JPS61137102A - Patterning method of diffraction grating - Google Patents

Abstract

PURPOSE:To suppress the generation of interference fringes in the stage of manufacturing a diffraction grating and to manufacture the beautiful pattern of a diffraction grating by diffusing the light of the component in the direction perpendicular to the direction where the interference fringes array as diffused light and averaging the phases of the light. CONSTITUTION:Light 22 from a laser light source is divided to two beams of light by a half mirror 24. The light past the mirror 24 is reflected by a mirror 26 and is then expanded by lens 28. The expanded light passes through a one-way diffusion plate 30 and arrives as the light diffused in an arrow 38 direction at a photosensitive material 12 by passing through a mask 10. On the other hand, the light reflected from the mirror 24 is reflected by a mirror 32 and is expanded by the lens. The expanded light passes through a one-way diffusion plate 36 and arrives as the light diffused in the arrow 38 direction at the material 12 by passing through the mask 10. Both beams of the light form the interference fringe on the material 12. Such fringe is recorded and the diffraction grating having the pattern which can be made by the mask 10 is formed. The unnecessary interference fringe is formed in the direction perpendicular to the arrow 38 direction in this stage, but the light has the diffusivity in the arrow 38 direction and therefore the phases of the interference light superpose randomly on each other at one point on the material 12 and the unnecessary interference fringe is annihilated.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention suppresses unnecessary interference fringes that occur when creating a diffraction grating on a photosensitive material using a laser beam through a mask such as a glass dry plate, thereby producing beautiful diffraction. This invention relates to technology for creating lattice patterns.

<Conventional technology> Laser light is used to pass through a mask onto the photosensitive material.

Two methods are known for erasing interference fringes generated by reflection between a mask and a photosensitive material when recording interference fringes.

The first method is as follows: −S −<,
This process brings the photosensitive material (12) into complete contact with the photosensitive material (11), and is carried out by creating a vacuum using a vacuum chamber (14).

As a result, if surfaces having substantially the same refractive index come into contact with each other at a length less than the wavelength, reflection can be suppressed and the generation of unnecessary interference fringes can be suppressed.

The second method is the method shown in FIG. 4, in which a mask (10) and a photosensitive material (1
By introducing a liquid (20) having approximately the same refractive index as 2), the difference in refractive index is reduced, reflection is reduced, and unnecessary interference fringe contrast is reduced.

<Problems to be Solved by the Invention> In the first method shown in FIG. 3, the mask and the photosensitive material are required to have perfect flatness on the wavelength order, and also to prevent the adhesion from deteriorating due to dust, etc. Since a high degree of cleanliness is also required, 2-1 is not suitable for practical use.

Furthermore, in the second method shown in FIG. 4, it is possible to obtain a liquid in which the refractive index is completely the same as that of the photosensitive material and the mask, and there is no chemical change in both. is very difficult.

Although this method can reduce unnecessary interference fringes, it cannot eliminate them.

<Means for Solving the Problems> FIG. 1 shows an optical system of the present invention. The present invention differs from conventional methods in that the two light beams forming the interference fringes are made into diffused light in one direction, and the phase of the light is averaged and erased. Light (22) emitted from a laser light source (not shown)
) is divided into two by a half mirror (24), and the light that passes through the half mirror (24) is reflected by the mirror (26), then spread by the lens (28), and sent through the unidirectional diffuser plate (30). After passing through, the light becomes diffused in the direction shown by the arrow (38), passes through the mask 00), and reaches the photosensitive material (12). On the other hand, the light reflected by the half mirror (24J) is reflected by the mirror (32), spread by the lens (34), passes through the unidirectional diffuser (36), and then passes through the arrow (38).
) The light becomes diffused in the direction shown by ) and reaches the photosensitive material (12) through the mask 00). Both lights form interference fringes on the photosensitive material, and by recording this, a mask (1
0), a diffraction grating with a pattern is created.

At this time, the direction in which interference fringes are formed is perpendicular to the direction indicated by the arrow (38). Unwanted interference fringes are also formed in this direction, but this is because light has diffusivity in the direction perpendicular to this, that is, in the direction of the arrow, as shown in Figure 2.
Considering one point (42) on the photosensitive material, coherent light from all directions reaches the point, so the phases overlap randomly and the interference fringes disappear.

<Function> As shown in the above <Means for solving the problems> section, the present invention provides a simple optical system that does not require special equipment such as vacuum pressure bonding or immersion liquid, and is completely Interference fringes caused by reflections from the mask and photosensitive material are removed, allowing the creation of beautiful diffraction grating patterns.

<Example> An example of fabricating a diffraction grating on a photoresist will be described. An Ar laser was used as the laser, a lenticular lens was used as the unidirectional diffuser plate, a photographic plate was used as the mask, and AZ-1350 photoresist from G-Play First Co. was used as the photosensitive material. Using the optical system shown in FIG. 1, a diffraction grating pattern without interference fringes generated between the mask and the photosensitive material was prepared.

Note that, in addition to a lenticilla lens, a hologram having such characteristics can also be used as the unidirectional diffuser to fulfill its role.

<Effects of the Invention> Conventionally, the pattern of a diffraction grating had bright and dark stripes remaining on the pattern, which did not look good, but with the present invention, only the fringes caused by two-beam interference remain, resulting in a beautiful pattern. It is industrially effective in the field of displays.

4 Brief Description of the Figures FIG. 1 is a perspective explanatory view showing the method of the present invention, and FIG. 2 is a side explanatory view of the method of the present invention.

Furthermore, since FIGS. 6 and 4 show the prior art method, both are side explanatory views.

Claims (1)

[Claims] 1) In a diffraction grating patterning method, an image of a patterned diffraction grating is created by recording interference fringes created by two-beam interference on a photosensitive material through a glass dry plate or film patterned with density changes. A diffraction grating patterning method characterized by converting light in a direction perpendicular to the direction in which interference fringes are arranged into diffused light.