JPH0658710A - Interferrometer - Google Patents

Abstract

PURPOSE:To easily perform work for changing kinds of standard lens and positions in response to an object to be inspected. CONSTITUTION:A parallel light flux is made with a collimator lens 7 from a body part 1a of an interferometer body 1 and a standard lens 2 is arranged at the parallel light flux position. Constitution is performed in that a standard lens mounting part 1b of the interferometer body 1 on which the standard lens 2 is mounted can be faced to an arbitrary position of a light axis in a light path.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an interferometer device for inspecting the surface condition of precision optical products such as lenses using a laser interferometer.

[0002]

2. Description of the Related Art As a precision optical product, for example, a structure in which a laser interferometer is used to inspect the finishing accuracy of a lens is known. For example, in a Fizeau interferometer, a reference lens that serves as a reference for a lens as a subject is arranged in the optical path of a laser beam from a laser light source, and a test lens is placed at a position on an extension line of the reference lens in this optical path. By arranging and measuring the number of interference fringes (usually called Newton's number) generated between the reflected light from the reference surface of the reference lens and the reflected light from the test surface of the test lens, this lens The surface condition of is inspected. In this way, by using a laser interferometer, the lens under test can be inspected in a non-contact manner,
This is extremely convenient because it can be precisely inspected without damaging the reference lens or the lens to be inspected.

[0003]

When inspecting an object to be inspected using an interferometer, the F value of the reference lens must be changed according to the type of the object to be inspected. The replacement work of the reference lens is extremely troublesome, and since the work of adjusting the optical axis is required after the replacement, the replacement work of the reference lens as a whole is extremely troublesome. Further, when inspecting an object to be inspected having a different radius of curvature or the like, it is necessary to adjust the position between the object to be inspected and the reference lens, but in the case of moving the reference lens side to adjust the position. Has to move the entire interferometer body including the reference lens, and since the interferometer body is a heavy object, it is difficult to position the interferometer strictly.

The present invention has been made in view of the above points, and an object thereof is to make it possible to easily move a reference lens.

[0005]

In order to achieve the above-mentioned object, the present invention provides an object to be inspected through a reference lens in a state where laser light emitted from a laser light source is made into a parallel light flux by a collimator lens. An interferometer device for irradiating a laser beam onto the optical axis of a parallel beam of the laser beam by mounting the reference lens on the displacement means. The feature is that it is configured to be.

[0006]

In the interferometer, when the laser light applied to the reference lens is applied as parallel light through the collimator lens, the reference lens must be located on the optical axis. However, the position in the optical axis direction is not limited. Therefore, if the reference lens is strictly positioned even in the optical axis direction, it can be configured as a movable lens that moves the reference lens in the optical axis direction or in a direction orthogonal to the optical axis.

From the above points, the reference lens is attached to the displacement means, and the reference lens can be moved in the optical axis direction or in the direction orthogonal to the optical axis. By moving the reference lens in the optical axis direction, you can adjust the position of the reference lens only in the optical axis direction without moving the entire interferometer body in the optical axis direction. The interval can be adjusted. Further, when a plurality of reference lenses having different F-numbers are mounted on a member that rotates or slides in a direction orthogonal to the optical axis and the members are moved, different types of reference lenses are used interchangeably. It will be possible.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings. First, in FIG. 1, reference numeral 1 denotes an interferometer main body, and the interferometer main body 1 includes a main body 1a and a main body 1a.
And a reference lens mounting portion 1b which is movable in the optical axis direction, and the reference lens 2 is mounted on the reference lens mounting portion 1b. The interferometer body 1 has a laser oscillator 3, and the laser light emitted from the laser oscillator 3 enters a diverging lens 4. The diverging lens 4 is for expanding the beam diameter of the laser light to an extent necessary for inspecting the lens 2 to be inspected, and the laser light passing through the diverging lens 4 is once condensed. It is supposed to diverge. A diaphragm 5 is arranged at this light collecting position. The light passing through the diaphragm 5 is incident on the beam splitter 6 while diverging, and its reflection surface 6
The 90 ° optical path is bent by being reflected at a. The light reflected by the beam splitter 6 is collimated by the collimator lens 7 at a position where the beam has a predetermined beam diameter.

