JPH05248987A - Automatic inspection device for lens joint surface - Google Patents

Abstract

PURPOSE:To automatically sense foreign matters over the whole area of the lens joint surface by casting light so that it is converged on the joint surface of a complex lens to be inspected in rotating, moving the light projecting part bit by bit, and sensing the transmitted photo-quantity by a photo-receiving part. CONSTITUTION:Light emitted by a semiconductor laser 13 is cast via a light projecting system 14 and converged on the joint surface 7a of a complex lens to be inspected 7. The lens 7 rotates round the optical axis at a frequency (f). If there is any foreign matter on the joint surface 7a, the received photo-quantity by a photo-diode 21 drops with the cyclic period 1/f. If the photo-reception signal is subjected to Fourie transform by a spectral analizer 33, the extreme value of received photo-quantity appears at the frequency nf (n is integer). Only signals with frequency nf can be extracted by giving an appropriate threashold to the received photo-quantity by the use of a personal computer 34, and the foreign matters are sensed. By motors 15, 18, gears 17, 20, etc., movement can be generated from the center of the lens 7 to the end while the light flux from the projecting part 1 focuses at the joint surface 7a, which enables inspection over the whole area of joint surface 7a. The photo-reception part 3 moves in compliance with the photo-projecting part 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens joint surface automatic inspection device for automatically detecting foreign matter mixed in a lens joint surface.

[0002]

2. Description of the Related Art Conventionally, the cemented surface of a cemented lens has been visually inspected, but there is an oversight by an inspector.
Further, there is a drawback that it is difficult to see foreign matter on the cemented surface depending on the lens shape.

Therefore, in order to solve the above-mentioned drawbacks, for example, Japanese Utility Model Laid-Open No. 58-63541 proposes the following device. As shown in FIG. 14, it is a method of inspecting a lens joint surface using a laser, in which 51 is a semiconductor laser, 52 is a hole having a hole coaxial with the optical axis in its center, and its lower surface 52a is a scattering surface. It is a plate. Reference numeral 53 denotes a plano-concave diffusion lens, which is adhered to the inside of the hole of the observation plate 52 without any space and is formed as a scattering surface.
3a is flush with the lower surface 52a of the observation plate 52.

Reference numeral 54 is one lens of the two cemented lenses, and 55 is the other lens. When laser light is incident on the surface 53a, it is scattered by the scattering surface and corresponds to the distance between the lens 54 and the lens 55. Since the scattered light causes interference, interference fringes appear on the surface 52a. The inspector observes the interference fringes, and the inspector determines the presence or absence of foreign matter based on the fringe shape.

[0005]

However, the apparatus described in Japanese Utility Model Laid-Open No. Sho 58-63541, although it is easy to see the interference fringes, has no choice but to rely on a manual visual inspection. Further, the interference fringes that should appear on the surface 53a in FIG. 14 cannot be observed because of the diffusion lens 53, and cannot be inspected over the entire bonding surface.

Therefore, the present invention was developed in view of the above problems in the prior art, and an automatic lens-joint surface inspection device capable of automatically detecting foreign matter such as bubbles and dust mixed in over the entire lens-joint surface. For the purpose of providing.

[0007]

1 to 3 are conceptual views showing the present invention, FIG. 1 shows the principle of a method for inspecting a lens joint surface, and FIG. 2 shows a locus of light on the lens joint surface. FIG. 3 shows the time variation of the amount of light received at the light receiving section. As shown in Figure 1,
Light projecting unit 1 capable of condensing on the lens joint surface 7a
And a light receiving and moving section 2 for moving the light projecting section 1 so that the light from the light projecting section 1 can be condensed from the center to the end of the lens joint surface 7a, and a light receiving section 3 for receiving the light from the light projecting section 1. , Floodlight 1
Light receiving moving unit 4 for moving the light receiving unit 3 according to the movement of the
And a rotation drive unit 5 that can press the cemented lens 7 to be inspected from the side surface and rotate at a constant frequency with respect to the optical axis, and a signal processing unit 6 that can select only a specific frequency for the detection signal of the light receiving unit 3. It was done.

