JP2005274510A - Apparatus and method for measuring eccentricity - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure a tilt of outer diameter of a body tube in an optical system to be tested, in order to carry out a speedy and precise eccentricity measurement using a measured result as a reference axis, even when it is difficult to hold the body tube in the optical system to be tested, while preventing it from tilting. <P>SOLUTION: An apparatus for measuring eccentricity is equipped with a holding member 2 which holds the body tube 1a in the optical system to be tested 1; a rotating/driving means 3 which rotates the holding member 2; a rotation angle detecting means 4 which reads out the rotational angle position of the holding member 2; an eccentricity measuring means 5 which measures the amount of eccentricity of the optical system to be tested 1; and a body tube fluctuation measuring means 6, which is arranged at a position perpendicular to the optical axis of the optical system in the eccentricity measuring means 5 and measures the amount of fluctuation of the body tube 1a in the optical system to be tested 1, with a timing, when the holding member 2 is rotated by the rotating/driving means 3. The eccentricity measuring means 5 measures the amount of eccentricity of the optical system to be tested 1, while carrying out corrections, based on the degree of the angle between the center axis 3a of a spindle 3 and the center axis of the body tube 1a calculated from the amount of fluctuation of the body tube 1a measured by the body tube fluctuation measuring means 6. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an eccentricity measuring apparatus and an eccentricity measuring method for measuring the amount of eccentricity of a lens system to be measured.

  FIG. 6 shows a conventional eccentricity measuring device disclosed in Patent Document 1. As shown in FIG. The decentration measuring apparatus includes a lens decentering measuring machine 100 that measures the decentering of the lens system 105 to be tested.

  The lens eccentricity measuring apparatus 100 includes a laser oscillator 101 that oscillates a randomly polarized laser, a beam splitter 102, a first imaging lens 103, a second imaging lens 104, a third imaging lens 108, and a two-dimensional point. And an image position detection sensor 109. The optical axis of the parallel beam-shaped laser beam emitted from the laser oscillator 101 coincides with the reference axis 106 of the lens system 105 to be tested. The beam splitter 102, the first imaging lens 103, and the second imaging lens 104 are Are arranged on this optical axis.

  The laser light emitted from the laser oscillator 101 passes through the beam splitter 102 and is converged by the first imaging lens 103 to be a point light source aiming light source 107. The light emitted from the aiming light source 107 is converged by the second imaging lens 104 and enters the lens system 105 to be measured. In such a structure, the light projecting optical system that projects the light of the aiming light beam 107 toward the lens system 105 by the laser oscillator 101, the beam splitter 102, the first imaging lens 103, and the second imaging lens 104 is provided. Composed.

  The light reflected in the autocollimation state on a specific measurement surface in the test lens system 105 is reflected by the beam splitter 102 through the second imaging lens 104 and the first imaging lens 103. The reflected light is converged by the third imaging lens 108 and is incident on the two-dimensional point image position detection sensor 109. As a result, a point image of the aiming light source 107 is formed on the two-dimensional point image position detection sensor 109.

In this eccentricity measuring apparatus 100, when the test lens system 105 is rotated about the reference axis 106 as a rotation axis, the locus of a circle drawn in conjunction with the rotation of the test lens system 105 is represented by the two-dimensional point image position detection sensor 109. And the amount of decentration of the lens system 105 to be detected is detected by a signal processing circuit (not shown).
JP-A-4-289426

  In the conventional decentration measuring apparatus, it is difficult to make the reference axis and the rotation axis of the lens system 105 to coincide with each other due to the structure of the holding member of the lens system 105 and the structure of the lens barrel of the lens system 105. In many cases, there is a problem that the tilt of the lens barrel of the held lens system 105 has an influence on the eccentricity measurement result.

  The present invention has been made in consideration of such problems of the prior art, and it is difficult to hold the lens barrel by the holding member without tilting due to the structure of the lens barrel of the lens system to be tested. However, it is an object of the present invention to provide an eccentricity measuring apparatus and an eccentricity measuring method capable of measuring the inclination of the outer diameter of the lens barrel of the lens system to be tested and using this as a reference axis for quick and highly accurate eccentricity measurement.

