JP2008275492A - Autocollimator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect and measure tilt between a first measuring surface and second measuring surface which are measuring surfaces of a subject installed in an optical system. <P>SOLUTION: Luminous flux from a laser light source 1 is travelled to the two subjects 4, 7 through a collimator lens 3. Reflected light reflected on the first measuring surface 5 of the subject 4 and the second measuring surface 8 of the other subject 7 is returned to an outward path, and is projected to a light receiving part 6 such as a CCD from a beam splitter 2 as a spotlight. A distances x of the two projected spotlight from an outer circumference part to another outer circumference part changes depending on an inclination angle between the measuring surfaces 5, 8 of the subject. The distance between the outer circumference parts of the spotlight projected on the light receiving part 6 and a diameter y of the spotlight are detected to obtain a ratio y/x. The value is displayed on a display part as the tilt of the measuring surfaces 5, 8 of the subject. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to an autocollimator, and in particular, can measure the inclination between two measurement surfaces of a subject installed in an optical system with high accuracy.

In various fields, various materials such as metal, glass, and plastic are used as an object, and the inclination between two measurement surfaces facing each other is measured.
An autocollimator is known as a device for measuring the inclination between measurement surfaces facing each other of a subject. The autocollimator will be briefly described with reference to the explanatory diagram of FIG. In FIG. A, a transparent glass plate 50 as an object has a front surface 51 used as a first measurement surface and a back surface 52 used as a second measurement surface. An inclination of an angle θ is generated between the two measurement surfaces 51 and 52, and the light source 53 of light having a wavelength of green (λ = 0.54 μm) is irradiated from the upper surface of such a glass plate 50, for example. Then, the light passes through the lens 54, the screen 55 with a cross line, the beam splitter 56, and the collimator lens 57 to become a parallel light beam and travels toward the glass plate 50. Therefore, the cross line 58 of the screen 55 is reflected by the first measurement surface 51 and the second measurement surface 52, returns to the collimator lens 57 as the first cross line 59 and the second cross line 60, and is reflected by the beam splitter 56. It is projected on the light receiving surface 61 as shown in FIG. The image of the cross line 58 projected on the light receiving surface 61 is projected at different positions according to the inclination θ between the first measurement surface 51 and the second measurement surface 52.
FIG. B shows this state, in which the first cross line 59 and the second cross line 60 are projected onto the light receiving surface 61 with a difference of the dimension w1. That is, the cross line 58 is projected onto the light receiving surface 61 with a difference of w1 due to the inclination θ of the two measurement surfaces 51 and 52 facing each other of the glass plate 50. When the inclination θ increases, the value of w1 also increases. Conversely, when the two cross lines 59 and 60 overlap and w1 = 0, the inclination θ also becomes 0 and the first measurement surface 51 and the second measurement surface 52 It is determined that there is no inclination in the parallel state. Accordingly, if the value of w1 is measured, the inclination angle θ can be estimated with a certain degree of accuracy. If w1 is visually recognized, the value of the inclination angle θ can be estimated empirically.

However, when the inclination angle θ is small and the cross lines 59 and 60 approach each other and are projected onto the light receiving surface 61, the two cross lines 59 and 60 are displayed so as to partially overlap each other as shown in FIG. It is difficult to determine the difference w2 (w1> w2). In particular, when the value of w2 is smaller than the Rayleigh limit that is the decomposition limit between two points, it is considerably difficult to determine the cross lines 59 and 60. Thus, since the detection becomes more difficult as the value of w2 approaches 0, the range that is generated as an error is not constant, and individual differences also occur. Therefore, when the value of θ is large, the inclination can be measured with a certain degree of accuracy. However, when the value of θ is small and the difference w2 between the two cross lines is small, the measurement accuracy is rough. Thus, when trying to measure the inclination of two opposing measurement surfaces with the conventional autocollimator, the measurement accuracy tends to become ambiguous as the inclination between the two approaches 0, and a small value of θ can be obtained. In the case of the necessary measurements, it was fatal. Also, it was possible to empirically estimate how much the value of w2 is the inclination angle θ with respect to 0 or how much the inclination angle θ due to w1 shown in FIG. B is. However, it cannot be understood as a digital number.
Patent Document 1 is known as an autocollimator for measuring the inclination of an object to be measured. According to this document 1, it is described that a microscope is used so that the measurement site of the object to be measured can be enlarged and confirmed. However, if the measurement site is to be confirmed using a microscope, the measurement site is often in a very fine region, so that confirmation is often difficult. Therefore, in this patent document 1, parallel light is irradiated to the object to be measured, a microscope that can be taken in and out of the parallel light beam is installed, and after positioning with the microscope, the inclination of the object to be measured is measured. However, this document 1 discloses an optical system that can position the microscope, but does not disclose any means for improving accuracy when measuring the tilt of the object to be measured. No mention is made of a specific method that enables measurement of a fine tilt while maintaining accuracy.
JP 2003-148939 A

Accordingly, an object of the present invention is to solve the above-described problem and to obtain a high-precision autocollimator that can perform measurement while maintaining measurement accuracy even when the inclination between the object measurement surfaces is close to zero. It is. Then, even when the inclination of the subject becomes large, it is possible to perform measurement while maintaining the measurement accuracy in the same manner. Further, the measurement result can be understood as a digital numerical value regardless of the inclination angle θ.
Therefore, in the present invention, (a) the two reflected light spots projected on the light receiving unit are used to detect the inclination with high accuracy. (B) The measurement conditions such as the wavelength (λ) of the light source used, the aperture of the reflected light from the object measurement surface incident on the collimator lens, the brightness of the collimator lens, and the surface processing accuracy of the object measurement surface vary. Be able to deal with it if any. (C) The accuracy of the inclination angle to be measured can be checked as needed so that the accuracy can be maintained. By doing so, the function as an autocollimator is enhanced so that versatility and operability can be improved.

