CN104970765A - Optical measuring device and method - Google Patents

Abstract

The present invention is an optical measurement device and method, and the optical measurement device includes a light source module, an optical coupling module, a reference lens group and a processing unit. The light source module can provide light. The light of the light source module can be transmitted to the reference lens group and the object to be measured via the optical coupling module. The light will be reflected by the reference lens group and the object to be measured to form a first light and a second light respectively. The first light and the second light are then transmitted to the processing unit via the optical coupling module. The processing unit will provide an adjustment signal based on the first light and the second light. The processing unit transmits the adjustment signal to the reference lens group, and the reference lens group adjusts the reference lens group based on the adjustment signal. The present invention adjusts the optical properties of the reference lens group through the interference result of the first light and the second light, thereby improving the overall measurement accuracy and overcoming the disadvantage that the measurement of different curved surfaces and multi-layer curved surfaces requires the pre-matching of a reference lens group with a suitable curvature range.

Description

Optical measuring device and method

technical field

The invention relates to an optical measurement device and method.

Background technique

Due to the advantages of non-invasive and fast response, optical measurement technology is often used in non-contact detection. For example, it can be applied to physiological detection, and the physiological detection effect is especially good when it is applied to high light transmission and vulnerable eyes.

Please refer to FIG. 1 , which is a schematic diagram of a known optical measurement device. The optical measurement device 1 in FIG. 1 at least includes a light source module 10 , a reference mirror group 12 , an optical coupling module 14 and a processing unit 16 .

The light source provided by the light source module 10 is transmitted to the reference mirror group 12 and the processing unit 16 respectively through the coupling module 14, and these light rays are respectively reflected by the reference mirror group 12 and the processing unit 16 to form the reference light R1 and the detection light D1, and then follow the The original optical path returns to the processing unit 16, and finally the surface curvature of the object O to be tested can be measured according to the interference result. Moreover, the user can cause interference between the reference light R1 and the detection light D1 by moving the position of the reference mirror group 12 .

However, the disadvantage of this optical measurement device is that it is necessary to know whether the curvature of the surface of the object to be measured is concave, convex or flat during measurement, and in order to obtain more accurate measurement results, it is necessary to refer to the curvature selected by the mirror group 12. The distance from the object to be measured should not be too large (choosing the wrong mirror will lead to an increase in the error of the measurement result). Moreover, even if the approximate curvature of the object to be measured is known, the curvature of the matching reference lens group 12 will also affect its measurement result. In other words, the optical measuring device 1 cannot meet the conditions of measuring irregular curved surfaces, multi-layer objects under test, precise measurement, and the like.

Therefore, how to provide an optical measuring device that can measure and improve detection accuracy, and can continuously measure and measure multilayer objects to be measured on irregular surfaces to be measured is one of the problems to be solved in this field.

Contents of the invention

In view of the above problems, the purpose of the present invention is to provide an optical measurement device, including a light source module, an optical coupling module, a reference mirror group and a processing unit.

The light source module can provide light. The light from the light source module can be transmitted to the reference mirror group and the object to be measured through the optical coupling module. The light rays will be reflected by the reference lens group and the object to be measured to respectively form the first light rays and the second light rays. The first light and the second light are transmitted to the processing unit through the optical coupling module. The processing unit provides adjustment signals according to the first light and the second light. The processing unit transmits the adjustment signal to the reference mirror group, and the reference mirror group adjusts the reference mirror group according to the adjustment signal.

In an embodiment of the present invention, the reference mirror group includes an actuator and a mirror, and the actuator adjusts the curvature of the mirror according to the adjustment signal.

In an embodiment of the present invention, the reference mirror group includes an optical path adjustment unit and a plurality of reference mirrors, and the optical path adjustment unit matches the second light with one of the reference mirrors according to the adjustment signal.

In one embodiment of the invention, the curvatures of the individual reference mirrors are different.

In one embodiment of the present invention, the reference lens group is an electrowetting type curvature lens or a dielectrophoretic type curvature lens.

In one embodiment of the present invention, the object to be tested is a spherical body with multiple curved surfaces.

In one embodiment of the invention, the spheroid is an eyeball.

The present invention also provides a method for optical measurement, the steps of which further include: providing a light to the reference lens group, and providing another light to the object to be measured. The light is reflected by the reference lens group to form the first light, and the other light is reflected by the object to be measured to form the second light.

