WO2005106566A1 - ビーム整形光学系およびレーザービームプリンタの光学系 - Google Patents
ビーム整形光学系およびレーザービームプリンタの光学系 Download PDFInfo
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- WO2005106566A1 WO2005106566A1 PCT/JP2005/008224 JP2005008224W WO2005106566A1 WO 2005106566 A1 WO2005106566 A1 WO 2005106566A1 JP 2005008224 W JP2005008224 W JP 2005008224W WO 2005106566 A1 WO2005106566 A1 WO 2005106566A1
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- optical system
- beam shaping
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- light source
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- 230000003287 optical effect Effects 0.000 title claims abstract description 191
- 238000007493 shaping process Methods 0.000 title claims abstract description 139
- 201000009310 astigmatism Diseases 0.000 claims abstract description 46
- 230000008859 change Effects 0.000 claims description 84
- 230000004075 alteration Effects 0.000 claims description 32
- 239000004065 semiconductor Substances 0.000 claims description 16
- 238000003384 imaging method Methods 0.000 claims description 13
- 238000000034 method Methods 0.000 claims 1
- 238000010586 diagram Methods 0.000 description 34
- 230000007613 environmental effect Effects 0.000 description 8
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/435—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of radiation to a printing material or impression-transfer material
- B41J2/47—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of radiation to a printing material or impression-transfer material using the combination of scanning and modulation of light
- B41J2/471—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of radiation to a printing material or impression-transfer material using the combination of scanning and modulation of light using dot sequential main scanning by means of a light deflector, e.g. a rotating polygonal mirror
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B19/00—Condensers, e.g. light collectors or similar non-imaging optics
- G02B19/0004—Condensers, e.g. light collectors or similar non-imaging optics characterised by the optical means employed
- G02B19/0009—Condensers, e.g. light collectors or similar non-imaging optics characterised by the optical means employed having refractive surfaces only
- G02B19/0014—Condensers, e.g. light collectors or similar non-imaging optics characterised by the optical means employed having refractive surfaces only at least one surface having optical power
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B19/00—Condensers, e.g. light collectors or similar non-imaging optics
- G02B19/0033—Condensers, e.g. light collectors or similar non-imaging optics characterised by the use
- G02B19/0047—Condensers, e.g. light collectors or similar non-imaging optics characterised by the use for use with a light source
- G02B19/0052—Condensers, e.g. light collectors or similar non-imaging optics characterised by the use for use with a light source the light source comprising a laser diode
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
- G02B27/0938—Using specific optical elements
- G02B27/0944—Diffractive optical elements, e.g. gratings, holograms
Definitions
- the present invention relates to a beam shaping optical system having an axially asymmetrical profile and shaping the shape of a beam from a light source, and a beam shaping having an axially asymmetrical profile and shaping the shape of a light source power beam.
- the present invention relates to an optical system of a laser beam printer including an element.
- the present invention particularly relates to a beam shaping optical system and an optical system of a laser beam printer, each including a diffraction grating surface having a phase function defined so as to minimize astigmatism.
- Devices using a semiconductor laser as a light source include an optical pickup device for an optical recording medium, a scanning optical system such as a laser printer, a laser processing machine, and an optical communication device.
- a scanning optical system such as a laser printer, a laser processing machine
- an optical communication device In these devices, from the viewpoint of energy efficiency and aberration reduction, the portion where the ratio of the energy value in the beam cross section perpendicular to the optical axis to the peak value is a certain value or more is an axisymmetric circle or an ellipse with a small aspect ratio. It is preferred that the shape be used, in many cases.
- the width and thickness of an active layer corresponding to a beam waist position of a semiconductor laser as a light source are greatly different.
- the spread angle of the radiated light beam in the plane direction parallel to the active layer is about 1/3 to 1/6 times the spread angle in the vertical direction
- the peak value of the energy value in the beam section perpendicular to the optical axis is The portion where the ratio to is equal to or greater than a certain value has an elliptical shape.