In order to solve the above problems, the present invention directs a light beam from a laser light source to a subject via a collimator lens and spots reflected light from the first measurement surface and the second measurement surface on the light receiving unit via the collimator lens. And the ratio y / x of the spot outer periphery distance x to the spot diameter y due to the both reflected lights projected onto the light receiving section with this optical system, and the tilt angle between the two measurement surfaces is calculated. And a control unit configured to display on the display unit.
According to the invention of claim 2, the light beam from the laser light source is directed to the subject via the collimator lens, and the reflected light from the first measurement surface and the second measurement surface is spotted on the light receiving unit via the collimator lens. A value corresponding to the ratio y / x of the distance x between the outer peripheral portions of the spots and the spot diameter y due to both reflected lights projected onto the light receiving unit by this optical system is the inclination angle θ between the two measurement surfaces. When both reflected light from the memory stored in advance and the reflected light from the subject are projected as a spot on the light receiving unit, the value corresponding to y / x is retrieved from the memory, and the inclination between the two measurement surfaces is retrieved. And a control unit configured to display the angle θ on the display unit.
According to a third aspect of the present invention, in the autocollimator according to the second aspect, a value corresponding to the ratio y / x of the distance x between the spot outer peripheries and the spot diameter y is set to a reflected light aperture from the subject measurement surface or a collimator. The memory is stored for each brightness of the lens.
According to a fourth aspect of the present invention, in the autocollimator according to the second aspect, the inclination interval d between the first measurement surface and the second measurement surface is sequentially changed by the drive unit, and the first and second measurement surfaces for each interval d. Two reference bodies in which reflected light from the light is obtained are installed in the optical system, and between the outer peripheries of both spots projected on the light receiving part for each of the set intervals d1, d2,. A distance x and a spot diameter y are calculated, and a ratio y / x is stored in advance as inclination angles θ1, θ2,... Θn for intervals d1, d2,.
According to a fifth aspect of the present invention, in the autocollimator according to the fourth aspect of the present invention, the reference body is constructed and arranged in a wedge shape in cross section.
According to the sixth aspect of the present invention, the light beam from the laser light source is reflected by the first beam splitter through the projection collimator lens, and the light beam is further divided into two by the second beam splitter. An optical system that irradiates the same surface of the reference body as the measurement optical system, returns both reflected lights to the outward path, and projects them as spots onto the light receiving section from the first beam splitter through the light receiving collimator lens, A measurement mirror that is installed in the second measurement optical system and that sequentially changes the reflection surface angle r to irradiate the reference body with measurement light for each reflection surface angle, and a reflection angle set by the measurement mirror A reflected light spot projected on the light receiving unit and a reflected light spot by the first measuring optical system are projected on the light receiving unit for each of r0, r1,. A ratio y / x of the diameter y is obtained and the value is stored in advance as inclination angles θ0, θ1,... Θn corresponding to the respective reflection angles r0, r1,. When the reflected light from the first speed bottom surface and the second speed bottom surface of the subject to be installed is projected as a spot on the light receiving unit, the memory is searched with the y / x value, and it is calculated between the two measurement surfaces. And a control unit configured to display the tilt angle θ on the display unit.

In the present invention, a light beam from a laser light source is directed to a subject via a collimator lens, and reflected light from the first measurement surface and the second measurement surface is projected as a spot on a light receiving unit via a collimator lens. It is based on the fact that the ratio y / x of the distance x between the outer peripheral portions of the spots due to the reflected light and the spot diameter y is calculated and displayed as the inclination angle between the two measurement surfaces. As a result, only by detecting a spot due to the reflected light from the two measurement surfaces on the light receiving unit, the measurement operation proceeds under the same conditions while maintaining the measurement accuracy even if there is an inclination angle between the two measurement surfaces. I can do it. Since the measurement result can be displayed as a numerical value regardless of the inclination angle, the evaluation work can be made constant.
Even if there are fluctuations in the measurement conditions such as the wavelength (λ) of the light source used and the brightness of the collimator lens, a predetermined corresponding inclination can be obtained by preparing a data group that assumes these fluctuation factors in advance. You can find the corner. Furthermore, since the accuracy of the inclination angle to be measured can be checked in accordance with the environment where the autocollimator is installed, the measurement accuracy can be maintained. By these, the function as an autocollimator can be improved and versatility and operativity can be improved.

As described above, according to the present invention, the light beam from the laser light source is directed to the subject via the collimator lens, and the reflected light from the first measurement surface and the second measurement surface is projected as a spot on the light receiving portion via the collimator lens. Then, the ratio y / x of the distance x between the outer peripheral portions of the spots and the spot diameter y by the projected both reflected lights is calculated and displayed as an inclination angle. Hereinafter, an autocollimator according to the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a schematic diagram for explanation showing the overall configuration of the autocollimator according to the first embodiment. In the figure, the light beam b from the laser light source 1 travels to the collimator lens 3 through the beam splitter 2. The light beam b that has passed through the collimator lens 3 becomes a parallel light beam, irradiates the first subject 4 such as a glass plate, and is reflected by the first measurement surface 5 on the back surface thereof. The light beam b reflected by the first measurement surface 5 has a diameter of φ and returns in the forward direction, enters the collimator lens 3, is reflected by the beam splitter 2, and is condensed as a spot on the light receiving unit 6 such as a CCD. In the figure, this condensed spot position is indicated as p1. The light that has passed through the first subject 4 is directed to the second subject 7 that is placed facing the subject 4 and reflected by the second measurement surface 8 on the surface thereof. If the second measurement surface 8 is inclined at an arbitrary angle θ with respect to the first measurement surface 5, the light reflected by the second measurement surface 8 returns to the collimator lens 3 with an inclination of 2θ, and the beam splitter 2 The light is reflected and condensed as a spot on the light receiving unit 6. In the figure, the position of the condensed spot is indicated as p2.
Both subjects 4 and 7 are accommodated in frames 9 and 10, respectively, and placed on the measurement table 11. The spots received at the positions p1 and p2 of the light receiving unit 6 are transmitted to the display unit 14 via the control unit 13 and displayed. The display screen 14a at this time is shown in FIG. 2, but when the light receiving unit 6 receives the two spots s1 and s2, the control unit 13 starts from the outermost peripheral position of the one spot s1 to the outermost position of the other spot s2. The distance x to the outer circumference position
x = f × tan 2θ (1)
f = calculated from the focal length of the collimator lens 3
FIG. 2 is an explanatory view showing a screen 14a of the display unit 14, and the above-mentioned distance x between the outer periphery portions of the spots is shown for reference. In FIG. 1, 15 is an input unit such as a keyboard and a mouse, and 16 is an output unit such as an external memory or a printer. Further, the specimens 4 and 7 are examples in which two measurement surfaces 5 and 8 are formed by a pair of two facing each other, but the front and back surfaces of one subject 50 are used as two measurement surfaces as shown in FIG. It can be handled in the same way when used.

