JP2009008594A - Optical element unit and interferometer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element unit held so that deformation or distortion does not occur even when the thickness of a correction plate as an optical element is small, and to provide an interferometer capable of measuring a subject lens at a high measurement accuracy using the optical element unit. <P>SOLUTION: The optical element unit has an optical element and a holding member for holding the optical element. The optical element is a flat plate that has a thickness of 0.05-0.15 mm and is made of synthetic resin or glass. The optical element is stuck to the holding member via a sphere. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical element unit holding a thin flat optical element and an interferometer including the optical element unit.

  Conventionally, an interferometer has been used for inspection of an objective lens for an optical pickup device.

  On the other hand, using a laser light source with a wavelength of 400 to 420 nm, which is shorter than the wavelength used for conventional DVDs (digital versatile discs), and an objective lens with an NA (numerical aperture) of about 0.85, higher density information High density optical discs that perform recording are known. In a high-density optical disk using an objective lens with an NA of 0.85, coma aberration generated due to the inclination (skew) of the optical disk increases, so the protective layer is thinner than DVD (compared to 0.6 mm of DVD). 0.1 mm).

In order to evaluate this objective lens with a high NA, a lens in which the reference spherical surface of the interferometer is a hemispherical lens and a thickness corresponding to a protective layer is added to the incident surface side is known (for example, Patent Documents). 1).
JP-A-10-90113

  However, when the hemispherical lens disclosed in Patent Document 1 is used as a reference spherical surface, noise caused by surface reflection, particularly vertex reflection, overlaps with interference fringes, and the measurement accuracy decreases, and the polarization direction of obliquely incident light changes. As a result, there is a problem that the measurement accuracy decreases.

  On the other hand, in the case where a correction plate having a thickness corresponding to the protective layer is interposed in front of the conventional reference spherical surface, the correction plate is very thin when the thickness of the correction plate is 0.1 mm as described above. There is a problem of causing a decrease in measurement accuracy.

  In view of the above problems, the present invention has an object to obtain an optical element unit that is held so as not to be deformed and distorted even if the thickness of a correction plate that is an optical element is thin, and by using the optical element unit, An object of the present invention is to obtain an interferometer capable of measuring a lens to be examined with high measurement accuracy.

  The above object is achieved by the invention described below.

  1. An optical element unit having an optical element and a holding member for holding the optical element, wherein the optical element is a flat plate made of synthetic resin or glass having a thickness of 0.05 mm to 0.15 mm, The optical element unit, wherein the optical element is bonded to the holding member via a sphere.

  2. An optical element unit having an optical element and a holding member for holding the optical element, wherein the optical element is a flat plate made of synthetic resin or glass having a thickness of 0.05 mm to 0.15 mm, The holding member is formed with an inclined surface, and the inclined surface is bonded to a side peripheral surface of the optical element.

  3. An optical element unit having an optical element and a holding member for holding the optical element, wherein the optical element is a flat plate made of synthetic resin or glass having a thickness of 0.05 mm to 0.15 mm, A plurality of tongue portions are formed on the holding member, and an end surface of the tongue portion and a side peripheral surface of the optical element are bonded to each other.

  4). An optical element unit having an optical element and a holding member for holding the optical element, wherein the optical element is a flat plate made of synthetic resin or glass having a thickness of 0.05 mm to 0.15 mm, The holding member is formed with a plurality of tongue portions, and the tongue portion and the optical surface of the optical element are bonded to each other.

  5). 5. The holding member according to 3 or 4, wherein a tongue-shaped portion in contact with a side peripheral surface of the optical element and a tongue-shaped portion in contact with the optical surface of the optical element are alternately formed. Optical element unit.

  6). The optical element unit according to any one of claims 1 to 5, wherein the optical element has a circular shape, and there are three attachment positions of the holding member to which the optical element is attached.