- this light beam is converted into a parallel light beam using an axisymmetric collimator, for example, the portion where the ratio of the energy value in the beam cross section perpendicular to the optical axis of the resulting parallel beam to the peak value is equal to or greater than a certain value is reduced. It remains elliptical.
- An elliptical beam emitted from such a semiconductor laser is shaped into a circle or an ellipse having an arbitrary ratio between a long axis and a short axis while suppressing wavefront aberration so as to conform to the optical characteristics of a device to which the semiconductor laser is applied.
- an axially asymmetric beam shaping element has different refractive powers in the X-axis direction and the y-axis direction when the optical axis is the z-axis. For this reason, an axially asymmetric beam shaping element has different optical characteristics in the X-axis direction and the y-axis direction with respect to the refractive index fluctuation caused by external factors such as the wavelength fluctuation of the light source and the environmental temperature. There is a problem that large astigmatism is caused.
- FIG. 1 is an optical path diagram of a beam shaping element in a cross section parallel to an active layer of a semiconductor laser as a light source
- FIG. 2 is an optical path diagram of a beam shaping element in a cross section perpendicular to the active layer.
- the light beam from the active layer of the semiconductor laser passes through the beam shaping element, so that the opening angle in the parallel direction and the opening angle in both the vertical direction change.
- the wavefront aberration of the emitted light beam is sufficiently low and the beam is generally shaped so as to form a spherical wave. Therefore, the virtual image point of the emitted light beam on a plane parallel to the active layer and the virtual image point of the emitted light beam on a plane perpendicular to the active layer coincide on the optical axis.
- the emitted light beam is a particularly collimated plane wave, the virtual image points coincide at infinity.
- the virtual image point When a change in the refractive index occurs due to a change in the light source wavelength or a change in the external environment, the virtual image point also moves in accordance with the change in the refractive power.
- a large amount of astigmatism is generated because the amounts of shift of the virtual image points in the parallel and vertical sections are different.
- an external factor such as a change in the wavelength of the light source or a change in the environmental temperature.
- a beam shaping optical system includes a beam shaping element that has an axially asymmetric profile and shapes the shape of a beam from a light source.
- the beam shaping optical system according to the present invention when the optical axis is the z-axis and the plane perpendicular to the optical axis is the xy plane, the light source power in the xz plane with respect to the wavelength change of the light source up to the imaging point or virtual image point Diffraction grating with X- and y-axis phase functions so that astigmatism is minimized by making the change in the reciprocal of the distance equal to the change in the reciprocal of the distance in the yz plane.
- a surface when the optical axis is the z-axis and the plane perpendicular to the optical axis is the xy plane, the light source power in the xz plane with respect to the wavelength change of the light source up to the imaging point or virtual image point Diffraction grating with X- and y-axis phase functions so that astig
- the light source force on the xz plane changes the reciprocal of the distance to the imaging point or virtual image point and the reciprocal of the distance on the yz plane.
- the change can be made equal, and astigmatism caused by a change in the reciprocal of the distance can be minimized.
- a beam shaping optical system includes a beam shaping element having an axially asymmetric profile and shaping the shape of a beam from a light source.
- the beam shaping optical system according to the present invention when the optical axis is the z-axis and the plane perpendicular to the optical axis is the xy plane, the light source force on the xz plane also changes from the imaging point or the virtual image point to the temperature change. Diffraction with phase functions in the X-axis and y-axis directions so that astigmatism is minimized by making the change in the reciprocal of distance equal to the change in the reciprocal of the distance in the yz plane. It has a lattice plane.
- the light source power on the xz plane changes the reciprocal of the distance to the imaging point or virtual image point, and changes the reciprocal of the distance on the yz plane.
- the beam shaping optical system further includes: a change in the wavelength of the light source or a change in the temperature; a change in the light source power in the xz plane; The phase functions in the x-axis direction and the y-axis direction are determined so that the change in the reciprocal of the distance on the plane is minimized.
- the wavelength change or temperature change of the light source can be minimized.
- the beam shaping optical system further includes an X-axis direction and a y-axis direction so that the amount of spherical aberration with respect to a wavelength change or a temperature change of the light source is minimized.
