JP2013195410A - Detector and detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that, in adjustment of a lens system, it is difficult to reduce variation of a relative position of each lens, especially in variation in a direction orthogonal to an optical axis.SOLUTION: A detector is for detecting a relative position of an optical element constituting a measured optical system, and includes: a light source unit for making irradiation light incident into the measured optical system; a stage for holding the measured optical system in an irradiated region; a light receiving unit for receiving light having passed through the measured optical system and converting the light into an electrical signal; and a processing unit for processing the electrical signal. The light receiving unit includes a wave surface sensor using a lens array, and the light source unit emits parallel luminous flux crossing the irradiation light in a section including a shaft of light projection.

Description

  The present invention relates to an apparatus and method for detecting the position of an optical element.

  An ultra-small imaging optical system is used for a camera module for a cellular phone. Along with the miniaturization of the optical system, such an imaging optical system is required to have high accuracy with respect to decentration (less decentration). The required accuracy is about the same as the processing accuracy of the component holding the lens. The decentering is a deviation (including inclination) of the optical axis of the optical element from the ideal optical axis of the optical system.

  In this case, the amount of variation in the relative position of each lens in the optical system is determined by the processing accuracy of the components that hold each lens. That is, the positioning accuracy of each lens is determined by the processing accuracy of the components that hold each lens. For example, if the processing accuracy of the component that holds the lens is 2 μm, the amount of variation in the relative position of each lens is approximately 2 μm.

  If the relative position of each lens varies, the imaging performance of the optical system is degraded. The variation in the relative position of each lens includes a variation in the optical axis direction and a variation in a direction orthogonal to the optical axis.

  As an apparatus for reducing the relative positional variation, there is a lens system adjusting apparatus disclosed in Japanese Patent Application Laid-Open No. 2005-228561. This lens system adjusting device includes a light source, a diffraction element, first and second holding units, a second moving mechanism, an image sensor, and an arithmetic control processing unit. In this lens system adjusting device, the MTF is calculated, and the position of the lens system is adjusted using the calculation result.

Japanese Patent No. 3766835

  However, since the lens system adjustment apparatus of Patent Document 1 is a technique for adjusting the lens system using the MTF, the measurement accuracy is lower than the method for adjusting the lens system using the wavefront measurement result. Further, since parallel light is generated using a diffraction element, second-order and third-order diffracted light is generated. Since the second-order and third-order diffracted light interferes with the measurement, the measurement accuracy is lowered. As a result, in adjusting the lens system, it is difficult to reduce variations in relative positions of the lenses, particularly variations in a direction orthogonal to the optical axis.

  The present invention has been made in view of the above, and an object of the present invention is to provide a detection device and a detection method for detecting the relative position of an optical element of a measured optical system with high accuracy.

In order to solve the above-described problems and achieve the object, the detection device of the present invention includes:
A detection device that detects a relative position of an optical element constituting an optical system to be measured,
A light source unit for making the irradiation light incident on the optical system to be measured;
A stage for holding the optical system under measurement in the irradiated area;
A light receiving unit that receives light transmitted through the optical system to be measured and converts it into an electrical signal;
A processing unit for processing electrical signals,
The light receiving unit has a wavefront sensor using a lens array, and
The light source unit is characterized in that it emits a parallel light flux in which the irradiation light intersects in a cross section including the projection axis.

Moreover, the detection method of the present invention comprises:
Irradiate the measured optical system with irradiation light,
A plurality of light spots are formed from the light emitted from the optical system to be measured,
For each position of the plurality of light spots, calculate the amount of deviation from the reference position,
A detection method for detecting a position of a movable optical system with respect to a fixed optical system of a measured optical system,
The irradiation light is a parallel light flux where the irradiation light intersects in a cross section including the projection axis,
The measured optical system is disposed at a position where the irradiation light intersects, and
The diameter of the irradiation light at the intersecting position is larger than the outer diameter of the optical system to be measured.

  ADVANTAGE OF THE INVENTION According to this invention, the detection apparatus and detection method which detect the relative position of the optical element of a to-be-measured optical system with high precision can be provided.

It is a figure which shows the group adjustment apparatus which is an example of the detection apparatus of this invention, Comprising: (a) is a front view, (b) is a side view. It is a figure which shows the structure of a light source unit. It is a figure which shows an axicon lens. It is a figure which shows the light beam radiate | emitted from a light source unit. It is a figure which shows the mode of the parallel light beam in position P2, and a to-be-measured optical system. It is a figure which shows the structure of a stage. It is a figure which shows the structure of a light-receiving unit. It is a figure which shows the mode of the light ray from a light source unit to a light reception unit. It is a figure which shows the mode of a light spot, Comprising: (a) is a figure which shows a mode after the wave front changes, (b) before the wave front changes. It is a figure which shows the structure of an adjustment mechanism. It is a figure which shows a measured optical system, Comprising: (a) is sectional drawing of a measured optical system, (b) is a figure which shows the state holding the measured optical system. It is a flowchart regarding the group adjustment method. It is a flowchart regarding a calibration. It is a conceptual diagram of a wavefront profile. It is a conceptual diagram of the wavefront profile acquired in the group adjustment apparatus 1 of this embodiment. It is a conceptual diagram of the wavefront aberration profile in an ideal state. It is a conceptual diagram about the behavior of the 8th-order coefficient and 15th-order coefficient of the Zernike polynomial. It is a figure which shows a mode that four lenses are each decentering.

  The detection device of the present embodiment is a detection device that detects the relative position of the optical elements that constitute the optical system to be measured, and includes a light source unit for making the irradiation light incident on the optical system to be measured, and an irradiation area. A stage that holds the optical system to be measured; a light receiving unit that receives light that has passed through the optical system to be measured and converts the light into an electrical signal; and a processing unit that processes the electrical signal. The light source unit emits a parallel light flux in which irradiation light intersects in a cross section including a light projection axis.

  The detection device of this embodiment will be described. As a more specific example of the detection device of this embodiment, there is a group adjustment device. FIG. 1 is a diagram illustrating a schematic structure of the group adjusting device. FIG. 1A is a front view of the group adjusting device, and FIG. 1B is a side view of the group adjusting device. The group adjustment apparatus 1 of this embodiment includes a main body 2, a light source unit 3, a stage 4, a light receiving unit 5, a processing unit 6, and an adjustment mechanism 7. The light source unit 3, the stage 4, the light receiving unit 5 and the adjustment mechanism 7 are held by the main body 2. Then, the optical system 8 to be measured is placed on the stage 4 during group adjustment. In FIG. 1, the measured optical system 8 includes a movable side optical system 8a and a fixed side optical system 8b.

  The light source unit 3 is disposed on one end side of the main body 2, and the light receiving unit 5 is disposed on the other end side of the main body 2. Thus, the light source unit 3 and the light receiving unit 5 are disposed so as to face each other. A stage 4 and an adjustment mechanism 7 are disposed between the light source unit 3 and the light receiving unit 5. In FIG. 1, the adjusting mechanism 7 is located on the light source unit 3 side, and the stage 4 is located on the light receiving unit 5 side.

  Although not shown, each of the light source unit 3, the stage 4, the light receiving unit 5, and the adjusting mechanism 7 (hereinafter referred to as the light source unit 3 and the like) has a moving mechanism. With this moving mechanism, the light source unit 3 and the like can move in a direction along the light projecting axis 9. Further, the light source unit 3 and the like can be moved in a direction orthogonal to the light projecting axis 9 by the moving mechanism. The light projecting axis 9 is a reference axis when adjusting the positions of the light source unit 3 and the light receiving unit 5.

  As shown in FIG. 1A, the light source unit 3 emits a light beam 10 as irradiation light. When the optical system 8 to be measured is placed on the stage 4, the light beam 10 (irradiation light) from the light source unit 3 has a parallel light beam shape in the cross section including the light projecting axis 9. Incident. The parallel light beam 10 is emitted from the light source unit 3 so as to intersect the light projection axis 9 at a predetermined angle. As described above, the light source unit 3 emits the parallel light flux 10 in which the irradiation light intersects in the cross section including the light projecting axis 9.

  FIG. 2 is a diagram showing the structure of the light source unit 3. As shown in FIG. 2, the light source unit 3 includes a light source 30, a pinhole 31, a lens 32, and an axicon lens 33. As the light source 30, a light emitting diode (LED), a semiconductor laser (LD), or the like is used. Note that a laser other than a semiconductor laser, for example, a helium neon racer, may be used for the light source 30. Alternatively, the light source 30 may be separated from the light source unit 3, and the light from the light source 30 may be guided to the light source unit 3 by an optical fiber.

  A pinhole 31 is disposed on the light emission side of the light source 30. When light passes through the pinhole 31, a point light source is formed. In addition, when using a light emitting diode for the light source 30, a lens is disposed between the light emitting diode (light source 30) and the pinhole 31, and the light emitted from the light emitting diode is condensed on the pinhole 31. Also good. In this case, a point light source with little light loss can be obtained. Further, when a laser is used as the light source 30, the laser can be regarded as a point light source, so that the arrangement of the pinhole 31 can be omitted.

  A lens 32 (first optical element) is disposed on the light emitting side of the pinhole 31. Here, the lens 32 is arranged so that the focal position thereof coincides with the position of the pinhole 31. Therefore, the light emitted from the lens 32 becomes a parallel light flux. The parallel light beam emitted from the lens 32 enters the axicon lens 33 (second optical element).

  An afocal zoom optical system may be arranged between the lens 32 and the axicon lens. In this way, the diameter of the parallel light beam incident on the axicon lens 33 can be changed. As a result, the diameter of the parallel light beam 10 can be changed.

