Method and apparatus for measuring eccentricity of aspherical lens having an aspherical surface on only one lens face

• US 5,548,396 A
• Filed: 07/26/1994
• Issued: 08/20/1996
• Est. Priority Date: 08/13/1993
• Status: Expired due to Fees

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Tada, Takeshi, Morita, Nobuhiro
• Primary Examiner(s): Gonzalez, Frank
• Assistant Examiner(s): VIERRA EISENBERG, JASON D
• Application Number:
  US08/280,614
• Time in Patent Office: 756 Days
• Field of Search: 356/124, 356/127
• US Class Current: 356/127
• CPC Class Codes: G01M 11/0221 by determining the optical axis or position of lenses

Abstract

In a method and an apparatus for measuring eccentricity of an aspherical lens, a detected lens as the aspherical lens is supported by a holding device and is rotated by a driving device around a rotating axis approximately conforming to an optical axis of the detected lens. Light is irradiated from a light source to the detected lens through a beam splitter and an optical system. Light reflected on the detected lens is reversely transmitted through the optical system and is focused and formed as a spot image. A pressing face of an alignment adjusting device is arranged in a position separated from the optical axis by a radius of the detected lens. The pressing face pushes an outer circumferential edge of the detected lens deflected outward by rotating the detected lens. Thus, the pressing face moves the detected lens and coarsely adjusts a position of the detected lens by approximately conforming the optical and rotating axes to each other. Thus, the spot image of the reflected light can be formed on an image forming face. Another method and another apparatus for measuring eccentricity of an aspherical lens are also shown.

Claims

1. A method for measuring eccentricity of an aspherical lens and having a process in which a detected lens having an aspherical surface on only one lens face is rotated around a rotating axis approximately conforming to an optical axis of the detected lens;

light is irradiated onto the detected lens in a direction of the rotating axis and reflected light from the detected lens is focused and formed as a spot image on an image forming face of an optical system; and

a shift between the optical axis and the rotating axis of the detected lens and a direction of this shift are detected by a size of a circle drawn by the spot image when the detected lens is rotated;

the eccentricity measuring method measuring eccentricity between an axis of the aspherical surface and the optical axis and comprising the steps of;

forming a pressing face for pushing and moving the detected lens in a direction approximately perpendicular to the optical axis in a state in which the pressing face comes in contact with an outer circumferential edge of the detected lens;

arranging the pressing face in a position separated from the optical axis by a radius of the detected lens before the spot image is focused and formed on said image forming face; and

coarsely adjusting a position of the detected lens while said lens is rotated.

2. A method for measuring eccentricity of an aspherical lens and having a process in which a detected lens having an aspherical surface on only one lens face is rotated around a rotating axis approximately conforming to an optical axis of the detected lens;

light is irradiated from a light source onto the detected lens in a direction of the rotating axis and reflected light from the detected lens is focused and formed as a spot image on an image forming face of an optical system; and

a shift between the optical axis and the rotating axis of the detected lens and a direction of this shift are detected by the size of a circle drawn by the spot image when the detected lens is rotated;

the eccentricity measuring method measuring eccentricity between an axis of the aspherical surface and the optical axis and comprising the steps of;

fixing the light source, the optical system and the image forming face onto the same stage; and

forming the spot image on the image forming face by moving the stage forward and backward in a direction of the optical axis.

3. A method for measuring eccentricity of an aspherical lens and having a process in which a detected lens having an aspherical surface on only one lens face is rotated around a rotating axis approximately conforming to an optical axis of the detected lens;

light is irradiated from a light source onto the detected lens in a direction of the rotating axis and reflected light from the detected lens is focused and formed as a spot image on an image forming face of an optical system; and

a shift between the optical axis and the rotating axis of the detected lens and a direction of said shift are detected by a size of a circle drawn bythe spot image when the detected lens is rotated;

the eccentricity measuring method measuring eccentricity between an axis of the aspherical surface and the optical axis and comprising the steps of;

detecting the shift between the optical axis and the rotating axis and the direction of the shift by arithmetic means; and

correcting said shift by the arithmetic means by moving the detected lens in a direction perpendicular to the optical axis in accordance with shape data of the detected lens inputted to the arithmetic means in advance.

4. An apparatus for measuring eccentricity of an aspherical lens, comprising:

means for holding a detected lens having an aspherical surface on only one lens face;

driving means for rotating the holding means around a rotating axis approximately overlapping an optical axis of the detected lens;

an angle sensor for detecting a rotating angle of the detected lens;

a light source for irradiating light onto the detected lens in a direction of the rotating axis;

an optical system for focusing and forming a spot image of reflected light from the detected lens;

means for detecting a position of the spot image and arranged on an image forming face of the optical system;

displacement measuring means for measuring a deflection of a detected face of the detected lens in a direction of the optical axis; and

a pressing face for moving the detected lens in a direction perpendicular to the optical axis in a state in which the pressing face comes in contact with an outer circumferential edge of the detected lens during rotation;

the pressing face being disposed in a position separated from the optical axis by a radius of the detected lens.

5. An apparatus for measuring eccentricity of an aspherical lens, comprising:

means for holding a detected lens having an aspherical surface on only one lens face;

first driving means for rotating the holding means around a rotating axis approximately overlapping an optical axis of the detected lens;

an angle sensor for detecting a rotating angle of the detected lens;

a light source for irradiating light onto the detected lens in a direction of the rotating axis;

an optical system for focusing and forming a spot image of reflected light from the detected lens;

means for detecting a position of the spot image and arranged on an image forming face of the optical system;

displacement measuring means for measuring a deflection of a detected face of the detected lens in a direction of the optical axis; and

second driving means for fixing the light source, the optical system and the spot position detecting means onto a single stage and moving the single stage forward and backward along the optical axis of the detected lens.

