JP2654941B2 - How to make a hologram - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] When producing a hologram optical element using a plurality of light waves having different optical axis angles with respect to a hologram recording medium,
Arranging a mask having a pinhole in advance at the irradiation position of the optical axis set on the hologram medium, and adjusting the position of the pinhole of the mask and the optical axis of the light wave corresponding to the pinhole. In addition to making the positioning of the optical axis accurate and easy, the hologram optical element is adjusted by irradiating the hologram recording medium with each light wave and exposing the interference fringes generated by the interference of each light wave. By making it, the hologram optical element can be made with high accuracy and easily.

[Industrial applications]

In order to collimate divergent light emitted from a laser or converge parallel light, a hologram optical element that is small, light, and inexpensive has been studied instead of a conventional optical lens. According to the present invention, a plurality of light waves used for manufacturing such a hologram optical element are positioned on each optic axis on a hologram recording medium, and each light wave (hologram forming light) is irradiated onto the hologram recording medium. About the method.

[Conventional technology]

FIG. 6 is a perspective view of a laser printer using a hologram. A laser beam 1 generated from a semiconductor laser is converged on a recording medium 4 by a hologram lens 2 and a hologram disk 3 for aberration correction. In addition, linear scanning is performed by diffracting the hologram disk 3 from one end to the other end of the recording medium 4 by rotation. Then, the laser light output is turned on in synchronization with the scanning timing.
By performing off-modulation, a dot printing position on the recording medium 4 is selected, and characters and the like are recorded by combining dots.

In order to form the hologram lens 2, a hologram recording medium is irradiated with a reference wave and an object wave, and the interference fringes are exposed and developed. It is only necessary to be able to create a hologram using a semiconductor laser used for reproducing a hologram, but the semiconductor laser for reproduction has a high diffraction efficiency in this wavelength band because the wavelength λ2 is as long as 780 to 800 nm. There is generally no material for the hologram recording medium. Therefore, as the hologram recording medium, a hologram recording medium sensitively sensitive to He-Ne laser light having a wavelength λ1 of 632.8 nm or Ar laser light of 488 nm is used.

In consideration of this wavelength ratio, as shown in FIG. 7, when the hologram lens 2 is formed, light L2 having an aberration in the opposite direction is generated by using the auxiliary optical system 5, and the reference wave L3 is generated.
It is proposed by the applicant of the present invention as Japanese Patent Application No. 60-168830 that the hologram recording medium 2a is irradiated with the hologram recording medium 2a to form a hologram lens 2 for aberration correction. When a reproduction wave is incident on the hologram disk 3 through the hologram lens 2 which has been given an aberration in advance in this way, the aberration is canceled by the two holograms 2 and 3, and the recording medium 4 is irradiated with a thin beam.

[Problems to be solved by the invention]

Here, when creating a hologram, it is necessary to align the position of the creating laser light on the hologram recording medium.

When creating the hologram 2 for aberration correction as described above, the auxiliary optical system 5 is used to generate an object wave L2 with aberration different from the incident light L1. It is particularly difficult to adjust the position of the auxiliary optical system at the time of creation.

The technical problem of the present invention is to solve such a problem at the time of creating a hologram, and to align a hologram forming laser beam on a hologram recording medium and a position of each optical element when using an auxiliary optical system. Another object of the present invention is to make it possible to accurately and easily perform irradiation of each light wave (hologram forming light) on a hologram recording medium with high accuracy and ease.

[Means for solving the problem]

FIG. 1 is a side view for explaining the basic principle of the hologram producing method according to the present invention. Reference numeral 6 denotes a mask in which a plurality of pinholes A, B, and C are previously opened at predetermined positions.
For example, when creating a hologram lens for aberration correction, the center pinhole B is located at the optical axis l3 position of the reference wave L3, and one pinhole A is located at the optical axis l1 position of the convergent spherical wave L1. The other pinholes C are opened at the positions of the optical axis 15 of the auxiliary optical system.