The reference lens 2 provided in the reference lens mounting portion 1b is arranged in front of the collimator lens 7, the incident surface 2a thereof is provided with an antireflection coating, and the opposite surface is the reference surface 2b. Has become. A test lens 8 as a test object is arranged in front of the reference lens 2, and light transmitted through the reference lens 2 is incident on a test surface 8a of the test lens 8 and a part of the light is incident on the test surface 8a. It is reflected by the surface 8a to be tested. Then, the reflected light from the surface 8a to be inspected and the reflected light from the reference surface 2b of the reference lens 2 interfere with each other to generate an interference fringe. The reflected light passes through the collimator lens 7 and the beam splitter 6, and the interference fringe image forming lens 9 is formed.
The interference fringes are photographed by the image pickup means 10 through the image pickup means 10 and the image thereof is displayed on a monitor device (not shown).

Here, the lens 8 to be inspected is a spherical lens, and it is not necessary to replace the reference lens 2 as long as it can be measured by a reference lens having a predetermined F value. Accordingly, it is necessary to change the distance between the lens 8 under test and the reference lens 2. On the other hand, when a large number of lenses 8 to be inspected are to be inspected, it is preferable that the lenses 8 to be inspected are always set at a fixed position in order to automate the attachment and detachment work of the lenses 8 to be inspected. Is preferred.
For this reason, the lens mount 11 on which the lens 8 to be inspected is set is fixed at a fixed position. On the other hand, if the whole interferometer body 1 is moved, it is difficult to perform positioning with extremely high accuracy because the interferometer body 1 has a considerable weight. From the above points, the interferometer body 1 is divided into two parts, and only the reference lens mounting portion 1b on which the reference lens 2 is mounted is moved in the optical axis direction.

2 and 3 show a position adjusting mechanism for the reference lens mounting portion 1b. In the figure, reference numeral 12 is a movable plate, and a reference lens holding portion 13 to which the reference lens 2 is attached is attached to the movable plate 12. Therefore, the movable plate 12 and the reference lens holding portion 13 constitute the reference lens mounting portion 1b. Further, three guide rods 14 are erected on the main body portion 1a, and the movable plate 12 is slidably supported by the guide rods 14. Where the guide rod 1
Reference numeral 4 is provided in a direction parallel to the optical path of the laser light from the interferometer body 1. Further, 15 is a screw shaft, and the screw shaft 15 has a nut member 1 attached to the movable plate 12.
6 is screwed in, and a gear 17 is connected to the tip of the screw shaft 15. The drive gear 1 is attached to the gear 17.
The drive gear 18 can rotate the input shaft 19 by a manual operation or a drive means such as a motor.

With the above structure, the lens mount portion 11 for setting the lens 8 to be inspected is fixed,
Further, when the main body 1a of the interferometer main body 1 is fixed and the input shaft 19 is operated to rotate the drive gear 18, the gear 17 connected to the screw shaft 15 follows this and rotates to move. The plate 12 is displaced along the guide rod 14. Here, since the guide rod 14 is provided in a direction parallel to the optical path of the object light from the interferometer body 1 to the lens 8 to be inspected, the reference lens 2 provided on the movable plate 12 is arranged along the optical axis. Close to the lens 8 to be inspected
Position adjustment is performed in the direction of separation.