  FIG. 3 is a diagram showing an axicon lens. As shown in FIG. 3, in the axicon lens 33 in the present embodiment, the shape of one surface 33a is a planar shape. The shape of the other surface 33b is conical, more specifically conical. The axicon lens 33 may be referred to as a conical lens or an axicon prism.

  For the axicon lens 33 in this embodiment, a glass material having a refractive index n of n = 1.52 (for example, N-BK7 manufactured by Schott) is used. The outer diameter (diameter) φ is φ = 25.4 mm, the cone angle α is α = 25 °, and the edge thickness te is te = 5 mm. The axicon lens 33 has a rotationally symmetric shape, and has a prism shape in a cross section including the rotationally symmetric axis 34.

  FIG. 4 is a diagram showing a light beam emitted from the light source unit 3. As shown in FIG. 4, the axicon lens 33 is arranged so that its rotational symmetry axis 34 coincides with the light projection axis 9 of the group measuring apparatus 1. Further, the axicon lens 33 is arranged so that the surface 33 a side faces the light source 30. With such an arrangement, a parallel light beam is incident along the rotational symmetry axis 34 from the surface 33a side. Each light beam of the parallel light flux incident from the surface 33a side is refracted by the surface 33b.

  Here, since the surface 33b is a conical surface, each light beam of the parallel light flux is bent at the same angle in a direction approaching the rotational symmetry axis 34. As a result, the light beam emitted from the axicon lens 33 becomes a parallel light beam that is refracted in the vertical direction with respect to the rotational symmetry axis 34 in the cross section including the rotational symmetry axis 34. Moreover, since the surface 33b is axisymmetric, each light beam emitted from the surface 33b is a continuous light beam around the rotationally symmetric axis 34. That is, the light beam is a parallel light beam in the cross section including the rotational symmetry axis 34, but becomes an annular light beam in the cross section perpendicular to the rotational symmetry axis 34.

In general, the refraction angle of the prism is obtained by the following equation (1). Here, n is the refractive index of the lens, α is the apex angle (cone angle), and δ is the declination angle (refraction angle). The declination δ is an angle with respect to the rotational symmetry axis 34 of each light beam emitted from the surface 33b.
δ = (n−1) × α (1)

  When the refractive index n of the axicon lens 33 is n = 1.52, the declination δ is δ≈ ± 12 ° in the cross section including the rotational symmetry axis 34. Therefore, the angle of the parallel light beam 10 with respect to the rotational symmetry axis 34 is also about ± 12 °. Although details will be described later, in the axicon lens 33 to be used, it is preferable that the value of the deviation angle δ is equal to or smaller than the maximum field angle of the optical system 8 to be measured.

  As described above, the group adjusting device 1 according to the present embodiment uses the axicon lens 33 in generating the intersecting parallel light beams 10. For this reason, the group adjusting device 1 of the present embodiment does not generate second-order or third-order diffracted light as in the case where a diffraction grating is used. That is, in the group adjustment apparatus 1 of the present embodiment, since the second-order and third-order diffracted light that interferes with measurement does not occur, the measurement accuracy and adjustment accuracy can be increased.

  FIG. 4 shows a cross-sectional shape of the parallel light beam 10. This cross-sectional shape is an in-plane shape orthogonal to the light projection axis 9. The cross-sectional shapes 10a, 10b, and 10c are cross-sectional shapes at positions P1, P2, and P3, respectively. As shown in the cross-sectional shape 10 c, the cross-sectional shape of the parallel light beam 10 has an annular shape at a position P 3 far from the light source unit 3. On the other hand, the cross-sectional shape of the parallel light beam 10 is circular because the circular rings overlap at the positions P1 and P2 in the vicinity of the light source unit 3. The diameter of the circle (ring) gradually decreases with distance from the light source unit 3, and becomes the smallest at the position P2.

  In the group adjustment apparatus 1 of the present embodiment, the optical system 8 to be measured is disposed at the position P2 to perform group adjustment (eccentric adjustment). In addition, in the group adjustment apparatus 1 of the present embodiment, the diameter of the parallel light beam 10 at the position P2 is sufficiently larger than the outer diameter of the optical system 8 to be measured. In other words, the light source unit 3 is configured so as to be in such a state. In addition, what is necessary is just to move the stage 4 along the light projection axis | shaft 9 arrangement | positioning to the position P2 of the to-be-measured optical system 8. FIG.

  FIG. 5 is a diagram showing a state of the parallel light beam 10 and the measured optical system 8 at the position P2. As shown in FIG. 5, the position where the optical system 8 to be measured is arranged is different between the position P4 and the position P5. However, the incident angle of the parallel light beam 10 with respect to the measured optical system 8 does not differ between the positions P4 and P5. Further, the diameter of the parallel light beam 10 is sufficiently larger than the outer diameter of the optical system 8 to be measured. Therefore, regardless of whether the position of the optical system 8 to be measured is the position P4 or the position P5, the diameter of the optical system 8 to be measured (the effective lens surface on the light source unit 3 side of the lens surface of the movable optical system 8a). The parallel light beam 10 is incident so as to satisfy the aperture. As a result, the light (wavefront or imaging state) emitted from the measured optical system 8 is the same regardless of the position of the measured optical system 8 at either the position P4 or the position P5.

  In the group adjustment apparatus 1 of the present embodiment, group adjustment is performed using light (wavefront) emitted from the optical system 8 to be measured. Therefore, the group adjustment of the optical system 8 to be measured can be performed anywhere within the range of the parallel light beam 10 at the position P2. As a result, it is possible to minimize the error when arranging the optical system to be measured (lens system). Moreover, installation of the optical system 8 to be measured is facilitated.

  FIG. 6 is a diagram showing the structure of the stage 4. The stage 4 has an opening 40 in the center. The size of the opening is such that all the light rays emitted from the optical system 8 to be measured can pass therethrough. A step 41 is formed around the opening 40. The measured optical system 8 can be placed on the stage 4 by inserting a holding member 80 described later into the stepped portion 41.

  FIG. 7 is a diagram showing the structure of the light receiving unit 5. The light receiving unit 5 includes a lens array 50 and an image sensor 53. The lens array 50 includes a plurality of lens elements 51, and the lens elements 51 are arranged vertically and horizontally in a plane. In this example, the focal length f_sensor of each lens element 51 is f_sensor = 7 mm. The lens array 50 has an area (outside dimension) of 10 mm × 10 mm in length and width, and 30 × 30 lens elements 51 are arranged in this area at a pitch of 300 μm. In addition, it is more preferable that the area | region of the lens array 50 is large. For example, it is more preferable that the length and width are 20 mm × 20 mm.

  In the image pickup element 53, a plurality of photoelectric conversion surfaces are two-dimensionally arranged. In the present embodiment, the image sensor 53 has an imaging region whose vertical and horizontal dimensions are about 10 mm × 10 mm, and a number of pixels whose vertical and horizontal dimensions are about 2500 pixels × 2500 pixels. In addition, it is more preferable that the imaging region is wider. For example, it is more preferable that the length and width are about 20 mm × 20 mm. The size of the photoelectric conversion surface of the image sensor 53 is preferably about 4 μm. The size of the photoelectric conversion surface is more preferably about 1 μm. If the size of the photoelectric conversion surface is about 1 μm, the resolution with respect to the angle of the wavefront 55 of the incident light 54 is improved.

  The lens array 50 condenses incident light 54 (wavefront 55) at a predetermined position. A light spot 52 is formed at this condensing position. The number of light spots 52 is the same as the number of lens elements 51. In addition, an image sensor 53 (photoelectric conversion surface of the image sensor 53) is disposed at this condensing position. When the incident light is a plane wave, the image sensor 53 is arranged at a distance of about the focal length f_sensor from the lens array 50.

  In the image sensor 53, the light intensity of the light spot 52 is converted into luminance value information and the coordinate information of the light spot 52 is obtained by the photoelectric conversion surface. The luminance value information and the coordinate information are output to the processing unit 6.

  FIG. 8 is a diagram illustrating a state of light rays from the light source unit 3 to the light receiving unit 5. The parallel light beam 10 emitted from the light source unit 3 enters the optical system 8 to be adjusted and is collected by the optical system 8 to be adjusted. The collected light diverges and the diverged light becomes incident light 54 and enters the light receiving unit 5. Therefore, the size of the effective surfaces of the lens array 50 and the image sensor 53 only needs to cover the light ray area of the incident light 54. Specifically, as described above, the size of the effective surfaces of the lens array 50 and the image sensor 53 may be about 10 mm × 10 mm, more preferably about 20 mm × 20 mm, or more.

  FIG. 9 is a diagram illustrating a state of the light spot 52. 9A shows a state before the wavefront 55 of the incident light 54 changes, and FIG. 9B shows a state after the wavefront 55 of the incident light 54 changes. As shown in FIG. 9, when the wavefront 55 of the incident light 54 (the angle of each ray of the incident light 54) changes, the position of each light spot 52 changes. From this change in position, the wavefront profile of the incident light 54 can be obtained. Thus, the light receiving unit 5 functions as a wavefront sensor. The processing for obtaining the wavefront profile of the incident light 54 is performed in the processing unit 6 described later.

  FIG. 10 is a view showing the structure of the adjusting mechanism 7. The adjusting mechanism 7 includes two sets of moving units 7a and 7b. The moving units 7a and 7b are arranged on a diagonal line. The moving units 7a and 7b have an adjusting arm 70 and an XY stage 71, respectively. The adjustment arm 70 is placed on the XY stage 71. Here, the adjustment arm 70 is moved in the X direction and the Y direction by the XY stage 71.