Then, this mask 6 is placed at the hologram forming position, and the optical axes l1, l3, and l5 are aligned with the pinholes A, B, and C of the mask 6, and the respective pinholes A, B, and C are aligned.
The position of each optical axis is adjusted so that the optical axis is located at a position where the optical power after passing through is maximized. At this time, a power meter or the like is placed at the back of the pinholes A, B, and C, and each optical axis is adjusted by adjusting the optical power after passing through each of the pinholes A, B, and C to a maximum. Easy alignment to the corresponding pinhole position.

When all the optical axis position adjustments have been completed, the mask 6 is removed, the hologram recording medium is placed at the same position, a reference wave and an object wave are irradiated, and exposure and development are performed.

In creating a hologram lens for aberration correction, an object wave is a light wave that has passed through an auxiliary optical system in which the optical axis 15 has been aligned, and this light wave and a reference wave are irradiated.

(Operation)

At the installation position of the hologram recording medium, a mask 6 in which pinholes A, B, and C are previously opened at a predetermined position is installed, and each of the pinholes A, B, and C is transmitted through the corresponding optical axis l1, l3, and l5. The optical axes l1, l3, and l5 are aligned as shown in FIG.
In addition, since the positions of the pinholes A, B, and C of the mask 6, that is, the coordinates at which the light beams come on the hologram recording medium, can be determined by computer simulation based on the design of the hologram, these pinholes A, B, and C are used. By aligning the optical axes l1, l3, l5 of each light, each optical axis l1, l
3, l5 will be accurately aligned to the predetermined position.

After the alignment is completed, the mask 6 is removed, the hologram recording medium is set at the same position, and a reference wave and an object wave are irradiated from the positions of the optical axes l1 and l3, and the alignment of the optical axis l5 is performed. By arranging the performed auxiliary optical system on the optical axis l1,
A hologram as designed is obtained.

〔Example〕

Next, practical examples of how the hologram forming method according to the present invention is embodied will be described with reference to examples. FIG. 2 to FIG. 4
The figure shows an example in which the method of the present invention is applied to the hologram forming method for correcting aberration shown in FIG. FIG. 7 shows a state when the creation light actually arrives. The aberration wave L2 having the two intersections 8 and 9 is set as an object wave, and together with the reference wave L3, is recorded on the hologram recording medium 2a on the substrate 2b. By irradiation, the hologram lens 2 for aberration correction is obtained. Such an object wave
To obtain L2, the spherical convergent wave L1 having the wavelength λ1 is transmitted through the auxiliary optical system 5 composed of a concave lens, and the object wave L2 and the reference wave
L3 is positioned and irradiated on the hologram recording surface to form interference fringes.

In order to create a hologram with an object wave having an aberration in this way, the optical axis l3 of the reference wave L3 and the optical axis l1 of the convergent spherical wave L1
It is necessary to position the optical axis l2 of the object wave L2 having the aberration and the optical axis l5 of the auxiliary optical system 5 at predetermined positions on the hologram recording medium 2a.

The positions of the respective optical axes l1, l3, l5 on the hologram recording medium 2a can be calculated in advance by the creation wave to be used, the auxiliary optical system 5, etc., so that predetermined positions are calculated according to the calculated values as shown in FIGS. A photomask 6a having three pinholes A, B, and C having a diameter of 10 to 100 μm is prepared at a position. Substrate 6b
The upper photomask 6a is a hologram recording medium on the substrate 2b.
The substrate thickness is such that it comes to the same position as the surface of 2a.

FIG. 2 is a side view of the hologram forming apparatus, in which a laser 10, a collimating lens 11, and a converging lens 12 for generating a long-wave forming wave are provided in order to obtain a convergent spherical wave L1. Further, by providing the auxiliary optical system 5, the aberration wave L2 in FIG. 7 is obtained.

Next, a method of producing a hologram according to the present invention will be described in the order of steps.