  7. An optical element unit having an optical element and a holding member for holding the optical element, wherein the optical element is a flat plate made of synthetic resin or glass having a thickness of 0.05 mm to 0.15 mm, The optical element unit, wherein the optical element is pressed against and held by the holding member at a plurality of locations by a leaf spring.

  8). A laser light source that emits a light beam having a predetermined wavelength, a reference plane, a reference spherical surface that reflects the light beam that has passed through the test lens, and the optical element unit according to any one of 1 to 7 are provided. Interferometer.

  9. 9. The interferometer according to claim 8, wherein the optical element unit is integrally fixed to the reference spherical surface.

  According to the present invention, it is possible to obtain an optical element unit that is held so as not to be deformed and distorted even when the thickness of the correction plate, which is an optical element, is thin. By using this optical element unit, high measurement is possible. It is possible to obtain an interferometer that maintains accuracy.

  Hereinafter, the present invention will be described in detail with reference to embodiments, but the present invention is not limited thereto.

  FIG. 1 is a diagram illustrating an example of an optical element unit 10 according to the present embodiment. FIG. 2A is a front view, FIG. 2B is a cross-sectional view taken along line AA shown in FIG. 1A, and FIG.

  An optical element unit 10 shown in FIG. 1 includes a correction plate 11 that is an optical element, a holding member 12, and a sphere 13 provided between the correction plates 11.

  The correction plate 11 is a translucent member, is a flat plate made of synthetic resin or glass having a thickness of 0.05 mm to 0.15 mm, and has a circular outer shape. The holding member 12 has an opening 12k at the center.

  The sphere 13 is placed on the holding member 12 with the adhesive B applied thereto, or the adhesive B is dropped after being placed on the holding member 12, and then the correction plate 11 is placed on the sphere 13. It is mounted and unitized.

  The spherical body 13 is a steel ball or the like, for example, and is placed at three positions between the correction plate 11 and the holding member 12 at approximately 120 degree intervals.

  In the case of the correction plate having the above thickness, the diameter of the sphere 13 is preferably Φ0.1 to Φ1.0 mm, and more preferably Φ0.3 mm to Φ0.5 mm.

  By adhering via the sphere 13 in this way, the correction plate 11 is bonded with the adhesive B in a minute space formed with the sphere 13, and excess adhesive is added to the correction plate 11. Therefore, the influence of solidification shrinkage can be suppressed, and the correction plate 11 can be bonded without distortion.

  If the diameter of the sphere 13 is smaller than Φ0.1 mm, the gap between the holding member 12 and the correction plate 11 is too small, and it is difficult to control the dripping amount of the adhesive B. On the other hand, if it is larger than Φ1.0 mm, the distortion of the bonded portion of the correction plate 11 due to the solidification shrinkage of the adhesive B becomes large, and there is a possibility that it may reach the region used for measurement.

  FIG. 2 is a diagram illustrating another example of the optical element unit 10 according to the present embodiment. FIG. 2A is a front view, FIG. 2B is a cross-sectional view taken along line AA shown in FIG. 1A, and FIG.

  The optical element unit 10 shown in FIG. 1 includes a correction plate 11 that is an optical element and a holding member 12.

  The correction plate 11 is a translucent member, is a flat plate made of synthetic resin or glass having a thickness of 0.05 mm to 0.15 mm, and has a circular outer shape.

  The holding member 12 has an opening 12k at the center. The holding member 12 has an opening 12k and inclined surfaces 12s formed at three locations at intervals of approximately 120 degrees.

  As shown in FIG. 3C, the side surface of the correction plate 11 and an inclined surface 12 s formed on the holding member 12 are bonded with an adhesive B.

  In this way, by bonding the inclined surface 12s formed on the holding member 12 and the side peripheral surface of the correction plate 11 which is an optical element, only the side peripheral surface of the correction plate 11 is bonded, The stress due to the solidification shrinkage acts on the correction plate 11 as a tension, and the correction plate 11 can be bonded without distortion.