- the correlation number is determined.
- spherical aberration can be minimized with respect to a wavelength change or a temperature change of a light source.
- a beam shaping optical system includes a term that is also an even function force of one or both of the phase function force and y of the diffraction grating.
- the light source is a semiconductor laser
- the active layer of the semiconductor laser is parallel to the xz cross section.
- a beam whose ratio of intensity to peak intensity is equal to or greater than a predetermined value can be represented by an ellipse is shaped into a beam whose ratio is equal to or greater than a predetermined value can be represented substantially by a circle.
- a beam shaping optical system according to another embodiment of the present invention is used in an optical pickup device.
- the beam from the laser light source where the ratio of the intensity on the plane perpendicular to the optical axis to the peak intensity is equal to or greater than the predetermined value, can be represented by an ellipse, the ratio is equal to or higher than the predetermined value.
- the astigmatism can be minimized with respect to a change in the wavelength or temperature of the light source, and the effect is minimized even in a short wavelength range used for a blue-ray disc.
- the light source is a semiconductor laser
- the active layer of the semiconductor laser is parallel to the xz cross section
- the light from the laser light source is perpendicular to the optical axis.
- a beam whose ratio of the intensity to the peak intensity is equal to or greater than a predetermined value is represented by an ellipse
- a beam whose ratio is equal to or greater than a predetermined value is represented by an ellipse having a ratio of a major axis to a minor axis different from the ellipse.
- a beam shaping optical system according to another embodiment of the present invention is used in an optical system of a laser beam printer.
- a portion where the ratio of the intensity from the laser light source on the plane perpendicular to the optical axis to the peak intensity is equal to or greater than a predetermined value is an ellipse. While the beam whose ratio is equal to or more than a predetermined value is shaped into a beam that can be represented by an ellipse having a ratio of the major axis to the minor axis different from the ellipse, the beam can be astigmatized with respect to the wavelength change or temperature change of the light source. Aberration can be minimized, and a shift in the imaging position in a direction parallel to the scanning direction and a direction perpendicular to the scanning direction can be prevented.
- a beam shaping optical system includes a single lens. Therefore
- the structure is simple and the dimensions can be reduced.
- the diffraction grating surface is separated from the beam shaping element.
- a diffraction grating surface having an axisymmetric phase function is separated from a diffraction grating surface having a phase function in which only the X term or only the y term has a force. ing.
- the mold is easy to manufacture and easy to manufacture.
- a diffraction grating surface having an axisymmetric phase function is superimposed on an axisymmetric refraction surface.
- the optical system of the laser beam printer according to the present invention includes a beam shaping element having an axially asymmetric profile and shaping the shape of a beam from a light source.
- the optical system of the laser beam printer according to the present invention when the optical axis is the z-axis and the plane perpendicular to the optical axis is the xy plane, the light source power in the xz plane with respect to the temperature change.
- a diffraction grating surface with phase functions in the X-axis and y-axis directions is provided so that astigmatism is minimized by making the reciprocal change equal to the reciprocal change of the distance in the yz plane. I can.
- the light source power in the xz plane with respect to a temperature change can be equal to the change in the reciprocal of the distance in the yz plane, and the change in the reciprocal of the distance Can be minimized.
- the optical system of the laser beam printer further includes a light source power in the xz plane, a change in the reciprocal of a distance to an image point, and a change in the yz plane in response to a temperature change.
- the phase function is determined so that the change in the reciprocal of the distance is minimized.
- the movement of the focal point (defocus) with respect to the temperature change can be minimized.
- the beam shaping element includes a portion where the ratio of the peak intensity to the peak intensity in a plane perpendicular to the optical axis from the laser light source is equal to or more than a predetermined value. Is shaped into a beam that can be represented by an ellipse where the ratio of the major axis to the minor axis is different from that of the ellipse.
- a beam from the laser light source where the ratio of the intensity on the plane perpendicular to the optical axis to the peak intensity is equal to or greater than a predetermined value, can be represented by an ellipse, While the portion having a predetermined value or more is shaped into a beam that can be represented by an ellipse whose major axis and minor axis are different from the ellipse, astigmatism can be minimized with respect to a wavelength change or a temperature change of the light source.
