JP4656879B2 - Optical pickup outgoing light measuring device and measuring method - Google Patents

Description

  The present invention relates to an outgoing light measuring apparatus and a measuring method for measuring characteristics such as astigmatism of outgoing light from an optical pickup.

  An information recording / reproducing apparatus for recording / reproducing an optical disc or the like records information by irradiating the optical disc with a laser beam, and reproduces information recorded on the optical disc by receiving reflected light. For this reason, the optical pickup provided in the information recording / reproducing apparatus focuses the laser beam on the information recording surface of the optical disc. At this time, aberration may occur in the laser light, and the beam spot formed on the optical disk may become an ellipse or the like instead of a perfect circle. Examples of the aberrations here include coma, astigmatism, and spherical aberration. In particular, astigmatism occurs due to the accuracy of optical components and the degree of optical adjustment, and reduces the reading accuracy of information from the optical disc and the writing accuracy of information.

  In order not to cause the above problems, the aberration of the optical pickup is usually measured and the optical system in the optical pickup is adjusted, or the one with a bad inspection result is discarded. For example, Patent Documents 1 to 3 describe a measurement device and an adjustment method for light emitted from an optical pickup. Specifically, the astigmatism is evaluated by expanding and defocusing the beam spot of the emitted light from the optical pickup using an optical head or the like, and measuring the shape of the beam spot. In this case, the shape of the beam spot to be measured is changed by moving the objective lens in the optical head using a piezo element. The reason why the piezo element is used is that high movement accuracy (for example, ± 1 μm) is required to move the objective lens and defocus the beam spot.

  However, in the above technique, since a piezo element is used, the measuring apparatus is expensive. Also, since the piezo element lacks durability, it is not suitable for continuous use such as inspection in the optical pickup production process.

JP 2002-90605 A JP 2003-207436 A JP 2002-177292 A

  Examples of the problem to be solved by the present invention are as described above. An object of the present invention is to provide an outgoing light measuring device and a measuring method for an optical pickup that is durable and inexpensive and simply configured.

In the invention according to claim 1, an outgoing light measuring device for an optical pickup that measures the characteristics of outgoing light emitted from the optical pickup includes an objective lens that emits the outgoing light from the optical pickup as parallel light, and A condensing lens that condenses parallel light emitted from the objective lens and forms a beam spot at a predetermined position, a moving means that moves the condensing lens in the optical axis direction, and the condensing lens that is disposed at the predetermined position. An imaging means for imaging the beam spot collected by the lens; a first position of the condenser lens corresponding to a first image of the beam spot imaged by the imaging means; and a beam spot imaged by the imaging means. Detecting means for detecting an astigmatism difference based on a distance from the second position of the condenser lens corresponding to the second image .

In the invention according to claim 6, in the method of measuring the emitted light of the optical pickup that measures the characteristics of the emitted light emitted from the optical pickup, the emitted light from the optical pickup is converted into parallel light by the objective lens, and the objective lens Condensing the emitted parallel light with a condensing lens to form a beam spot on the imaging means, a moving step of moving the condensing lens in the optical axis direction, and moving the condensing lens A measurement step of measuring the characteristics of the emitted light based on the image of the beam spot imaged by the imaging means, and the measurement step corresponds to a first image of the beam spot imaged by the imaging means Based on the distance between the first position of the condenser lens and the second position of the condenser lens corresponding to the second image of the beam spot imaged by the imaging means. And detecting the astigmatism.

In a preferred embodiment of the present invention, an outgoing light measuring device for an optical pickup that measures the characteristics of outgoing light emitted from an optical pickup comprises: an objective lens that emits the outgoing light from the optical pickup as parallel light; A condensing lens that condenses parallel light emitted from the objective lens and forms a beam spot at a predetermined position, a moving means that moves the condensing lens in the optical axis direction, and the condensing lens that is disposed at the predetermined position. An imaging means for imaging the beam spot collected by the lens; a first position of the condenser lens corresponding to a first image of the beam spot imaged by the imaging means; and a beam spot imaged by the imaging means. Detecting means for detecting an astigmatic difference based on a distance from the second position of the condenser lens corresponding to the second image .