  FIG. 3 is a diagram illustrating another example of the optical element unit 10 according to the present embodiment. FIG. 2A is a front view, FIG. 2B is a cross-sectional view taken along line AA shown in FIG. 1A, and FIG.

  The optical element unit 10 shown in FIG. 1 includes a correction plate 11 that is an optical element and a holding member 12.

  The correction plate 11 is a translucent member, is a flat plate made of synthetic resin or glass having a thickness of 0.05 mm to 0.15 mm, and has a circular outer shape.

  The holding member 12 has an opening 12k at the center. In addition, on the inner peripheral side of the holding member 12, tongue-like portions 12t are formed at three locations at intervals of approximately 120 degrees. The tongue-shaped portion 12t is formed to have a thickness substantially equal to that of the correction plate 11.

  As shown in FIG. 2C, the side peripheral surface of the correction plate 11 and the tongue-like portion 12 t formed on the holding member 12 are bonded by an adhesive B.

  In this way, by bonding the tongue 12t formed on the holding member 12 and the side peripheral surface of the correction plate 11 which is an optical element, only the side peripheral surface of the correction plate 11 is bonded. The stress due to solidification shrinkage acts as a tension on the correction plate 11, and the correction plate 11 can be bonded without distortion.

  FIG. 4 is a diagram illustrating another example of the optical element unit 10 according to the present embodiment. FIG. 2A is a front view, FIG. 2B is a cross-sectional view taken along line AA shown in FIG. 1A, and FIG.

  The optical element unit 10 shown in FIG. 1 includes a correction plate 11 that is an optical element and a holding member 12.

  The correction plate 11 is a translucent member, is a flat plate made of synthetic resin or glass having a thickness of 0.05 mm to 0.15 mm, and has a circular outer shape.

  The holding member 12 has an opening 12k at the center. In addition, on the inner peripheral side of the holding member 12, tongue-like portions 12t are formed at three locations at intervals of approximately 120 degrees.

  As shown in FIG. 3C, the optical surface of the correction plate 11 and the tongue-like portion 12 t formed on the holding member 12 are bonded with an adhesive B.

  In this manner, the correction plate 11 can be bonded without distortion by bonding the tongue 12t formed on the holding member 12 and the optical surface of the correction plate 11 which is an optical element. In such a case, it is preferable that the width of the tongue-shaped portion 12t be as thin as possible. By doing so, the correction plate 11 can be bonded with a minimum bonding area, and the correction plate 11 can be bonded without distortion.

  FIG. 5 is a diagram showing another example of the optical element unit 10 according to the present embodiment. FIG. 2A is a front view, FIG. 2B is a cross-sectional view taken along line AA shown in FIG. 1A, and FIG.

  The optical element unit 10 shown in FIG. 1 includes a correction plate 11 that is an optical element and a holding member 12.

  The correction plate 11 is a translucent member, is a flat plate made of synthetic resin or glass having a thickness of 0.05 mm to 0.15 mm, and has a circular outer shape.

The holding member 12 has an opening 12k at the center. Further, on the inner peripheral side of the holding member 12, tongue-like portions 12t are formed at six locations at intervals of approximately 60 degrees. The tongue-shaped portion 12t is formed with a tongue-shaped portion 12t ₁ in contact with the side peripheral surface of the correction plate 11 and a tongue-shaped portion 12t ₂ in contact with the optical surface of the correction plate 11 alternately. That is, the tongue-shaped portion 12t ₁ is formed at intervals of 120 degrees, the tongue-shaped portion 12t ₂ is also formed at intervals of 120 degrees, and the tongue-shaped portions 12t ₁ and 12t ₂ are formed in a state shifted by 60 degrees. Further, the tongue-shaped portion 12t ₁ is formed to have a thickness substantially equal to that of the correction plate 11. Such a shape of the holding member 12 can be formed by, for example, producing two plate materials in which the tongue-like portions 12t ₁ are formed in increments of 120 degrees by etching and bonding them in a state shifted by 60 °.

