JP2001202654A - Light spot inspection device and optical substrate for aberration correction used for this device as well as optical pickup device subjected to inspection of light spot shape by using this device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light spot inspection device which is capable of realizing aberration correction under different conditions with one pseudo disk without using an intricate switching mechanism and an optical substrate used for this device. SOLUTION: This light spot inspection device 10 is used to inspect the shape of a light spot which is emitted from a light source 2 and is focused near the recording surface 6a of the disk 6 which is an information recording medium via optical systems 3 (31, 32, 33 and 5). The device is constituted by arranging the optical substrate 21 for aberration correction having a reflection surface to allow the transmittance of a prescribed light quantity and to reflect the prescribed light quantity between an objective lens 11a of the light spot inspection device 10 and an objective lens 5 of the optical pickup device 1 for the optical disk. The optical path length within the optical substrate 21 of the light, which is emitted from light source and for which the aberration correction more than the thickness size of the optical substrate 21, is assured by suitably utilizing the transmitted light and reflected light at the variable reflection surface, by which the desired aberration correction is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light spot inspection apparatus for inspecting a shape of a light spot irradiated from a light source such as a laser beam used for an optical pickup device for an optical disk and focused on a disk surface, and the optical spot inspection apparatus. The present invention relates to an optical substrate for aberration correction used in an apparatus and an optical pickup apparatus in which a light spot shape is inspected using the apparatus.

[0002]

2. Description of the Related Art FIG. 11 is a view for inspecting a shape of a light spot irradiated from a laser diode (hereinafter, referred to as an LD) as a light source of an optical pickup device (not shown) for an optical disk and focused on a disk surface. A light spot inspection device is shown.

In an optical pickup device for an optical disk, which is a part of a recording / reproducing device, a laser beam emitted from an LD, which is a light source, is condensed by an objective lens 5 through a predetermined optical system. Focusing is performed on a recording surface 6a of a disk 6 serving as an information recording medium loaded on a tray. The laser light focused on the recording surface 6a is reflected by the recording surface 6a and
And is received by the photodiode of the recording / reproducing apparatus.

The light spot inspection device 10 irradiates the light spot from the LD of the optical pickup device and focuses on the recording surface 6a of the disk 6 via a predetermined optical system (including the objective lens 5). It is to be inspected. The light spot inspection apparatus 10 includes a microscope optical system 11 having a lens system such as an objective lens 11a for enlarging a light spot focused on the recording surface 6a, and a CCD camera 12
And a monitor 13. Then, the focus position of the microscope optical system 11 is adjusted to the focus position of the light spot, the light spot is enlarged by the microscope optical system 11, photographed by the CCD camera 12, and the photographed image is projected on the monitor 13, and Is to be observed.

The disk 6 as a recording medium is provided on the front side of the recording surface 6a formed of a metal thin film or the like, that is, on the LD side serving as a light source, from polycarbonate for protecting the recording surface 6a from damage and dust. Protective layer 6b is formed. Therefore, light from the LD side of the optical pickup device for an optical disk passes through the protective layer 6b and is focused on the recording surface 6a.

[0006] The light spot inspection apparatus 10 uses the protective layer 6.
In order to inspect the shape of the light spot at the in-focus position in consideration of the thickness and the refractive index of b, the optical substrate 14 as an aberration correction plate for correcting aberration of light includes the objective lenses 5 and 1.
1 is provided. That is, the optical substrate 14 is disposed in place of the disk 6, and has the same properties as the disk 6, that is, the same thickness and the same thickness, in order to accurately inspect the light spot on the recording surface 6a of the disk 6. This is a pseudo disk having a refractive index. The light spot inspection device 10 can inspect a light spot that has passed through the optical substrate 14 to inspect a light spot shape equivalent to a light spot shape that passes through the protective layer 6b and is focused on the recording surface 6a. .

[0007]

In recent years, various playback devices have been developed for loading a compact disk (CD) and a digital universal disk (DVD) on the same tray. In such a device, although a predetermined optical system is used in common, an objective lens 5 having a different NA and a disk 6 having a different thickness are used. That is, as shown in FIG. 12, an objective lens for focusing light on each of the recording surfaces 61a and 62a of a compact disk (CD) 61 and a digital universal disk (DVD) 62 has two lenses having different focal positions. Objective lens 51 for each used CD
And an objective lens 52 for DVD.

As shown in FIG. 12, the thickness of the protective layers 61b and 62b of each of the above-mentioned disks 61 and 62 is 1.2 mm in the case of the compact disk (CD) 61 and 0 in the case of the digital universal disk (DVD) 62. 0.6 mm. Therefore, each recording surface 61 of the CD 61 and the DVD 62
a, 62a from the objective lenses 51, 52, d1,
A difference of 0.6 mm occurs in d2, and the focal positions of the objective lenses 51 and 52 need to be changed correspondingly.