In order to achieve the above object, an eccentricity measuring apparatus according to a first aspect of the present invention reads a holding member that holds a lens barrel of a lens system to be examined, a rotation driving means that rotates the holding member, and a rotation angle position of the holding member. A rotation angle detecting means, an eccentricity measuring means for measuring the amount of eccentricity of the lens system to be examined, and a position perpendicular to the optical axis of the optical system in the eccentricity measuring means; A lens barrel shake measuring means for measuring the lens barrel shake amount when the lens system is rotated, and the eccentricity measuring means is calculated by the tilt of the lens barrel measured by the lens barrel shake measuring means. The decentering amount of the lens system to be measured is measured using the central axis of the lens barrel as a reference axis.

  In the first aspect of the invention, the lens barrel shake measuring means measures the shake amount of the lens barrel when the lens system to be tested is rotated by the drive of the rotation driving means. The inclination of the central axis of the lens barrel is calculated based on the shake amount, and the eccentric amount of the test lens system is measured using the calculated central axis as a reference axis. The influence of the deviation between the rotation axis and the central axis on the amount of eccentricity can be eliminated. For this reason, it can measure with high precision. Further, since the inclination of the central axis is corrected by calculation, no mechanical correction is required, and measurement can be performed quickly.

  The invention according to claim 2 is the eccentricity measuring apparatus according to claim 1, wherein the lens barrel shake measuring means is arranged so as to be in a non-contact state with the lens barrel of the lens system to be measured. To do.

  In the invention of claim 2, since the lens barrel shake measuring means is in a non-contact state with the lens barrel of the lens system to be measured, the lens barrel caused by the contact does not come into contact with the lens barrel when measuring the shake amount. Therefore, measurement can be performed smoothly and easily.

  According to a third aspect of the present invention, there is provided an eccentricity measuring method in which a lens barrel shake measuring means is arranged so as to be orthogonal to the optical axis of the optical system of the eccentricity measuring means for measuring the amount of eccentricity of the subject lens system, and the subject lens system is rotated The inclination of the central axis of the lens barrel is calculated by detecting the shake amount of the lens barrel of the lens system to be detected by the lens barrel shake measuring means, and the test is performed using the calculated central axis of the lens barrel as a reference axis. The decentering amount of the lens system is measured.

  According to the third aspect of the present invention, the inclination of the central axis of the lens barrel is calculated based on the lens barrel shake amount measured by the lens barrel shake measuring means, and the amount of eccentricity of the test lens system is calculated using the calculated center axis as a reference axis. Since the measurement is performed, the influence of the deviation between the rotation axis of the lens barrel and the central axis due to the tilt of the lens system to be examined on the eccentricity can be eliminated, and the measurement can be performed with high accuracy. In addition, since the inclination of the central axis is corrected by calculation, no mechanical correction is required and measurement can be performed quickly.

  A fourth aspect of the present invention is the eccentricity measuring method according to the third aspect, wherein the lens barrel shake measuring means measures the amount of shake of the lens barrel in a non-contact state with the lens system to be measured.

  In the invention of claim 4, since the lens barrel shake measuring means measures the shake amount in a non-contact state with the lens barrel of the lens system to be examined, the lens barrel position caused by the contact does not contact the lens barrel. There is no deviation, and the measurement can be performed smoothly and easily.

  According to the eccentricity measuring apparatus of the present invention, the inclination of the central axis of the lens barrel is calculated based on the amount of shake of the lens system measured by the lens barrel measuring means, and the eccentricity measuring means is based on the calculated central axis as a reference axis. However, since the amount of eccentricity of the lens system to be measured is measured, the influence of the deviation between the rotation axis of the lens barrel and the central axis on the amount of eccentricity can be eliminated, and the amount of eccentricity can be measured with high accuracy and speed. Accordingly, it is not necessary to perform coaxial processing or the like in order to make the center axis of the replaced holding member coincide with the rotation axis, and the lens barrel is held by the holding member without tilting due to the structure of the lens barrel. Even when this is difficult, the amount of eccentricity can be measured quickly.