As shown in FIG. 4C, the side peripheral surface of the correction plate 11 and the tongue-shaped portion 12t ₁ are bonded by the adhesive B, and the tongue-shaped portion 12t ₂ is a receiving portion of the correction plate 11.

In this way, the tongue-like portion 12t ₁ in contact with the side peripheral surface of the correction plate 11 and the tongue-like portion 12t ₂ in contact with the optical surface of the correction plate 11 are alternately formed, and the side peripheral surface of the correction plate 11 and the tongue-like portion 12t are formed. By adhering ₁ , only the side peripheral surface of the correction plate 11 is bonded, and the stress due to solidification contraction acts as a tension on the correction plate 11, and the correction plate 11 can be bonded without distortion.

In addition, the width of the tongue-shaped portion 12t ₂ in contact with the optical surface of the correction plate 11 can be formed to be extremely thin, and the tongue-shaped portion 12t ₂ and the optical surface of the correction plate 11 can be bonded with a minimal bonding area. An effect can be obtained.

  FIG. 6 is a diagram illustrating another example of the optical element unit 10 according to the present embodiment. The figure (a) is a front view, The figure (b) is sectional drawing cut | disconnected by the AA line shown to the figure (a).

  The optical element unit 10 shown in FIG. 1 includes a correction plate 11, which is an optical element, a holding member 12, and a leaf spring member 14.

  The correction plate 11 is a translucent member, is a flat plate made of synthetic resin or glass having a thickness of 0.05 mm to 0.15 mm, and has a circular outer shape.

  The holding member 12 has an opening 12k at the center. Further, the leaf spring member 14 is annular, and tongue-shaped pressing portions 14p are formed at three locations at intervals of approximately 120 degrees on the inner peripheral portion thereof. The leaf spring member 14 is fixed to the holding member 12.

  As shown in FIG. 2B, the correction plate 11 is sandwiched between the holding member 12 and the holding portion 12 within the holding member 12.

  In this way, by holding and pressing the holding member 12 with the holding portions 14p formed at a plurality of positions on the plate spring member 14, the optical plate held so as not to be deformed and distorted even if the correction plate 11 is thin. An element unit can be obtained. In the case of this example, there is also an effect that adjustment of the pressing force for pressing the correction plate 11 is easy.

  The optical element unit according to the present embodiment described with reference to FIGS. 1 to 6 provides an optical element unit that is held so as not to be deformed and distorted even if the correction plate as an optical element is thin. It becomes possible.

  In the interferometer, the above-described optical element unit is used by being disposed between a test lens that is an objective lens for an optical disk having an NA of about 0.85 and a reference spherical surface. The interferometer is applied to a Twiman Green interferometer or a Fizeau interferometer, and will be described below by taking a Twyman Green interferometer as an example.

  FIG. 7 is a diagram showing an outline of a Twiman Green interferometer having the optical element unit according to the present embodiment.

  In the interferometer 1 shown in the figure, a light beam having a wavelength of 400 to 420 nm oscillated from the laser light source 21 is converted into a parallel light beam by the lens 22, a light beam that passes through the semi-transparent mirror 23, and a light beam that reflects to the reference plane 24. It is divided into.

  The light beam directed toward the reference plane 24 is reflected by the reference plane 24 and returns. The light beam that has passed through the semi-transparent mirror 23 is incident on a test lens 25 that is an objective lens for an optical disk having an NA of about 0.85, and is collected by the test lens 25 so as to form a light spot. The optical element unit 10 described above is disposed in the condensing optical path of the test lens 25. In this example, a correction plate having a thickness of, for example, 0.0875 mm is used.

  The light beam that has passed through the test lens 25 has a spherical wavefront, and is reflected by the reference spherical surface 26 after passing through the correction plate of the optical element unit 10. The reference spherical surface 26 is a spherical concave mirror.