[0008]

In the above-mentioned structure, the cemented surface, not the surface of the cemented lens 7 to be inspected, is attached to the cemented lens 7 to be inspected rotating at the constant frequency f about the optical axis of the cemented lens 7 to be inspected by the rotation drive section 5. Since the inspection is performed, a certain amount of light is emitted from the light projecting unit 1 so as to be focused on the lens joint surface 7a, and the light receiving unit 3
The amount of light transmitted through the cemented lens 7 to be tested is detected.

Since the cemented lens 7 to be tested is rotating, the light illuminates the same circle having the same center as that of the cemented lens 7 to be tested as indicated by the dotted line in FIG. Here, the lens joint surface 7a
It is assumed that the foreign matter 8 is present at an arbitrary position as shown in FIG. In the section where the light is irradiated with the rotation of the cemented lens 7 to be tested, there is no foreign matter (the section from position 10 to position 9 in FIG. 2), the light is transmitted through the lens cemented surface 7a, but Light is scattered in a certain section (section from position 9 to position 10 in FIG. 2).

As a result, as shown in FIG. 3, the amount of received light drops in a section where there is a foreign substance (section from the time 11 when the light irradiates the position 9 to the time 12 when the light irradiates the position 10). As shown in FIG. 3, since the cemented lens 7 to be inspected is rotating at the frequency f, the cycle in which the amount of received light changes is T (= 1 / f). Therefore, the signal processing unit 6 selects only the signal whose light amount change period is T from the received light signal to distinguish it from the false signal such as noise, and automatically detects the foreign matter mixed in the lens joint surface 7a.

Further, by moving the light projecting unit 1 by the light projecting moving unit 2 so that the light is focused on the lens joint surface 7a, the optical axis can be passed from the center to the end of the lens joint surface 7a. Therefore, since the light receiving unit 3 can be moved by the light receiving moving unit 4 to capture the light from the light projecting unit 1, it is possible to inspect the entire lens bonding surface.

[0012]

[Embodiment 1] FIGS. 4 to 7 show the present embodiment, FIG. 4 is a schematic configuration diagram, FIG. 5 is a cross-sectional view of a rotary drive unit 5, and FIG. FIG. 7 is an explanatory diagram showing a condition for focusing on the lens cemented surface 7a when doing, and FIG. 7 is a characteristic diagram showing a signal after Fourier exchange.

13 of the light projecting portion 1 is a semiconductor laser, 14 is a light projecting lens system for condensing light from the semiconductor laser 13 onto the lens joint surface 7a to a diameter of several tens of μm, and 15 on the lens joint surface 7a. A motor for moving the light projecting lens system 14 so as to collect light, 16 is a lens holder of a lens of the light projecting lens system 14 that is moved for collecting light, and 17 is a motor 1.
5 is a gear that converts rotation of 5 into movement parallel to the optical axis of the lens holder 16.

Reference numeral 18 of the light projecting and moving section 2 moves the light projecting section 1 so that the light from the light projecting section 1 is vertically incident on the first lens surface 7b, and 19 is a semiconductor laser 13 and a light projecting lens system. A fixing plate that integrally fixes 14 and the motor 15 and a gear 20 that converts the rotation of the motor 18 into a movement having a curvature equal to the curvature of the lens first surface 7b of the light projecting unit 1.

Reference numeral 21 of the light receiving portion 3 is a photodiode for detecting the amount of light transmitted from the semiconductor laser 13, reference numeral 22 is a light receiving lens system for focusing the light on the photodiode 21, 2
3 is a motor for moving the light receiving lens system 22, 24 is a lens holder of the moving lens of the light receiving lens system 22,
Reference numeral 25 denotes a gear that converts the rotation of the motor 23 into a movement parallel to the optical axis of the lens holder 24.

Reference numeral 26 of the light receiving moving unit 4 is a motor for moving the light receiving unit 3 in accordance with the movement of the light projecting unit 1, and 27 is a photodiode 21, a light receiving lens system 22 and a motor 23.
Is a fixing plate that is fixed so that the
Is a gear that converts the rotation of the light into a movement that allows the light from the light projecting unit 1 to be captured by the light receiving system 3.