The light beam b from the laser light source 1 is irradiated to the two subjects 4 and 7 via the collimator lens 3, the reflected light from the first measurement surface 5 of one subject 4 and the second of the other subject 7. When the optical system that projects the reflected light from the measurement surface 8 onto the light receiving unit 6 via the collimator lens 3 projects the spots s1 and s2 on the positions p1 and p2 of the light receiving unit 6, the control unit 13 Thus, the distance x between the outermost peripheral portions of the spots s1 and s2 is calculated by the equation (1). In accordance with the calculation of x, the control unit 13 further calculates the diameter y of the spot s by the following equation. FIG. 2 is an explanatory diagram of the display screen 14a as described above, but the spot diameter is also displayed as y for reference.
y = 1.22 × Fλ
= 1.22 × (f / φ) × λ (2)
1.22 = constant
φ = Reflected light aperture control unit 13 from the subject reflection surface calculates the ratio y / x from the calculated values of x and y, and displays it as the inclination angle θ ′ between the two reflection surfaces 5 and 8. Displayed on the unit 14. That is, the distance x between the outer peripheries of the two spots s1 and s2 projected on the light receiving unit 6 varies depending on the difference in inclination angle created between the two reflecting surfaces 5 and 8.
This spot s will be further described with reference to FIG. This figure is an explanatory diagram of the spot s displayed on the display unit 14. When the diameter of the spot s projected on the light receiving unit 6 is detected as y and the distance is detected as x1, the control unit 13 displays “y / x1 "is calculated, and" 0.9 "is obtained as shown in the first column 18a of the figure. Then, “0.9” is displayed on the display screen 14 a as the inclination angle θ ′ between the reflecting surfaces 5 and 8. When a value of “0.9” is displayed, it is a value close to “1”, so that the inclination angle θ ′ is estimated to be a value close to “0”. Similarly, if the diameter of the spot s is y and the distance is x2, the control unit 13 calculates “y / x2” and obtains “0.8” as shown in the second column 18b of FIG. The value “0.8” is displayed on the display screen 14 a as the inclination angle θ ′ between the reflecting surfaces 5 and 8. In the same manner, “y / x” when x3, x4, x5,..., Xn is calculated, and the value is displayed on the display screen 14a as the inclination angle θ ′. Since 'is due to "y / x", it is different from the actual inclination angle θ. Therefore, it is treated as a temporary inclination angle θ ′ with respect to the actual inclination angle θ. However, if the temporary inclination angle θ ′ is obtained, the true inclination angle θ can be estimated empirically.
In the above description, x and y are obtained and the ratio y / x is calculated, and the obtained value is set as a temporary inclination angle θ ′. If x and y of the spot s are obtained, an ellipse is obtained. Therefore, if the eccentricity of the ellipse is regarded as “y / x” mathematically, the value can be treated as a temporary inclination angle θ ′ in the same manner as in the above example.
As described above, in the first embodiment, the two spots s1 and s2 projected on the light receiving unit 6 are detected to obtain the x and y, the ratio between the two is calculated, and the provisional tilt angle θ ′ is obtained on the display unit 14. It is trying to display. If the actual inclination angle θ between the two reflecting surfaces 5 and 8 is estimated based on the displayed temporary inclination angle θ ′, a result as a preliminary evaluation work can be obtained. However, the display of this temporary inclination angle θ ′ can always be taken as a numerical value regardless of the magnitude of the inclination angle between the reflecting surfaces 5, 8. Work can be advanced.

Next, a conversion table for converting the temporary inclination angle θ ′ described above into a true inclination angle θ and obtaining an accurate measurement result will be described. This conversion table is prepared in advance to convert the temporary inclination angle θ ′ displayed on the display screen 14a, for example, “0.9” into a true inclination angle θ, and the values of x are x1, x2, x3. , ... xn, each y / x when changed in advance is experimentally calculated and entered as y / x values as tilt angles θ1, θ2, θ3, ... θn It is a thing. If such a conversion table is prepared, if the temporary inclination angle θ ′ is displayed on the display screen 14a, the corresponding true inclination angle θ can be searched from the conversion table.
4 and 5 illustrate a method for writing a data group such as a true inclination angle θ in the conversion table. FIG. 4 is an explanatory diagram of the autocollimator as in FIG. 1, and FIG. It is a figure explaining the work content at the time of writing. In FIG. 4, the light beam b from the laser light source 1 passes through the beam splitter 2 and the collimator lens 3 to become a parallel light beam and travels toward the reference bodies 4a and 7a. The reference bodies 4a and 7a are formed of the same or equivalent material as the specimens 4 and 7 in FIG. 1 and are installed on the measurement table 11 in place of the specimens 4 and 7. The first measurement surface 5a and the second measurement surface 8a are used as a completely flat original device and are accommodated in frames 9 and 10, respectively. The light reflected by the reference body first measurement surface 5a and the second measurement surface 8a returns to the collimator lens 3 as a parallel light beam having a diameter φ, is reflected by the beam splitter 2, and is condensed as a spot on the light receiving unit 6 such as a CCD. To do. In the figure, this condensed spot position is shown as p0. Since the two reflecting surfaces 5a and 7a are completely flat, the reflected light spot s1 from the first measuring surface 5a and the reflected light spot s2 from the second measuring surface 8a are the same position p0 if they are installed in parallel. Condensed to A drive unit 17 having a structure similar to, for example, a micrometer is attached to the housing frame 9 of the reference body 4a. When the drive unit 17 is rotated by operating this, the drive unit 17 side of the reference body 4a is in relation to the other reference body 7a. It floats up and the inclination interval d (column 18 in FIG. 5) between the first measurement surface 5a and the second measurement surface 8a is changed. Conversely, by operating this drive unit 17, it is possible to adjust so that spots from the two reflecting surfaces 5a and 8a are condensed at the same position p0. The reference bodies 4a and 7a thus adjusted so that the two reflecting surfaces 5a and 8a are parallel to each other are used as a master. This is because the inclination of the indoor floor where the measuring table 11 of the autocollimator is installed, the indoor temperature, It can also be adjusted in advance according to the installation environment, such as the presence or absence of vibration.
The adjusted reference bodies 4a and 7a are shown in the column 18 of the first row 19a in FIG. This column 18 shows the adjustment state of the two reference bodies 4a and 7a as a front view. In this case, the inclination interval between the reflecting surfaces 5a and 8a is “d = 0”. In order to display “d = 0”, the meter 17a (FIG. 4) attached to the drive unit 17 is set to zero. When “d = 0”, the two spots s1 and s2 are overlapped and displayed as shown in the column of the display screen 14a in FIG. Therefore, since the distance x between the outer periphery of one spot s1 and the outer periphery of the other spot s2 is 0, “x = 1” and “y = 1” are calculated by the control unit 13 and further “ 1 "is required. In FIG. 5, this state is shown in the right column 13a. Accordingly, when the two spots s1 and s2 are projected on the light receiving unit 6 in a state where they overlap and coincide with each other, the control unit 13 sets “x = 1” and “y = 1” as in the first row 19a. “Y / x = 1” is calculated, and “θ0” is written as a value corresponding to “y / x = 1” in the right column 20 representing the conversion table. That is, when “y / x = 1” is displayed as a temporary inclination angle, “1” is confirmed, and “θ0” having a value corresponding to the measurement surface interval “d = 0” is set as a true inclination angle. Fill in the conversion table 20.