  An opening 72 is formed at the center of the adjustment mechanism 7. Inside the opening 72, the movable optical system 8a of the optical system 8 to be measured is located. In FIG. 10, the adjustment arm 70 of the moving unit 7a is in contact with the outer peripheral surface of the movable optical system 8a. Therefore, when the XY stage 71 of the moving unit 7a is moved in the X1 and Y1 directions, the movable optical system 8a can be moved in the X1 and Y1 directions via the adjustment arm 70. When the movable optical system 8a is moved in the X2 and Y2 directions, the moving unit 7b may be used. Since the movable optical system 8a can be moved in this way, the position adjustment (eccentricity adjustment) of the movable optical system 8a can be performed.

  FIG. 11 is a diagram showing the optical system 8 to be measured. FIG. 11A is a cross-sectional view of the optical system 8 to be measured, and FIG. 11B is a diagram illustrating a state in which the optical system 8 to be measured is held by the holding member 80. As shown in FIG. 11A, the measured optical system 8 includes a movable side optical system 8a and a fixed side optical system 8b. The fixed-side optical system 8b is composed of a plurality of lenses, but in FIG. 11A, it is shown as a single lens block.

  The optical system 8 to be measured is a photographic lens for a camera module, and includes four lenses. The movable optical system 8a includes a first lens (hereinafter referred to as a lens L1). The movable optical system 8a is a focusing lens, and is movable in the direction of the optical axis by a drive unit (not shown). The fixed-side optical system 8b includes second to fourth lenses (hereinafter referred to as a lens L2, a lens L3, and a lens L4). The lenses L2 to L4 are assembled together and stored in the lens barrel. For the lenses L2 to L4, the positional relationship between the lenses has already been adjusted appropriately.

  Further, the movable side optical system 8a and the fixed side optical system 8b are not bonded. Therefore, the movable side optical system 8a can be slid in a direction orthogonal to the light projecting axis 9. As shown in FIG. 11B, the fixed-side optical system 8b is held by the holding member 80. Here, the outer diameter of the holding member 80 is substantially the same as the inner diameter of the stepped portion 41 of the stage 4 (FIG. 6). Therefore, the fixed-side optical system 8 b can be fixed on the stage 4 by inserting the holding member 80 into the step portion 41. In addition, even when the position of the movable optical system 8a is moved by the adjusting mechanism 7 during group adjustment, the fixed optical system 8b does not move.

  In such a state, the eccentricity adjustment described below is performed, and the position of the movable side optical system 8a in the eccentric direction is accurately adjusted. After completion of the decentering adjustment, the movable side optical system 8a and the fixed side optical system 8b are fixed by bonding. When the movable side optical system 8a and the fixed side optical system 8b are fixed, they can be used as a lens assembly with a focus function. For example, it can be incorporated into an arbitrary image sensor and used as a camera with a focus function.

  The processing unit 6 will be described. The processing unit 6 calculates a wavefront profile based on the coordinate information of the light spot output from the light receiving unit 5. Further, a best fit curve is obtained for this wavefront profile. Next, the wavefront aberration profile is obtained by taking the difference between the wavefront profile and the best fit curve. Further, the wavefront aberration profile is developed with a Zernike polynomial, and the wavefront aberration profile is quantified as each coefficient of the Zernike polynomial. In calculating the wavefront profile, the luminance value information of the light spot may be used.

  Each coefficient of the Zernike polynomial can be regarded as an aberration coefficient. Therefore, during the group adjustment, for example, during the eccentricity adjustment, each coefficient of the Zernike polynomial is repeatedly obtained. Then, information necessary for the eccentricity adjustment is calculated based on each coefficient of the Zernike polynomial. This information is the moving direction and moving amount when moving the movable optical system 8a. Based on this information, by moving the adjustment arm 70 of the adjustment mechanism 7, the movable side optical system 8 a is moved in a plane perpendicular to the light projecting axis 9.

  In the eccentric adjustment, the movable side optical system 8a is moved so that each coefficient of the Zernike polynomial is reduced. Then, when each coefficient of the Zernike polynomial becomes minimum, it is determined that the movable side optical system 8a is fixed. Alternatively, when a predetermined part of the coefficients of the Zernike polynomial, that is, the coefficient corresponding to coma and astigmatism is minimized, it is determined that the movable side optical system 8a is fixed.

  The adjustment arm 70 may be moved manually or automatically. When the adjustment arm 70 is moved manually, information on the direction and amount of movement is displayed on the display unit of the processing unit 6 or a computer (not shown). The user may move the XY stage 71 based on the displayed information. On the other hand, when the adjustment arm 70 is automatically moved, information on the movement direction and the movement amount is transmitted from the processing unit 6 or the computer to the drive unit (not shown) of the XY stage 71. The adjustment arm 70 is moved by the movement of the XY stage 71 in response to a signal from the drive unit.

  The detection method of the present embodiment irradiates the measurement target optical system with irradiation light, forms a plurality of light spots from the light emitted from the measurement target optical system, and sets each of the plurality of light spots from the reference position. Is a detection method for calculating the amount of deviation of the measured optical system and detecting the position of the movable optical system with respect to the fixed optical system of the optical system to be measured. The measured optical system is arranged at a position where the irradiated light intersects, and the diameter of the irradiated light at the intersecting position is larger than the outer diameter of the measured optical system. Based on the wavefront information obtained from

  FIG. 12 is a flowchart regarding a group adjustment method which is an example of a detection method. Here, eccentricity adjustment will be described as an example of group adjustment. The group adjustment method is used in the group adjustment apparatus 1.

  First, the user turns on the power of the group adjustment apparatus 1 (and the computer). After starting up the group adjustment apparatus 1 (and the computer), calibration is performed as necessary (step S1). Details of calibration will be described later.

  Next, the optical system and arm operation are confirmed (step S2). The optical system here is the optical system of the light source unit 3. In this step, an axicon lens is placed on the light source unit 3. As the axicon lens to be placed, an axicon lens that generates a parallel light beam 10 corresponding to the angle of view of the optical system 8 to be measured is selected. Further, the operation of the adjustment arm 70 of the adjustment mechanism 7 is confirmed.

  Next, the measured optical system 8 is set (step S3). In this step, the user places the measured optical system 8 b on the stage 4. After placing the optical system to be measured 8b, the stage 4 is moved so that the position of the optical system to be measured 8b substantially coincides with the position P2 (FIG. 4). When the position of the optical system 8b to be measured substantially coincides with the position P2, the movable side optical system 8a is placed on the fixed side optical system 8b. Then, if necessary, the stage 4 is moved so that the position of the movable optical system 8a substantially coincides with the position P2. The optical system 8 to be measured may be set in a state where the movable side optical system 8a is placed on the fixed side optical system 8b.

  Here, the movable-side optical system 8a has an autofocus lens. The movable side optical system 8a can move (slide) in an eccentric direction, that is, a direction orthogonal to the light projecting axis 9. The movable side optical system 8a is held by a holding frame. By applying a force to the holding frame, the movable side optical system 8a can be moved. Further, the holding frame is provided with a drive unit that drives an autofocus lens.

  Next, eccentricity adjustment is performed (step S4). In this step, the user inputs a command for starting the eccentricity adjustment to the computer. A command is sent from the computer to the group adjusting device 1, and a parallel light beam 10 is emitted from the light source unit 3. The parallel light beam 10 is applied to the optical system 8 to be measured. The light emitted from the measured optical system 8 becomes incident light 54 and enters the light receiving unit 5.

  In the light receiving unit 5, the luminance value information and the coordinate information of the light spot 52 are output to the processing unit 6. In the processing unit 6, the analysis is performed using the coordinate information of the light spot 52 (and possibly using the luminance value information). Then, the analysis result and the amount of eccentricity are transmitted to the computer, and the analysis result and the amount of eccentricity are displayed on a computer monitor (not shown).

  Based on the analysis result and the amount of eccentricity, the eccentricity adjustment is performed. In the eccentric adjustment, the adjustment arm 70 of the adjustment mechanism 7 moves according to an instruction from the computer while the amount of eccentricity is monitored. Since the amount of eccentricity is constantly monitored, the movable optical system 8a is moved so that the amount of eccentricity is minimized. Then, when the amount of decentration is minimized, the decentering adjustment of the movable side optical system 8a is finished.

  Next, an adhesive is applied (step S5). In this step, an ultraviolet curable adhesive is applied from a nozzle (not shown) to the outer peripheral portion of the movable-side optical system 8a and the outer peripheral portion (boundary between the two outer peripheral portions) of the fixed-side optical system 8b.

  Next, curing (ultraviolet irradiation) is performed (step S6). In this step, after the adhesive is applied, the application portion is irradiated with ultraviolet light (not shown). After the irradiation, the adhesive is cured when a predetermined time elapses. Thereby, the relative position of the movable side optical system 8a and the fixed side optical system 8b is fixed, thereby completing the bonding step.

  Next, the position of the abnormality confirmation / adjustment arm is reset (step S7). In this step, it is confirmed whether or not there is any abnormality in the adjusting device and the bonding state. Further, the adjustment arm 70 is moved to the initial position. This step can be omitted.

  Finally, the measured optical system 8 that has been cured is taken out from the stage (step S8).

  FIG. 13 is a flowchart regarding calibration. The calibration is performed when the measured optical system 8 is replaced with another measured optical system or when the setting of the group adjustment apparatus 1 is changed. For example, when the optical specifications (field angle, effective aperture, focal length, aperture diameter, etc.) of the optical system 8 to be measured are changed, or when the axicon lens 33 is replaced, the positions of the light source unit 3 and the light receiving unit 5 are changed. Calibration is performed when the stage height is changed after adjustment.