In such a reproducing apparatus in which the CD 61 and the DVD 62 are loaded on a common tray, when the optical spots for the CD and the DVD are respectively inspected, the optical substrate 14 as the pseudo disk described above is also used for the CD. It is necessary to switch between DVD and DVD. That is, CD
The thickness of the protective layer 61b of the DVD 61 and the thickness of the protective layer 62b of the DVD 62 are different, and the objective lenses 51 and 52 corresponding thereto are different.
Are different from each other, the optical substrate 14 is also used for CD and D.
This is because it is necessary to make the thicknesses optimal for VD.

[0010] Therefore, such a CD61 / DVD6
2. The apparatus for inspecting the light spot of the common reproducing apparatus includes a switching mechanism for switching the optical substrate 14 in an extremely narrow space between the objective lens 11a of the microscope optical system 11 and the objective lens 5 on the optical pickup device side. Or a switching mechanism for switching the objective lens 11a on the microscope optical system 11 side with a revolver, to which the optical substrate 14 corresponding to each of the CD and DVD is attached, by using a revolver. , 6
It is necessary to correspond to the thickness of 2b.

However, when a switching mechanism for switching the optical substrate 14 is provided in the space between the objective lens 11a of the microscope optical system 11 and the objective lens 5 on the optical pickup device side, since the space is extremely narrow, the two It is very difficult to switch the optical substrate 14 so as to be perpendicular to the optical axis.

When a mechanism for switching the two objective lenses 11a to which the optical substrate 14 for CD and the optical substrate 14 for DVD are respectively mounted by a revolver is provided, it is necessary to provide two microscope objective lenses having extremely large NA. There is a problem that the cost is very high. Further, in the case of this configuration, a relief portion of the holding portion of the aberration correction plate when rotating with a revolver is required, but it is difficult to form such a relief portion in a small space in terms of arrangement. . Further, if there is a problem in the rotation accuracy and durability of the revolver, the position accuracy of the optical substrates 14 for CD and DVD is affected, so that it is necessary to strictly control the rotation accuracy and durability.

In either case, the difference between the in-focus position of the CD light spot and the in-focus position of the DVD light spot is 0.6 mm, as described above. Needs to be switched each time.

An object of the present invention is to provide an optical spot inspection apparatus capable of realizing aberration correction under different conditions with a single pseudo disk without using a complicated switching mechanism, an optical substrate used in the apparatus, and this apparatus. To provide an optical pickup device whose light spot shape is inspected by using the optical pickup device.

[0015]

In order to achieve the above object, the present invention provides a light spot irradiated from a light source and focused through a predetermined optical system near a recording surface of a disc serving as an information recording medium. In a light spot inspection device for inspecting a shape, a reflection surface that transmits a predetermined amount of light and reflects a predetermined amount of light is provided between a light source side and each objective lens provided in the light spot inspection device, and is formed of a reflection surface. By appropriately using the transmitted light and the reflected light, it is possible to secure the optical path length in the optical substrate of the light emitted from the light source and requiring the aberration correction equal to or more than the thickness dimension of the optical substrate, and perform the desired aberration correction. It is possible. According to another aspect of the present invention, in addition to the above-described light spot inspection apparatus, the optical substrate can correct a plurality of lights having different optical path lengths required for the aberration correction, respectively.

Therefore, according to each of the above-mentioned inventions, even if a plurality of pseudo disks (optical substrates) having different thicknesses are not provided for a CD and a DVD, for example, a plurality of different pseudo disks are provided by one optical substrate. The same effect as having a disk can be obtained. That is, by appropriately using the reflected light and the transmitted light formed on the reflection surface, the optical path length of the light in the optical substrate can be freely set. There is no need to use it.

According to another aspect of the present invention, in addition to the above-described light spot inspection apparatus, when no optical substrate is provided, a plurality of lights having light spots formed at different positions on the optical axis of a predetermined optical system are formed. By arranging the optical substrate, a light spot is formed at substantially the same position. Therefore, by arranging the optical substrate, it is possible to form a plurality of light spots that are originally focused at different positions at substantially the same position on the optical path, and it is necessary to largely change the focal position of the microscope optical system used for inspection. Disappears.

According to another aspect of the present invention, in addition to the above-described light spot inspection apparatus, a spot forming position of each light is located outside the optical substrate. Therefore, the light spot can be easily inspected without being affected by bubbles in the optical substrate or dust on the surface.

According to another aspect of the present invention, in addition to the above-described light spot inspection apparatus, the optical substrate is formed by laminating and bonding two substrates in the optical axis direction, and a light source side surface of the optical substrate ( Hereinafter, a first surface) and a bonding surface (hereinafter, referred to as a second surface) are defined as reflection surfaces, and a spot formation position of light transmitted through the first and second surfaces and a light transmitted through the first surface. The spot forming position of the light that has been reflected on the second surface and further transmitted on the second surface after being reflected on the first surface is substantially the same position on the optical axis.

Therefore, two optical spots having different original focal positions can be made substantially the same without changing the magnification of the pseudo disk and the microscope optical system by using one optical substrate having a simple configuration of two sheets. Can be inspected by location. As a result, it is possible to reduce the time for focusing the light spot inspection apparatus on the focus position of the light spot.