  When the above operation is completed, the process proceeds to the entry operation in the second column 19b of the conversion table 20. In the second row 19b, first, the drive unit 17 of FIG. 4 is operated and rotated, and the inclination interval d of the first measurement surface 5a with respect to the second measurement surface 8a is increased while looking at the meter 17a, for example, “d = 1”. To do. When expanded to “d = 1”, the reflected light spot s1 from the first measurement surface 5a and the reflected light spot s2 from the second measurement surface 8a change projection positions on the light receiving unit 6, for example, in the second column of FIG. It becomes like the column of the display screen 14a of 19b, and the distance between the outer peripheral parts of the spots s1 and s2 is x1. When the values of x1 and y are calculated by the equations (1) and (2), “x1 = 1.1” and “y = 1” are calculated by the control unit 13, and “y / x1” is further calculated. The obtained “0.9” is calculated as the provisional inclination angle as shown in the column 13a, and the value is displayed as shown in the first column 18a of FIG. The displayed “0.9” is confirmed, and “0.9 = θ1” is written in the conversion table 20 as a value corresponding to the reflecting surface interval “d = 1”. This completes the work of entering the true inclination angle “θ1” in the second column 19b of the conversion table 20 when the inclination interval between the measurement surfaces 5a and 8a is “d = 1”.

When the conversion table 20 entry work in the second column 19b is completed, the operation proceeds to the next third column 19c. In the third row 19c, first, the drive unit 17 of FIG. 4 is operated and rotated, and the inclination interval d of the first measurement surface 5a with respect to the second measurement surface 8a is increased while looking at the meter 17a, for example, “d = 2”. To do. When expanded to “d = 2”, the reflected light spot s1 from the second measurement surface 5a and the reflected light spot s2 from the second measurement surface 8a change their projection positions on the light receiving unit 6, for example, the display screen 14a in FIG. The distance between the outer peripheral portions of the spots s1 and s2 is x2. When the values of x2 and y are calculated, for example, “x2 = 1.2” and “y = 1” are calculated, and “y / x2” is obtained based on these values, and “ 0.8 "is calculated as the temporary inclination angle. When the temporary inclination angle is calculated as “0.8” and is displayed on the display screen 14a as in the second column 18b of FIG. 3, it is confirmed and the conversion table 20 indicates that the measurement surface interval “d = “0.8 = θ2” is entered as a value corresponding to “2”. This completes the work of entering the true inclination angle “θ2” as shown in the third column 19c when the inclination interval between the measurement surfaces 5a and 8a is “d = 2”.
Similarly, the process proceeds to the entry operation in the fourth column 19d, and the inclination interval of the first measurement surface 5a with respect to the second measurement surface 8a is expanded to, for example, “d = 3”, and the reflected light spot s1 from the first measurement surface 5a The distance between the outer peripheral portions of the reflected light spot s2 from the second measurement surface 8a is set to x3. When the values of x3 and y are obtained, “x3 = 1.3” and “y = 1” are calculated. Further, y / x3 is obtained, and “0.7” is set as the temporary inclination angle as in the column 13a. Calculated. It is confirmed that this value is displayed on the display screen 14a as in the third column 18c of FIG. 3, and “0.7 = θ3” is set in the conversion table 20 as a value corresponding to the measurement surface interval “d = 3”. Fill in. This completes the work of entering the true inclination angle “θ3” as shown in the fourth column 19d when the inclination interval between the measurement surfaces 5a and 8a is d = 3. In the same manner, the necessary true inclination angle θ is sequentially entered in the conversion table 20.