- the diffraction grating surface is separated from the beam shaping element.
- the mold is easy to manufacture and easy to manufacture.
- a diffraction grating surface having an axially symmetric phase function is superimposed on an axially symmetric refraction surface.
- the die can be turned on a lathe, which facilitates manufacture.
- FIG. 1 is an optical path diagram of a beam shaping element in a cross section parallel to an active layer of a semiconductor laser.
- FIG. 2 is an optical path diagram of a beam shaping element in a cross section perpendicular to an active layer of a semiconductor laser.
- FIG. 3 is an optical path diagram in the xz section of the beam shaping element of Numerical Example 1.
- FIG. 4 is an optical path diagram in a yz section of the beam shaping element of Numerical Example 1.
- FIG. 5 is a diagram showing a relationship between wavelength fluctuation and aberration of a beam shaping element having no astigmatism correction function.
- FIG. 6 is a diagram showing the relationship between wavelength fluctuation and aberration of the beam shaping element of Numerical Example 1.
- FIG. 7 is an optical path diagram in the xz section of the beam shaping element of Numerical Example 2.
- FIG. 8 is an optical path diagram in a yz section of the beam shaping element of Numerical Example 2.
- FIG. 9 is a diagram showing a relationship between temperature fluctuation and aberration of a beam shaping element having no astigmatism correction function.
- FIG. 10 is a diagram illustrating the relationship between temperature fluctuation and aberration of the beam shaping element of Numerical Example 2.
- FIG. 11 is a diagram showing a configuration of a laser beam printer optical system.
- FIG. 12 is an optical path diagram in a scanning direction cross section of an incident optical system of a conventional laser beam printer.
- FIG. 13 is an optical path diagram in a cross section in the sub-scanning direction of an incident optical system of a conventional laser beam printer.
- FIG. 14 is an optical path diagram in a scanning direction cross section of an incident optical system of a laser beam printer using the beam shaping element of Numerical Example 2.
- FIG. 15 is an optical path diagram in a sub-scanning direction cross section of an incident optical system of a laser beam printer using the beam shaping element of Numerical Example 2.
- FIG. 16 is an optical path diagram in the xz section of the beam shaping optical system of Numerical Example 3.
- FIG. 17 is an optical path diagram in a yz section of the beam shaping optical system of Numerical Example 3.
- FIG. 18 is an optical path diagram of the beam shaping optical system of Numerical Example 4 in the xz section.
- FIG. 19 is an optical path diagram in a yz section of a beam shaping optical system of Numerical Example 4.
- FIG. 20 is a diagram illustrating a configuration of a laser beam printer optical system according to Numerical Example 5.
- FIG. 21 is an optical path diagram in the xz section of the beam shaping optical system of Numerical Example 5.
- FIG. 22 is an optical path diagram in a yz section of the beam shaping optical system of Numerical Example 5.
- FIG. 23 is a diagram showing the amounts of astigmatism and total wavefront aberration of the optical system of the laser beam printer of Numerical Example 5.
- Equation (5) the small change in Equation (5) can be expressed as a function of ⁇ . Assuming that n, d, Pl, and P2 of the beam shaping element are determined and leaving only the distribution ratio of the refraction power and diffraction power on the exit surface as the degree of freedom, the equation is obtained by ignoring the high-order term of the minute change. (5)
- the virtual image points in each of the xz and yz sections may be similarly changed with respect to environmental changes.
- the suffix X represents the XZ section
- the subscript y represents the yz section, and the quadratic coefficients qx and qy of the phase function may be selected so as to satisfy the following equation (11). Generally at this time
- astigmatism is reduced by making the light source power in the xz plane and the change in the distance to the image point or the virtual image point equal to the change in the distance in the yz plane with respect to the temperature change.
- minimization has been described.
- the same formula is used in consideration of only the refractive index change due to the wavelength change by the following formula instead of formulas (3) and (4). be able to.