The outgoing light measuring device of the optical pickup is preferably used for measuring aberrations such as astigmatism of outgoing light emitted from the optical pickup. In this emitted light measuring apparatus, the emitted light from the optical pickup is converted into parallel light by the objective lens, and the parallel light emitted from the objective lens is condensed as a beam spot at a predetermined position by the condenser lens. Basically, the magnification ratio of the beam spot is defined by the focal length of the objective lens and the condenser lens, and an enlarged beam spot is formed at a predetermined position. The condenser lens is moved in the optical axis direction by the moving means. Then, the emitted light measuring device defocuses the emitted light from the optical pickup by moving the condenser lens by a predetermined amount on the optical axis, and characteristics such as aberration based on the shape of the beam spot at that time. Measure. In this case, by making the optical path from the condenser lens to a predetermined position sufficiently longer than the optical path on the optical pickup side of the objective lens, high resolution can be eliminated when moving the condenser lens. . That is, when compared with the configuration of the comparative example in which the condenser lens is fixed and the objective lens is moved, the movement accuracy of the condenser lens in the above output light measuring device is required for the movement of the objective lens in the comparative example. It is considerably lower than the accuracy required. Therefore, it is not necessary to use high-precision moving means as moving means for the condensing lens, the emitted light measuring device can be configured at low cost, and measurement operation is facilitated.
In addition, the above-described emitted light measuring device of the optical pickup corresponds to a first image of the beam spot which is arranged at a predetermined position and images the beam spot collected by the condenser lens, and the beam spot captured by the imaging unit. Detecting means for detecting an astigmatism based on a distance between a first position of the collecting lens and a second position of the collecting lens corresponding to the second image of the beam spot imaged by the imaging means; Is provided. Thereby, the astigmatic difference indicating the degree of astigmatism can be detected appropriately. Therefore, the optical pickup can be evaluated on the basis of the astigmatic difference between the detected beam spots.

In one aspect of the emitted light measuring apparatus of the optical pickup, the first image is positioned closer to the objective lens than the focal point on the optical axis where the shape of the beam spot captured by the imaging unit is a perfect circle. The second image is an image at a second focal point that is located closer to the imaging means than the focal point.

  In another aspect of the emitted light measuring device of the above optical pickup, the optical pickup device further includes a plurality of lenses through which the light beam emitted from the condenser lens passes. By passing the light beam emitted from the condenser lens through a plurality of lenses, the direction of the image obtained at a predetermined position can be made coincident with the direction of the original beam spot, and the work in measurement becomes easy.

  In one preferred example, the moving means may be a moving mechanism that mechanically moves the condenser lens. In a preferred example, the objective lens is fixed. As described above, since the condensing lens is moved instead of the objective lens, the movement does not require such high accuracy that a piezo element or the like is required. Therefore, for example, a structure in which the condenser lens is moved by a mechanism such as a motor and a ball screw can be employed. As a result, the apparatus can be configured at low cost, and the operation of the moving means is not required to have so high accuracy, and the operation can be performed easily and quickly.

In another embodiment of the present invention, there is provided a method of measuring an outgoing light of an optical pickup that measures a characteristic of outgoing light emitted from an optical pickup, wherein the outgoing light from the optical pickup is converted into parallel light by an objective lens. A condensing step of condensing the emitted parallel light by a condensing lens to form a beam spot on the imaging means, a moving step of moving the condensing lens in the optical axis direction, and moving the condensing lens A measurement step of measuring the characteristics of the emitted light based on the image of the beam spot imaged by the imaging means, and the measurement step corresponds to a first image of the beam spot imaged by the imaging means Based on the distance between the first position of the condenser lens and the second position of the condenser lens corresponding to the second image of the beam spot imaged by the imaging means. Detecting the astigmatism. Even with this method of measuring the emitted light of the optical pickup, the accuracy required for moving the condenser lens is not so high compared to moving the objective lens with a piezo element, etc. Measurements can be made. Also, the astigmatic difference can be appropriately detected based on a plurality of beam spot images obtained by changing the defocused state of the beam spot, and the optical pickup is appropriately evaluated based on the astigmatic difference. Can do.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[Configuration of outgoing light measurement device]
First, the configuration of the emitted light measurement apparatus 100 according to an embodiment of the present invention will be described with reference to FIG. The emitted light measuring device 100 includes the optical head 20 and the image processing system 40, and is a device that measures aberrations of the light beam b2 emitted from the optical pickup 10 or the like, for example, astigmatism.