As described above, when the conversion table 20 is created, the reference bodies 4a and 7a formed of the same or equivalent material as the subject are prepared as a prototype, and the inclination interval d between the two reflecting surfaces 5a and 8a is set. It is changed sequentially by the drive unit 17. Then, the distance x between the outer peripheral portions of the two reflected light spots s1, s2 on the light receiving portion 6 and the spot diameter y, which change at intervals d1, d2,... Dn, are obtained by the equations (1) and (2). The ratio y / x is calculated and displayed as a temporary tilt angle. Then, the displayed value is confirmed, and the true inclination angles corresponding to the displayed value are entered in the conversion table 20 as θ1, θ2,.
When the inclination angle θ between the subjects 4 and 7 is actually obtained, the reference bodies 4a and 7a as originals are removed from the measurement table 11 and the subjects 4 and 7 are installed. Then, if the reflected light from the reflection surfaces 5 and 8 is directed to the light receiving unit 6, spots s1 and s2 corresponding to the inclination angles of the two measurement surfaces are projected. The x and y values of the spots s1 and s2 are detected, and the ratio y / x is obtained and displayed on the display screen 14a as a temporary tilt angle. If the conversion table 20 created using the reference bodies 4a and 7a is searched based on the displayed tilt angle, the true tilt angle θ can be obtained.
In this way, by calculating in advance the values corresponding to the inclination angles of the two measurement surfaces of the reference body and preparing the conversion table 20 describing the values, x and x of the spots s1 and s2 projected on the light receiving unit 6 are prepared. The required true inclination angle θ can be obtained simply by obtaining y. In addition, even if the result varies in the detection of the x and y values, the accuracy obtained does not vary because the result obtained using the prototype is collated. In FIG. 4, reference numeral 21 shown in the control unit 13 is a memory, and details thereof will be described in the second embodiment. Similarly, the illumination unit 22 in the figure will be described later.

Next, a specific configuration example of the reference bodies 4a and 7a will be described with reference to FIG. In the figure, reference bodies 4a and 7a are accommodated in frames 9 and 10, respectively, and both frames are connected by metal fittings. A drive unit 17 with a meter is attached to one frame 9, and the attachment angle of the other reference body 4 a with respect to the reference body 7 a is changed by rotating it. The other frame 10 is provided with a receiving portion 23a, and a scale 23 described in FIG. Further, the surface 5b opposite to the first measurement surface 5a of the reference body 4a is formed as an inclined surface, and is configured such that the shape when the reference body 4a is cross-section is a wedge shape. Similarly, the surface 8b opposite to the second measurement surface 8a of the reference body 7a is formed as an inclined surface, and is configured such that the shape when the reference body 7a is taken as a cross section is a wedge shape.
Now, assuming that the first measurement surface 5a and the second measurement surface 8a are adjusted to be parallel to each other as shown in FIG. 6, the light from the light source 1 of FIG. 4 is directed to both reference bodies 4a and 7a. Then, the light 24 reflected by the inclined surface 5b of the reference body 4a is cut as an oblique ray and cannot return to the collimator lens 3 of FIG. On the other hand, the light 25 reflected by the first measurement surface 5a is directed to the collimator lens 3 as perpendicular light orthogonal to the first measurement surface 5a, and is projected onto the light receiving unit 6 as a spot s1.
Of the light that has passed through the reference body 4a and directed to the other reference body 7a, the light 26 reflected by the second measurement surface 8a becomes perpendicular light that is orthogonal to the second measurement surface 8a toward the collimator lens 3, and the spot It is projected onto the light receiving unit 6 as s2. On the other hand, the light 27 reflected by the inclined surface 8 b is cut as an oblique light and cannot return to the collimator lens 3.
By constructing the two reference bodies 4a and 7a so as to have a wedge-shaped cross section as described above, one of the light beams reflected by the two reflecting surfaces of each reference body 4a and 7a can be cut as an oblique ray. Therefore, it is effective when determining the spots s1 and s2. The reference bodies 4a and 7a thus configured are installed on the measurement table 11 as necessary when measuring the subject, and it is confirmed whether the values entered in the conversion table 20 match the current values. Then, the accuracy of the detected tilt angle can be checked in accordance with the currently set environment, so that the accuracy can be maintained and guaranteed.

Next, Example 2 will be described. In the second embodiment, the conversion table 20 described above is accommodated in the control unit 13 as a memory 21 so that the true inclination angle θ can be directly displayed on the display unit 14. First, the relationship between the memory 21 and the display screen 14a will be described with reference to FIG. In the drawing, the left column represents the display screen 14a and represents the positional relationship between the two spots s1 and s2 to be displayed. The right column of the figure is the memory 21, the left column 21a stores the y / x value, and the right column 21b stores the inclination angle θ. The memory 21 is accommodated in the control unit 13 of FIG. 4, but various types such as a hard disk, a USB memory, a chip memory, and a memory base can be employed.
The display screen 14a of the first row 28a in FIG. 7 is a case where the distance between the outer peripheral portions of the two spots s1 and s2 is detected as x1 and the diameter is y. When the state of the first row 28a is projected on the light receiving unit 6 as the reflected light spots s1 and s2 from the reference body measurement surfaces 5a and 8a, “y / x1 = 0 calculated in the left column 21a of the memory 21”. .9 ”is stored, and“ θ1 ”is stored in the right column 21b as the tilt angle at that time. Accordingly, when the subjects 4 and 7 are placed in the optical system instead of the reference bodies 4a and 7a, the spots s1 and s2 from the reflecting surface are detected as the diameter y, and the outer peripheral distance between them is detected as x1. Then, “y / x1 = 0.9” is retrieved from the first column 28a of the memory 21, and the inclination at that time is read as “θ1”. The inclination between the reflecting surfaces 5 and 8 is displayed on the display unit 14 as θ1. The method of actually displaying on the display unit 14 may be displayed by a known method. Therefore, although a description thereof is omitted, a dedicated display screen may be provided.
As described above, when the reflected light spots s1 and s2 from the two object measurement surfaces 5 and 8 are projected onto the light receiving unit 6, if the distance between the outer peripheral portions is detected as x1 and the spot diameter is detected as y, The first column 28a is retrieved from the data group in the memory 21, and the inclination θ1 is obtained and displayed on the display unit 14.