- the energy distribution of the light beam cross section perpendicular to the optical axis after passing through the optical element is almost axially symmetric, and the astigmatism and spherical aberration due to the change in the light source wavelength at the best focus are obtained. Optimized to reduce the occurrence of Therefore, it is suitable for a pickup of a Blu-ray optical storage or the like.
- FIGS. 3 and 4 are optical path diagrams of the beam shaping element of Numerical Example 1 in the xz section and the yz section.
- the beam shaping element according to Numerical Embodiment 1 has a free-form surface represented by Expression (12) as the first surface and the second surface.
- This free-form surface is a so-called biconic having a different curvature and a different conic coefficient in a horizontal section (xz section) and a vertical section (yz section), and is a free-form surface obtained by superimposing x and y polynomials as correction terms.
- another surface such as an anamorphic aspherical surface may be used instead of the curved surface in Expression (12).
- the lens data is as follows.
- FIG. 5 is a diagram showing a relationship between wavelength fluctuation and aberration at best focus after emission from a beam shaping element having no astigmatism correction function.
- the vertical axis represents the total wavefront aberration and the astigmatism
- the horizontal axis represents the wavelength variation.
- the above-described beam shaping element having no astigmatism correction function has optical characteristics similar to those of the numerical example 1 except for chromatic aberration correction by the diffraction grating.
- a wavefront aberration of about 30 m is generated for a wavelength variation of 0.005, and most of the components are astigmatism.
- FIG. 6 shows the relationship between the wavelength variation and the aberration of the beam shaping element of Numerical Example 1 as a similar graph.
- the generation of astigmatism is well suppressed, and the spherical aberration component is also slightly suppressed by the axially symmetric grating component! Absent.
- the optical pickup system includes an actuator mechanism for moving the optical element at any time so as to cancel the defocus component. There is no need to cancel the defocus component. Therefore, even in Numerical Example 1, optimization is performed so as to leave the defor- mation force component. The aberration is also evaluated on the best focus surface. Utilizing this remaining degree of freedom, it is possible to reduce the variation in spherical aberration due to the change in the wavelength of the light source. If necessary, it is also possible to design to cancel the defocus component.
- the beam shaping element according to Numerical Example 2 is designed not only to generate astigmatism with respect to temperature change but also to prevent defocus.
- the shaped beam is collimated light, and its cross-sectional energy distribution is an elliptical shape with a small aspect ratio of 4: 3, making it ideal for a laser printer light source, for example.
- the refractive index is 1.486 for one wavelength of 780 nm.
- FIGS. 7 and 8 are optical path diagrams of the beam shaping element of Numerical Example 2 in the xz section and the yz section.
- the beam shaping element according to Numerical Example 2 superimposes the incident surface that can be expressed as a free-form surface of Expression (1) and the lattice surface of the phase difference represented by Expression (2) on the free-form surface of Expression (1). This is a beam shaping element with a reduced exit surface force.
- the coefficients of Numerical Example 2 are as follows.
- FIG. 9 is a diagram showing the relationship between temperature fluctuation and aberration of a beam shaping element having no astigmatism correction function.
- the vertical axis represents the total wavefront aberration and the astigmatism at the fixed image plane position after the beam shaping element emission, and the horizontal axis represents the wavelength variation.
- the shaping element having no astigmatism correction function has the same optical characteristics as the beam shaping element of Numerical Example 2 except for the temperature compensation function by the diffraction grating.
- the relationship between the refractive index, the light source wavelength and the temperature is as shown in the following relational expression.
- FIG. 10 is a diagram showing the relationship between temperature fluctuation and aberration of the beam shaping element of Numerical Example 2. The generation of wavefront aberration including astigmatism is suppressed very well.
- the LBP optical system basically includes an incident optical system for parallelizing diffused light from a light source and adjusting to an arbitrary ellipticity, and a deflecting element (polygon) for changing the direction of a light beam. And a scanning optical system for forming an image at a desired position on the image plane.