Here, since the light emitted from the main body 1a of the interferometer main body 1 is collimated by the collimator lens 7, as long as it is placed in the optical path of this collimated light, the reference lens 2 has the optical axis. No matter what position in the direction, there is no optical difference. Therefore, if only the reference lens 2 is moved to adjust the position between the reference lens 2 and the lens 8 to be inspected, the positioning accuracy is improved as compared with the case where the entire interferometer main body 1, which is relatively heavy, is moved. However,
The optical axis of the reference lens 2 must be matched with the main body 1a of the interferometer main body 1 and the lens 8 to be inspected.
The main body portion 1a and the lens mount portion 11 on which the lens 8 to be inspected is set are both fixed, and if the optical axes between the main body portion 1a and the lens mount portion 11 are made to coincide exactly during assembly, both There is no risk of misalignment of the optical axis between them. Therefore, the reference lens mounting portion 1b is attached to the main body portion 1a.
The guide rod 14 is provided so as to be supported on the main body 1a and is guided and displaced by the guide rod 14 projecting from the main body portion 1a. Therefore, it is necessary to extend the guide rod 14 accurately in the direction parallel to the optical axis. There is no possibility that the reference lens 2 will be displaced from the optical axis.

Next, FIGS. 4 and 5 show a second embodiment of the present invention, in which the reference lens is displaceable in the direction orthogonal to the optical axis. Has been done. Reference numeral 20 in the drawing denotes a rotating disc as a reference lens mounting portion, and five types of reference lenses 21a to 21e are mounted on the rotating disc 20 at positions on a concentric circle. The rotary disc 20 is rotatably mounted on a shaft 22, and the shaft 22 is fixed to the main body 1 a of the interferometer main body 1. Further, a screw portion 23 is formed on the outer peripheral surface of the rotary disc 20, and a drive gear 24 is meshed with the screw portion 23. The drive gear 24 has the input shaft 2
5 are connected. Therefore, if the drive gear 24 is rotated by operating the input shaft 25, any of the reference lenses 21a to 21e can be exposed to the optical path.

Here, as the reference lenses 21a to 21e mounted on the rotary disc 20, different types of lenses such as those having different F-numbers and those having different reference plane shapes are provided. As a result, when changing the type of inspection or the lens to be inspected, the reference lens can be replaced very easily by operating the input shaft 25. Although different types of reference lenses may have different thicknesses, the light emitted from the main body 1a is a parallel light. There is no particular problem even if the position of is changed. When the reference lenses 21a to 21e face the optical path, the reference lenses 21a to 21e must be held so as not to tilt or deviate from the optical axis. If the mechanical precision of the section is made sufficient, it is possible to prevent the inclination and displacement with respect to the optical axis.

Next, FIG. 6 shows a third embodiment of the present invention. In this embodiment, a plurality of reference lenses can be exchanged, which is different from the above-mentioned second embodiment. Similar, but using a slide plate 30 as a means for replacement is shown. This slide plate 30 has
Three reference lenses 31a to 31c are provided and configured to be slidable along the guide rod 32 in a direction orthogonal to the optical axis. A motor 33 is provided to displace the slide plate 30, and the motor 33 rotates the screw shaft 34 inserted in the slide plate 30 to rotate one of the three reference lenses 31a to 31c. It becomes possible to selectively face the optical path.

Further, FIG. 7 shows a fourth embodiment of the present invention. In this embodiment, similarly to the third embodiment, three reference lenses 41a to 41c are mounted on the slide plate 40, and the slide plate 40 is moved along the guide rod 42 in the direction orthogonal to the optical axis. Not displaceable, motor 43
Driven by a screw shaft 44 connected to the reference lens 4
It is configured such that any one of 1a to 41c can be selectively exposed to the optical path. Moreover, in addition to this, brackets 45 at both ends to which the guide rod 42 and the screw shaft 44 are connected are fixedly provided to the elevating block 46, and the elevating block 46 can be moved along the guide rod 47 in the optical axis direction. Also, the screw shaft 48 is used to lift and lower the block 4.
6 and the motor 49 is connected to the screw shaft 48 so that the slide plate 40 can be displaced also in the optical axis direction.

According to the structure of the fourth embodiment, the reference lens is exchanged and the distance between the reference lens and the reference lens is adjusted according to the lens to be inspected only by moving the slide plate 40. Further, since the movement of the slide plate 40 can be performed by the operation of the motors 43 and 49, the selection and position adjustment of the reference lens according to the lens to be inspected can be all automated.