The left side of the second row 28b in FIG. 7 displays on the screen 14a the state when the diameters of the two spots s1 and s2 from the reference body measurement surfaces 5a and 8a are detected as y and the distance between the outer peripheral portions is detected as x2. Shows the case. When the state of the second row 28b is detected by the light receiving unit 6, "y / x2 = 0.8" calculated is stored in the left column 21a of the memory 21, and the inclination angle at that time is stored in the right column 21b. “Θ2” is stored. Accordingly, when the subjects 4 and 7 are placed in the optical system instead of the reference bodies 4a and 7a, the spots s1 and s2 from the measurement surface are detected as the diameter y, and the outer peripheral distance between them is detected as x2. The second column 28b is retrieved from the data group of the memory 21, and the two measurement surface angles “θ2” are read and displayed on the display unit 14.
Similarly, the states of the third row 28c, the fourth row 28d, and the fifth row 28e are detected as spots s1 and s2 from the reference body measurement surfaces 5a and 8a, and the distances between the outer circumferences are obtained as x3, x4, and x5. Then, the respective y / x values and the inclination angles “θ3”, “θ4”, and “θ5” are stored in the memory 21. Similarly, when the distance between the spots s1 and s2 is detected as xn, y / xn and the inclination angle “θn” are stored in the memory 21n.

  The diameter y of the spot s varies depending on the wavelength λ of the light source 1, the brightness of the collimator lens 3, and the reflected light aperture φ from the subject measurement surface incident on the collimator lens 3, as can be seen from the equation (2). Further, it varies depending on the processing accuracy of the measurement surfaces 5 and 8 of the specimens 4 and 7, for example, when they are polished or coated. Accordingly, if the memory 21 storing the value θ calculated in advance according to these variable elements is prepared and used by installing it in the control unit 13, a measurement result corresponding to the variable element is obtained. I can do it.

  As described above, in the second embodiment, the outer periphery of the spot due to the two reflected lights on the light receiving unit 6 that changes in accordance with the inclination angle θ between the first measurement surface 5 and the second measurement surface 8 of both the subjects 4 and 7. The ratio y / x between the part distance x and the spot diameter y is obtained, and the corresponding inclination angle θ is selectively retrieved from the data group of the memory 21 in which the corresponding value is stored in advance. It is a feature. Accordingly, the inclination θ between the two object measurement surfaces can be obtained only by detecting the values of x and y. Further, by preparing the memory 21 corresponding to the variable factors such as the wavelength λ of the light source, the brightness of the collimator lens 3, the reflected light aperture from the measurement surface, and the surface processing accuracy of the subject measurement surface 8, the brightness and size of the spot are prepared. And the like, the corresponding inclination angle can be searched from the data group of the memory 21.

  Next, a case where the detection of the tilt angle θ described with reference to FIGS. 5 and 7 is calculated with higher accuracy will be described. In FIG. 4, an illumination unit 22 that emits monochromatic light is installed below the optical system unit 30 and illuminates two reference bodies 4a and 7a. Then, if the inclination θ is given between the two 4a and 7a by the drive unit 17 or the like, the reflected lights from the first measurement surface 5a and the second measurement surface 8a interfere with each other to generate interference fringes. This interference fringe is generated every λ / 2, and the state of occurrence thereof can be visually recognized from the reference body 4a. The relationship between the interference fringes and the inclination angle θ will be described with reference to FIG.

In FIG. 8, A is a plan view showing two reference bodies 4a and 7a installed in the optical system facing each other, and is an example in which three interference fringes 31a, 31b, and 31c are generated. Yes. Reference numeral 23 denotes a scale which is installed together with the reference bodies 4a and 7a on the measurement table 11 of FIG. 4. By checking the scale of the scale 23, the distance L between the interference fringes 31 can be measured. . FIG. B is a view of the reference bodies 4a and 7a of FIG. A when viewed from the front. Between the two, there is an inclination interval of dn2 on the right side and an interval of dn1 on the left side. In this example, if the inclination angle θn1 between the reference bodies 4a and 7a is to be obtained,
θn1 = arctan (dn2-dn1) / L
= Arctan (λ / 2) / L (3)
Is required.
If the interval between the interference fringes 31a and 31b is L = 30 mm and λ is λ = 0.54 μm according to the above example, θn1 = (0.54 / 2) μm / 30 mm = 1.86 seconds. Become. This 1.86 seconds is the tilt angle θn1 set between the reference bodies 4a and 7a by the drive unit 17. In this state, when the illumination unit 22 is turned off and the light from the light source 1 of the optical system unit 30 is applied, x and y due to the spots s1 and s2 described with reference to FIGS. Thus, accurate x and y and y / x at the inclination angle θn1 (1.86 seconds) are calculated and stored in the memory 21.

  If the illumination unit 22 of monochromatic light is installed as described above to illuminate the reference bodies 4a and 7a to generate the interference fringes 31, and the distance L is measured with the scale 23, an accurate value of the inclination angle θ can be obtained. I can do it. Accordingly, the drive unit 17 is operated to sequentially change the inclination interval d, and x, y, and y / x are calculated and stored in the memory 21 according to the interval between the interference fringes 31 at that time. The inclination angles of the subjects 4 and 7 can be measured. The receiving portion 23 a described with reference to FIG. 6 is a portion where the scale 23 installed on the measurement table 11 is installed on the frame 10 so that the interval L of the generated interference fringe 31 can be measured near the interference fringe 31. To do. Of course, if the distance L between the interference fringes 31 is measured not only by the scale 23 but also by an interferometer, more accurate measurement can be performed.

FIG. 8C shows a case where the subjects 4 and 7 are installed in place of the reference bodies 4a and 7a in FIG. 8A. In FIG. 8A, since the reference bodies 4a and 7a are used as original devices with guaranteed flatness, the generated interference fringes 31a, 31b, and 31c all have the same shape and posture. That is, the same result can be obtained regardless of the position (for example, virtual lines g1, g2, g3... In FIG. 8C) on the second measurement surface 8a and the second measurement surface 5a.
On the other hand, FIG. 8C shows a state in which the test objects 4 and 7 are installed on the measurement table 11 and the interference fringes 31 are generated in a state corresponding to FIG. 8A. However, the generated interference fringes 31d, 31e, and 31f all have different shapes and postures. This is because the first measurement surface 5 and the second measurement surface 8 of the subject are not guaranteed flatness and are distorted or uneven, and in such a case, the tilt angle of the subject is measured at which position. The question is whether it should be done. For example, if arbitrary virtual lines g1, g2, g3,... In FIG. 8C are set as the measurement positions of the inclination angle, the measurement results may be different for each position. Therefore, it is necessary to select an optimum measurement position. However, since the interference fringes 31 are generated and visually confirmed, it can be confirmed that distortions and irregularities are generated, so that it is possible to determine that the measurement position needs to be selected. Further, the interference fringes 31 can be used as a guide when selecting the optimum measurement position.