According to another aspect of the present invention, in addition to the above-described optical spot inspection apparatus, the two substrates constituting the optical substrate are formed to have substantially the same thickness in the optical axis direction. Therefore, C
As in the relationship between D and DVD, when used as a pseudo disk of each disk in which the thickness of the protective layer of one disk is twice the thickness of the protective layer of the other disk, each light spot formation position is It is easily possible to set a substantially common position such as on a surface opposite to the light source. As a result, it is possible to reduce the time for focusing the light spot inspection device at the time of switching.

Further, in addition to the above-described light spot inspection apparatus, another invention is characterized in that, when an optical substrate is not arranged, a plurality of light spots are formed at different positions on the optical axis of a predetermined optical system. On the other hand, the light whose light spot formation position is closer to the light source is light for irradiating the recording surface of a DVD (digital universal disc), and the light whose light spot position is farther from the light source is C.
The light is used to irradiate the recording surface of D (compact disk). Therefore, the respective light spots for DVD and CD of the device for loading DVD and CD on the same tray are:
Inspection can be easily performed without using a complicated switching mechanism.

Further, the present invention is used in a light spot inspection apparatus for inspecting the shape of a light spot irradiated from a light source and focused on a recording surface of a disc serving as an information recording medium through a predetermined optical system. An optical substrate for aberration correction as a pseudo disk to be transmitted, which has a reflecting surface that transmits a predetermined amount of light from a light source and reflects a predetermined amount of light, and is illuminated from the light source by utilizing the transmission and reflection of the optical substrate. It is possible to secure the optical path length in the optical substrate of the light requiring the aberration correction equal to or larger than the size, and to perform the desired aberration correction.
Therefore, it is possible to cope with a plurality of aberration correction optical path lengths by using the reflection surface.

An optical substrate according to another aspect of the present invention is formed by laminating and bonding two substrates in the optical axis direction, and a light source side surface (hereinafter referred to as a first surface) of the optical substrate and a laminating surface. The mating surface (hereinafter, referred to as a second surface) is a reflection surface. By using one optical substrate having such a simple configuration, it is possible to cope with two optical path lengths for correcting aberration.

An optical substrate according to another aspect of the present invention is composed of two substrates having substantially the same thickness in the optical axis direction. Therefore, like the relationship between CD and DVD, the thickness of the protective layer of one disk is equal to the thickness of the protective layer of the other disk.
When used as a common pseudo disk when the size is doubled, the light spot position can be easily aligned on a surface opposite to the light source or the like.

Further, the optical pickup device of the present invention includes an optical substrate for correcting aberration having a reflection surface that transmits a predetermined amount of light and reflects the predetermined amount of light, and appropriately transmits transmitted light and reflected light formed by the reflection surface. Utilize a light spot inspection device that can secure the optical path length in the optical substrate of the light that is emitted from the light source and needs aberration correction equal to or greater than the thickness of the optical substrate, and can perform the desired aberration correction. The shape of the light spot is inspected, and the light emitted from the light source and a predetermined optical system are adjusted according to the inspection result. Therefore, the light spot shape is simply and reliably adjusted.

[0027]

Embodiments of the present invention will be described below. The same members as those shown in FIGS. 11 and 12 will be denoted by the same reference numerals, and the description thereof will be omitted or simplified.

FIG. 1 is a diagram showing an embodiment of a light spot inspection apparatus according to the present invention. That is, FIG. 1 shows an optical pickup device 1 for an optical disk which is a part of a recording / reproducing device, and a light spot shape which is irradiated from an LD 2 which is a light source of the device 1 and is focused on a disk surface 6a. The light spot inspection apparatus 10 of FIG.

As shown in FIG. 1, the optical pickup device 1
The laser light emitted from the LD 2 serving as the light source is focused on the recording surface 6 a of the disk 6 via the predetermined optical system 3. That is, the laser light from the LD 2 is semi-transmitted by the beam splitter 31, and the transmitted light is reflected by the reflecting mirror 32 to be collimated by the collimating lens 3.
3, the light is converted into parallel light, and is condensed by the objective lens 5. As a result, the light is focused on the recording surface 6a of the disk 6, and the focused light is reflected by the recording surface 6a and returned, passes through the objective lens 5 and the collimating lens 33, and is reflected by the reflection mirror 32. You. The light that has returned to the beam splitter 31 due to the reflection is partially reflected and is incident on the sensor lens 7, and the light condensed by the sensor lens 7 is received by the photodiode 8.

The light spot inspection apparatus 10 inspects the shape of a light spot focused on the recording surface 6a of the disk 6, and includes a microscope optical system 11 having an objective lens 11a and a CCD camera 12 , A monitor 13, and an optical substrate 2 for correcting aberration, which is a pseudo disk of the disk 6.
1 is comprised. Then, the focus of the microscope optical system 11 is adjusted to the focus position of the light spot focused through the optical substrate 21 as a pseudo disk, and the microscope optical system 1
1 to enlarge the light spot and shoot with the CCD camera 12,
The photographed image is projected on the monitor 13 to observe this image.