- the incident optical system generally includes a cylindrical lens having power only in a direction perpendicular to the scanning direction (sub-scanning direction). The purpose of this is to provide an optical system that forms an image on a polygon mirror only in the sub-scanning direction, and has the effect of relaxing the vertical accuracy tolerance of the polygon mirror surface (the permissible amount for any surface tilt).
- FIGS. 12 and 13 show optical path diagrams of cross sections in the scanning direction and the sub-scanning direction of a conventional incident optical system.
- 14 and 15 are optical path diagrams of a cross section in the scanning direction and the sub-scanning direction of the incident optical system including the beam shaping element of Numerical Example 2.
- the refractive lens and the diffraction grating are separated, and the diffraction grating is disposed on a plate-like element. Therefore, as compared with the case where the diffraction grating is arranged on the surface of the refractive lens, the mold is easily manufactured and the manufacturing is easy.
- the beam shaping element according to Numerical Example 3 is designed not only to generate astigmatism with respect to a temperature change but also to prevent defocus.
- the shaped beam is collimated light, and its cross-sectional energy distribution is elliptical with a small aspect ratio of 4 to 3.
- the refractive index is 1.486 for a laser wavelength of 780 nm.
- FIGS. 16 and 17 are optical path diagrams of the beam shaping optical system of Numerical Example 3 in the xz section and the yz section.
- the beam shaping element according to Numerical Example 3 includes an incident surface that can be expressed as a free-form surface of Expression (1), a beam shaping device that also has an exit surface force that can be expressed as a free-form surface of Expression (1), and Expression (2)
- the diffraction plate force provided with the phase correlation number on the second surface also becomes.
- the coefficients of Numerical Example 3 are as follows.
- the design temperature is 10 to 40 ° C.
- the relationship between the refractive index, the wavelength of the light source, and the temperature is represented by the following relationship.
- the beam shaping optical system according to Numerical Example 4 includes two beam shaping elements.
- the first beam shaping element is a refractive lens having axially asymmetric refracting surfaces on both surfaces, and has a beam shaping function.
- a diffraction grating surface having an axially asymmetric phase function is arranged on the first surface of the second beam shaping element, and a diffraction grating surface having an axially symmetric phase function is arranged on the second surface.
- the second surface of the second beam shaping element is an axially symmetric refraction surface, on which a diffraction grating surface having an axially symmetric phase function is superimposed.
- beam shaping and astigmatism correction are performed up to the first surface of the first and second optical elements, and collimation and defocusing of the light beam are performed on the final surface. Is corrected.
- the beam shaping element according to Numerical Example 4 is designed not only to generate astigmatism with respect to a temperature change but also to prevent defocus.
- the shaped beam is collimated light, and its cross-sectional energy distribution is elliptical with a small aspect ratio of 11:10.
- the refractive index is 1.486 for a laser wavelength of 780 nm.
- FIGS. 18 and 19 show the beam shaping optical system of Numerical Example 4 on the xz section and the yz section, respectively.
- FIG. 18 shows the beam shaping optical system of Numerical Example 4 on the xz section and the yz section, respectively.
- the beam shaping optical system according to Numerical Example 4 has an incident surface that can be expressed as a free-form surface of Expression (1) and an exit surface force that can be expressed as a free-form surface of Expression (1). And a second optical element.
- the second optical element has a diffraction grating on the first surface, which can be expressed by the phase function of Expression (2), where r is the distance from the optical axis, and the bending surface of Expression (14) and Expression (15) below.
- a diffraction grating that can be represented by a phase function is provided on the second surface.
- the phase function of Expression (2) which is arranged on the first surface of the second optical element, is a force only in the X term, has power only in the X direction, and is axially asymmetric.
- the refractive surface of the second optical element in equation (14) and the phase function in equation (15) are axially symmetric. As described above, correction of astigmatism is performed on the first surface of the second optical element, and collimation of light and correction of defocus are performed on the second surface of the second optical element.
- the design wavelength is 780 nm
- the design temperature is 10 to 40 ° C.
- the relationship between the refractive index, the light source wavelength, and the temperature is represented by the following relational expression.