The first light interferes with the second light. It is judged whether the interference meets the predetermined interference range, if not, an adjustment signal is generated according to the interference, and the reference mirror group adjusts the reference mirror group according to the adjustment signal.

In an embodiment of the present invention, the reference mirror group adjusts the curvature of the reference mirror group according to the adjustment signal.

In an embodiment of the present invention, the reference mirror group includes an actuator and a reflector, and the step further includes: the actuator adjusts the curvature of the reflector according to the adjustment signal.

In one embodiment of the present invention, the reference mirror group includes an optical path adjustment unit and a plurality of reference mirrors, and the curvature of each reference mirror is different, and the step further includes: the optical path adjustment unit matches the second light with one of the reference mirrors according to the adjustment signal .

In one embodiment of the present invention, the step further includes forming an image of the surface of the object under test based on interference.

In one embodiment of the present invention, the object to be measured has a plurality of curved surfaces, and the step further includes: repeating the measuring method to measure these curved surfaces.

In an embodiment of the present invention, the step further includes: superimposing these curved surfaces to form a stereoscopic image.

In summary, the present invention adjusts the optical characteristics of the reference lens group through the interference result of the first light and the second light, thereby improving the accuracy of the overall measurement, and overcoming the need to pre-match suitable curvatures for measuring different curved surfaces and multi-layer curved surfaces Disadvantages of scope reference optics.

Description of drawings

FIG. 1 is a schematic diagram of a known optical measuring device.

FIG. 2A is a schematic diagram of a first embodiment of the optical measuring device of the present invention.

FIG. 2B is an enlarged schematic view of the reference lens group in FIG. 2A .

FIG. 2C is another enlarged schematic diagram of the reference lens group in FIG. 2A .

Fig. 3 is a flowchart of the steps of the optical measuring device of the present invention.

FIG. 4A is a schematic perspective view of a second embodiment of the reference lens group of the optical measurement device of the present invention.

4B and 4C are schematic cross-sectional views along AA and BB in FIG. 4A .

FIG. 4D is a schematic diagram of the operation of the reference lens group in FIG. 4A .

FIG. 5 is a schematic perspective view of a third embodiment of the reference lens group of the optical measurement device of the present invention.

FIG. 6 is a schematic perspective view of a fourth embodiment of the reference lens group of the optical measurement device of the present invention.

FIG. 7A is a schematic perspective view of a fifth embodiment of the reference lens group of the optical measurement device of the present invention.

FIG. 7B is another schematic diagram of FIG. 7A .

FIG. 7C is another schematic diagram of FIG. 7A .

FIG. 8A is a schematic perspective view of the sixth embodiment of the reference lens group of the optical measurement device of the present invention.

FIG. 8B is another schematic diagram of FIG. 8A .

FIG. 8C is another schematic diagram of FIG. 8A .

FIG. 9A is a schematic perspective view of a seventh embodiment of the reference lens group of the optical measuring device of the present invention.

FIG. 9B is another schematic diagram of FIG. 9A .

FIG. 9C is another schematic diagram of FIG. 9A .

[Symbol Description]

1, 2: Optical measuring device

10, 20: Light source module

12, 22, 32, 52, 62, 72, 82, 92: reference lens group

221: Actuator

222, 421, 721, 821, 921: mirrors

14, 24: Optical coupling module

16, 26: processing unit

32a, 32b, 32c, 32d, 521: reference mirrors

322: Optical path adjustment unit

522: fiber optic array

72a, 72b, 72c: electrowetting type curvature lens

822, 922, 923: fluid chamber

AA, BB: Secant

R1: reference light

D1: Detection light

O, O1: the object to be tested

S1～S4: method steps

C: electrode plate

Detailed ways

An optical measurement device and method according to preferred embodiments of the present invention will be described below with reference to the relevant drawings, wherein the same components and steps will be described with the same reference symbols. Moreover, in the following embodiments and drawings, elements and steps not directly related to the present invention have been omitted and not shown; and the dimensional relationship among the elements in the drawings is only for easy understanding, and is not used to limit the actual scale.

An optical measuring device and method of a preferred embodiment of the present invention will be sequentially described below.

First of all, please refer to FIG. 2A, FIG. 2B, FIG. 2C and FIG. 3. FIG. 2A is a schematic diagram of the first embodiment of the optical measurement device of the present invention, and FIG. 2B and FIG. 2C are respectively enlarged schematic diagrams of the reference mirror group in FIG. FIG. 3 is a flow chart of the steps of the optical measurement device of the present invention.