  The light reflected by the reference spherical surface 26 returns after passing through the correction plate of the optical element unit 10, passes through the test lens 25, and becomes a planar wavefront again, and is reflected by the semi-transparent mirror 23 toward the lens 27. Interference with the wavefront of the plane reflected and returned by the reference plane 24 forms an interference fringe. The interference fringes are displayed on a monitor (not shown) using the imaging device 28, and the state of the wavefront formed by the lens 25 to be measured is quantitatively determined.

  If the correction plate is distorted during this measurement, the wavefront will be disturbed due to causes other than the lens to be tested, and correct performance evaluation of the lens to be tested will not be possible. It is possible to obtain an interferometer that can measure the lens with high measurement accuracy.

  When measuring with an interferometer, the reference spherical surface and the optical element unit may need to be moved to replace the test lens. To maintain the mutual positional relationship, the reference spherical surface and the optical element unit are integrated. It is preferable that the configuration is suitable.

It is a figure which shows an example of the optical element unit which concerns on this Embodiment. It is a figure which shows the other example of the optical element unit which concerns on this Embodiment. It is a figure which shows the other example of the optical element unit which concerns on this Embodiment. It is a figure which shows the other example of the optical element unit which concerns on this Embodiment. It is a figure which shows the other example of the optical element unit which concerns on this Embodiment. It is a figure which shows the other example of the optical element unit which concerns on this Embodiment. It is a figure which shows the outline of the twiman green interferometer which has the optical element unit which concerns on this Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Interferometer 10 Optical element unit 11 Correction board 12 Holding member 13 Sphere 14 Leaf spring member 21 Laser light source 23 Semi-transparent mirror 24 Reference plane 25 Test lens 26 Reference spherical surface 28 Imaging device

Claims (9)

An optical element unit having an optical element and a holding member for holding the optical element,
The optical element is a flat plate made of synthetic resin or glass having a thickness of 0.05 mm to 0.15 mm,
The optical element unit, wherein the optical element is bonded to the holding member via a sphere. An optical element unit having an optical element and a holding member for holding the optical element,
The optical element is a flat plate made of synthetic resin or glass having a thickness of 0.05 mm to 0.15 mm,
The holding member is formed with an inclined surface, and the inclined surface and the side peripheral surface of the optical element are bonded to each other. An optical element unit having an optical element and a holding member for holding the optical element,
The optical element is a flat plate made of synthetic resin or glass having a thickness of 0.05 mm to 0.15 mm,
A plurality of tongue portions are formed on the holding member, and an end surface of the tongue portion and a side peripheral surface of the optical element are bonded to each other. An optical element unit having an optical element and a holding member for holding the optical element,
The optical element is a flat plate made of synthetic resin or glass having a thickness of 0.05 mm to 0.15 mm,
The holding member is formed with a plurality of tongue portions, and the tongue portion and the optical surface of the optical element are bonded to each other. 5. The holding member is formed with a tongue-shaped portion in contact with a side peripheral surface of the optical element and a tongue-shaped portion in contact with the optical surface of the optical element alternately. The optical element unit described. 6. The optical element unit according to claim 1, wherein the optical element has a circular shape, and the bonding positions of the holding member to which the optical element is bonded are three positions. An optical element unit having an optical element and a holding member for holding the optical element,
The optical element is a flat plate made of synthetic resin or glass having a thickness of 0.05 mm to 0.15 mm,
The optical element unit, wherein the optical element is pressed against and held by the holding member at a plurality of locations by a leaf spring. A laser light source that emits a light beam of a predetermined wavelength, a reference plane,
A reference spherical surface that reflects the light beam that has passed through the test lens; and
An interferometer comprising: the optical element unit according to claim 1. The interferometer according to claim 8, wherein the optical element unit is integrally fixed to the reference spherical surface.

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