  The optical pickup 10 includes a laser diode 1 that emits a beam having a specific wavelength. The optical system provided in the optical pickup 10 adjusts the parallelism and optical axis angle of the light beam emitted from the laser diode 1, and guides the light beam to a predetermined path by a mirror. Then, the optical pickup 10 emits the light beam b2 collected by the objective lens 8 to the optical head 20. The optical pickup 10 is an apparatus that irradiates a light beam onto an information recording surface of an optical disc when information is recorded on or reproduced from an optical disc such as a DVD (Digital Versatile Disc) or a CD (Compact Disc). Yes, it is mounted on information recording devices and information reproducing devices.

  The light beam b <b> 2 emitted from the optical pickup 10 enters the optical head 20 through the objective lens 21. Although details will be described later, in the optical head 20, the light beam b <b> 2 is converted into parallel light by the objective lens 21, and the parallel light is condensed by a condenser lens and irradiated to an imaging means such as a CCD camera. Then, the beam spot of the light beam collected by the optical lens is imaged by the CCD camera, and the image data S 1 of the imaged beam spot is supplied to the image processing system 40.

  The image processing system 40 includes a PC (personal computer) 41 and a monitor 42. The PC 41 acquires the image data S1 from the optical head 20 and displays it on the monitor 42. A user (for example, a person who inspects the optical pickup 10) looks at the shape of the beam spot displayed on the monitor 42 and operates the PC 41 to change the position of the condensing lens in the optical head 20. The degree of defocusing of the light beam in the optical head 20 can be adjusted. In this case, the PC 41 supplies a control signal S2 corresponding to a user operation to the optical head.

  The adjustment of the position of the condensing lens in the optical head 20 is not limited to being performed by operating the PC 41, and the user may be configured to directly operate the optical head 20.

[Configuration of optical pickup]
Next, a specific configuration of the optical pickup 10 will be described. FIG. 2 is a perspective view showing a schematic configuration of the optical pickup 10.

  The optical pickup 10 includes a laser diode 1, a collimator lens 2, half mirrors 3 and 4, a mirror 5, a multi lens 6, a light receiving element 7, an objective lens 8, an actuator 9, and a casing 11. Prepare.

  The laser diode 1 emits a light beam b1 having a specific wavelength and makes the light beam b1 incident on the collimator lens 2. The collimator lens 2 makes the light beam b1 parallel light. The light beam b1 that has passed through the collimator lens 2 is guided to a predetermined path by the half mirrors 3 and 4 and the mirror 5, and enters the objective lens 8.

  The objective lens 8 is fixed on the actuator 9, collects the incident light beam b1, and emits it as a light beam b2. The actuator 9 is movably disposed in the casing 11 and can move the objective lens 8 in the radial direction of the optical disc D as indicated by an arrow 9a. This makes it possible to perform so-called tracking servo in which the spot of the light beam b2 emitted from the objective lens 8 is arranged on the target track of the optical disc D.

  The light beam b2 emitted from the objective lens 8 is applied to the information recording surface of the optical disc D. At this time, the reflected light b3 reflected by the optical disc D enters the objective lens 8. The reflected light b <b> 3 is reflected by the mirror 5, passes through the half mirror 4, and enters the multilens 6. The reflected light b <b> 3 is collected by the multi lens 6 and received by the light receiving element 7. Thereby, the information recorded on the optical disc D can be read.

  Here, astigmatism of the light beam b2 emitted from the optical pickup 10 will be described with reference to FIG.

  For example, the light beam b2 emitted from the objective lens 8 has astigmatism, and the shape (cross-sectional shape) differs depending on the focal position. Specifically, the shape of the light beam b2 is an ellipse extending in one direction as indicated by reference numeral 50 near the focal point on the objective lens 8 side, and indicated by reference numeral 52 near the focal point on the side away from the objective lens 8. The ellipse extends in a direction perpendicular to the tip of the tip, and a perfect circle as indicated by reference numeral 51 is provided at a substantially intermediate position between the two focal positions. The position 53 where the shape of the light beam b2 is a perfect circle is referred to as “focusing point”. The distance E between the focal positions is called “astigmatic difference”. The optical pickup 10 preferably has an astigmatic difference E of approximately 1 μm or less.

  The emitted light measuring apparatus 100 according to the present embodiment changes the condensing point of the emitted light from the optical pickup 10 on the CCD camera (that is, defocuses the light beam), and photographs the shape of the beam spot. The astigmatic difference E is measured based on the shape of the beam spot. Based on the obtained astigmatic difference E, the optical pickup 10 is evaluated.