- FIG. 20 shows the configuration of the optical system of the laser beam printer of Numerical Example 5.
- the optical system of the laser beam printer of Numerical Example 5 includes two beam shaping elements 1 and 2, a cylindrical lens, a polarizing element, and two scanning lenses 1 and 2.
- FIGS. 21 and 22 are optical path diagrams of the beam shaping optical system in the optical system of the laser beam printer of Numerical Example 5 in the xz section and the yz section.
- the beam shaping optical system in Numerical Embodiment 5 is similar to Numerical Embodiment 4 in that the entrance surface that can be expressed as a free-form surface of Expression (1) and the exit surface that can be expressed as a free-form surface of Expression (1) And a first optical element and a second optical element having a beam shaping function.
- the optical element 2 has a diffraction grating on the first surface that can be expressed by the phase function of equation (2), and can be expressed by the refraction surface of equation (14) and the phase function of equation (15), where r is the distance from the optical axis.
- a diffraction grating is provided on the second surface.
- phase function of Expression (2) which is arranged on the first surface of the second optical element, is a force only in the X term, has power only in the X direction, and is axially asymmetric.
- the refracting surface of the second optical element in equation (14) and the phase function in equation (15) are axially symmetric.
- beam shaping and astigmatism correction are performed up to the first surface of the first optical element and the second optical element, and collimation and defocusing of the light beam are performed on the final surface.
- the correction of astigmatism and the correction of focus include correction for a cylindrical lens and two scanning lenses.
- the configuration and each coefficient of the scanning optical system of Numerical Example 5 are as follows.
- Raw material PMMA NA before injection (parallel) 0.0958, NA before injection (vertical) 0.233 Beam radius after injection (parallel) 2.183 Beam radius after injection (vertical) 2.268 Surface shape factor
- the surface shape of the toroidal surface in the cross section of the scanning surface including the optical axis that is, the shape of the generating line in the present embodiment is expressed by the following equation (16).
- the coefficient r in the toroidal surface shape data is the radius of gyration for rotating the generatrix.
- the design wavelength is 780 nm
- the design temperature is 10 to 40 ° C.
- the refractive index is 1.486 for a laser wavelength of 780 nm
- the relationship between the refractive index, the light source wavelength, and the temperature is as follows.
- the refractive index is 1.511 for the laser wavelength of 780 nm, and the relationship between the refractive index, the light source wavelength and the temperature is as follows. To do.
- FIG. 23 shows the amounts of astigmatism and total wavefront aberration of the optical system of the laser beam printer of Numerical Example 5.
- the change in the aberration amount is very small with respect to the change in the environmental temperature.
- a resin beam shaping element with a temperature compensation mechanism is inserted immediately after the light source of an optical system with a high image magnification used for a laser beam printer, astigmatism and defocus may occur.
- the image formation position where the occurrence is remarkable is shifted by several mm or more in the optical axis direction, which is not practical.
- the optical element according to the present invention is manufactured by injection molding.
- a die can be cut by a three-dimensional kneading machine having a plurality of processing axes.
- Examples of the material of the optical element include PMMA (polymethyl methacrylate, acrylic resin) and the like. Use fat. Further, flint glass or the like may be used. In Numerical Example 1, flint glass was used, and in Numerical Examples 2 to 5, PMMA was used.
