JPH0384502A - Grid polarizer - Google Patents

Abstract

PURPOSE:To obtain the grid polarizer which covers a wide wavelength range, is less deteriorated in polarization characteristic with respect to an incident angle and has the excellent polarization characteristic by forming parallel line patterns of a high density consisting of conductors on both surfaces of a substrate having a high transmittance to measuring light and forming the patterns in such a manner that the arranging directions of the grids on both surfaces of the substrate are parallel. CONSTITUTION:This grid polarizer is formed by arranging the Au grid patterns 3 on both surfaces of, for example, the KRS-5 substrate 1 subjected to polishing on both surfaces in such a manner that the arranging directions of the patterns are parallel on both surfaces of the substrate. The Ni-Cr patterns 2 of 20Angstrom thickness are formed between the KRS-5 substrate 1 and the Au grid patterns 3 for increasing an adhesion between the substrate and Au grid patterns. The KRS-5 substrate 1 has the good transmittance over the entire IR region and the good transmittance even in a visible region and is transparent in the region of about 0.6 to 60mum. The transmittance in this region is about 70%. The performance of the grid polarizer is improved in this way and the use up to the long wavelength side of the visible region is possible.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a grid polarizer which is a polarizing element effective in the infrared region.

B. Prior art and its problems As shown in Fig. 3, a grid polarizer is a grid polarizer in which fine conductor wires are arranged in parallel in a grid pattern with a pitch d that is less than the wavelength of seven conductor grids, and the polarizer vibrates in a direction parallel to the conductor grid. -7) The electric field component of the light is reflected by this grid polarizer G, and the electric field component of the light vibrating in the direction perpendicular to the conductor grid has a property of being transmitted through the grid polarizer. Gribut polarizer G
The pitch d and width a of the conductor grid affect its polarization characteristics.The smaller the pitch distance d is, the better the polarization characteristics are.A/
It is said that d is preferably 0.5 to 0.7. Therefore, the shorter the wavelength A, the pitch dy of the conductor grid G.
z must be made small, but if it is made small, it will be difficult to maintain the gap between the conductors in a hollow state with the conductor grid alone. Although it is an effective polarizing element in the infrared region where there is no suitable polarizing material, it has the disadvantage that it has inferior polarization properties such as polarization degree and extinction ratio compared to polarizing prisms in the visible region, and requires highly pure polarized light. In the field of measurement, etc., it is desired to improve the polarization properties of the optical shield layer. Also.

There was a desire for a grid polarizer that could cover the long wavelength range of the visible range to the infrared range with a single piece of gold.

In order to cover the long wavelength side 1, the pitch is 0°1 μm.
An 8 degree grid polarizer is required, which is extremely difficult with current manufacturing technology.

The present invention is a grid polarizer that covers a wide wavelength range with a single grid polarizer and has the characteristics of little deterioration of polarization characteristics depending on the incident angle. The purpose is to provide a solicitation.

C Structure of the Invention The Glybut polarizer of the present invention is formed by forming a conductor in a high-density parallel line pattern on both sides of a substrate that has a high transmittance to measurement light, and in which the grids on both sides of the substrate are arranged in parallel. It was formed to be.

Polarized light perpendicular to the grid direction of the hollow grid polarizer (S
Let the transmission rate of polarized i) be gold Tl, and the transmittance of parallel polarized light (P-polarized light) 'kTz. In a conventional grid polarizer in which a grid is formed only on one side of the substrate, if the substrate transmittance is T, then S
@9 Transmittance #iT HT.

P polarized light transmittance is T2T.

In the case of a grid polarizer according to the present invention in which the entire grid is cut out on both sides of the substrate so that the grid arrangement direction is parallel to both sides of the substrate, the S-polarized light transmittance is T, XTXT, 4=T
? Similarly, the P-polarized light transmittance becomes T and T.

Here, the typical 'ii values of a conventional single-sided grid polarizer are substrate transmittance T = 0.7, T+ = 0.98.
.

Comparing the degrees of polarization for both at 'r2 = 0.02, the conventional product has an S polarization transmittance of 0.69 (69%), a P polarization transmittance of 0.014 (1.4%), and a polarization 'y , the degree is 0.96
(96%). On the other hand, in the case of the grid polarizer of the present invention.