The optical measuring device 2 of this embodiment may at least include a light source module 20 , an optical coupling module 24 , a reference mirror group 22 and a processing unit 26 .

The light source module 20 can provide light. And if it is applied to the measurement of the cornea and retina of the human eye, the light source module 20 can be a broadband laser light source in order to take into account the comfort of the person being measured. For example, if it is applied to the retina, the wavelength can be adjusted to about 840nm, if it is applied to the cornea, it can be adjusted to 1060nm or 1310nm, if it is applied to the skin, it can be adjusted to about 1310nm, and the bandwidth of the light source module is about 20nm to 40nm. In other words, the actual wavelength and bandwidth will be adjusted according to different application objects.

The optical coupling module 24 can transmit and converge the light from the light source module 20 to the reference mirror group 22 and the object O1 respectively. The optical coupling module 24 of this embodiment can be an optical splitter, but is not limited to an optical splitter. For example, 50% of the light from the light source module 20 can be reflected into the reference lens group 22 , while the remaining 50% of the light can penetrate into the object under test O1 to achieve the effect of optical coupling. In addition, the object to be tested O1 in this embodiment is a spherical body, and the eyeball is used as an example, but not limited to the eyeball.

The reference mirror group 22 in this embodiment may include an actuator 221 (micro-actuator) and a reflector 222 , the reflector 222 is made of a flexible material and attached to the actuator 221 . The actuator 221 can adjust the curvature of the mirror 221 according to the adjustment signal provided by the processing unit 26 , for example, it can be adjusted to be convex ( FIG. 2B ), concave ( FIG. 2C ) or flat ( FIG. 2A ). Specifically, the degree of deformation of the actuator 221 can be adjusted according to different adjustment signals, thereby changing the curvature of the mirror 222 to obtain better measurement results. The detailed way of generating the adjustment signal will be described below.

In addition, the reference mirror group 22 of this embodiment can be moved back and forth (for example, it can be moved by a transmission platform), so as to obtain better interference results.

In practical application, firstly, the light source module 20 can provide one light to the reference lens group 22 and another light to the object under test (step S1 ). According to the architecture of this embodiment, the light from the light source module 20 can be transmitted to the reference mirror group 22 and the object O1 through the optical coupling module 24 .

Next, the light is reflected by the reference lens group 22 to form the first light, and the light will be reflected by the object O1 to form the second light. (step S2). In short, the light transmitted to the reference lens group 22 and the surface of the object O1 to be measured is all reflected. At this time, the reflected first light and the second light are transmitted to the processing unit 26 through the optical coupling module 24 .

The first ray interferes with the second ray (step S3). At this time, the processing unit 26 may record the relative optical path length (optical path difference, OPD) of the first light and the second light at this time, as a basis for subsequent judgment. In detail, the processing unit 26 can include a storage unit, which can store the interference results corresponding to different optical path lengths, that is, it can be judged by looking up the table. If not, an adjustment signal is generated according to the interference, and the reference mirror group 22 adjusts the reference mirror group according to the adjustment signal. (step S4).

Taking the framework of this embodiment as an example, the processing unit 26 will search for the corresponding correction method according to the interference result of the first light and the second light (there will be a database in the processing unit 26 that can correspond to the adjustment method for the search interference result, such as increasing or decreasing curvature) to provide an adjustment signal. Then, the processing unit 26 will transmit the adjustment signal to the reference mirror group 22, and the reference mirror group 22 will adjust the reference mirror group 22 according to the adjustment signal (that is, the actuator 221 will deform the mirror 222 to change the curvature of the mirror. ).

For example, the preset curvature of the reference mirror group 22 is 0 (that is, it is preset as a plane) for the first measurement, and then the curvature of the reference mirror group 22 is adjusted to be convex and concave, and then for the concave and convex surfaces respectively Take measurements. At this time, the processing unit 26 will compare these measurement results, and adjust the reference lens group 22 to a curvature closer to that of the object to be measured, so as to obtain more accurate measurement results.

Or, when the curvature range of the surface of the object to be measured is roughly known (for example, the age of the measurer is known and the cornea is to be measured), at this time, the pre-measurement processing unit 26 can search the corneal curvature of the age according to the database. The average value is set as the curvature of the reference lens group 22 during the first measurement, and the curvature is used as the basis for subsequent adjustments. It is also possible to first adjust the reference mirror to a convex surface (the cornea is a convex surface), then gradually reduce the curvature of the convex surface, and measure the interference between the reflected second light and the first light. If the interference is poor, the processing unit will send the adjustment The signal stops decreasing the convexity curvature and increases the convexity curvature until the optimum value is measured.