In each of the embodiments described above, the Fizeau interferometer is shown, but the point is that it is applicable if the optical path incident on the reference lens is collimated by the collimator lens. Alternatively, for example, as shown in FIG. 8, it may be configured as a Michelson type interferometer device. Here, in the interferometer apparatus of FIG. 8, after the laser light emitted from the laser oscillator 50 passes through the diverging lens 51, it is collimated by the collimator lens 52, and then the reference light and the object light are emitted by the beam splitter 53. The reference light is reflected by the reflection mirror 54, and the reflected light is transmitted through the beam splitter 53.
Further, the object light is irradiated onto the test lens 56 through the reference lens 55 that diverges after being condensed at a predetermined position on the optical path, and the reflected light from the test lens 56 is reflected by the reference lens 56.
After collimating the parallel light again, the beam splitter 53
The optical system 57 for forming the interference fringes causes the image pickup means 58 to form an image of the interference fringes. In this type of interferometer device, the interferometer main body 59 is mounted on the main body 59a except the reference lens 56, and the reference lens 56 is the same as that shown in each of the above-described embodiments.
The reference lens mounting portion 59b may be movable in the optical axis direction or in the direction orthogonal to the optical axis.

[0020]

As described above, according to the present invention, a collimator lens is used to form a parallel light beam, and when the parallel light beam is applied to the object to be measured through the reference lens, the reference lens is attached to the displacement means. The displacement means allows the laser beam converted into the parallel light flux to face any position on the optical axis in the optical path. Therefore, by moving only the reference lens, It becomes possible to adjust the interval between them, and to replace multiple reference lenses to face the optical path, making it extremely easy to adjust the optimum reference lens and its position according to the type of object to be inspected. In addition, various effects such as being able to be performed accurately can be achieved.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the configuration of a laser interferometer.

FIG. 2 is a structural explanatory view showing a reference lens displacement mechanism of the first embodiment of the present invention.

FIG. 3 is a plan view of FIG.

FIG. 4 is a structural explanatory view showing a reference lens displacement mechanism of a second embodiment of the present invention.

FIG. 5 is a side view of FIG.

FIG. 6 is a structural explanatory view showing a reference lens displacement mechanism of a third embodiment of the present invention.

FIG. 7 is a structural explanatory view showing a reference lens displacement mechanism of a third embodiment of the present invention.

FIG. 8 is a configuration explanatory view of a laser interferometer of a type different from that of FIG.

[Explanation of symbols]

1,59 Interferometer body 1a, 59a Body portion 1b, 59b Reference lens mounting portion 2, 21a to 21e, 31a to 31c, 41a to 41
c, 55 Reference lens 7,52 Collimator lens 11 Lens mount part 12 Movable plate 13 Reference lens holding part 14, 32, 42, 47 Guide rod 15, 23, 34, 44, 48 Screw shaft 17 Gear wheel 18, 24 Drive gear wheel 19 , 25 Input shaft 20 Rotating disk 30, 40 Slide plate 33, 43, 49 Motor 46 Lift block

Claims (4)

[Claims] 1. An interferometer apparatus in which laser light emitted from a laser light source is collimated by a collimator lens to illuminate an object to be measured through a reference lens, and the reference lens is displaced by a displacement means. An interferometer device, characterized in that it is mounted on the optical axis and can be made to face an arbitrary position on the optical axis in the optical path of a laser beam made into a parallel light flux by this displacement means. 2. The interferometer according to claim 1, wherein the displacing means displaces the reference lens in the optical axis direction so as to adjust the distance between the reference lens and the object to be inspected. apparatus. 3. The displacing means is composed of a member to which a plurality of types of reference lenses are attached and which is displaceable in a direction orthogonal to the optical axis, and an arbitrary reference lens is selectively selected from the plurality of types of reference lenses. The interferometer device according to claim 1, wherein the interferometer device is configured to be exposed to the optical path. 4. The displacement means is provided with a plurality of types of reference lenses, the reference lenses are selectively exposed to the optical path, and the position can be adjusted in the optical axis direction. The interferometer device according to 1.