First, at the hologram creation position, the pinhole A,
The mask 6 with the openings B and C is arranged, and the reference wave L3 is aligned with the pinhole B. For that, a collimating lens
14 is removed, and the photomask 6 is moved so that the pinhole B comes to the beam position emitted from the laser 15,
The optical axis 13 is adjusted by the power meter 7b disposed below the pinhole B so that the optical output is maximized.

The angles of the optical axes of the reference wave L3 and the convergent spherical wave L1 are set in advance according to design values. Therefore, the photomask 6a is moved so that the pinhole B is aligned with the position of the optical axis 13 of the reference wave L3.

With no auxiliary optical diameter 5, the optical axis 11 of the convergent spherical wave L1 emitted from the lens 12 is aligned with the pinhole A.
For this purpose, with the lenses 11 and 12 also removed, a short-wavelength laser 10 beam is applied to the pinhole A and monitored by the power meter 7a on the back, so that the light output from the laser 10 is maximized. The beam is translated in parallel with the photomask surface.

Next, the lenses 11 and 12 are inserted on the optical axis l1 to obtain a convergent spherical wave L1. Then, the lens 12 is moved along the optical axis l1,
The distance d between the convergence point 13 and the photomask 6a is adjusted to a design value.

The convergent spherical wave shaping lenses 11 and 12 are removed, and the optical axis of the auxiliary optical system 5 for generating aberration is set out. For this purpose, as shown in FIG. 3, a laser different from the hologram forming wave, for example, a He-Ne laser 16 is used, and the optical axis 1 is set to an angle θ according to a design value. Then, the beam from the laser 16 is moved in parallel with the photomask surface, and the optical axis 15 is aligned with the pinhole C so that the output of the power meter 7c at the back becomes maximum.

The auxiliary optical system 5 is inserted into the optical axis 15 and its optical axis is aligned with the optical axis 15 of the laser beam.

With the optical axis of the auxiliary optical system 5 coincident with that of the laser beam, the auxiliary optical system 5 is moved along the optical axis l5 as shown in FIG. Are positioned so as to enter the central pinhole B. This is performed while monitoring with the power meter 7b behind the pinhole B.

Since the alignment of each optical axis is completed as described above, as shown in FIG. 2, the convergent spherical wave forming lenses 11, 12 are returned on the optical axis l1, and a convergent spherical wave L1 is formed. Further, by inserting the collimating lens 14 on the optical axis l3 to form the reference wave L3, the hologram can be created as shown in FIG.

The hologram 2 for aberration correction can be obtained by removing the mask 6, replacing the hologram recording medium 2a, and irradiating the object wave L2 and the reference wave L3 having aberrations.

[Another embodiment]

Instead of the photomask 6a in which the pinholes A, B and C are formed, a thin plate having pinholes may be used.

When the laser beam for aligning the optical axis is thick, as shown in FIG.
Insert 18 and narrow the beam for more accurate alignment.

〔The invention's effect〕

As described above, according to the present invention, a pinhole is provided at the optical axis position on the hologram recording medium surface known in advance by calculation, and the optical axis is aligned with the pinhole of the mask and the optical axis. We are adjusting. Therefore, it is possible to accurately and easily perform the position alignment of the light extraction of the forming light at the time of forming the hologram.

Further, an auxiliary optical system for generating a predetermined aberration in the first light wave among the plurality of light waves having different optical axis angles is disposed on the optical path of the first light wave, and the first light wave and the second light wave are transferred to the hologram recording medium. In producing the hologram optical element by irradiating, the position to be irradiated with the optical axis of the second light wave at the position where the hologram is formed and the optical axis of the first light wave passing through the auxiliary optical system And a mask in which pinholes are formed in advance at positions where the optical axis of the first light wave not passing through the auxiliary optical system is to be irradiated, respectively, are arranged at the hologram forming position, and each pin of the mask is After aligning and adjusting the hole and the optical axis of each light wave corresponding to each of these pinholes, remove the mask, place the hologram recording medium at the hologram creation position, and pass the first light wave through the auxiliary optical system. Let The light wave and the second light wave are both irradiated on the hologram recording medium to expose the interference fringes generated by the interference of the light waves, so that the hologram optical element (HOE) is formed by using an auxiliary optical system for aberration correction. In the production, even if the light extraction is complicated, the alignment of the optical axis becomes easy, and the hologram optical element can be produced with high accuracy and easily.