  Prior to the calibration, the movable side optical system 8a and the fixed side optical system 8b are removed from the stage 4. Further, the axicon lens 33 is removed from the light source 30 (step S11).

  Next, the light source unit 3 is turned on (step S12). Thereby, a parallel light beam is irradiated from the light source unit 3 toward the stage 4. The parallel light flux passes through the opening 40 of the stage 4 and enters the light receiving unit 5. In this way, the light receiving unit 5 is irradiated with a parallel light beam (plane wave).

  Next, it is confirmed whether the parallel light flux is normally incident on the light receiving unit 5 (step S13). When the light receiving unit 5 is irradiated with a parallel light beam (plane wave), an image of a plurality of light spots is obtained from the image sensor 53 of the light receiving unit 5 as shown in the left diagram of FIG. Here, the interval between adjacent light spots corresponds to the interval between adjacent lens elements 51 of the lens array 5, that is, the arrangement pitch of the lens elements 51.

  In this state, image data (luminance value information and coordinate information) from the light receiving unit 5 is acquired by the computer (or the processing unit 6), and the interval between adjacent light spots is calculated. Here, since there is no optical system between the light source unit 3 and the optical unit 5, the intervals between the plurality of light spots are usually equal. If the interval between adjacent light spots is substantially the same for any light spot, it can be confirmed that the parallel light flux is normally incident on the light receiving unit 5.

  If the light receiving unit 5 has a tilt greater than a specified value, the intervals between the light spots are not uniform in the vertical and horizontal directions. Thereby, it can be confirmed that the parallel light beam 10 is abnormally incident on the light receiving unit 5.

  Next, the coordinates (position) of each light spot are recorded (step S14). This recording is performed by the processing unit 6 or a computer. The recorded coordinates of each light spot become reference coordinates. Although details will be described later, the recorded coordinates of each light spot are referred to as the reference coordinates (reference position) of the spot when the parallel light is incident. That is, it becomes the reference position for calculating the wavefront profile.

  Next, the axicon lens 33 is attached to the group adjusting device 1 (step S15). In this step, the axicon lens 33 is attached so that the rotational symmetry axis 34 of the axicon lens 33 coincides with the light projection axis 9. Further, the axicon lens 33 is attached so that the surface 33a faces the light source 30 side. In this way, as shown in FIG. 4, the parallel light beam 10 emitted from the axicon lens 33 becomes a circle having the smallest diameter at the position P2.

  Next, it is confirmed whether the parallel light beam 10 is normally incident on the light receiving unit 5 (step S16). The light receiving unit 5 is located closer to the position P3 than the position P2. For this reason, the cross-sectional shape of the parallel light beam 10 incident on the light receiving unit 5 has an annular shape as indicated by the position P3. The annular parallel light beam enters the light receiving unit 5. Therefore, a region where no light is incident is formed on the lens array 5. This region corresponds to the region that becomes the center of the ring, and no light beam enters the lens element 51 corresponding to this region. Therefore, an area where the light spot 52 is not formed is generated on the image sensor 53. The region where the light spot 52 is not formed is a central region of the image sensor 53 (a circular region centered on the light projection axis 9).

  On the other hand, light is incident on the lens element 51 in another region. Therefore, although the exact position of the light spot 52 is unknown for the central region of the image sensor 53, the exact position of the light spot 52 can be grasped for other regions, that is, the annular region. Therefore, the mounting state of the axicon lens 33 can be confirmed from the luminance value information and the coordinate information of the light spot 52 formed in the annular region.

  For example, when the brightness value information of each light spot 52 is the same, or when the coordinate information is substantially rotationally symmetric with respect to the light projection axis 9, the parallel light beam 10 is normally incident on the light receiving unit 5. Will be. This indicates that the rotational symmetry axis 34 of the axicon lens 33 coincides with the light projecting axis 9.

  In addition, when the axicon lens 33 is attached so that the surface 33 b faces the light source 30, the parallel light beam 10 deviates from the imaging area of the imaging element 53. Therefore, it is possible to detect that the axicon lens 33 is attached abnormally.

  In step S <b> 16, the height of the light receiving unit 5 may be adjusted in order to allow the parallel light beam 10 to properly enter the light receiving unit 5. Thereby, it is possible to detect where the light projecting axis 9 is located in the imaging area of the imaging device 53. The coordinates of the projection axis 9 are referred to as initial values when obtaining a best-fit curve described later.

  Next, the optical system 8 to be measured is temporarily placed on the stage 4 (step S17).

  Next, with respect to each of the light source unit 3, the stage 4, and the light receiving unit 5, the position adjustment and height adjustment are performed as necessary (step 18). When the parallel light beam 10 emitted from the axicon lens 33 is not irradiated on the entire surface within the effective aperture (aperture region) of the optical system 8a to be measured, the stage 4 is moved in the direction along the light projecting axis 9.

  At the position P2, the light beam diameter of the parallel light beam 10 is sufficiently large with respect to the effective aperture of the optical system 8a to be measured. Since the effective aperture of the measurement optical system 8a is known, an axicon lens that can be in such a state is selected in advance for the axicon lens 33. However, in some cases, the axicon lens may be replaced with a more appropriate one (conical angle). Further, it is confirmed that the light (incident light 54) that has passed through the optical system 8 to be measured enters the image sensor 53, and the light spot 52 is appropriately formed in the image pickup area of the image sensor 53.

  Next, it is confirmed from the signal obtained on the processing unit side that the light beam is normally incident (step 19). With the processing up to step 18, the hardware adjustment of the light source unit 3, the stage 4, the light receiving unit 5 and the like is completed. In this step, it is confirmed from the signals obtained in the light receiving unit 5 and the processing unit 6 that the development of the wavefront profile and the polar coordinate polynomial (Zernike polynomial) operates normally from the coordinates of each spot described later in detail. At this time, if the adjustment of the light source unit 3, the stage 4 and the like is appropriate and the light beam is normally incident as shown in FIGS. 1 and 8, the wavefront profile obtained in the light receiving unit is substantially axially symmetric and the region is Become wider. However, for example, when the inclination of the stage 4 or the light receiving unit is large with respect to the light projecting axis 9 in FIG. 8, the number of successful light spot correspondences to be described later decreases. Therefore, by confirming the number of spots and coordinate positions that can be associated with each other, it is confirmed that the adjustment up to step 17 described above is properly performed, that is, the light projection axis 8 shown in FIG. It is confirmed that the positional relationship such as degree and optical axis is appropriate.

  In the calibration, each adjustment value obtained by the light receiving unit 5 is appropriately displayed on the computer so that the positional relationship of the light receiving surface of the light receiving unit 5 and the orthogonality of the stage with respect to the light projecting axis 9 is optimized. The adjustment value and instruction screen are displayed. That is, the number of spots that have been successfully matched is displayed. Further, the tilt component of the Zernike coefficient described later is a component corresponding to the tilt angle of the light receiving unit 5 with respect to the light projecting axis 9. Therefore, the Zernike coefficients described later are displayed also in the calibration.

  With the above calibration, the light receiving surface of the light receiving unit 5 and the orthogonality / parallelism of the stage 4 and the distance relationship are appropriately adjusted with respect to the light projecting axis 9 for the main components of the group adjusting apparatus 1. Further, as shown in FIG. 8, the height of the light receiving unit 5 is appropriately adjusted so that the region of the light beam 54 irradiated on the light receiving unit 5 substantially coincides with the light receiving unit 5.

  Details of the eccentricity adjustment (step S4) will be described. The processing unit 6 first acquires the luminance value information and coordinate information of the light spot 52 from the light receiving unit 5. The coordinates of the light spot 52 (the position of the light spot 52) may be, for example, the barycentric position of the luminance distribution of the light spot 52. The coordinates of the light spot 52 may be obtained by the processing unit 6. In the following description, the coordinates of the light spot 52 are the coordinates of the light spot 52 obtained during the eccentricity adjustment.

  The processing unit 6 obtains the shift amount for each light spot 52 from the difference between the coordinates of each light spot 52 and the reference coordinates. As described above, the reference coordinates are acquired in advance at the time of calibration and recorded in the processing unit 6. At the time of calibration, parallel light beams enter the light receiving unit 5, thereby forming a plurality of light spots 52 on the image sensor 53. The reference coordinates are individual positions of the plurality of light spots 52.

  In obtaining the shift amount, the coordinates of each light spot 52 are associated with the reference coordinates. This association is determined by the distance from the reference coordinates to the coordinates of the light spot 52. The interval between the two adjacent light spots 52 is approximately the same as the pitch of the lens array 50 (the interval between the two adjacent lens elements 51). Therefore, if there is a light spot 52 within a distance that is half the pitch of the lens array 50 from the reference coordinates, it is determined that the coordinates of the light spot 52 correspond to the reference position. When there are a plurality of coordinates of the light spot 52 within a distance that is half the pitch of the lens array 50 from the reference coordinates, it is determined that the coordinates of the light spot 52 closest to the reference coordinates correspond to the reference coordinates. To do. In this process, if there is a spot 52 that has not been associated with the reference coordinate, the association is performed by assigning the spot 52 that is closest to the reference coordinate that has not yet been associated. In this manner, the coordinates of each light spot 52 are associated with the reference coordinates.

  Depending on the optical specifications of the optical system 8 to be measured, the tilt angle (tilt amount) of the incident light 54 incident on the light receiving unit 5 increases. Then, since the shift amount of the light spot 52 is increased, the light spot 52 is formed at a position away from a distance that is half the pitch of the lens array 50 for some of the light spots 52. As a result, it becomes difficult to associate the coordinates of each light spot 52 with the reference coordinates.