[Configuration of optical head]
Below, the structure of the optical head 20 of the emitted light measuring apparatus 100 which concerns on a present Example is demonstrated. Prior to the description of the optical head 20 shown in FIG. 1, the basic operation and the like will be described based on the optical head 20a having the same basic configuration. FIG. 4 is a diagram showing a configuration of the optical head 20a. FIG. 4 shows a cross-sectional view along a plane parallel to the optical axis direction of the optical head 20a. In FIG. 1, the optical head 20 receives the light emitted from the optical pickup 10 from below, but in the basic configuration shown in FIG. 4, in order to facilitate understanding, along the length direction of the optical head 20 a. It is assumed that light emitted from the optical pickup is supplied.

  The optical head 20 a includes an objective lens 21, an objective lens holding part 22, a condenser lens 23, a condenser lens holding part 24, an actuator 25, a CCD camera 26, and a casing 27.

  The light beam b2 emitted from the objective lens 8 of the optical pickup 10 enters the objective lens 21 of the optical head 20a. The objective lens 21 is fixed to the objective lens holding part 22, and the objective lens holding part 22 is fixed to the casing 27. That is, the objective lens 22 is disposed in the optical head 20a in a state where it cannot move. The objective lens 21 emits the parallel light b <b> 4 a and makes it incident on the condenser lens 23.

  The condenser lens 23 is disposed substantially perpendicular to the parallel light b <b> 4 a and is fixed to the condenser lens holding unit 24. The condenser lens holder 24 is held by an actuator 25 so as to be movable. The actuator 25 includes a mechanical movement mechanism such as a motor and a ball screw, for example, and moves the condenser lens holding unit 24 in the direction indicated by the arrow 55, that is, in the optical axis direction. Thereby, the condensing lens 23 can be moved and the degree of defocus of the parallel light b4a can be changed. Note that the actuator 25 is controlled by a control signal S2 supplied from the PC 41, the moving direction, the moving amount, and the like, and functions as a moving unit.

  The condenser lens 23 condenses the parallel light b4a and irradiates the CCD camera 26 with the light beam b4b to form a beam spot. The CCD camera 26 images the beam spot of the supplied light beam b4b and supplies image data S1 of the captured beam spot to the PC 41.

  Here, the reason for moving the condenser lens 23 instead of the objective lens 21 in the optical head 20a of the present embodiment will be described with reference to FIG.

  FIG. 5 is a diagram schematically showing the relationship between the objective lens 21 and the condenser lens 23 in the optical head 20a, and the positional relationship between the original object and the image formed by the objective lens 21 and the condenser lens 23. Is shown. The image A ′ of the object A at the position 57 a on the optical axis appears at the position 57 b by the objective lens 21 and the condenser lens 23. The light incident on the objective lens 21 is indicated by b4aa, and the light emitted from the condenser lens 23 is indicated by b4ba.

In this case, the lateral magnification beta is _{β = -f out / f in =} -A '/ A becomes defined by the focal length f _out of the focal length f _in and the condenser lens 23 of the objective lens 21, the longitudinal magnification alpha alpha = the β ^2. In the arrangement of FIG. 5, the focal length f _in the objective lens 21 is equal to the distance between the original object A and the objective lens 21. The focal length f _out of the condenser lens 23 is equal to the distance between the image A ′ created by the objective lens 21 and the condenser lens 23 and the condenser lens 23.

Next, it is assumed that the object A is moved by a distance C in a direction away from the objective lens 21. That is, the same object B as the object A is arranged at the position 58a. In this case, the light incident on the objective lens 21 is indicated by reference numeral b4ab, the light emitted from the condenser lens 23 is indicated by reference numeral b4bb, and the image B ′ of the object B is created at the position 58b. The distance delta (i.e., the distance between the position 57b to the position 58b) of the image A 'and the image B' becomes Δ = Cα = Cβ ^2. For example, when the focal length f _out of the condenser lens 23 is 50 times the focal length f _in the objective lens 21, i.e., when the lateral magnification beta = 50 (longitudinal magnification alpha = 2500), a distance delta = 2500C. Therefore, the distance between the created images A ′ and B ′ is shifted by a distance 2500 times the distance C between the original objects A and B. Since moving the objective lens 21 is equivalent to moving the original object, moving the objective lens 21 by the distance C is equivalent to moving the condenser lens 23 by the distance Δ.