In short, the interference result of the adjusted first light and the second light will be more accurate, and the surface curvature of the object O1 to be tested can be measured. It should be added that the above correction method is to adjust the surface curvature of the reference lens group 22 to a similar curvature or a similar curvature range to the surface of the object O1 to be measured. Moreover, it can be repeatedly measured and adjusted to the required accuracy according to different requirements.

In addition, the optical measurement device 2 of this embodiment may further include an image analysis unit (not shown in the figure), which may be used to analyze and construct a plane or stereoscopic image of the object to be measured. And specifically, the image analysis unit can be a CCD camera or a CMOS camera.

As before, the steps in this embodiment further include: forming an image of the surface to be measured of the object to be measured according to the interference. Through calculation, the relative optical path lengths measured at multiple points and regions on the object to be measured are plotted to construct an image (plane image) of the surface of the object to be measured O1. The drawing method may be a calculation method of interferometric surface profiling, but is not limited thereto.

In addition, if the object to be measured is an irregularly curved surface, the surface of the object to be measured can be divided into multiple areas (divided into multiple ring-shaped areas or checkerboard-shaped areas), and the above-mentioned adjustments and measurements can be carried out for each area. After the operation, an image of the surface of the object to be measured is formed.

Alternatively, if the object to be tested has multiple curved surfaces and a multi-layer structure, after adjusting and measuring each curved surface, the curved surfaces with different depths can be superimposed to form a three-dimensional pattern.

Or, if it is applied to eyeball measurement, the present embodiment can measure the structures of cornea, corneal thickness, and retina, etc., without having to use different reference mirrors (also known as optical measuring instruments) for cornea and retina. That is to use more than two measuring instruments), and can directly form a stereoscopic image of the eyeball. In other words, the optical measuring device of this embodiment can at least have the following advantages: saving cost (no need to match different optical measuring devices for different curvatures), saving time (saving the time for changing instruments), achieving more accurate measurement results (refer to The mirror has an adjustable function, which can be closer to the surface curvature of the actual object to be measured).

In short, through the interference result of the first ray and the second ray, it can be judged whether the curvature of the reference mirror group matches with the reference mirror, and the curvature of the reference mirror is adjusted by adjusting the signal so that it is in line with the curved surface or local curved surface of the object to be measured. Matching, thereby improving the accuracy of the overall measurement, and overcoming the shortcomings of measuring different curved surfaces and multi-layer surfaces that must be pre-matched with a reference lens group with a suitable curvature range.

Next, please refer to FIG. 4A to FIG. 4D together. FIG. 4A is a schematic perspective view of a second embodiment of the reference lens group of the optical measurement device of the present invention. 4B and 4C are schematic cross-sectional views along AA and BB in FIG. 4A . FIG. 4D is a schematic diagram of the operation of the reference lens group in FIG. 4A .

This embodiment illustrates another possible reference mirror group 32, the reference mirror group may include an optical path adjustment unit 322, a plurality of reference mirrors 32a, 32b, 32c, 32d, and the optical path adjustment unit 322 may adjust the second The light is matched with one of the reference mirrors, that is, the incident angle of the light is changed according to the adjustment signal to enter different reference mirrors. And the curvature of each reference mirror 32a, 32b, 32c, 32d is different, and although this embodiment exemplifies that these reference mirrors 32a, 32b, 32c, 32d are arranged in the form of a 2×2 matrix, it is not necessary to arrange in this way. Restricted to a single component. In addition, the number of reference mirrors is only indicative and can be increased or decreased according to different requirements.

The optical path adjustment unit 322 of this embodiment may include a plurality of reflectors, each of which may be equipped with a driving device (not shown in the figure), and adjust the deflection angle of the corresponding reflector surface according to different adjustment signals, so that the light is incident on the mirrors with different curvatures. Reference mirror (Figure 4D) to improve overall measurement accuracy. For example, if the measured curvature of the surface of the object to be measured is relatively close to the reference mirror 32b, the processing unit will send an adjustment signal to deflect the reflector corresponding to the reference mirror 32b, so that the second light is incident on the reference mirror 32b, In other words, the reference mirror 32b will serve as a reference mirror for measuring the object under test.