  According to the eccentricity measuring method of the present invention, there is no need to match the central axis of the holding member to the rotation axis by coaxial processing or the like, and the lens barrel can be held without tilting by the structure of the lens barrel. Even when it is difficult to hold the lens, it is possible to measure the inclination of the outer diameter of the lens barrel of the lens system and to perform the eccentric measurement quickly and with high accuracy.

  Embodiments of the present invention will be described below with reference to the drawings. In each embodiment, the same members are assigned the same reference numerals.

(Embodiment 1)
1 to 4 show a first embodiment of the present invention, FIG. 1 is a perspective view of the overall configuration, FIG. 2 is a cross-sectional view thereof, and FIGS. 3 and 4 are explanatory diagrams showing procedures for measuring eccentricity. is there.

  The eccentricity measuring apparatus of this embodiment rotates a spindle 3 as a holder 2 as a holding member for holding the lens barrel 1a of the lens system 1 to be tested, a spindle 3 as a rotation driving means for rotating the holder 2, and the spindle 3. The encoder 4 as a rotation angle detecting means for reading the rotation angle position of the holder 2, the eccentricity measuring means 5 for measuring the amount of eccentricity of the lens system 1 to be tested, and the lens system 1 to be tested when the spindle 3 is rotated. A lens barrel shake measuring means for measuring the amount of shake of the lens barrel 1a is provided.

  The decentration measuring means 5 is disposed above the lens system 1 in the optical axis direction. The lens barrel shake measuring means includes a high-performance CCD camera 6 and a light source 7 disposed at a position orthogonal to the optical axis of the optical system (see FIG. 2) of the eccentricity measuring means 5, and the CCD camera 6 and the light source. 7 is a facing position. The CCD camera 6 has a known imaging magnification β and pixel size p, and the CCD camera 6 is irradiated with the light source 7 to the lens system 1 to be examined.

  As shown in FIG. 2, the eccentricity measuring means 5 includes a measurement light source 20, and the image of the target 21 irradiated by the measurement light source 20 enters the daylighting lens 22 and further enters the half prism 23. Then, the light reflected by the half prism 23 is reflected by an arbitrary test surface of the test lens system 1, and the decentering measurement means 5 is moved up and down so that the object point position of the decentering measurement means 5 is aligned with the imaged target image position. Let The light reflected by an arbitrary test surface of the test lens system 1 enters the half prism 23 again and forms an image through the imaging lens system 24. The formed target image is magnified by the magnifying lens 25. The light emitted from the magnifying lens 25 is condensed on the light position detecting element 26 for detecting the center position of the magnified image.

  Next, the measurement of the eccentricity by the eccentricity measuring apparatus of the embodiment will be described. When the test lens system 1 is replaced, as shown by an arrow G in FIG. 1, the rotation angle θ of the holder 2 is read by the encoder 4 while rotating the holder 2 around the rotation axis 3a of the spindle 3, and the CCD The distance L from the CCD camera end to the lens barrel 1a is measured by the camera 6. FIG. 3 shows an image of the CCD camera 6 at this time. Between the distance L and the rotation angle θ, the equation shown in Equation 1 is established (see FIG. 4).

The above equation will be described with reference to FIG. FIG. 4 is a view of the lens barrel 1a as viewed from above. Reference numeral 27 denotes a camera end of the CCD camera 6. Reference numeral 28 denotes a locus drawn by the end surface of the lens barrel 1a when the spindle 3 is rotated. r is the radius of the trajectory barrel 1a when the rotation of the spindle 3 is drawn, theta ₀ is at an angle with respect to the X-axis of the end surface of the lens barrel 1a when the rotation angle theta of the holder 2 which is rotated by the spindle 3 is 0 ° is there. a is the X direction component of the vector of magnitude (radius) r and slope θ ₀ , and b is the vector Y direction component of magnitude (radius) r and slope θ ₀ . c is the distance from the CCD camera end 27 to the center of rotation of the lens barrel 1a. After measuring θ and L at at least three points, a, b, and c are calculated using mathematical means. As a result, r and θ ₀ are derived as in Equation 2 and Equation 3.