  In the optical system constituted by the objective lens 21 and the condenser lens 23 in the optical head 20a shown in FIG. 4, in order to change the defocus state of the incident light beam, either the objective lens 21 or the condenser lens 23 is used. One side may be moved. Normally, the distance F1 from the tip of the optical head 20a to the objective lens 21 is smaller than the distance F2 between the condenser lens 23 and the CCD camera 26. That is, since the focal length of the condenser lens 23 is considerably larger than the focal length of the objective lens 21, as in the example of FIG. 5, moving the objective lens 21 by C moves the condenser lens 23 by Δ. Is equivalent to Therefore, in order to make the light beam incident on the optical head 20a the same defocused state, it is easier to move the condenser lens 23 with a lower resolution than to move the objective lens 21 with a higher resolution.

  For this reason, in this embodiment, the condenser lens 23 is moved instead of the objective lens 21 in order to change the shape of the incident light beam in a defocused state. Thereby, the apparatus which moves the condensing lens 23 can be comprised with simple apparatuses, such as the actuator 25. FIG. Since there is no need to use an expensive piezo element or the like unlike the configuration in which the objective lens 21 is moved, the emitted light measuring device 100 can be configured at low cost.

  Next, a measurement example of the beam spot shape using the optical head 20a according to the present embodiment will be specifically described with reference to FIG.

  FIG. 6A shows a method for moving the condenser lens 23. The PC 41 controls the actuator 25 so that the condenser lens 23 moves in the direction indicated by the arrow 60. Then, when the condensing lens 23 reaches the positions indicated by the symbols K1, K2, K3, K4, and K5, the shape of the beam spot is imaged by the CCD camera 26. Images captured at these positions are displayed on the monitor 42 as shown in FIGS. Note that the positions to be imaged are equally spaced.

  6 (b), (c), (d), (e), and (f), the CCD camera 26 is obtained when the condenser lens 23 is disposed at the positions indicated by reference numerals K1, K2, K3, K4, and K5. The shapes of the beam spots SPa, SPb, SPc, SPd, SPe (hereinafter referred to as “beam spot SP” when including “all”) imaged in FIG. The beam spot SP is displayed on the monitor 42 so that the color changes stepwise according to the laser power. 6B to 6F, the color change is roughly shown by hatching. Specifically, as shown in FIG. 6B, the area indicated by reference numeral 61a in the center of the beam spot SPa has the strongest laser power, and the area from the center to the area indicated by reference numeral 61b and the area indicated by reference numeral 61c. The laser power decreases as the distance increases. The beam spot SPa corresponding to the position K1 has an elliptical shape extending in one direction, and the above laser power distribution is widened.

  As shown in FIG. 6C, the beam spot SPb corresponding to the position K2 also has an elliptical shape extending in the same direction, and the laser power distribution is widened. However, the long side is gentler than the beam spot SPa, and the spread of the laser power distribution is small. As shown in FIG. 6D, it can be seen that the beam spot SPc corresponding to the position K3 has a perfect circle shape, and the ratio of the region having the strongest laser power is large. That is, the beam spot SPc corresponds to the in-focus position 53 in FIG.

  As shown in FIG. 6E, the beam spot SPd corresponding to the position K4 has an elliptical shape extending in a direction substantially perpendicular to the beam spot SPb, and the laser power distribution is widened. Further, as shown in FIG. 6F, the beam spot SPe corresponding to the position K5 has an elliptical shape extending in a direction substantially perpendicular to the beam spot SPa, and the laser power distribution is widened. That is, it can be seen that the shape of the beam spot SP and the distribution of the laser power are substantially line symmetric with respect to the focal point position 53. If the positions K1 and K5 corresponding to FIGS. 6B and 6F are focal points, the astigmatic difference E corresponds to the distance between K1 and K5 in FIG. Therefore, the astigmatic difference E can be obtained by calculating the distance between the positions K1 to K5 based on the moving distance of the actuator 25. In this way, by displaying the beam spot SP on the monitor 42, it is possible to measure the astigmatism E and evaluate the optical pickup 10.

  Next, the optical head 20 shown in FIG. 1 will be described.

  FIG. 7 is a schematic configuration diagram of the optical head 20 shown in FIG. FIG. 7 is a sectional view taken along a plane parallel to the optical axis direction of the optical head 20. In addition, the same code | symbol is attached | subjected about the component same as the above-mentioned optical head 20a, and the description is abbreviate | omitted.