[Brief description of the drawings]

FIG. 1 is a side view for explaining the basic principle of the method for producing a hologram according to the present invention, and FIGS. 2 to 4 are views showing an embodiment of the method of the present invention.
FIG. 3 is a side view of a hologram forming apparatus, FIG. 3 is a side view showing an optical axis alignment step of a reference wave, an object wave, and an auxiliary optical system, FIG. The figure is a side view showing an embodiment for improving the alignment accuracy of the optical axis, FIG. 6 is a perspective view showing a laser printer using a hologram for aberration correction, and FIG. 7 is a method for producing a hologram for aberration correction. FIG. In the figure, LD is a semiconductor laser for reproduction, 2 is a hologram (lens) for aberration correction, 5 is an auxiliary optical system (concave lens), 6 is a mask, 6a is a photomask, A, B, and C are pinholes, and L1 is Convergent spherical wave, l1 is optical axis of convergent spherical wave, L2
Is an aberration wave, l2 is the optical axis of the aberration wave, L3 is the reference wave, l3 is the optical axis of the reference wave, 15 is the optical axis of the auxiliary optical system, and 7a, 7b, and 7c are power meters.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Jun Amako 1015 Uedanaka, Nakahara-ku, Kawasaki City Inside Fujitsu Limited (72) Inventor Masayuki Kato 1015 Kamikodanaka, Nakahara-ku, Kawasaki City Fujitsu Limited (72) Inventor Satoshi Maeda 1015 Uedanaka, Nakahara-ku, Kawasaki City Fujitsu Limited (72) Inventor Fumio Yamagishi 1015, Uedanaka, Nakahara-ku, Kawasaki Fujitsu Limited (72) Inventor Hiroyuki Ikeda 1015, Uedakanaka, Nakahara-ku, Kawasaki Fujitsu Limited In-house (56) References JP-A-55-133566 (JP, A) JP-A-54-139461 (JP, A) Jpn.

Claims (2)

(57) [Claims] 1. A method for producing a hologram optical element for irradiating a hologram recording medium with a plurality of light waves having different optical axis angles with respect to the hologram recording medium, wherein a pinhole is previously formed at an irradiation position of the optical axis set on the hologram recording medium. Positioning the opened mask at the hologram creation position, adjusting the pinholes of the mask and the optical axes of the light waves corresponding to the pinholes, removing the mask, and recording holograms at the hologram creation position A method for producing a hologram optical element, comprising: a step of arranging a medium; and a step of irradiating both light waves to a hologram recording medium and exposing interference fringes generated by interference of the light waves. 2. An auxiliary optical system for generating a predetermined aberration in a first light wave among a plurality of light waves having different optical axis angles on a light path of the first light wave, and a hologram for the first light wave and the second light wave. A method for producing a hologram optical element by irradiating a recording medium to produce a hologram optical element, wherein the first light wave passing through the auxiliary optical system and an optical axis of a second light wave at a position where the hologram is produced A mask in which pinholes are previously formed at a position where the optical axis of the first light wave is to be irradiated and a position where the optical axis of the first light wave not passing through the auxiliary optical system is to be irradiated. Positioning the hologram at the hologram creation position, aligning and adjusting each pinhole of the mask and the optical axis of each lightwave corresponding to each pinhole, removing the mask and creating the hologram Arranging a hologram recording medium on the hologram recording medium; irradiating the hologram recording medium with the light wave obtained by passing the first light wave through the auxiliary optical system and the second light wave together; And a step of exposing the hologram optical element.