6. An apparatus for measuring eccentricity of an aspherical lens, comprising:

means for holding a detected lens having an aspherical surface on only one lens face;

first driving means for rotating the holding means around a rotating axis approximately overlapping an optical axis of the detected lens;

angle sensor for detecting a rotating angle of the detected lens;

a light source for irradiating light onto the detected lens in a direction of the rotating lens;

an optical system for focusing and forming a spot image of reflected light from the detected lens;

means for detecting a position of the spot image and arranged on an image forming face of the optical system;

displacement measuring means for measuring a deflection of a detected face of the detected lens in a direction of the optical axis;

second driving means for fixing the light source, the optical system and the spot position detecting means onto a single stage and moving the single stage forward and backward along the optical axis of the detected lens;

stage position detecting means for detecting a position of the single stage on the optical axis; and

arithmetic means for controlling an operation of said second driving means,

wherein the arithmetic means performs feedback control of said second driving means based on shape data of the detected lens, data of the optical system and stage position data from the stage position detecting means.

7. An apparatus for measuring eccentricity of an aspherical lens, comprising

means for holding a detected lens having an aspherical surface on only one lens face;

first driving means for rotating the holding means around a rotating axis approximately overlapping an optical of the detected lens;

an angle sensor for detecting a rotating angle of the detected lens;

a light source for irradiating light onto the detected lens in a direction of the rotating axis;

an optical system for focusing and forming a spot image of reflected light from the detected lens;

means for detecting a position of the spot image and arranged on an image forming face of the optical system;

displacement measuring means for measuring a deflection of a detected face of the detected lens in a direction of the optical axis;

second driving means for fixing the light source, the optical system and the spot position detecting means onto a single stage and moving the single stage forward and backward along the optical axis of the detected lens; and

arithmetic means for detecting a shift between the optical axis and the rotating axis and a shifting direction;

wherein the arithmetic means corrects said shift by moving the detected lens in a direction perpendicular to the optical axis in accordance with shape data of the detected lens inputted to the arithmetic means in advance.

8. A method for measuring eccentricity of an aspherical lens, comprising the steps of:

rotating a detected lens having an aspherical surface on only one lens face around a rotating axis approximately conforming to an optical axis of the detected lens;

irradiating light onto the detected lens in a direction of the rotating axis;

focusing and forming reflected light from the detected lens as a spot image on an image forming face of an optical system;

detecting a shift between the optical axis and the rotating axis by a size of a circle drawn by the spot image when the detected lens is rotated;

setting a reference position in an outer circumference of the detected lens;

calculating a direction of said shift from an angle formed between a line connecting the reference position and a rotating center of the detected lens to each other and a line connecting the spot image and the rotating center of the detected lens to each other;

measuring a deflection of the aspherical surface caused by rotating the detected lens in an optical axis direction;

calculating a correction value of said deflection from the size of the circle and the shifting direction; and

calculating eccentricity between the optical axis and an aspherical surface axis by subtracting the correction value from said deflection measured.

9. A method for measuring eccentricity of an aspherical lens, as claimed in claim 8, wherein the measuring method further comprises the steps of:

displacing the detected lens in a direction approximately perpendicular to the optical axis of the detected lens;

calculating the deflection of the aspherical surface caused by this displacement in the optical axis direction;

calculating a changing amount of the shift between the optical and rotating axes of the detected lens; and

calculating said correction value by using a ratio of the changing amount of the shift and an amount of said deflection.

10. A method for measuring eccentricity of an aspherical lens, as claimed in claim 8, wherein the eccentricity of the aspherical surface is corrected by calculating the deflection of the aspherical surface in the optical axis direction from a shape parameter of the detected lens when an angle between the optical and rotating axes of the detected lens is changed by φ

.

11. An apparatus for measuring eccentricity of an aspherical lens, comprising:

means for holding a detected lens having an aspherical surface on only one lens face;

driving means for rotating the holding means around a rotating axis approximately conforming to an optical axis of the detected lens;

an angle sensor for detecting a rotating angle of the detected lens;

a light source for irradiating light to the detected lens in a rotating axis direction;

an optical system for focusing and forming reflected light from the detected lens as a spot image;

means for detecting a position of the spot image and arranged in an image forming position of the optical system;

displacement measuring means for measuring the deflection of a detected face of the detected lens in an optical axis direction; and

arithmetic means for calculating a correction value with respect to a deflecting value measured by said displacement measuring means from a shift between the rotating axis and the optical axis of the detected lens and a direction of said shift detected by the spot position detecting means and the angle sensor.

12. An apparatus for measuring eccentricity of an aspherical lens, as claimed in claim 11, wherein the measuring apparatus further comprises an actuator for moving the detected lens forward and backward in a direction approximately perpendicular to the optical axis of the detected lens.

13. An apparatus for measuring eccentricity of an aspherical lens, as claimed in claim 12, wherein the actuator displaces the detected lens by the correction value calculated by the arithmetic means in the direction approximately perpendicular to the optical axis of the detected lens in cooperation with the arithmetic means, the displacement measuring means and the actuator.