  The optical head 20 is different from the optical head 20a in that the parallel light b4a emitted from the objective lens 21 is reflected by the mirror 28 and is incident on the condenser lens 23. As a result, the optical pickup 10 can be disposed below the optical head 20, and the measurement environment can be saved.

  The optical head 20 is different from the optical head 20a in that the beam b4b emitted from the condenser lens 23 is further incident on the objective lens 30 and the condenser lens 31. Specifically, the beam b 4 b emitted from the condenser lens 23 is incident on the objective lens 30, and the parallel light b 5 a emitted from the objective lens 30 is incident on the condenser lens 31. Then, the condensing lens 31 supplies the light beam b <b> 5 b to the CCD camera 26. Since the beam spot that passes through only the objective lens 21 and the condenser lens 23 and is picked up by the CCD camera 26 is upside down, left and right, the light beam emitted from the condenser lens 23 is further converted into the objective lens 30. By passing the condenser lens 31, the up / down / left / right directions are reversed again. Thereby, the moving direction of the light beam emitted from the optical pickup 10 and the moving direction of the beam spot imaged by the CCD camera 26 can be matched, and the user can easily adjust the apparatus while viewing the monitor 42. Become.

  In the optical head 20 shown in FIG. 7, the light beam path is linearly arranged for simplification of description, but actually, the light beam path is optically changed by using a plurality of mirrors. It is possible to make a detour within the head 20. Even with the same optical configuration, the length of the actual optical head can be shortened by bypassing the path of the light beam in relation to other optical components and moving mechanisms mounted on the optical head 20. It is possible to reduce the size of the optical head.

It is a figure which shows schematic structure of the emitted light measuring apparatus which concerns on the Example of this invention. It is a perspective view which shows schematic structure of an optical pick-up. It is a figure for demonstrating the astigmatism which arises with an optical pick-up. It is a figure which shows the basic composition of the optical head based on the Example of this invention. It is a figure which shows typically the optical system by the objective lens and condensing lens in an optical head. It is a figure which shows the specific example of the beam spot shape displayed on a monitor. It is a figure which shows schematic structure of the optical head shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser diode 10 Optical pick-up 20, 20a Optical head 23, 31 Condensing lens 25 Actuator 40 Image processing system 41 PC (personal computer)
42 Monitor 100 Emission Light Measuring Device

Claims (6)

An optical output measuring device for an optical pickup that measures the characteristics of the outgoing light emitted from the optical pickup,
An objective lens that emits light emitted from the optical pickup as parallel light; and
A condensing lens that condenses the parallel light emitted by the objective lens and forms a beam spot at a predetermined position;
Moving means for moving the condenser lens in the optical axis direction;
An imaging means that images the beam spot arranged at the predetermined position and collected by the condenser lens;
The first position of the condenser lens corresponding to the first image of the beam spot imaged by the imaging means, and the second position of the condenser lens corresponding to the second image of the beam spot imaged by the imaging means And a detecting means for detecting an astigmatic difference based on the distance between the optical pickup and the emitted light measuring apparatus for an optical pickup.   The first image is an image at a first focal point located on the objective lens side with respect to the focal point on the optical axis where the shape of the beam spot captured by the imaging unit is a perfect circle, and the first image 2. The emitted light measuring apparatus for an optical pickup according to claim 1, wherein the second image is an image at a second focal point located closer to the imaging unit than the in-focus point.   The emitted light measuring apparatus for an optical pickup according to claim 1, further comprising a plurality of lenses through which the light beam emitted from the condenser lens passes.   The emitted light measuring apparatus for an optical pickup according to claim 1, wherein the moving unit is a moving mechanism that mechanically moves the condenser lens.   The emitted light measuring device according to any one of claims 1 to 4, wherein the objective lens is fixed. A method for measuring the outgoing light of an optical pickup for measuring the characteristics of outgoing light emitted from the optical pickup,
A condensing step of making the emitted light from the optical pickup into parallel light by an objective lens, condensing the parallel light emitted by the objective lens by a condenser lens, and forming a beam spot on the imaging means;
A moving step of moving the condenser lens in the optical axis direction;
Measuring the characteristics of the emitted light based on the image of the beam spot imaged by the imaging means while moving the condenser lens , and
In the measuring step, the first position of the condenser lens corresponding to the first image of the beam spot imaged by the imaging unit and the condensing corresponding to the second image of the beam spot imaged by the imaging unit. An astigmatism difference is detected based on a distance from a second position of a lens, and a method for measuring emitted light of an optical pickup.

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