The collocation relationship of the other components, the reference lens group and other components is similar to that of the foregoing embodiments, so it will not be described again.

Please refer to FIG. 5 , which is a three-dimensional schematic diagram of a third embodiment of the reference lens group of the optical measurement device of the present invention.

The difference from the aforementioned reference mirror group 32 in FIG. 4A is that the reference mirror group 52 of this embodiment is composed of an optical fiber array 522 and a reference mirror 521. Each optical fiber will correspond to a reference mirror, and these reference mirrors can also be have different curvatures. In actual operation, one of the optical fibers will be turned on and the light will be transmitted to the corresponding reference mirror 521, and then the processing unit will judge whether to adjust and open different optical fibers (change transmission path) to correspond to different mirrors to improve the accuracy of the overall measurement.

The collocation relationship of the other components, the reference lens group and other components is similar to that of the foregoing embodiments, so it will not be described again.

FIG. 6 is a schematic perspective view of a fourth embodiment of the reference lens group of the optical measurement device of the present invention.

The difference from the foregoing embodiments is that the reference mirror group 62 of this embodiment is composed of multiple digital control micro-mirrors. The advantage of using multiple digital control micro-mirrors is that each mirror can be adjusted independently (horizontal position, angle adjustment, etc.) etc.), so finer adjustments can be achieved to conform to the measurement results of irregular surfaces.

If it is combined with the measurement of irregular curved surfaces, the surface of the object to be measured can be divided into several sub-areas, and the digital control micro-mirror corresponding to each sub-area, that is, each sub-area will carry out at least one adjustment and measurement steps to measure to better curvature.

7A to 7C are three-dimensional schematic diagrams of a fifth embodiment of the reference lens group of the optical measurement device of the present invention.

The difference from the foregoing embodiments is that the reference mirror group 72 of this embodiment is composed of an electrowetting type curvature lens and a reflector 721, and a mirror treatment can also be performed on the electrode plate C provided with the electrowetting type curvature lens , so that it can provide an effect similar to that of a mirror, or achieve the purpose of reflection by selecting different liquids. The electrowetting curvature lens uses liquid as a zoom lens, which has the advantages of high performance, low cost, small size, and low power consumption. The principle is to use a conductive aqueous solution and a non-conductive oil to change the contact area between the aqueous solution and the oil through the passing of an electric current. Therefore, the expansion of the contact area will increase the curvature, causing the focus to move as if it were focusing, and produce a change in optical power.

In detail, the electrowetting type curvature lens may include two conductive layers separated by an insulating layer, and the conductive layer is a transparent conductive material such as indium tin oxide (ITO). The accommodating space formed by the insulating layer and the two conductive layers can be filled with liquid. The liquid in this embodiment can be mercury, which can form a metal reflective surface, and different liquids will produce different effects. A voltage is applied to the conductive layer, so that the tortuosity of the fluid changes due to the difference in conductivity and insulation, so that the focal length of the lens changes. In short, the adjustment signal can change the curvature of the adjustable curvature lens through the application of voltage or not.

In addition, this embodiment can be composed of multiple electro-wetting curvature lenses 72a, 72b, 72c, and the configurations of each electro-wetting curvature lenses 72a, 72b, 72c can be the same or different. When the curvature needs to be adjusted, the external voltage can be controlled by the adjustment signal The curvature of the specific electrowetting fluid surface is caused to change.

In addition, these electrowetting type curvature lenses 72a, 72b, 72c can also move according to the adjustment signal to receive light and generate second light (the arrow in FIG. 7B is the moving direction).

In short, in this embodiment, in addition to adjusting the curvature change of the reflector by configuring different electro-wetting curvature lenses, it can simulate the same or similar reflection characteristics of the object to be measured and achieve better measurement results. On the other hand, the adjustable curvature lens can also be a dielectrophoretic curvature lens. Dielectrophoresis uses the electric coupling induced by the external electric field to interact with the external electric field to drive the particles. Therefore, the particles themselves do not need to be charged, and the dielectrophoretic force is driven by AC voltage.

8A to 8C are three-dimensional schematic views of the sixth embodiment of the reference lens group of the optical measurement device of the present invention.

The difference from the foregoing embodiments is that the reference mirror group 82 of this embodiment is composed of a flexible reflector 821 and a fluid cavity 822, and the curvature of the reflector 821 of this embodiment will pass through the fluid cavity 822. Depending on the amount of gas or liquid. For example, when filled with more fluid, the mirror 821 will appear convex (FIG. 8B). When the fluid is expelled according to the adjustment signal, a concave surface will appear (Figure 8C). Therefore, the processing unit can adjust the curvature of the reference mirror group 82 accordingly.