By the above procedure, r and θ ₀ are calculated at arbitrary lens barrel positions P1 and P2 having different heights. Let r and θ ₀ calculated by this operation be P1 (r ₁ , θ ₀₁ ) and P2 (r ₂ , θ ₀₂ ), respectively.

Also, the distance D between the two lens barrel positions measured is d, the pixel interval on the CCD camera 6 between the lens barrel positions P1 and P2, the pixel size of the CCD camera 6 is p, and the imaging magnification is β. , (D × p) / β. Further, a distance D ₀ between the uppermost portion of the lens system 1 to be tested and Pl is represented by (d ₀ × p) / β where the pixel distance on the CCD camera 6 is d ₀ .

  As a result, the degree of inclination (inclination ε and bias δ) formed by the central axis of the lens barrel 1a of the lens system 1 to be measured with respect to the central axis 3a of the spindle 3 is calculated as in Expressions 4 and 5. Is done.

  Next, after adjusting the eccentricity measuring means 5 in the optical axis direction so that the target image reflected by an arbitrary test surface of the test lens system 1 is formed on the optical position detection element 26, the spindle 3 Is driven to obtain an eccentricity on an arbitrary test surface from the amount of movement of the target image on the optical position detection element 26. This operation is repeated to calculate the amount of eccentricity on each surface of the lens system 1 to be examined. Thereafter, the calculated eccentric amount of each surface of the lens system 1 is corrected so that the tilt axis A of the lens barrel 1a becomes the reference axis.

  The calculation based on the above-described formula and the correction of the central axis of the lens barrel 1a are performed by calculation means (not shown) provided in the eccentricity measurement means.

  In such an embodiment, the degree of inclination of the central axis of the lens barrel 1 a with respect to the central axis 3 a of the spindle 3 is calculated based on the shake amount of the lens barrel 1 a measured using the CCD camera 6. In order to measure the amount of decentration of the lens system 1 to be corrected based on the degree of tilt, the center axis of the lens barrel 1a caused by the tilt of the lens system 1 and the center axis 3a of the spindle 3 are measured. The influence of the deviation on the amount of eccentricity can be eliminated. For this reason, it can measure with high precision. In addition, since the degree of inclination of the central axis of the lens barrel 1a is corrected by calculation, no mechanical correction is required and measurement can be performed quickly.

  In this embodiment, since the tilt of the lens barrel 1a of the lens system 1 to be tested is measured in a non-contact manner using the CCD camera 6 and the light source 7, the lens barrel 1a of the lens system 1 to be tested is measured. There is no problem that the position of the lens barrel 1a is shifted. Further, the CCD camera 6 and the light source 7 can be installed at positions that do not affect the eccentricity measurement by the eccentricity measuring means 5. For this reason, there is no worry of mechanical interference, and there is no need to retract the CCD camera 6 and the light source 7 during the eccentricity measurement.

(Embodiment 2)
FIG. 5 shows a second embodiment of the present invention, in which a gripping jig 30 is used as a holding member of the lens system 1 to be tested instead of the holder 2 of FIG.

  The holding jig 30 is arranged on the spindle 3 shown in FIG. The gripping jig 30 includes a pair of slide tables 33 that can move in a direction for gripping and releasing the lens system 1 to be tested, a pair of moving members 32 provided on the slide tables 33, and a moving member 32. A pair of gripping members 31 are provided so as to face each other and perform gripping and releasing of the lens barrel 1a of the lens system 1 to be examined.