Reference numeral 29 of the rotation driving unit 5 is a toy having a support shaft 29a and a spring 29b so that the cemented lens 7 to be inspected can be pressed from the side surface, and 30 is a toy 29 in the center direction from the side surface of the cemented lens 7 to be inspected. A lens holder that has a hole 30a that guides the support shaft 29a so that it can be pressed toward and has a mechanism that can rotate in conjunction with the rotation of the rotating body 32.
1 is a motor for rotating the cemented lens 7 to be inspected, 32
Is a rotating body that transmits the rotation of the motor 31 to the lens holder 30. The signal processing unit 6 includes a spectrum analyzer 33 and a personal computer 34.

As shown in FIG. 4, the apparatus having the above-described structure is a projection lens arranged so that the laser light emitted from the semiconductor laser 13 is condensed on the lens bonding surface 7a to have a diameter of several tens of μm. The cemented lens 7 to be tested is irradiated via the system 14. The locus of movement of the light projecting portion 1 due to the motor 18, the fixed plate 19 and the gear 20 is the lens first surface 7 of the cemented lens 7 to be tested.
Light incident on the first lens surface 7b is perpendicular to the first lens surface 7b because it is equal to the curvature of b.

Now, as shown in FIG. 6, the lens joint surface 7a
To inspect on a circle of radius R from the center of, we want to focus on the circle of radius R. When a light beam having a thickness D and a divergence angle α is vertically incident on the first lens surface 7b, in order to focus on the lens joint surface 7a, the thickness D of the incident light beam and the divergence angle α are calculated by the following equation. Need to meet. However, the curvature r1 of the first surface of the lens is sufficiently larger than the thickness D of the incident light beam.

[0020]

[Equation 1]

If the divergence angle α is constant, if the thickness D of the incident light beam is adjusted by the arrangement of the light projecting lens system 14 so that the above expression is satisfied, the light from the semiconductor laser 13 has a radius of the lens cemented surface 7a. Focus on the R circumference. Tested cemented lens 7
The light that has passed through is collected by the photodiode 21 by the light receiving lens system 22 and the light amount of the laser light is detected. Here, the light detected by the photodiode 21 is light for detecting the amount of light, and it is not necessary to capture it as a symmetrical light flux so as to focus it.

Arrangement of the projection lens system 14 by the motor 15, the lens holder 16 and the gear 17, and the motor 23,
It is assumed that the arrangement of the light receiving lens system 22 by the lens holder 24 and the gear 25 is known in advance by simulation. Here, the rotation of the motor 31 is transmitted to the lens holder 30 via the rotating body 32, and the test cemented lens 7 rotates at a constant frequency f. If there is no foreign matter on the lens joint surface 7a, the amount of received light is constant, and if there is a foreign matter on the lens joint surface 7a, the amount of received light drops at the same cycle T (= 1 / f) as the lens rotation.

When the received light signal is Fourier transformed by the spectrum analyzer 33, when there is a foreign substance, the same frequency f as the lens rotation or the frequency nf of its harmonic component (n = 2, 3, 4, ...) As shown in FIG. An extreme value of the amount of received light appears at. If an appropriate threshold value is given to the amount of received light using the personal computer 34, the frequency nf (n =
1, 2, 3, ...) can be extracted, and the presence or absence of foreign matter on the lens joint surface 7a can be inspected.

Here, the laser light is condensed to a diameter of several tens of μm on the lens cemented surface 7a of the cemented lens 7 to be inspected, but is spread over a certain range on the first lens surface 7b and the second lens surface 7c. Hit Therefore, the photodiode 2
The amount of received light detected in 1 is not affected by small dust or the like on the first lens surface 7b and the second lens surface 7c.

According to this embodiment, the presence or absence of foreign matter on the lens cemented surface 7a can be automatically inspected without detecting small dust or the like adhering to the surfaces 7b and 7c of the cemented lens 7 to be tested. Further, by the motor 15, the lens holder 16 and the gear 17, and the motor 18, the fixing plate 19 and the gear 20, the light flux from the light projecting unit 1 moves from the center of the cemented lens to the end while being focused on the lens cemented surface 7a. It is possible to inspect the entire joint surface.

[0026]

Second Embodiment FIG. 8 is a schematic configuration diagram of the signal processing unit 6 in the present embodiment. In this embodiment, the signal processing unit 6 from the photodiode 21 in the first embodiment is replaced. In this embodiment, the spectrum analyzer 33 and the personal computer 34 in the first embodiment are eliminated, and instead, the lock-in amplifier 35, the oscillator 36,
The phase shifter 37, the LPF 38, and the voltage indicator 39 are different from each other in configuration, and other configurations are the same in configuration. Therefore, the description of the configuration will be omitted and the operation will be described using the same reference numerals. To do.