As shown in FIGS. 2A and 2B, the optical substrate 21 has a configuration in which two circular substrates 21a and 21b are stacked in the optical axis direction and adhered with an adhesive. ing. Each of the substrates 21a and 21b has a thickness of 0.3
mm, the entire thickness of the optical substrate 21 is about 0.6 mm, which is almost the same as the thickness of the protective layer 62b of the DVD 62 described above. Become.

Then, the surface of the optical substrate 21 on the LD2 side, that is, the surface of the optical pickup device 1 on the side of the objective lens 5 (hereinafter, referred to as the surface).
The first surface 22) and the second surface 23, which is a bonding surface of the two substrates 21a and 21b, are reflection surfaces that transmit a predetermined amount of light and reflect a predetermined amount of light.

That is, the substrate 21a disposed on the objective lens 5 side is provided on both surfaces of the first surface 22 facing the objective lens 5 side and the second surface 23 which is a bonding surface with the substrate 21b. The following coatings are applied by vapor deposition. This coating surface was coated with magnesium fluoride (MgF2) from the glass surface side at 0.05λ (λ
= 650 nm, the same applies hereinafter), zirconium oxide (ZrO
2) 0.78λ, magnesium fluoride (MgF2) 0.28λ, zirconium oxide (ZrO2) 0.75λ
λ, magnesium fluoride (MgF2) is deposited in order of 0.08λ.

On the other hand, both surfaces of the substrate 21b arranged on the microscope optical system 11 side are as follows. The surface to be the bonding surface is not coated, and the surface facing the microscope optical system 11 is magnesium fluoride (M
gF2) is coated with a ４λ single layer by vapor deposition. The coated surface of the substrate 21b is a non-reflective surface (AR film = anti-reflection film) that hardly reflects (reflectance: 0.1%), and prevents burning and oxidation of glass. For the purpose.

The two substrates 21a, 21 thus constructed
By bonding the bonding surface of b with an adhesive to form one optical substrate 21, the outer surface (first surface) 22 of the substrate 21a and the second surface 23 serving as a bonding surface are
A reflective surface having the above-mentioned coating is formed. Since the same coating is applied to both surfaces of the substrate 21a as described above, the substrate 21a has no surface selectivity, and has a structure in which either surface may be used as a bonding surface. Therefore, in the manufacturing process, a problem such as a mistake in surface selection in the bonding process cannot occur, and it is easy to manufacture. The first and second surfaces 22 and 23 serving as the reflection surfaces of the optical substrate 21 configured as described above are 50
% Of light is transmitted, and the remaining 50% of light is reflected.

The optical substrate 21 configured as described above
Are predetermined optical systems (a collimator lens 3, a beam splitter 4) of the optical pickup device 1 for reading an optical disc.
And the focus position p corresponding to the objective lens 5), L
D2, more specifically, the focus position p is substantially opposite to the incident surface (corresponding to the above-described first surface 22) of the optical substrate 21 (the above-described non-reflective surface = hereinafter, the third surface). Surface)
24.

In this embodiment, the optical substrate 21 is set such that the DVD focusing position p is substantially on the third surface 24.
Is arranged, the focusing position p may be set anywhere between the objective lens 11a of the microscope optical system 11 and the objective lens 5 on the light source side, and the optical substrate 21 of the microscope optical system 11 Objective lens 11a and objective lens 5 on the light source side
It may be placed anywhere as long as it is between a. In the present embodiment, the light spot formation position of the optical substrate 21 is set in consideration of the fact that the image projected on the microscope optical system 11 side can be observed without being affected by bubbles in the optical substrate 21 or dust on the surface. Third surface 24 outside and on the microscope optical system 11 side
The position is slightly shifted to the microscope side from above.

The optical spot inspection apparatus 10 in which such an optical substrate 21 is disposed at a predetermined position on the optical axis of the optical system uses a transmitted light and a reflected light formed by the optical substrate 21 to respectively use a CD. Both when the objective lens 51 operates and when the DVD objective lens 52 operates, focusing is performed on substantially the same position on the third surface 24 (in the present invention, “focusing on substantially the same position” is performed). I will make you scorch "
Means to be in the fine adjustment range by the microscope).
In this case, it is easy to correspond to the DVD 62 by passing light and focusing as usual.
It is necessary to devise to deal with the problem.

That is, the light passing through the CD objective lens 51 is reflected by a first surface 22 and a second surface 23 which will be described later.
The optical path length in the optical substrate 21 is ensured by the two reflections at. For this reason, although the light from the CD objective lens 51 originally needs aberration correction twice as long as the thickness dimension of the optical substrate 21, the aberration correction is performed by two reflections. Will be done. In addition, the position focused by the two reflections is substantially the same as the focus position of the light for DVD having the aberration correction dimension of １ ／ length (the third surface 2).
4).

Hereinafter, a DVD objective lens 52 is disposed at a predetermined position of the optical pickup device 1 for an optical disk.
An objective lens 51 for CD is disposed at a focus position of light when laser light is emitted from the LD for VD and a predetermined position of the optical pickup device 1 for optical disk, and the LD for CD.
The focus position of light when a laser beam is emitted from the camera will be described with reference to FIGS. 3, 4, and 5A and 5B.