S-biased 51e transmittance H0,67(674), P-biased ft
, transmittance 2.8 x 10-' (0,028 Hayabusa),
The degree of polarization is 0.999 (99.9%), and compared to conventional products, there is almost no decrease in S-polarized light transmittance, and compared to that, P-polarized light transmittance can be significantly reduced, and the polarization degree is almost l.
Performance has improved significantly.

Embodiment D FIG. 1 shows the structure of an embodiment of the present invention. Au grid patterns 3 were formed on both sides of a double-sided polished KH2-5 substrate 1 (thickness: 2 m, outer diameter: 30 nφ) so that the directions of the patterns were parallel to each other on both sides of the substrate.

In order to strengthen the adhesion between the substrate and the Au grid pattern,
A Ni--Cr pattern 2 with a thickness of 20' is formed between the KH2-5 substrate 1 and the Au grid pattern 3. K
The H2-5 substrate 1 has good transmittance in the entire infrared region, and also has good transmittance in the night range. That's about it. The pitch of the grid pattern 3 was 0.4μ. Conventionally, with a pitch of 0.4 μm, the wavelength range used was longer than 2 μm.

According to the present invention, it has become possible to use the wavelength range longer than 0.6 μm.

FIG. 2 shows the manufacturing process of an embodiment of the present invention.

4 N1-CR layer 2 with a thickness of 2 on one side of the KH2-5 board 1
At 0 A, AU layer 3 was sequentially vacuum-deposited to a thickness of 1000 A, and then photoresist 4 was deposited with 0FPR5000M2.
Pre-baked in a fresh air oven at 90°C for 30 minutes.

(B) Two nine-bundle interference fringes were printed on the photoresist 4 formed in step - above by the holographic exposure method.
For the source, a He-Cd laser (λ = 4416A) is used, a parallel light beam is created by a sub-spatial filter and a 411 external radial lens, and the picture interval is 0.4 Plnl<25
00X/Ml),! : L7'c. NextKifi'kf
l'k.

The cross-sectional shape of the photoresist 4 is a half-sine wave, that is, a /
d was set to 0.5. The cross-sectional shape can be adjusted by adjusting the exposure time and development time.

(C) Next, Ar ion beam etching was performed using the photoresist pattern 4 as a mask.

N1-CrJ So2. The glyphed pattern of AU layer 3 has a shape r.
There was a situation.

The above human r ion beam etching has an acceleration voltage of 500ev.
, under gas pressure of 1.6 x 10-' Torro.

(Next, the photoresist used as an etching gas was removed by ashing with 02 plasma using a 4-hole μ type plasma etching device.

Thereafter, the same steps of (A), (B), (C), and (b) above were performed again on the back surface on which the glyphed pattern was not formed, to complete a grid polarizer. In the above embodiment, the graffiti was formed on one side and then the graffiti was formed on the other side, but each step can also be performed on both sides simultaneously.

In the above embodiment, the Au f conductor attachment film 2 is not required on the conductor glyph 3. In addition, when using λ11 in the conductor glyph 5, carbon dioxide gas (C
C14) is used.

Further, although the KH2-5 substrate is used in the above embodiment, the present invention is not limited to this, and it goes without saying that a transparent substrate sound within a desired wavelength range may be used. Furthermore, in the case of a substrate with poor transparency and low absorption, a substrate coated with an antireflection film on both sides may be used. In such a narrow wavelength range, the transparency can be made approximately 100, and further improvement in polarization performance can be expected.

, E Effects of the Invention Since the grid polarizer of the present invention has a configuration in which high-density, parallel conductor patterns are formed on both sides of the substrate so that the arrangement direction is the same, the performance of the grid polarizer is dramatically improved. , can now be used at long wavelengths #J''& in the visible range.

[Brief explanation of drawings]

FIG. 1d is a block diagram of an embodiment of the present invention, FIG. 2 is a manufacturing process diagram of an embodiment of the present invention, and FIG. 3 is a diagram of the principle of a grid polarizer.

Claims (1)

[Claims] (1) A high-density parallel line pattern of metal conductors is arranged on both sides of a substrate that has high transmittance in a desired wavelength range in the infrared or visible long wavelength range, or has a transmittance range over a wide wavelength range. A grid polarizer characterized by being formed so that the directions are parallel on both sides of a substrate.