The apparatus having the above-mentioned configuration is the same as that of the first embodiment.
Similarly, the detected light receiving signal is multiplied by the lock-in amplifier 35 by the reference signal of the frequency f generated by the oscillator 36 and synchronized with the light receiving signal by the phase shifter 37.
A periodic light receiving signal can be extracted by extracting a DC component through the LPF 38.

Assuming that there is no foreign matter on the lens cemented surface 7a, the received light signal is constant, and even when multiplied by the reference signal of the frequency f, there is no DC component and the output of the LPF 38 is at a low level. If there is a foreign substance on the lens cemented surface 7a, the amount of received light drops at the cycle T. Therefore, when multiplied by the reference signal of frequency f (= 1 / T), a DC component proportional to the amplitude of the received light signal appears and the LPF 38 The output goes high. Therefore, it is possible to determine the presence or absence of foreign matter on the lens cemented surface 7a.

According to this embodiment, as in the first embodiment, it is possible to automatically inspect the entire surface of the lens joint surface for foreign matter. Further, since it is not necessary to use an expensive measuring instrument as compared with the first embodiment, it is possible to make the configuration inexpensive and compact.

[0030]

Third Embodiment FIGS. 9 to 12 show the present embodiment, FIG. 9 is a schematic configuration diagram, FIG. 10 is a plan view of a diaphragm 40, and FIGS. 11 and 12 are plan views showing the operation of the diaphragm 40. Examples are
The difference is that the toy 29 and the lens holder 30 of the rotary drive unit 5 in the first embodiment are eliminated and a diaphragm 40 is provided instead, and other configurations are made up of the same components. Are assigned the same numbers and explanations thereof are omitted.

Reference numeral 40 is a diaphragm having a mechanism capable of rotating in association with the rotation of the rotating body 32. The diaphragm 40 is composed of a ring-shaped outer side 40a and an inner side 40b, and the outer side 40a and the inner side 40b can be rotated separately. The diaphragm 40 has a pressing member 41 and a fixing screw 42,
A hole 40c is formed in the inner side 40b of the diaphragm 40.

A pressing member 41 supports the cemented lens 7 to be inspected. A pressing shaft 41a supporting the cemented lens 7 to be inspected is erected at the tip of the sharpest apex of the triangle, and the tips of the other acute angles are at the tips. The outside 40a of the diaphragm 40 and the tip of the obtuse apex are pivotally supported inside 40b of the diaphragm 40, respectively. Reference numeral 42 is a fixing screw for fixing the outer side 40a and the inner side 40b of the diaphragm 40.

In the apparatus having the above structure, the diaphragm 40, the pressing member 41, and the fixing screw 42 are used to press the cemented lens 7 to be tested from the side surface. A mechanism for pressing the cemented lens 7 to be inspected from the side will be described with reference to FIGS. 11 and 12.

When no force is applied to the diaphragm 40 from the outside, the position of the pressing member 41 is assumed to be as shown in FIG. The pressing shaft 41a of the pressing member 41 is gathered at the center of the diaphragm 40. Here, it is assumed that the inner side 40b of the diaphragm 40 is not moved and the outer side 40a is rotated clockwise. Since the two vertices of the triangular portion of the pressing member 41 are axially supported by the inner side 40b and the outer side 40a of the diaphragm 40 rotating separately, the pressing member 41 is supported by the point pivotally supported by the inner side 40b of the diaphragm 40. The pressing shaft 41a of the above moves from the center of the diaphragm 40 toward the end.

Thus, in FIG. 12, a space is created between the three pressing members 41, and the pressing shaft 41a of the pressing member 41 sandwiches and holds the cemented lens 7 to be tested. The inner side 40b and the outer side 40a of the diaphragm 40 are fixed by tightening the fixing screw 42 after the sandwiching is completed, and when the diaphragm 40 is rotated, the test cemented lens 7 can also be rotated.

According to the present embodiment, in the same manner as in the first embodiment, not only the presence or absence of foreign matter on the entire surface of the lens joint surface can be automatically inspected, but also the cemented lenses to be inspected having various diameters can be inspected.