The collocation relationship of the other components, the reference lens group and other components is similar to that of the foregoing embodiments, so it will not be described again.

9A to 9C are schematic perspective views of a seventh embodiment of the reference lens group of the optical measurement device of the present invention.

The difference from the sixth embodiment is that the reference mirror group 92 of this embodiment is composed of a flexible reflector 921 and two fluid cavities 922, 923. Similarly, the reflector 921 of this embodiment The curvature will be changed by the amount of gas or liquid in the fluid chambers 922,923. The curvature of the reflector 921 is regulated by the two fluid chambers 922 and 923 , and this combination can achieve a wider curvature variation range than that of the sixth embodiment. It should be noted that the type of fluid filled in the upper fluid cavity 922 will affect the route of the second light reflection, so it is better to set the upper fluid cavity 922 with gas.

The collocation relationship of the other components, the reference lens group and other components is similar to that of the foregoing embodiments, so it will not be described again.

In summary, the present invention adjusts the optical characteristics of the reference lens group through the interference result of the first light and the second light, thereby improving the accuracy of the overall measurement, and overcoming the need to pre-match suitable curvatures for measuring different curved surfaces and multi-layer curved surfaces Disadvantages of scope reference optics.

The above description is for illustration only, not for limitation. Any equivalent modification or change without departing from the spirit and scope of the present invention shall be included in the claims.

Claims (14)

1. An optical measuring device comprising: The light source module provides light; Optical coupling module; reference optics; and processing unit; Wherein, the light from the light source module is transmitted to the reference mirror group and the object to be measured through the optical coupling module, and the light is reflected by the reference mirror group and the object to be measured to form a first light and a second light respectively. A light and the second light are transmitted to the processing unit through the optical coupling module, Wherein, the processing unit generates and provides an adjustment signal according to the first light and the second light, and the processing unit transmits the adjustment signal to the reference mirror group, and the reference mirror group adjusts the reference mirror group according to the adjustment signal. 2. The measuring device as claimed in claim 1, wherein the reference mirror group comprises an actuator and a mirror, and the actuator adjusts the curvature of the mirror according to the adjustment signal. 3. The measuring device according to claim 1, wherein the reference mirror group comprises an optical path adjustment unit and a plurality of reference mirrors, and the optical path adjustment unit matches the second light with one of the reference mirrors according to the adjustment signal. 4. The measuring device according to claim 3, wherein the curvature of each of said reference mirrors is different. 5. The measuring device according to claim 1, wherein the reference lens group is an electrowetting type curvature lens or a dielectrophoretic type curvature lens. 6. The measuring device as claimed in claim 1, wherein the object to be measured is a spherical body having a plurality of curved surfaces. 7. The measuring device of claim 6, wherein the spheroid is an eyeball. 8. A method for optical measurement, the steps further comprising: Provide one light to the reference lens group and another light to the object under test; The light is reflected by the reference mirror group to form a first light, and the another light is reflected by the object to be measured to form a second light; the first ray interferes with the second ray; It is judged whether the interference conforms to the predetermined interference range, if not, an adjustment signal is generated according to the interference, and the reference mirror group adjusts the reference mirror group according to the adjustment signal. 9. The optical measurement method as claimed in claim 8, wherein the reference mirror group adjusts the curvature of the reference mirror group according to the adjustment signal. 10. The method for optical measurement as claimed in claim 9, wherein the reference mirror group includes an actuator and a mirror, and the steps further include: The actuator adjusts the curvature of the mirror according to the adjustment signal. 11. The method for optical measurement as claimed in claim 9, wherein the reference mirror group comprises an optical path adjustment unit, a plurality of reference mirrors, and the curvature of each of the reference mirrors is different, and the steps also include: The optical path adjustment unit matches the second light with one of the reference mirrors according to the adjustment signal. 12. The method for optical measurement as claimed in claim 9, wherein the steps further comprise: According to the interference, an image of the surface of the object under test is formed. 13. The method for optical measurement as claimed in claim 12, wherein the object to be measured has a plurality of curved surfaces, and the steps further comprise: This measurement method is repeated to measure the curved surface. 14. The optical measurement method according to claim 13, wherein the step further comprises: superimposing the curved surfaces to form a stereoscopic image.