  In such a case, the axicon lens 33 may be replaced with an axicon lens having a smaller cone angle α. In this way, the inclination angle of the incident light 54 incident on the light receiving unit 5 can be reduced. As a result, it is possible to associate the coordinates of each light spot 52 with the reference coordinates.

  When all the light spots 52 have been associated with the coordinates and the reference coordinates, the shift amount is obtained. The shift amount can be obtained from the difference between the coordinates of the light spot 52 and the reference coordinates. This shift amount corresponds to the inclination angle of the wavefront 55 in FIG. Therefore, by integrating the shift amounts, or from the optical design data of the lens array 51, a wavefront profile corresponding to the wavefront 55 shown in FIG.

  FIG. 14 is a conceptual diagram of a wavefront profile. This wavefront profile indicates information including information such as the amount of eccentricity of the incident light 54 (wavefront 55). Further, since the wavefront profile corresponds to the unevenness information of the incident light 54 (wavefront 55), it is precise wavefront shape information having a resolution comparable to the wavelength. As described above, since the light source unit 3 uses a visible light LED as the light source 30, the wavelength of light in the measurement is 1 μm or less. Therefore, the incident light 54 includes information on the uneven shape of the wavefront 55 with a resolution of about 1 μm or less. Therefore, in the group adjustment apparatus 1 of the present embodiment, highly accurate group adjustment of 1 μm or less, for example, eccentricity adjustment is possible.

  FIG. 15 is a conceptual diagram of a wavefront profile acquired in the group adjustment apparatus 1 of the present embodiment. As shown in FIG. 15, the wavefront information cannot be obtained at the center of the wavefront profile. This is because the group adjusting device 1 shown in FIG. 1 has a region where the light spot 52 is not formed at the center of the light receiving unit 5 (image sensor 52).

  For areas where the light spot 52 is not formed, luminance value information cannot be obtained. Therefore, the coordinate information of the light spot 52 cannot be obtained for some of the coordinates of each light spot 52. As a result, for some of these coordinates, the coordinates of the light spot 52 cannot be associated with the reference coordinates. As a matter of course, a region where coordinates are not associated among all regions of the wavefront profile does not represent a correct wavefront.

  Therefore, in a region where the coordinates are not associated (region not representing a correct wavefront), fitting described later is not performed. That is, in the process of calculating the best fit curve and the subsequent process, the calculation process is performed only for the region representing the correct wavefront in the wavefront profile.

  As shown in FIG. 15, the wavefront profile is roughly rotationally symmetric. Therefore, it is possible to develop the wavefront profile with the Zernike polynomial (details of the development with the Zernike polynomial will be described later). Therefore, even when a wavefront profile as shown in FIG. 15 is obtained, the wavefront profile can be decomposed into coefficients of an axially symmetric component and an axially asymmetric component. Therefore, a wavefront profile as shown in FIG. 15 can be used for eccentricity adjustment.

  The region where the light spot 52 is not formed is when the light beam is scattered or the light receiving unit 5 is irradiated with an annular light beam in the optical system between the light source unit 3 and the light receiving unit 5. Arise.

  Next, a best fit curve (best fit surface) is obtained for the wavefront profile. In obtaining the best fit curve, a provisional best fit curve (hereinafter referred to as a provisional curved surface) is set. The provisional curved surface can be selected from spherical surfaces having various radii R on the computer input screen.

  Subsequently, the provisional curved surface is fitted to the wavefront profile. For the fitting, for example, a least square method can be used. Specifically, the difference at each coordinate is obtained based on the center coordinates (X, Y, Z) and radius R of the provisional curved surface and the center coordinates and radius of the wavefront profile. Then, the central coordinates (X, Y, Z) and R values of the provisional curved surface are increased or decreased so that this difference becomes smaller. The provisional curved surface when the difference becomes the smallest is taken as the best fit curve.

  Here, the spherical surface is used as the provisional curved surface, but another axially symmetric curved surface may be used as the provisional curved surface. Examples of the provisional curved surface include a rotating paraboloid, a rotating hyperboloid, and a curved surface represented by an even degree polynomial.

  In some cases, the lens array 51 of the light receiving unit 5 has an aberration. In such a case, even if a perfect spherical wave is incident on the light receiving unit 5, the obtained wavefront profile deviates from the perfect spherical surface. Therefore, the provisional curved surface may be arbitrarily set according to the configuration of the group adjustment apparatus 1.

  The provisional curved surface may be a curved surface based on optical system design data. That is, a wavefront profile that should be obtained when the decentration is zero is obtained from the optical design data of the optical system 8 to be measured, and it may be a temporary curved surface. Then, the provisional curved surface may be subtracted from the wavefront profile as a best fit curve. For example, depending on the design, the focal length of the non-measuring optical system 8 may be very long. At this time, the best fit curve has a planar shape. Therefore, as the provisional curved surface, the radius R may be selected to be infinite (planar shape).

  Next, a best fit curve is subtracted from the wavefront profile to obtain a wavefront aberration profile (difference profile). As a result, an ideal imaging state or an amount of difference from the design data can be extracted as a wavefront aberration profile. In the decentering adjustment, the position of the movable optical system 8a is adjusted basically so as to reduce the wavefront aberration profile (difference amount). FIG. 16 is a conceptual diagram of a wavefront aberration profile in which the difference amount is zero, that is, in an ideal state. Actually, the wavefront aberration profile has a shape such as unevenness or a non-axisymmetric curve according to decentration and various aberrations.

  Further, the wavefront aberration profile is developed with Zernike polynomials up to the 37th order. The Zernike polynomial is a polar coordinate polynomial defined by a radial radius ρ and an angle φ. In the embodiment of the present invention, what is called a Fringe Zernike Polynomial is used as the Zernike polynomial. In addition to the Zernike polynomials, there are a standard Zernike polynomial (Standard Zernike Polynomials), a standardized Fringe Zernike polynomial, and the like.

  Polar coordinates are obtained by converting coordinates (X, Y) on the surface of the image sensor 50 into polar coordinates. ρ is a radius that is standardized so that the maximum value is 1, and the distance from the rotation center is the radius at which the rotation radius is maximum (that is, the maximum radius of the light beam region that can be incident on the light receiving unit 5). Calculate by dividing by.

  Further, in the present embodiment, “Zernike polynomials up to 37th order” indicates that among polynomials defined as Zernike polynomials, polynomials and coefficients having a lower order up to 37 are used. For example, “Zernike polynomials of up to 8th order” refers to polynomials of low order up to 8 polynomials.

  Specifically, the procedure of developing with the Zernike polynomial is to create a virtual wavefront aberration profile (hereinafter referred to as a virtual profile) by multiplying the Zernike polynomial by each coefficient and taking the sum. Then, the virtual profile is changed by increasing or decreasing each coefficient of the Zernike polynomial. Then, the virtual profile closest to the wavefront aberration profile (the virtual profile that most accurately reproduces the wavefront aberration profile), that is, the coefficient of the Zernike polynomial is specified.

  For the specification of this coefficient, the least square method can be used similarly to the calculation of the best fit curve. That is, by taking the difference between the virtual profile and the wavefront aberration profile at a position corresponding to the arrangement of the lens array 50 (each XY region), and increasing or decreasing each coefficient so that the square sum of the difference is minimized. Identify the final coefficient.

  As described above, the Zernike polynomial is a polynomial using polar coordinates. By expanding the wavefront aberration profile with the Zernike polynomial, the wavefront aberration profile can be decomposed into an axially symmetric component, an axially asymmetric component, and the like. This makes it possible to quantitatively grasp each factor such as the eccentric component. That is, in a conventional MTF measuring instrument or the like, when there is a tilt of the light receiving unit 5 (imaging device 50), it is difficult to distinguish between the eccentricity of each lens and the tilt of the light receiving unit 5, but the above-described processing is performed. Thus, by decomposing the wavefront aberration profile into coefficients, it is possible to separate simple tilt components, eccentric components, and the like.

  In the eccentricity adjustment, the position of the movable optical system 8a with respect to the fixed optical system 8ab of the optical system 8 to be measured is adjusted so that the coefficient (coefficient component) of the Zernike polynomial is small.

  Next, a method for switching the amount of eccentricity of each lens will be described. FIG. 17 is a conceptual diagram of the behavior of the 8th and 15th order coefficients of the Zernike polynomial. FIG. 18 is a diagram showing how the four lenses are decentered.

  For example, the behavior (change) of each coefficient of the Zernike polynomial is rarely the same when the lens L1 is decentered and when the lens L2 is decentered. Different. Therefore, if the behavior of each coefficient is regarded as a vector, it can be said that each vector has a specific direction with respect to the degree of freedom of decentering of each lens. Here, the length of the vector is substantially proportional to the amount of eccentricity.

  The behavior of each coefficient of the Zernike polynomial can be obtained in advance. Specifically, it can be obtained by moving each lens on the design data of the optical system to be measured. Therefore, the vector component when each lens is decentered is recorded in the processing unit 6.

  Each coefficient of the Zernike polynomial obtained by the measurement is regarded as a vector, and these vectors are decomposed into vectors when the lenses 1 to L4 are moved. Then, it is possible to separate the eccentric variations of individual lenses. That is, in the conventional MTF measuring device, when a plurality of lenses vary, it is difficult to determine which lens varies. However, according to the present embodiment, it is possible to grasp as a numerical value how much each lens varies.