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Lenses (AREA)
- Optical Head (AREA)
- Diffracting Gratings Or Hologram Optical Elements (AREA)
- Mechanical Optical Scanning Systems (AREA)
Abstract
Description
Claims
Priority Applications (2)
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JP2006512850A JP4867033B2 (ja) | 2004-04-30 | 2005-04-28 | ビーム整形光学系およびレーザービームプリンタの光学系 |
US11/579,043 US20070285781A1 (en) | 2004-04-30 | 2005-04-28 | Beam Shaping Optical System And Optical System Of Laser Beam Printer |
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JP2004-136515 | 2004-04-30 | ||
JP2004136515 | 2004-04-30 |
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WO2005106566A1 true WO2005106566A1 (ja) | 2005-11-10 |
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PCT/JP2005/008224 WO2005106566A1 (ja) | 2004-04-30 | 2005-04-28 | ビーム整形光学系およびレーザービームプリンタの光学系 |
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US (1) | US20070285781A1 (ja) |
JP (1) | JP4867033B2 (ja) |
WO (1) | WO2005106566A1 (ja) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
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US20090306477A1 (en) * | 2006-07-03 | 2009-12-10 | Takayoshi Togino | Optical System |
Families Citing this family (4)
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JP2009058677A (ja) * | 2007-08-30 | 2009-03-19 | Ricoh Co Ltd | 光走査装置・画像形成装置 |
JP2009265614A (ja) * | 2008-04-03 | 2009-11-12 | Ricoh Co Ltd | 光走査装置及び画像形成装置 |
CN102354056A (zh) * | 2011-10-27 | 2012-02-15 | 中国科学院上海光学精密机械研究所 | 高功率高光束质量光学相控阵扫描装置 |
CN110208942B (zh) | 2019-05-30 | 2021-09-07 | 珠海奔图电子有限公司 | 光学扫描单元及电子照相成像装置 |
Citations (5)
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JPH06118346A (ja) * | 1992-10-02 | 1994-04-28 | Minolta Camera Co Ltd | レーザビーム光源装置及びレーザビーム走査光学系 |
JP2000292718A (ja) * | 1999-02-02 | 2000-10-20 | Canon Inc | 走査光学装置及びカラー画像形成装置 |
JP2001154153A (ja) * | 1999-11-29 | 2001-06-08 | Ricoh Co Ltd | 光学素子及び光学装置及び記録再生装置 |
JP2001194581A (ja) * | 2000-01-14 | 2001-07-19 | Konica Corp | 対物レンズ及び光ピックアップ装置 |
JP2003161819A (ja) * | 2001-09-13 | 2003-06-06 | Matsushita Electric Ind Co Ltd | ビーム整形素子,光ディスク装置,およびビーム整形素子の製造方法 |
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EP1122579B1 (en) * | 2000-01-28 | 2007-10-03 | Canon Kabushiki Kaisha | Scanning optical device and image forming apparatus |
US6898010B2 (en) * | 2001-09-13 | 2005-05-24 | Matsushita Electric Industrial Co., Ltd. | Beam-shaping device, optical disc device, and fabrication method of beam-shaping device |
JP4037281B2 (ja) * | 2002-03-04 | 2008-01-23 | シャープ株式会社 | ビーム整形素子およびそれを用いた光源ユニット並びに光ピックアップ |
-
2005
- 2005-04-28 US US11/579,043 patent/US20070285781A1/en not_active Abandoned
- 2005-04-28 WO PCT/JP2005/008224 patent/WO2005106566A1/ja active Application Filing
- 2005-04-28 JP JP2006512850A patent/JP4867033B2/ja active Active
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
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JPH06118346A (ja) * | 1992-10-02 | 1994-04-28 | Minolta Camera Co Ltd | レーザビーム光源装置及びレーザビーム走査光学系 |
JP2000292718A (ja) * | 1999-02-02 | 2000-10-20 | Canon Inc | 走査光学装置及びカラー画像形成装置 |
JP2001154153A (ja) * | 1999-11-29 | 2001-06-08 | Ricoh Co Ltd | 光学素子及び光学装置及び記録再生装置 |
JP2001194581A (ja) * | 2000-01-14 | 2001-07-19 | Konica Corp | 対物レンズ及び光ピックアップ装置 |
JP2003161819A (ja) * | 2001-09-13 | 2003-06-06 | Matsushita Electric Ind Co Ltd | ビーム整形素子,光ディスク装置,およびビーム整形素子の製造方法 |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20090306477A1 (en) * | 2006-07-03 | 2009-12-10 | Takayoshi Togino | Optical System |
Also Published As
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JP4867033B2 (ja) | 2012-02-01 |
JPWO2005106566A1 (ja) | 2008-03-21 |
US20070285781A1 (en) | 2007-12-13 |
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