First, the case of a DVD will be described.
FIG. 3 shows a predetermined wavelength (650 nm) from an LD for DVD.
FIG. 3 is a diagram illustrating a focus position of light when a laser beam is emitted and an objective lens 52 for DVD is arranged at a predetermined position of the optical pickup device 1. Note that DV
The plate thickness required for correcting the aberration of the light for D is substantially the same as the thickness of the optical substrate 21 described above. Therefore, in this DVD light, the focused position is inspected without using reflection.

According to FIG. 3, 50% of the amount of light condensed by the objective lens 52 is transmitted through the first surface 22 of the optical substrate 21 to the second surface 23 side (the transmitted light is reflected at one point). Dashed line),
50% of the light amount is reflected toward the objective lens 52 (reflected light is indicated by a dotted line). Then, the transmitted light transmitted to the second surface 23 side is reduced by 50% in the second surface 23 to the third surface 24.
Side (the transmitted light is indicated by a dashed line), 50% of the light amount
Is reflected to the first surface 22 side (reflected light is indicated by a dotted line).

The transmitted light transmitted through the first and second surfaces 22 and 23 and having the amount of light of 25% of the light condensed by the objective lens 52 passes through the third non-reflective surface 24. Almost the entire amount of light is transmitted to focus on the focus position p1 on the third surface 24.
Further, the light transmitted through the first surface 22 and reflected by the second surface 23 is focused on a focus position p2 on the first surface 22. In this state, if the microscope optical system 11 of the light spot inspection apparatus 10 is focused on the focus position p1, the light spot at the focus position p2 is sufficiently defocused, and the DVD light spot shape at the focus position p1 is obtained. Can be observed as a clear image.

Next, the case of a CD will be described. FIG.
5A and 5B, a laser beam of a predetermined wavelength (780 nm) is emitted from an LD for a CD, and an objective lens 51 for a CD is arranged at a predetermined position of an optical pickup device 1 for an optical disk. FIG. 6 is a diagram for explaining a focus position of light when it is turned on. Note that the plate thickness required for correcting aberration of CD light is approximately twice as large as that of the optical substrate 21 described above.
2 mm. Therefore, it is necessary to secure the optical path length in the optical substrate 21 and appropriately perform aberration correction for the CD light by appropriately using transmission and reflection.

According to FIG. 4, 50% of the amount of the light condensed by the objective lens 51 is transmitted through the first surface 22 of the optical substrate 21 to the second surface 23 side (the transmitted light is reflected by one point). Dashed line),
50% of the light amount is reflected toward the objective lens 5 (reflected light is indicated by a dotted line). Then, the transmitted light transmitted through the second surface 23 is transmitted through the second surface 23 at an amount of 50% to the third surface 24 (the transmitted light is indicated by a dashed line), and is transmitted through the second surface 23 at 50% of the amount of light. Is reflected to the first surface 22 side (reflected light is indicated by a dotted line).

The transmitted light transmitted through the first and second surfaces 22 and 23 and condensed by the objective lens 51 and having a light amount of 25% passes through the third surface 24 of the non-reflection surface almost in total light amount. Is transmitted and focuses at a focal position p0 away from the third surface 24 to the microscope optical system 11 side. The light spot at the focal position p0 has a large light amount of 25%, but the optical substrate 21 is 0.6 m
m, the spherical aberration is large. Therefore, if the microscope optical system 11 is focused on a focal position p1 described later, the light spot at the focal position p0 is sufficiently defocused,
This does not affect the image of the light spot formed at the focal position p1.

Further, the light is transmitted through the first surface 22 and the second surface 2
3, the light reflected on the first surface 22 side is 50% of the light amount.
Is reflected by the first surface 22 toward the second surface 23, and the remaining 50
% Of the light passes through the first surface 22. At this time, the amount of light reflected on the second surface 23 side is about 12.5% of the amount of light first collected by the objective lens 51. 50% (about 6.25% of the initial light amount) of about 12.5% of the light traveling toward the second surface 23 is transmitted through the second surface 23 and furthermore, the non-reflective third surface 24. And focuses on the focus position p1 on the third surface 24.

For this reason, in this state, if the focus of the microscope optical system 11 of the light spot inspection device 10 is adjusted to the focus position p1, the light focused at the focus position p0 described above and the focus position p2 described later is obtained. The CD light spot shape at the focus position p1 can be observed without being affected by the spot.

The in-focus position p1 is determined by the above-described DV.
It substantially coincides with the focus position p1 of the light spot for D. Therefore, the light spot inspection apparatus 10 not only does not need to switch the optical substrate 21 as a pseudo disk, but also finely adjusts the focal position of the microscope optical system 11 without greatly changing the light for each of DVD and CD. Both spots are focused at the focus position p1, and the images are converted to the microscope optical system 11
Can be observed at

The first surface 22 is transmitted through the second surface 23
And the remaining 50 of the light reflected by the first surface 22
% (Approximately 6.25% of the initial light amount) is reflected by the second surface 23, returns to the first surface 22 side again, and is focused at the focus position p2 on the first surface 22. However, this focus position p
The light spot focused at 2 is also sufficiently defocused when observing an image at the focus position p1, so that the focus position p
It does not affect the image of the light spot focused in step 1.