  In FIG. 17, the arrows shown as L1 eccentricity and L2 eccentricity are conceptual diagrams showing changes in the Zernike aberration coefficient when the lens L1 and the lens L2 are each eccentric by 2 μm. This arrow can be obtained in advance from the design of the optical system to be measured. Further, as already described, the coefficient (actual measurement) of the Zernike polynomial can be specifically obtained at the time of adjusting the eccentricity of the optical system to be adjusted. The points shown as actual measurements in FIG. 16 are conceptual diagrams in which the components of the Zernike polynomial whose orders are 8th and 15th are plotted. At this time, as indicated by a dotted line in FIG. 17, the length (coefficient, the length of the dotted line) of each vector that best reproduces the point obtained by actual measurement at the time of eccentricity adjustment can be specified numerically. By this processing, the amount of decentering of each lens can be obtained from the actual measurement of the wavefront aberration profile within the optical system that is the object to be adjusted.

  For example, when the length of the dotted line in FIG. 17 is twice as long as the arrows of L1 eccentricity and L2 eccentricity, and the point measured by superimposing these can be explained, the eccentricity amount of L1 is +4 μm, L2 The decentering amount is +4 μm, and the decentering amount of each lens (L1, L2) can be estimated numerically. At this time, the value indicated by the arrow (Zernike coefficient at the time of eccentricity of 2 μm) is obtained in advance from the lens data of the optical system to be adjusted by simulation and recorded in the processing unit 6.

  In the group adjustment apparatus 1 in the present embodiment, it is desired to adjust the eccentricity of only the lens L1. Therefore, optimization is performed so that the vector length of the lens L1 becomes zero when the vector obtained by actual measurement is decomposed by the vector of each eccentric component. Thereby, it is possible to configure a group adjusting device that further reduces the influence of the lens L2 eccentricity and other variations of the placement error (overall eccentricity).

  According to the above, for example, the focus shift component and the tilt amount of the light receiving unit 5 can also be estimated from each coefficient of the Zernike polynomial. Therefore, when the tilt or focus deviation variation of the light receiving unit 5 is more than a certain value, it is possible to notify the error and notify the user to perform calibration again, that is, to monitor the abnormal state. Become.

  Moreover, in the group adjustment apparatus 1 in this embodiment, it is hard to receive the influence of the placement error (variation) with respect to the stage 4 of the fixed side optical system 8b. However, it is naturally possible to obtain vector components for the placement error of the fixed-side optical system 8b. Therefore, if the eccentric adjustment can be performed in consideration of this vector component, the group adjustment apparatus 1 that is not affected by the placement error can be realized.

  Next, the order of the coefficients of the Zernike polynomial will be described. If there are two components (degrees of freedom) of the non-axisymmetric components of the coefficients of the Zernike polynomial, the Y eccentricity of L1 and the Y eccentricity of L2 can be separated. That is, if there are two degrees of freedom of the coefficients, the degree of freedom of the two variations can be determined.

When the number of lenses (total number of optical components constituting the fixed-side optical system 8b and the movable-side optical system 8a) is n0, and it is desired to cut the eccentric direction (XY), the degree of freedom is 2 × n0. . Therefore, the order n1 of the coefficients of the Zernike polynomial necessary for specifying the variation of each lens may be as shown in the following formula (2).
2 × n0 ≦ n1 (2)

Furthermore, when it is desired to separate the tilt, each lens has four degrees of freedom. Therefore, the following expression (3) is sufficient.
4 × n0 ≦ n1 (3)

  As shown in FIG. 18, when the number of lenses is four and the XY eccentricity of each lens can be cut off, eight degrees of freedom may be used. In the Zernike polynomial, for example, if the wavefront aberration profile is developed using only the coefficients of the Zernike polynomial up to the eighth order, the degree of freedom of the non-axisymmetric component is six. Here, for example, if the coefficients of Zernike polynomials up to the 15th order are used, there are 12 non-axisymmetric components, and it is possible to cut out the variation of each lens.

  Even if the Zernike polynomials up to the eighth order are used, for example, when the non-axisymmetric component can be adjusted to be completely zero, the inside of the optical system may be regarded as being axially symmetric. Therefore, in order to simplify the adjustment, the order may be lowered.

  As described above, according to the detection apparatus and the detection method of the present invention, it is possible to detect the position of the optical element constituting the optical system to be measured with high accuracy. And by using this detection result, according to the group adjustment apparatus 1 and the group adjustment method of this embodiment, the arrangement | positioning (installation) error of the to-be-measured optical system at the time of group adjustment can be made as small as possible. In addition, it is possible to measure the relative positional variation (for example, eccentricity) of each lens (lens group), particularly the positional variation in the direction orthogonal to the optical axis with high accuracy. Further, since the variation is adjusted based on this highly accurate measurement result, it is possible to obtain an optical system under measurement with little variation in position.

  The present invention can take various modifications without departing from the spirit of the present invention. In the above description, an example of a device that adjusts the eccentricity of the movable part of the camera module is given as the group adjusting device 1 in the present embodiment, but the present invention is not limited to this. For example, not only the adjustment between the groups but also the positional relationship between the groups can be detected. Therefore, the adjustment mechanism 7, the adhesion mechanism (not shown), and the UV light source (not shown) may be removed, and a detector for detecting the positional relationship between the groups may be configured. Group adjustment includes adjusting the positional relationship in the optical axis direction, the positional relationship in the eccentric direction, and the positional relationship in the tilt direction.

  In addition, as an example of the group adjusting device in the present embodiment, an example of a device for adjusting the eccentricity of the focusing lens is given, but the present invention is not necessarily limited thereto. For example, the group adjustment device in the present embodiment may be used as a decentering adjustment device for a zoom optical system.

  Moreover, although the example of eccentricity adjustment was given in the group adjustment apparatus in this embodiment, it is not necessarily restricted to this. That is, since the coefficient of the Zernike polynomial can be arbitrarily set, for example, it may be used for focus position adjustment, tilt adjustment, and the like.

  Although the axicon lens 33 having a cone angle α = 25 degrees is illustrated as an axicon lens, it is not necessarily limited to this. That is, when the cone angle α is reduced, the angle at which the parallel light beam 10 intersects the light projection axis 9 is reduced. That is, the parallel light beam 10 is almost parallel to the light projection axis 9. In this case, the influence of the placement error of the measured optical system 8 can be reduced. However, the sensitivity to eccentricity (shift amount of the light spot 52) becomes small. For this reason, it is difficult to take a correspondence between the resolution performance of the imaging module (measurement optical system 8), particularly the resolution performance with respect to off-axis light and the amount of eccentricity.

  Conversely, when the cone angle α is increased, the angle at which the parallel light beam 10 intersects the light projection axis 9 increases. In this case, it is possible to obtain the parallel light beam 10 suitable for the eccentric adjustment of the imaging module having a large angle of view and the eccentric adjustment at the wide angle end of the zoom lens. That is, it is possible to adjust the eccentricity corresponding to the resolution when shooting at a wide angle of view (wide angle end).

  The axicon lens 33 does not necessarily have to have a conical shape on all surfaces. For example, the apex portion of the conical shape may be flat. In this way, when the axicon lens is irradiated with a parallel light beam, the position of the light projecting axis 9 of the group adjusting device can be easily determined. Therefore, the calibration process can be further simplified.

  Further, the lens 32 and the axicon lens 33 are not necessarily separate parts. For example, the lens 32 and the axicon lens 33 may be integrated so that one lens is convex and the other surface has an axicon shape.

  Further, in the group adjusting device in the present embodiment, the axicon lens 33 can be easily replaced. That is, it is easy to finely adjust the necessary adjustment accuracy and sensitivity only by exchanging the axicon lens 33. Therefore, it is possible to provide a general-purpose eccentricity adjustment device that is suitable for adjusting any imaging module or the like.

  In a small imaging module, since the half angle of view is about 30 degrees, it is sufficient that the angle at which the parallel light beam 10 intersects the light projection axis 9 is about 5 degrees to 20 degrees. That is, if α ≧ 20 degrees, an adjustment device with good sensitivity corresponding to the resolution performance can be realized. That is, according to the present embodiment, it is possible to realize an adjustment device that is compatible with the resolution performance obtained by the MTF measuring instrument or the like.

  Further, if 20> α ≧ 5 degrees, the correlation between the resolution performance with respect to off-axis light and the amount of eccentricity becomes small, but an adjustment device that reduces the influence of the placement error can be provided. For example, it is suitable for realizing an adjusting device that is not affected by a placement error of about several μm.

  Moreover, in the group adjustment apparatus of this embodiment, although the parallel light beam 10 is entered from the movable side optical system 8a side, it is not necessarily restricted to this. For example, the parallel light beam 10 may be incident from the fixed optical system 8b side. That is, the fixed side optical system 8b may be disposed on the light source unit 3 side, and the movable side optical system 8a may be disposed on the light receiving unit 5 side.

  Moreover, in the group adjustment apparatus of this embodiment, the optical system of the camera module for mobile phones was illustrated as the measured optical system 8, but it is not necessarily limited to this. For example, group adjustments can be made for a capsule endoscope, an endoscope optical system, a zoom lens, a replacement lens, a microscope objective lens, and the like. In mobile phone cameras and capsule endoscopes, the camera module is extremely small. The ultra-small camera module is a module in which, for example, the size of the camera (optical system) portion is about 10 mm or less.

  Moreover, the effect regarding the group adjustment apparatus of this embodiment has the following effects.

  According to the group adjustment device of the present embodiment, it is possible to perform group adjustment with sensitivity equivalent to that when off-axis light is incident while main components are arranged on the axis. Thereby, it is possible to provide a group adjustment device with good sensitivity.

  The performance of the imaging system is usually evaluated by the degree of off-axis resolution degradation. In a conventional adjustment device using on-axis light, there may be a problem that even if the resolution is good on the axis and the eccentricity adjustment is passed, there are problems such as coma and one-side blurring off the axis. That is, since the management item at the time of adjustment and the phenomenon in the actual performance evaluation are different, a problem may occur. In the group adjustment apparatus of the present embodiment, a light beam equivalent to off-axis light at the time of imaging is incident on the optical system to be measured at the time of eccentricity adjustment. Therefore, in the group adjustment device of the present embodiment, it is possible to guarantee performance corresponding to the imaging performance.