Next, Example 3 will be described with reference to FIG. In this embodiment, data group writing such as the inclination angle θ by the interference fringes 31 described with reference to FIG. 8 is performed by a measurement mirror. In FIG. 8B, when the value of dn2 with respect to dn1 increases, that is, when the value of d shown in the column 18 of FIG. 5 increases, the value of the distance L between the interference fringes 31 in FIG. 8A decreases. Then, the interference fringes 31a, 31b, and 31c come close to each other and it becomes difficult to determine the boundary between them, and the L value specification is hindered. If the value of L is unstable, the calculation result by the above equation (3) also becomes unstable. Therefore, the method according to the third embodiment provides a suitable method when the value of d increases and the inclination angle θ increases. For example, when the inclination angle θ is a θ value from 0.2 seconds to 5 seconds, the method shown in FIG. 8 is applied, and when the inclination value is more than that, the embodiment shown in FIG. 9 is adopted. If so, the features of both can be utilized.

In FIG. 9, the light from the laser light source 1 passes through the collimating lens 3a for projecting to become a parallel light beam, is reflected by the first beam splitter 32, is further divided into two by the second beam splitter 33, and one of the lights travels straight as it is for the first measurement. It becomes the optical system 34 and irradiates the surface of the reference body 4a. The other light reflected by the second beam splitter 33 becomes the second measurement optical system 35 and goes to the measurement mirror 36, where it is reflected and irradiates the surface of the reference body 4a. The reference body 4a is composed of one sheet, and its surface acts as the first measurement surface 5a. The reflected light from the first measurement optical system 34 and the second measurement optical system 35 that irradiates the surface of the reference body returns in the forward path, and travels from the first beam splitter 32 to the light receiving unit 6 through the light receiving collimator lens 3b. Accordingly, if the reflecting surfaces of the second beam splitter 33 and the measuring mirror 36 are installed in parallel and the reflecting surface of the measuring mirror 36 is installed at 90 degrees with respect to the reference body 4a surface, the first measuring optical system is used. The light reflected from the surface of the reference body 4a by the reference numeral 34 and the second measurement optical system 35 is condensed as a spot at the same position (for example, position p0 in FIG. 4) of the light receiving unit 6.
The measurement mirror 36 installed in the optical path of the second measurement optical system 35 in the optical system unit 30a is attached on the turntable 37 so that the angle of the reflection surface can be arbitrarily changed. The turntable 37 is connected to the drive unit 17b, and the drive unit 17b has a structure similar to, for example, a micrometer. When the knob 17c is rotated, the turntable 37 rotates a predetermined amount. In order to grasp the rotation amount, a meter similar to the meter 17a shown in FIG. 4 is installed, but is omitted in FIG.
When the rotary table 37 is rotated by operating the knob 17c, the reflection surface angle r of the measurement mirror 36 changes, the direction of the light beam of the second measurement optical system 35 toward the reference body 4a changes, and the irradiation on the reference body 4a is changed. Change position. Accordingly, if the reflection surface angle is sequentially changed to r0, r1,... Rn, an irradiation position corresponding to the reflection surface angle r is obtained, and reflected light from the irradiation position is directed to the light receiving unit 6. It becomes like this.

For example, when the reflection surface angle is set to r0, that is, if the irradiation light beam directed from the measurement mirror 36 toward the reference body 4a surface is set to be 90 degrees with respect to the reference body 4a surface, it is shown in FIG. Similar to the first row 19a, the process of “d = 0” is performed. Specifically, since the reflected light spot s1 from the surface of the reference body 4a by the first measurement optical system 34 and the reflected light spot s2 by the second measurement optical system 35 are condensed at the same position of the light receiving unit 6, the control unit 13 Detects the distance between the outer peripheral portions of the spots s1 and s2 as x and the diameter of the spots s1 and s2 as y, and stores the corresponding inclination angle from “y / x = 1” in the memory 21 as “θ0”.
When the rotary table 37 is rotated by operating the knob 17c and the reflection surface angle of the measurement mirror 36 is set to r1, the irradiation light beam directed to the surface of the reference body 4a changes its angle, as shown in the second row 19b of FIG. The process of “d = 1” is advanced. Specifically, the reflected light spot s2 from the surface of the reference body 4a by the second measurement optical system 35 corresponds to the amount of change of the reflection surface angle of the measurement mirror 36 from the light receiving portion condensing position at the time of the first row 19a to r1. Move as much as equivalent. Thereby, the distance between the outer peripheral portions of the spots s1 and s2 is detected as x1, and the spot diameter is detected as y, and the corresponding inclination angle is stored in the memory 21 as “θ1” from “y / x1 = 0.9”. Similarly, when the reflection surface angle of the measurement mirror 36 is set to r2, the process of “d = 2” is advanced as in the third row 19c of FIG. 5, and the distance between the outer peripheral portions of the spots s1, s2 is x2. The spot diameter is detected as y, and the corresponding inclination angle is stored in the memory 21 as “θ2” from “y / x2 = 0.8”.
In the same manner, the surface of the reference body 4a is changed using the first measurement optical system 34 and the second measurement optical system 35 while sequentially changing the reflection surface angle of the measurement mirror 36 as r3, r4,. Irradiate. Then, a ratio y / x of the distance x between the spot outer peripheral portions and the diameter y is obtained from the reflected light, and the value is set as the inclination angles θ3, θ4,... Θn according to the reflection angles r3, r4,. If the data is stored in the memory 21, the memory 21 similar to that of the second embodiment can be obtained.