The path of the light focused at the in-focus position p1 may be as shown in FIG. 5B in addition to the normal path shown in FIG. 5A. That is, as shown in FIG.
Light condensed by the objective lens 51, transmitted through the first surface 22 and the second surface 23, and slightly reflected without being transmitted by the third surface 24 is further reflected by the third surface 24 on the third surface 24. The focus position p on the third surface 24 after being reflected toward the surface 24 and transmitted through the third surface 24
There is a light spot focused at 1 (slightly on the microscope side).

However, the light spot formed in this manner becomes 25% of the initial light amount when transmitted through the first surface 22 and the second surface 23, and the third surface of the light amount of 25% Only 0.1% of the light is reflected at 24 and 50% of this light is reflected and formed on the third surface 24 side, so that 0.006% of the initial light amount
Is just the amount of light. That is, the light spot formed along the path shown in FIG. 5B has only about 1/500 of the brightness of the light spot formed along the path shown in FIG. There is almost no effect on the image.

Although the above-described embodiment is an example of a preferred embodiment of the present invention, the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention. It is. For example, although the present embodiment has been described as an apparatus optimal for inspecting the light spot shape of an apparatus of a type in which a CD disk and a DVD disk are loaded on a common tray, it is particularly possible to switch between CD and DVD. However, the present invention is not limited to such an apparatus, and may be a general-purpose inspection apparatus for a dedicated CD machine or a dedicated DVD machine.

In the above embodiment, the objective lens 51 for CD and the objective lens 52 for DVD are composed of separate lenses, and these two lenses 51 and 52 are connected by an objective lens switching mechanism or the like. The description has been made on the assumption that the switching can be performed. However, as shown in FIGS. 6A and 6B, the present invention is also applicable to a case where one lens is used for both CD and DVD. .

As shown in FIG. 6A, the lens 53
When the information recorded on the DVD is read by irradiating the recording surface of the VD, light passing through the entire lens surface, that is, light passing outside the lens surface (near the edge) is also effectively used. Light is collected at a high NA.
On the other hand, as shown in FIG. 6B, when the lens 53 irradiates the CD recording surface and reads information recorded on the CD, the lens 53 moves to the disk side from the above-described DVD reading, and a part of the lens surface, ie, a part of the lens surface. Light that passes outside the lens surface is not used, and only light that passes near the center is used effectively. At this time, the light that passes is collected with a not so high NA. As described above, the present invention exerts the same effect in such a device that is used for both DVD and CD with one lens.

Further, in this embodiment, the optical substrate 21 is formed by laminating and bonding two glass plates each having a thickness of 0.3 mm, but the number of laminated substrates is not limited to two but may be three or more or not. May be only one. Further, the thickness of each glass material is not limited to 0.3 mm. That is, if the optical substrate 21 is an optical substrate having a reflective surface, and has a configuration in which the optical path length in the optical substrate 21 is secured by utilizing transmission and reflection of light on the reflective surface. The number and the thickness of the glass plate members may have other configurations.

For example, the configuration shown in FIGS. 7 and 8 may be adopted. FIG. 7 shows a configuration in which two 0.3 mm-thick plate members are adhered to each other in the same manner as in the above-described embodiment, and the focal length is the incident surface (corresponding to the first surface 22 of the above-described embodiment). ) Corresponds to a lens 0.6 mm behind and a lens 1.2 mm behind. However, as in the above-described embodiment, the third
Instead of observing the focal position on the surface 24, as shown in FIG. 7, observe the light spot formed at the focal position p2 'on the first surface 22 using the transmitted light and the reflected light. May be.

In the example shown in FIG. 7, the in-focus position p2 '
In order to secure the amount of light at the surface, a reflection surface is provided on a bonding surface (corresponding to the second surface 23 in the above embodiment) and a surface behind the optical path (corresponding to the third surface 24 in the above embodiment). Have
The incident surface (corresponding to the first surface 22 of the above-described embodiment) may be a non-reflective surface.

FIG. 8 shows a single plate member having a thickness of 0.6 mm, both surfaces of which are reflecting surfaces. FIG. 8 shows a lens in which the focal length is 0.6 mm rearward from the entrance surface, and 1.
This corresponds to a lens that is 8 mm behind. 0.6
Although the focal position of the lens for mm was originally on the reflection surface behind the optical path of the plate, the focal position of the lens for 1.8 mm was aligned to this focal position using two reflections on both sides of the plate. It has become something.

In the above-described embodiment, each light spot observed by the microscope optical system 11 is focused at the focusing position p1 on the third surface 24. However, as shown in FIG. The focus position of each light spot may be slightly shifted to the microscope optical system 11 side (in the above-described embodiment, the focus position is slightly shifted to the microscope side, but is further shifted further than that. meaning). Further, as shown in FIG. 10, the light source side may be shifted to the objective lens 5 side. Also,
In addition, the focus position of each light spot to be observed is set on the optical substrate 2.
The focus position may be inside the optical substrate 21 in consideration of the influence of bubbles in glass and dust on the glass surface during observation.