  In the group adjustment apparatus of this embodiment, a light beam (tangential light beam) incident on the optical system to be measured becomes a parallel light beam in a cross section including the projection axis. On the other hand, a plane (sagittal ray) that does not include the optical axis (projection axis) deviates from the parallel light flux. However, when the eccentricity adjustment reaches the acceptable level, the tangential MTF is lower than the sagittal MTF by design. Therefore, if adjustment is performed by managing tangential rays having a low MTF value, the eccentricity adjustment is sufficient.

  If an axicon lens is used as in the group adjusting device of this embodiment, a tangential beam can be used as a parallel beam. If the light spot diameter is managed in the cross-sectional direction including the rotationally symmetric axis (projecting axis), the performance corresponding to the tangential ray can be guaranteed. This is advantageous because the difference between the adjustment result and the image quality performance can be eliminated.

  In imaging inspection after eccentricity adjustment, for example, MTF inspection or imaging evaluation, it is common to evaluate off-axis resolution. According to the prior art, even if the on-axis performance can be satisfactorily adjusted, off-axis light is not confirmed. Therefore, there is a problem that the adjustment result does not correlate with the result of the resolution inspection such as MTF or the photographing test. Specifically, there has been a problem that a product that has passed the eccentricity adjustment may be rejected in the subsequent resolution inspection.

  On the other hand, in the group adjusting apparatus of the present embodiment, the light incident on the optical system to be measured corresponds to off-axis light in the cross section of the optical axis (light projection axis). This means that a light beam similar to the light beam for evaluating off-axis light is used for adjustment in the MTF evaluation. Therefore, according to the group adjustment device of the present embodiment, an adjustment device having a good correlation with the imaging performance can be configured.

  Generally, the imaging module is designed so that the resolution performance is good when a parallel light beam is incident on an optical system. In addition, image degradation at the time of shooting is likely to occur largely not on the axis but off-axis around the imaging area. The group adjustment apparatus of the present embodiment is configured based on such points.

  Further, in the group adjusting device of the present embodiment, a parallel light beam is incident in a cross section including the rotationally symmetric axis of the axicon lens. In general, when a completely parallel light beam is incident, the parallel movement of the component to be measured (measured optical system) affects the overall positional relationship of the light spots formed by the light receiving unit (interval between adjacent light spots). No longer.

  In the group adjustment apparatus of this embodiment, the best fit curve is extracted on the light receiving module side, thereby detecting the rotational symmetry center of the light beam and evaluating the relative coordinates of the image with respect to the rotational symmetry center. In this way, the parallel movement variation (placement error) can be completely canceled. As a result, it is possible to eliminate or reduce variations due to placement errors and adjustment devices.

  In addition, according to the group adjustment device of the present embodiment, a single axicon lens can substantially create a plurality of off-axis rays (corresponding to each quadrant). That is, the tilt angle of the intersecting rays can be determined with the accuracy of processing tolerance of a single lens.

  On the other hand, in the prior art in which a mirror and a light source are placed off-axis, the number of components such as a light source, a mirror, and a lens increases. As the number of parts increases, the positional relationship between the light beams increases by the number of parts, and thus repeatability at the time of adjustment is lost.

  Here, a plane orthogonal to the optical axis (light projection axis) is set as a virtual plane, and two axes orthogonal to each other are set in the virtual plane. With these two axes, the virtual plane can be divided into four quadrants. Here, for example, when a light source and a lens are arranged in the first and third quadrants, the respective members have a variation of about several μm to several hundred μm.

  In this case, since the relative position variation in the third quadrant as viewed from the first quadrant is about (several μm to several hundreds μm) × the number of parts (for example, 2 to 4 points), the variation as a whole is about several tens of μm. End up. As described above, since the positional relationship varies, for example, even if an attempt is made to adjust the eccentricity within 2 μm, the adjustment becomes almost impossible. Or, each time the measuring instrument is used, highly accurate positioning adjustment is required.

  According to the group adjusting apparatus of the present embodiment, off-axis light is generated by only one lens, so if a parallel light beam is emitted first, the crossing angle of the light rays can be roughly determined by the processing accuracy order of the single lens. Can be. Compared with a conventional off-axis type adjustment device that increases the number of parts, the number of parts on the adjuster side is reduced, so that adjustment with higher accuracy and high repeatability becomes possible.

  Moreover, according to the group adjustment apparatus of this embodiment, the influence of a parallel movement is canceled by irradiating a parallel light beam as shown in FIG. 5, and using a best fit curve. For this reason, variations (placement errors) when the fixed-side optical system is mounted on the stage 4 are less likely to affect the wavefront aberration profile and the value of the coefficient of the Zernike polynomial. Therefore, the influence on adjustment accuracy can be reduced.

  Incidentally, as a conventional technique using a wavefront sensor, there is an apparatus disclosed in Japanese Patent No. 4860378. In this case, the position of the wavelength order can be detected. However, since a spherical wave is used, the adjustment device is still a reference. That is, since the center of the spherical wave becomes the reference position of the adjustment device, the placement error of the fixed optical system with respect to this reference position affects the adjustment accuracy. This is a factor that degrades the measurement accuracy.

  Some decentering adjustment devices rotate the entire optical system (both the movable side optical system and the fixed side optical system). However, if there is a movable part, the variation of the position of the variation of the movable part results in repeated reproducibility. According to the group adjustment apparatus of the present embodiment, the fixed-side optical system is not moved, and thus is not affected by the movable part play. Adjustment accuracy can be improved because there is no moving part play.

  In the case of adjusting the eccentricity as described above, for example, a rotation method as shown in Japanese Patent No. 4774332 can be considered. The technique of Japanese Patent No. 4774332 is intended to evaluate fluctuations in reflected light and the like by rotating the entire optical system.

  However, since the rotation mechanism is usually composed of a plurality of parts, the movable part play at the time of rotation generally exceeds about 10 μm. That is, when returning to the original position even after one rotation at the time of evaluation, the axis of the optical system to be measured itself is shaken, so that it is difficult to achieve the accuracy of 2 μm. Further, 2 μm is almost in the wavelength order. Therefore, adjustment is difficult by a mechanical system. In the prior art in which the fixed-side optical system is moved, it is difficult to achieve the necessary adjustment accuracy.

  Moreover, in the group adjustment apparatus of this embodiment, since the optical system and the irradiation area are axially symmetric, accurate analysis of the axially asymmetric component can be performed by development with a polar coordinate polynomial.

  In the prior art, there is one in which a light source is arranged off-axis in order to generate ambient light (off-axis light). This increases the size and complexity of the light source. As a result, since the positional deviation of the light source affects the adjustment accuracy so as to be proportional to the size and the number of parts, the variation amount is integrated according to the number of parts.

  However, according to the group adjustment apparatus of the present embodiment, the main components are arranged on the axis of the apparatus, so the number of parts is reduced. This means that the accumulated variation becomes small. As a result, according to the group adjustment device of the present embodiment, an adjustment device suitable for highly accurate adjustment of about several μm can be provided.

  Further, in the conventional technique, when a large number of parts are arranged in the off-axis direction, positional variations and deformation variations in the eccentric direction occur. On the other hand, according to the group adjusting device of the present embodiment, since the parts placed outside the shaft are reduced, the influence of variation in the eccentric direction and deformation are minimized. Thereby, an apparatus with good adjustment accuracy can be provided.

Further, when a light source or the like is disposed far off the axis of the adjusting device, deformation occurs in an eccentric direction of about several μm due to the temperature variation of the light source itself and the environmental temperature. For example, it is assumed that the light source is arranged at a position away from the optical axis of the adjusting device by about R1 = 100 mm. Here, for the sake of approximation, it is assumed that aluminum is used for the member (exterior) of the light source portion. Further, it is assumed that the temperature rise of the light source portion is about ΔT = 5 ° C. In this case, since the linear expansion coefficient α of industrial pure aluminum is about α = 2.4 × 10 ⁻⁵ / K, the amount of thermal deformation in the direction orthogonal to the optical axis is about R1 × α × ΔT≈12 μm. This deformation affects the variation in the eccentric direction.

  That is, the fact that the light source that generates the irradiation light is shifted by 12 μm is equivalent to the fact that the optical system to be measured is shifted. If a light source (which becomes a heat source) or the like is disposed off the axis, each member is displaced, which causes position variation. A similar influence is also given to fluctuations in environmental temperature. The same applies not only to the light source but also to the lens and mirror of the adjuster, and if there is a temperature difference between the parts by arranging a mirror or the like as a reference off-axis, deformation of about several μm can occur. For this reason, adjustment accuracy is deteriorated.

  In the prior art, there are those in which a plurality of light sources are arranged off-axis. Each light source serves as a heat source, but there are individual variations in temperature rise and the like. Therefore, the temperature difference of each member becomes a variation factor of the positional relationship. When these variations are integrated, it exceeds 2 μm.

  On the other hand, in the group adjustment apparatus of the present embodiment, there are no parts arranged far away from the axis. Therefore, there is no factor that causes thermal deformation in the eccentric direction. As described above, in the group adjustment device of the present embodiment, the variation caused by the adjustment device, that is, the variation due to thermal deformation is optimized. Moreover, although the light source is arrange | positioned on an axis | shaft, the parallel light beam is produced | generated. In this case, the shift in the axial direction of the light source arranged on the axis does not affect the adjustment accuracy. Therefore, in the group adjustment apparatus of this embodiment, the influence of thermal deformation etc. is also minimized.

