first and second probes (8 and 9);

b. replacing the standard film with a measured lens, moving the object carrying plate (6) to the reading zero position of the second probe (9), and recording the moving distance y of the object carrying plate (6);

c. translating the carrier plate (6) until the vertex of the convex surface and the concave surface of the lens are positioned on the axes of the first probe and the second probe (8,9), and recording readings y1 and y2 of the first probe and the second probe (8, 9);

d. calculating the thickness of the lens by using the thickness d of the standard sheet and readings y1 and y2 of the first probe and the second probe (8 and 9);

e. the lens rise is calculated using the distance y of movement of the carrier plate (6) and the reading y2 from the second probe (9).

7. Method according to claim 6, characterized in that in step (a) the carrier plate (6) and the first probe (8) are moved successively to a calibration position, the probe of the micrometer (10) is brought against the carrier plate (6), and the readings of the micrometer (10) and the first and second probe (8,9) are subsequently cleared.

8. The method of claim 6, wherein the formula for calculating the thickness A in the lens in step (d) is: a ═ d + y1+ y 2;

the formula for calculating the lens rise B in the step (e) is as follows: b ═ y + y 2.

9. The method of claim 6, wherein the formula for calculating the thickness A in the lens in step (d) is: a-d-y 1-y 2;

the formula for calculating the lens rise B in the step (e) is as follows: b-y 2.

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