Further, in the above-described embodiment, the reflectance on each reflection surface (first and second surfaces 22, 23) of the optical substrate 21 is set to 50%, but the reflection / transmission ratio is set to 50%: 5
It does not have to be 0%. In the above-described embodiment, the reflectivity of each reflecting surface is set to be equal to the CD of 780 nm even in the case of a DVD laser beam having a wavelength of 650 nm.
In the case of the laser beam, the reflection surface is set to 50%. However, each reflection surface may be configured such that the reflection / transmission ratio varies depending on the wavelength of light. With this configuration, it is possible to equalize the light amounts of light emitted at different wavelengths at the same focal position, or suppress the reflectance of light emitted at a specific wavelength to efficiently guide the light to the focal position. Becomes

[0062]

As described above, the light spot inspection apparatus according to the present invention utilizes the transmitted light and the reflected light formed by the optical substrate for aberration correction provided with the reflecting surface, respectively. Desired aberration correction is performed by securing the optical path length. Therefore, for example, CD
Even if a plurality of pseudo disks (optical substrates) having different thicknesses are not provided corresponding to the disk and the DVD, the same effect as having a plurality of different pseudo disks with one optical substrate can be obtained. That is, the pseudo disk can be shared. As a result, there is no need to provide a plurality of microscope optical systems and switch between them with a revolver or the like, thereby improving the durability of the inspection apparatus, simplifying the inspection apparatus itself, and reducing the cost. In addition, inspection workability is improved.

In addition, by securing the optical path length, 2
If the focusing positions of the two lights are set to substantially the same position, it is possible to inspect the light spots that follow two different paths at substantially the same position, and each light spot can be inspected only by finely adjusting the focal position of the microscope optical system. Can be observed. As a result, observation workability is improved.

Further, since the optical substrate of the present invention has a reflecting surface for transmitting a predetermined amount of light from the light source and reflecting the predetermined amount of light, an optical path length in the optical substrate is secured by using the reflecting surface. Thereby, it becomes possible to correct aberrations that are greater than the plate thickness. As a result, for example, even if a plurality of pseudo disks (optical substrates) having different thicknesses are not provided for a CD and a DVD, an effect equivalent to providing a plurality of different pseudo disks by one optical substrate is obtained. Will play. That is, the optical substrate is shared in the light spot inspection apparatus, and not only the cost of the optical substrate is reduced, but also
It is possible to reduce the cost and improve the workability of the light spot inspection device provided with the optical substrate.

[Brief description of the drawings]

FIG. 1 shows a light spot inspection apparatus according to the present invention and a CD and a DVD.
FIG. 3 is a schematic diagram showing a relationship with an optical pickup device for an optical disk that performs recording / reproduction or the like using an optical disk such as an optical disk as an information recording medium.

FIGS. 2A and 2B are diagrams showing an optical substrate of the light spot inspection apparatus of FIG. 1, wherein FIG. 2A is a plan view, and FIG. 2B is a view of FIG. It is the figure seen from the arrow B direction.

FIG. 3 is a schematic diagram showing a path of light from a light source when an objective lens for DVD is arranged on an optical axis in the optical pickup device of FIG. 1;

FIG. 4 is a schematic diagram showing a path of light from a light source when an objective lens for CD is arranged on an optical axis in the optical pickup device of FIG. 1;

FIG. 5A is a schematic diagram showing a light path focused on a regular focus position in the light path of FIG. 4, and FIG.
FIG. 5 is a schematic diagram illustrating a light path different from (A) of the light paths in FIG. 4.

FIG. 6 is a schematic diagram showing an example in which a single lens is used for both DVD and CD objective lenses in a first modification of the embodiment of the present invention.

FIG. 7 is a schematic diagram showing an example of observing a focused light spot passing through each lens and on an incident surface of an optical substrate in a second modification of the embodiment of the present invention.

FIG. 8 shows a third modification of the embodiment of the present invention, in which the optical substrate is constituted by a single plate and an optical spot passing through each lens and focused on the incident surface of the optical substrate is observed. FIG.

FIG. 9 is a schematic diagram showing an example in which the focal position is shifted from the third surface of the optical substrate toward the microscope optical system in a fourth modification of the embodiment of the present invention.

FIG. 10 is a schematic diagram showing an example in which a focal position is shifted from a first surface of an optical substrate to a light source side in a fifth modification of the embodiment of the present invention.

FIG. 11 shows an objective lens and C of a conventional light spot inspection apparatus.
FIG. 3 is a schematic diagram showing a relationship with an optical pickup device for an optical disc that performs recording / reproduction or the like using an optical disc such as D or DVD as an information recording medium.