A case where the tilt angle of the subject is actually obtained using the memory 21 prepared in this way will be described. First, the reference body 4a as a prototype is removed from the measurement table 11, and the objects 4 and 7 having the first and second measurement surfaces are installed instead. Then, the knob 17c is operated to reset the reflection surface angle of the measurement mirror 36 to r0, and the reflected light from the subject reflection surfaces 5 and 8 is directed to the light receiving unit 6 as a spot. Then, since the spots s1 and s2 corresponding to the inclination angles of the two reflecting surfaces are projected, the y / x value based on the spots s1 and s2 is obtained, and the corresponding data is retrieved from the memory 21, so that a predetermined inclination angle θ is obtained. Can be obtained.
As described above, in the third embodiment, the first measurement optical system 34 and the second measurement optical system 35 are provided, and the reflection mirror angle of the measurement mirror 36 of the second measurement optical system 35 is changed so that the d value can be handled. . As a result, even when the d value becomes large and measurement by the interference fringe 31 becomes difficult, it can be dealt with. In the drawing, a diaphragm 38 provided in the first measurement optical system 34 and the second measurement optical system 35 is for adjusting the beam diameters of both the optical systems 34 and 35.

The autocollimator of the present invention has been described above. In these embodiments, the entire optical system is of a vertical type. However, if the optical system is rotated by 90 degrees to be a horizontal type, the optical system for the subjects 4 and 7 becomes light from the horizontal direction. Further, the optical system 30 illustrates only basic elements, and various members that are normally installed in the optical system, for example, a diaphragm installed between the collimator lens 3 and the subject 4 are omitted and will be described in detail. Not done. Similarly, the structure of the driving body 17 and the structure of the turntable 37 that change the inclination angle between the first measurement surface 5 and the second measurement surface 8 and the structure of the turntable 37 are the ones that have been combined with existing ones and designed within an allowable range. It can be adopted. The control unit 13 and the display unit 14 can be replaced with a general personal computer.

Schematic for description which showed the whole structure of the autocollimator by this application. Explanatory drawing which showed the screen of the display part. Explanatory drawing of the spot displayed on a display part. Explanatory drawing of an autocollimator. The content explanatory view when writing data in a conversion table. The figure which showed the specific structural example of the reference | standard body. The figure explaining a memory and a display screen. The figure explaining the relationship between an inclination angle and an interference fringe. Explanatory drawing of Example 3. FIG. The figure explaining the conventional autocollimator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Laser light source 2 ... Beam splitter 3 ... Collimator lens 4 ... Test object 5 ... 1st measurement surface 6 ... Light-receiving part 7 ... Test object 8 ... 2nd Measurement surface 11 ... Measurement table 13 ... Control unit 14 ... Display unit 17 ... Drive unit 20 ... Conversion table 21 ... Memory 22 ... Lighting unit 23 ... Scale 30 .... Optical system unit 31 ... Interference fringes 32 ... First beam splitter 33 ... Second beam splitter 34 ... First measurement optical system 35 ... Second measurement optical system 36 ... Measurement Mirror 37 ... Turntable 50 ... Glass plate 51 ... First measurement surface 52 ... Second measurement surface 53 ... Light source 55 ... Screen 57 ... Collimator lens 58 ... Cross Line 59 ... first cross line 60 ... second cross line 1 ... the light-receiving surface

Claims (6)

  An optical system for directing a light beam from a laser light source to a subject via a collimator lens and projecting reflected light from the first measurement surface and the second measurement surface as a spot on a light receiving unit via the collimator lens, and the optical system The ratio y / x of the distance x between the outer peripheral portions of the spots and the spot diameter y due to the both reflected light projected on the light receiving portion is calculated and displayed on the display portion as the inclination angle between the two measurement surfaces. And an autocollimator.   An optical system for directing a light beam from a laser light source to a subject via a collimator lens and projecting reflected light from the first measurement surface and the second measurement surface as a spot on a light receiving unit via the collimator lens, and the optical system A value corresponding to the ratio y / x of the distance x between the outer peripheral portions of the spots and the spot diameter y due to the both reflected light projected onto the light receiving unit in advance as the inclination angle θ between the quantity measuring surfaces; When both reflected light from the subject is projected as a spot on the light receiving unit, a value corresponding to y / x is retrieved from the memory and displayed as a tilt angle θ between the two measurement surfaces on the display unit. And an automatic collimator. A value corresponding to a ratio y / x between the distance x between the spot outer peripheral portions and the spot diameter y is stored in the memory for each reflected light aperture from the subject measurement surface and the brightness of the collimator lens. The autocollimator according to claim 2. An optical system includes two reference bodies in which an inclination interval d between the first measurement surface and the second measurement surface is sequentially changed by a driving unit so that reflected light from the first and second measurement surfaces can be obtained for each interval d. The distance x between the outer peripheries of both spots projected on the light receiving part and the spot diameter y are calculated for each of the set distances d1, d2,. 3. The autocollimator according to claim 2, wherein a memory preliminarily stored as inclination angles θ1, θ2,... θn for each of d1, d2,. 5. The autocollimator according to claim 4, wherein the reference body is configured and arranged in a wedge shape in cross section. The light beam from the laser light source is reflected by the first beam splitter through the projecting collimator lens, and the light beam is further divided by the second beam splitter, so that the same reference body is used as the first measurement optical system and the second measurement optical system. An optical system that irradiates the surface and returns both reflected lights to the outward path and projects them as a spot from the first beam splitter through the light receiving collimator lens to the light receiving unit; and installed in the second measuring optical system. , The measurement mirror which sequentially changes the reflection surface angle r and irradiates the reference body with the measurement light for each reflection surface angle, and the reflection angles r0, r1,... Rn set by the measurement mirror The reflected light spot projected on the light receiving part and the reflected light spot by the first measuring optical system are projected on the light receiving part, and the ratio y / x between the distance x between the outer peripheral parts of both spots and the spot diameter y is obtained. Are stored in advance as inclination angles θ0, θ1,... Θn corresponding to the respective reflection angles r0, r1,... Rn, a first measurement surface of the object and a second object installed in place of the reference body. When reflected light from the measurement surface is projected as a spot on the light receiving unit, the memory is searched with the y / x value and is displayed on the display unit as the inclination angle θ between the two measurement surfaces. And an autocollimator.