  The end surface of the gripping member 31 that contacts the lens barrel 1a of the lens system 1 to be tested is V-grooved so that the lens barrel 1a is stable even when the diameter of the lens barrel 1a varies depending on the type of the lens system 1 to be tested. And can be gripped.

  A connecting member 34 is connected to the pair of moving members 32 in an engaged state. The connecting member 34 is in the shape of a horizontally long plate and extends in a direction in which the pair of moving members 32 are spanned. The connecting members 34 are engaged with the moving members 32 by inserting pins 34 a into the respective moving members 34. The connecting member 34 is rotatable around the center of the lens system 1 to be tested.

  Further, a hook pin 34b is erected on one end side of the connecting member 34, and one end of an elastic member 36 made of a compression coil spring is locked to the hook pin 34b. The other end of the elastic member 36 is locked to a hook post 35 provided on the spindle 3 on the fixed side. The elastic member 36 urges the pair of moving members 32 to move in the direction of gripping the lens barrel 1 a of the lens system 1 to be tested via the rotating member 34.

  In such an embodiment, the moving member 32 provided on the slide table 33 is opened in the releasing direction, and the lens barrel 1a of the lens system 1 to be tested is inserted between the released gripping members 31. Next, the moving member 32 is moved in a direction in which the lens barrel of the lens system 1 to be tested is gripped. At the same time, the rotating member 34 is rotated by the urging force from the elastic member 36 in the contracting direction, and the moving member 32 is moved in the direction in which the lens system 1 is gripped. Thereby, the holding state of the lens barrel 1a by the holding member 31 can be held.

  In such an embodiment, since the lens barrel 1a of the lens 1 to be tested is gripped by the gripping jig 30, the member to be held is replaced whenever the shape and size of the lens barrel 1a of the lens system 1 to be tested are different. Thus, the amount of eccentricity can be measured quickly.

It is a perspective view of the eccentricity measuring apparatus in Embodiment 1 of this invention. 2 is a cross-sectional view of the eccentricity measuring apparatus according to Embodiment 1. FIG. It is a side view explaining eccentricity measurement. It is a top view explaining eccentricity measurement. FIG. 10 is a perspective view of a holding member in a second embodiment. It is a front view which shows the optical path of the conventional eccentricity measuring apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lens system 1a Lens barrel 2 Holder 3 Spindle 3a Rotating shaft 4 Encoder 5 Eccentricity measuring means 6 CCD camera 7 Light source

Claims (4)

  A holding member for holding the lens barrel of the lens system to be tested, a rotation driving means for rotating the holding member, a rotation angle detecting means for reading the rotation angle position of the holding member, and an eccentricity for measuring the amount of eccentricity of the lens system to be examined A measuring unit is disposed at a position orthogonal to the optical axis of the optical system in the decentering measuring unit, and measures the shake amount of the lens barrel of the lens system to be measured when the holding member is rotated by the rotation driving unit. A lens barrel shake measuring means, and the eccentricity measuring means measures the amount of eccentricity of the lens system to be measured with the central axis of the lens barrel calculated by the tilt of the lens barrel measured by the lens barrel shake measuring means as a reference axis. An eccentricity measuring device.   2. The eccentricity measuring apparatus according to claim 1, wherein the lens barrel shake measuring means is arranged so as to be in a non-contact state with the lens barrel of the lens system to be examined.   A lens barrel of the test lens system when the lens barrel shake measuring means is arranged so as to be orthogonal to the optical axis of the optical system of the decentration measuring means for measuring the amount of eccentricity of the test lens system, and the test lens system is rotated. The inclination of the central axis of the lens barrel is calculated by detecting the amount of camera shake by the lens barrel shake measuring means, and the amount of eccentricity of the lens system to be measured is measured using the calculated center axis of the lens barrel as a reference axis. Eccentricity measuring method.   4. The method of measuring eccentricity according to claim 3, wherein the lens barrel shake measuring means measures the amount of shake of the lens barrel in a non-contact state with the lens system to be examined.

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