12 is a schematic diagram for explaining focusing of a light spot on a recording surface of a CD and focusing of a light spot on a recording surface of a DVD shown in FIG. 11;

[Explanation of symbols]

 Reference Signs List 1 optical pickup device 2 laser diode = LD (light source) 3 predetermined optical system 5 objective lens (part of predetermined optical system) 6 disk 6a recording surface 10 light spot inspection device 21 optical substrates 21a, 21b substrate 22 first Surface (reflective surface and incident surface) 23 Second surface (reflective surface and bonded surface) 24 Third surface (surface opposite to the incident surface) 31 Beam splitter (part of predetermined optical system) 32 Reflecting mirror (part of predetermined optical system) 33 Collimating lens (part of predetermined optical system) 51 Objective lens (for CD) 52 Objective lens (for DVD)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuo Higashiura 9959, Okaya-shi, Nagano F-term in the Nagano Prefecture Business Support Center (reference) 2F065 AA56 BB03 BB23 BB29 CC03 EE08 FF01 FF42 GG06 GG12 HH04 HH13 JJ01 JJ03 JJ09 JJ18 JJ26 LL04 LL12 LL46 PP24 SS02 SS13 2G086 EE02 2H042 AA02 AA07 AA31 5D119 AA38 BA01 DA20 JA09 PA05

Claims (11)

[Claims] 1. A light spot inspection apparatus for inspecting a shape of a light spot irradiated from a light source and focused on a recording surface of a disc serving as an information recording medium through a predetermined optical system, wherein the light source side and the light source side are inspected. An aberration correction optical substrate having a reflection surface for transmitting a predetermined amount of light and reflecting the predetermined amount of light between objective lenses provided on the side of the light spot inspection apparatus, respectively; By appropriately using the reflected light, it is possible to secure the optical path length in the optical substrate of the light emitted from the light source and requiring the aberration correction of the thickness dimension of the optical substrate or more, and perform the desired aberration correction. A light spot inspection device characterized by being possible. 2. The light spot inspection apparatus according to claim 1, wherein the optical substrate is capable of performing a desired aberration correction on a plurality of lights having different optical path lengths required for the aberration correction. . 3. When the optical substrate is not disposed, a plurality of light beams at which light spots are formed at different positions on the optical axis of the predetermined optical system are placed at substantially the same position by disposing the optical substrate. The light spot inspection device according to claim 1, wherein a light spot is formed. 4. A spot forming position of each light is outside the optical substrate.
The light spot inspection apparatus according to the above. 5. The optical substrate is formed by laminating and bonding two substrates in an optical axis direction, and the light source side surface (hereinafter, referred to as a first surface) and a bonding surface (hereinafter, referred to as a first surface) of the optical substrate. Hereinafter, the second surface is referred to as the reflection surface, and the spot forming position of the light transmitted through the first and second surfaces is referred to as the first surface.
And that the spot forming position of the light transmitted through the second surface after being transmitted through the second surface, reflected on the second surface, and further reflected on the first surface is substantially the same position on the optical axis. The light spot inspection apparatus according to claim 2, 3 or 4, wherein: 6. The two substrates constituting the optical substrate,
The light spot inspection apparatus according to claim 5, wherein the light spot inspection apparatus is formed to have substantially the same thickness in the optical axis direction. 7. When a plurality of light spots are formed at different positions on the optical axis of the predetermined optical system, the light spot forming position is closer to the light source when the optical substrate is not disposed. DVD (digital universal disc) for near light
7. The light for irradiating the recording surface of (1) or the light whose light spot formation position is further away from the light source is used as the light for irradiating the recording surface of a CD (compact disk). Light spot inspection equipment. 8. A pseudo disk used in a light spot inspection apparatus for inspecting the shape of a light spot irradiated from a light source and focused on a recording surface of a disk serving as an information recording medium via a predetermined optical system. An optical substrate for aberration correction as described above, including a reflecting surface that transmits a predetermined amount of light from a light source and reflects a predetermined amount of light, and is illuminated from the light source using the transmission and reflection, and is a thickness dimension of the optical substrate. Ensuring the optical path length of the light requiring the above aberration correction in the optical substrate,
An optical substrate for aberration correction, capable of performing desired aberration correction. 9. The optical substrate is formed by laminating and bonding two substrates in the optical axis direction, and a surface on the light source side (hereinafter, referred to as a first surface) and a bonding surface (hereinafter, referred to as a first surface) of the optical substrate. The optical substrate for aberration correction according to claim 8, wherein a second surface) is used as the reflection surface. 10. The optical substrate for aberration correction according to claim 9, wherein the two substrates constituting the optical substrate are formed to have substantially the same thickness in the optical axis direction. 11. An aberration correcting optical substrate having a reflecting surface that transmits a predetermined amount of light and reflects a predetermined amount of light, and appropriately uses transmitted light and reflected light formed by the reflecting surface.
Using an optical spot inspection device capable of securing the optical path length in the optical substrate of light that is irradiated from the light source and needs aberration correction equal to or greater than the thickness dimension of the optical substrate and that can perform desired aberration correction An optical pickup device wherein an inspection of a light spot shape is performed, and light emitted from a light source and a predetermined optical system are adjusted based on the inspection result.