  In the prior art, since the placement error is strong, it is difficult to separate the placement error and the lens eccentricity (the eccentricity of the movable optical system with respect to the fixed optical system). On the other hand, in the group adjustment apparatus of the present embodiment, it is easy to separate the placement error and the lens eccentricity.

  Further, in the group adjustment apparatus of this embodiment, there are few restrictions on the optical system to be measured. Further, since the parallel light beam is made incident from the movable side optical system, it is possible to reduce erroneous detection of the light spot position and improve the adjustment accuracy. In addition, the intersection of rays can be minimized. This will be described below.

  In the description of the group adjustment device of the embodiment, the number of light sources is one. However, when light is incident from a plurality of places (when there is an overlap of light beams), there is a case where the light spot does not become one point for one lens array. In addition, a plurality of light spots may be generated. In this case, the light spot position may be erroneously detected.

  However, according to the group adjustment device of the present embodiment, it is possible to arrange the collimated light beam incident from the movable side optical system. Here, in the design of the image pickup system, it is usual that the image forming point when parallel light is incident is optimized to be one point. Then, in the group adjustment apparatus of the present embodiment, when viewed in a cross section including the optical axis (light projection axis), the image forming points are concentrated at almost one point. Light diffused from an ideal point only spreads as the light travels, and no overlap can occur. Therefore, the light emitted from one point (condensing point) becomes diffused light, and it is difficult for light to overlap on the lens array surface.

  If the light beams overlap, the spot position detection accuracy deteriorates. However, according to the group adjustment apparatus of the present embodiment, the parallel light beam can be incident from the movable side optical system, so that the detection accuracy can be further improved. That is, the light spot position can be accurately detected in the light receiving unit, and the detection accuracy can be further improved.

  As another method, in thinking experiments, when the fixed side optical system is mounted on the adjustment device, the movable side optical system is used so that high-precision positioning is performed, and further, no positional deviation occurs in the fixed side optical system. In addition, it is possible to adjust the eccentricity of the fixed-side optical system and the movable-side optical system.

  However, in such a system, the adjustment process is required twice. Further, since the fixed side optical system must not be moved when the movable side optical system is mounted, it is not realistic. Also, for products with a large number of productions such as camera modules for mobile phones, the tact time at the time of adjustment is more than doubled, which is not realistic. According to the present application, since the influence of the placement error is reduced, the tact time at the time of adjustment can be reduced.

  In addition, there exist the following as a prior art and subject relevant to the group adjustment apparatus of this embodiment. Japanese Patent No. 3739295 discloses a technique related to positioning of a fixed optical system such as a single focus lens. Here, a technique for determining the positional relationship of a plurality of lenses overlapping in the optical axis direction is disclosed. In this technique, if the position of at least one lens is determined, the positional relationship of the next stage lens is determined.

  According to the above technique, the relative displacement amount of each lens is determined by the accuracy of each adjacent lens component. That is, the positioning accuracy is determined by the accuracy of the mold parts. For example, if the decentering accuracy of the optical surface of the mold part is 2 μm, the relative positional variation amount of the optical surface is roughly the same.

  However, in such a situation, if the optical system is divided into a movable side optical system and a fixed side optical system and a drive mechanism such as focus adjustment is added to the movable side optical system, a problem arises. That is, a plurality of parts are required to configure a driving mechanism such as focus adjustment. At this time, the amount of variation is integrated so as to be proportional to the number of components and the complexity of the configuration, and as described above, it is difficult to obtain positional accuracy of the same degree (2 μm) as that of a single component.

  Therefore, decentering adjustment is required for this movable optical system. However, the adjustment accuracy required for the eccentric adjustment requires the accuracy of the mold part (about several μm) for the above reason. However, it is difficult to obtain the required accuracy with the conventional eccentricity adjusting device.

  As a conventional eccentricity adjusting device, there are adjusting devices described in Japanese Patent No. 4774332, Japanese Patent No. 4860378, and Japanese Patent No. 4661015.

  Japanese Patent No. 4860378 discloses a chart type adjusting device. Since this adjustment device employs an optical measurement method, the measurement accuracy can be improved as compared with a measurement method that relies on mechanical rotation or the like. However, since the adjustment device side has a measurement (adjustment) reference, it is affected by the placement error of the fixed-side optical system.

That is, if a reference device such as a chart is arranged in the adjustment device, each of the fixed-side optical system and the movable-side optical system has variations with respect to the reference adjustment device. Therefore, as shown in the following equation, the amount of variation of the movable side optical system as viewed from the fixed side optical system exceeds 2 μm because each variation amount is integrated.
P1 + P2> 2μm
here,
P1 is the amount of variation in the distance from the optical axis of the fixed-side optical system to the light projection axis of the adjusting device,
P2 is the amount of variation in the distance from the light projection axis of the adjusting device to the optical axis of the drive side optical system,
It is.

  As described above, when the adjusting device has a reference axis or a condensing point (chart, jig lens, etc.), the adjusting device has a measurement (adjustment) reference. Therefore, when viewed on the basis of the adjustment device, the fixed-side optical system and the movable-side optical system have variations. Then, when viewed from the fixed-side optical system, each variation amount is accumulated in the movable-side optical system, so that it is difficult to achieve an accuracy of 2μ (mold accuracy of a single molded product).

  Further, as an adjusting device, there is a device disclosed in Japanese Patent No. 4661015. In this apparatus, since the axial light is used, the eccentricity sensitivity is insufficient. That is, in general, on-axis resolution is relatively good in the resolution of an imaging system such as a camera. On the other hand, resolution deterioration tends to be greater at off-axis, that is, around the imaging area than on-axis. The same is true when there is an eccentricity, and the degradation of the resolution on the axis due to the eccentricity is small compared to the off-axis. Thus, in the adjustment using the on-axis light, the sensitivity at the time of adjustment tends to be low.

  As described above, the device disclosed in Japanese Patent No. 4661015 uses on-axis light. Therefore, for example, even if the image quality is deteriorated around the imaging area due to adjustment variations, if the image in the center of the imaging area is good, an erroneous determination may be made that the adjustment is sufficient. There is sex. As described above, since the resolution with respect to the axial light is good, there is a problem that adjustment sensitivity cannot be obtained when the axial light is used for adjustment.

  In this case, it can be considered that the adjustment standard for the on-axis light is excessively strict. However, there is essentially no direct correlation between the excessively good on-axis resolution and the good off-axis resolution. Then, in the above apparatus, items that are not directly correlated with items that should be adjusted are merely adjusted excessively. Therefore, the above apparatus does not essentially solve the problem that the adjustment result and the resolution inspection result are not correlated.

  As described above, the present invention is suitable for a detection apparatus that detects the relative position of the optical element of the optical system to be measured with high accuracy and a group adjustment apparatus that can perform group adjustment using the detection result.

DESCRIPTION OF SYMBOLS 1 Adjustment apparatus 2 Main body 3 Light source unit 4 Stage 5 Light reception unit 6 Processing unit 7 Adjustment mechanism 7a, 7b Movement unit 8 Optical system to be measured 8a Movable side optical system 8b Fixed side optical system 9 Light projection axis 10 Parallel light beams 10a, 10b, 10c Cross section of parallel light beam 30 Light source 31 Pinhole 32 Lens 33 Axicon lens 33a Axicon lens lens surface 33b Axicon lens lens surface 34 Axis of rotation 40 Opening 41 Stepped portion 50 Lens array 51 Lens element 52 Light spot 53 Image sensor 54 Incident light 55 Wavefront 70 Adjustment arm 71 XY stage 72 Aperture 80 Holding member L1 First lens L2 Second lens L3 Third lens L4 Fourth lens

Claims (7)

A detection device that detects a relative position of an optical element constituting an optical system to be measured,
A light source unit for making irradiation light incident on the optical system to be measured;
A stage for holding the optical system to be measured in an irradiated area;
A light receiving unit that receives light transmitted through the optical system to be measured and converts it into an electrical signal;
A processing unit for processing the electrical signal,
The light receiving unit has a wavefront sensor using a lens array, and
The light source unit emits a parallel light beam intersecting with the irradiation light in a cross section including a projection axis. The light source unit is
A light source;
A first optical system for generating parallel light;
A second optical system having a deflection surface including a conical shape,
The detection device according to claim 1, wherein the parallel light beams are generated by deflecting the parallel light on the deflection surface.   The detection device according to claim 2, wherein the cone shape of the deflection surface is a cone shape. The processing unit generates a wavefront profile based on information from the light receiving unit;
4. The detection apparatus according to claim 1, wherein difference profile information is output from the wavefront profile and a predetermined best fit surface. The difference profile information is expanded by a polar coordinate polynomial,
The detection apparatus according to claim 4, wherein the position of the optical element is adjusted so that a predetermined coefficient component of the polar coordinate polynomial is small. The following expression (2) is satisfied, where n0 is the total number of optical components constituting the fixed side optical system and the movable side optical system, and n1 is the order of the polar coordinate polynomial. Detection device.
2 × n0 ≦ n1 (2) Irradiate the measured optical system with irradiation light,
A plurality of light spots are formed from the light emitted from the optical system to be measured,
For each position of the plurality of light spots, calculate the amount of deviation from the reference position,
A detection method for detecting a position of a movable side optical system with respect to a fixed side optical system of the measured optical system,
The irradiation light is a parallel light flux intersecting the irradiation light in a cross section including a projection axis,
The measured optical system is disposed at a position where the irradiation light intersects, and
The detection method according to claim 1, wherein a diameter of the irradiation light at the intersecting position is larger than an outer diameter of the optical system to be measured.

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