FIG. 13 is a schematic configuration diagram showing this embodiment. The present embodiment is different in that the light projecting moving unit 2 and the light receiving moving unit 3 in the previous embodiment are modified and a surface foreign matter removing unit is provided, and other configurations are the same in configuration. The same components are assigned the same numbers and their explanations are omitted.

The light projecting unit 1, the light receiving unit 3, the rotation driving unit 5, and the signal processing unit 6 are the same as those in the first embodiment, and 43 is the direction of the light projecting unit 1 in the direction normal to the lens first surface 7b. A changing motor, 44 is a gear for converting the rotation of the motor 43 to the direction of the light receiving unit 1, and 45 is an XY stage that can move the light receiving unit 1, the motor 43, and the gear 44 integrally.

Reference numeral 46 is a motor for changing the direction of the light receiving section 3, 47 is a gear for converting the rotation of the motor 46 to the direction of the light receiving section 3, and 48 is the light receiving section 3, the motor 46 and the gear 47 are integrally moved. It is an XY stage that can be done.

Numeral 49 is an air blow for removing foreign matters such as dust on the lens surface by blowing air toward the surface of the cemented lens 7 to be inspected, and numeral 50 is a solenoid valve for controlling the air blowing state of the air blow 49. ..

The apparatus constructed as described above is the same as that of the first embodiment.
Similarly, by rotating the cemented lens 7 to be tested by the rotation driving unit 5 and processing the received light signal by the signal processing unit 6, it is possible to automatically inspect the lens cemented surface 7a for the presence of foreign matter.

The inspection accuracy is further improved by adding the steps described below. Before the inspection is started, air is blown from the air blow 49 by the solenoid valve 50 to remove foreign matter adhering to the surface of the cemented lens 7 to be inspected. When the removal is completed, the electromagnetic valve 50 is turned off to stop the air blow from the air blow 49. Then, at the time of inspection, laser light from the semiconductor laser 13 reaches the photodiode 21 in addition to foreign matter on the lens bonding surface 7a. The number of objects that block light is reduced, and the accuracy of the amount of light received by the photodiode 21 is improved.

According to the present embodiment, in addition to the automatic inspection of foreign matter on the lens cemented surface as in the case of Embodiment 1, it is possible to inspect cemented lenses having various lens surface curvatures. Further, the inspection accuracy is higher than that in the first embodiment.

[0044]

As described above, according to the automatic lens joint surface inspection apparatus of the present invention, it is possible to automatically inspect the presence or absence of foreign matter on the lens joint surface.
The entire bonding surface can be inspected, and excellent effects can be obtained.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing the present invention.

FIG. 2 is a conceptual diagram showing the present invention.

FIG. 3 is a conceptual diagram showing the present invention.

FIG. 4 is a schematic configuration diagram showing a first embodiment.

FIG. 5 is a transverse sectional view showing the first embodiment.

FIG. 6 is an explanatory view showing the first embodiment.

FIG. 7 is a characteristic diagram showing Example 1.

FIG. 8 is a schematic configuration diagram showing a second embodiment.

FIG. 9 is a schematic configuration diagram showing a third embodiment.

FIG. 10 is a plan view showing a third embodiment.

FIG. 11 is a plan view showing a third embodiment.

FIG. 12 is a plan view showing a third embodiment.

FIG. 13 is a schematic configuration diagram showing a fourth embodiment.

FIG. 14 is a schematic configuration diagram showing a conventional example.

[Explanation of symbols]

 1 Light emitting unit 2 Light emitting moving unit 3 Light receiving unit 4 Light receiving moving unit 5 Rotation drive unit 6 Signal processing unit

Claims (1)

[Claims] 1. A light projecting section for collecting light on a lens cemented surface, and a light projecting moving section for moving the light projecting section so that light from the light projecting section can be condensed from the center to the end of the lens cemented surface. , A light-receiving unit that receives light from the light-projecting unit, a light-receiving moving unit that moves the light-receiving unit according to the movement of the light-projecting unit, and a cemented lens to be inspected from the side surface at a constant frequency with respect to the optical axis. An automatic lens joint surface inspection device comprising a rotation drive unit for rotating and a signal processing unit capable of selecting only a specific frequency for a detection signal from the light receiving unit.