JPS6184605A - Polarizing element - Google Patents

Abstract

PURPOSE:To provide the mechanical strength to a polarizing element and to permit the increase in the size thereof by grasping a thin layer consisting of a single crystal of any among KNO3, LiIO3 or alpha-HIO3 by light transmittable optical members consisting of optical glass, quartz, various transparent resins, etc. CONSTITUTION:The thin layer 10 consisting of the single crystal of KNO3 is grasped by a pair of the light transmittable optical members 12, 14 of a rectangular prism type. The layer 10 is cut out of the single crystal in such a manner that incident light is made incident from the b-axis direction to maximize the difference of the main refractive index to be determined by the optical elastic axis of the single crystal. The light oscillating in certain direction among the incident rays is totally reflected on the surface of the layer 10 by selecting adequately the refractive indices of the members 12, 14 and the light oscillating in the direction orthogonal therewith transmits the layer 10 while refracting in said layer. Since the single crystal to be used can be artificially manufactured, the increase in the size of the polarizing element is easily made possible, by which the cost is reduced and the ease of handling is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a polarizing element, and more particularly to a polarizing element used as a polarizing prism.

(Prior Art) Polarizing prisms are used in optical pickups such as DADs (digital audio discs) and various measuring devices that utilize polarized light.

Conventionally, as a polarizing element used as a polarizing prism, one using a thin plate of calcite (Applied Physics 匪(15) 55
(1966) ) and one using mica thin plate (H
andbook of optics, McGra
w-Hill) is known, but when calcite is used, since naturally produced calcite is used, the cost is high and it is difficult to increase the size of the device. On the other hand, when mica is used, it has strong disintegration properties and is brittle, resulting in poor handling and problems in use.

(Purpose) The present invention was made in view of the above circumstances, and
The cost is low and it is easy to increase the size.

Moreover, it has the same extinction properties as when calcite is used.
The purpose is to provide a new polarizing element.

(composition) The present invention will be explained below.

The polarizing element of the present invention has a structure in which it is sandwiched between thin, single-crystal, light-transmitting optical members. As a single crystal material,
Either KNO3, KnCoAsQ, LiIO3, or α-HIO3 is used.

These KNO3, KH4As04, LiIO3,
A single crystal of α-HIO3 can be easily produced artificially. Therefore, it is easy to increase the size of the device,
The cost is also low. Further, since the single crystal thin layer made of these substances is sandwiched between light-transmitting optical members, the light-transmitting optical members can provide the element with sufficiently strong mechanical strength.

The material for the translucent optical member is optical glass.

Examples include quartz and various transparent resins.

Hereinafter, description will be given based on specific examples.

In the embodiment shown in FIG. 1, reference numeral 10 indicates a thin layer of single crystal KNO3, and reference numeral 12.14 indicates a light-transmitting optical member.

As shown in FIG. 1, the side surface of this polarizing element is rectangular, and the thin layer 10 is held between a pair of right-angle prism-shaped translucent optical members 12 and 14.

When light enters the polarizing element of FIG. 1 from the left as shown in the figure, the thin layer 10 of a single crystal of KNOs is determined by the optical elastic axis of the single crystal. The single crystal is cut out so that the light enters from the b-axis direction, which maximizes the difference in principal refractive index.

In this case, by appropriately selecting the refractive index of the translucent optical member 12, 14, the incident light rays vibrating in a certain direction are totally reflected on the surface of the thin layer 10, and the above-mentioned It is possible to realize a state in which light vibrating in a direction perpendicular to this direction is transmitted through the thin layer 10 while being refracted.

The refractive index of a single crystal of KNO3 is γ is 1.5064, α
is 1,3346, so the translucent optical member 12.14
If we choose optical glass with a refractive index of 1.92 as the material.

The angle of incidence θl on the thin layer 10 is greater than 44°, and 51.
When the angle is as small as 5°, the incident light can be separated into transmitted light and total internal reflection depending on the polarization direction.

A specific experimental example regarding this example will be described below.

(Experimental Example 1) 450 cc of water was placed in a beaker, the temperature was maintained at 50°C, and accurately weighed KNO3 was dissolved using a 300-y stirrer. Thereafter, this solution was heated at 42±0.2°C.
The sample was left in a water bath whose temperature was adjusted to 24 hours. As a result, supersaturated KNO was added to the beaker.
3 has been precipitated, the supernatant in the beaker is transferred to another beaker, and from among the precipitated KNO3 microcrystals, one that is transparent and does not contain a "s" is selected, and this is used as a seed crystal to transfer the supernatant to the above-mentioned beaker. Place a beaker of the above capacity in the clear liquid and heat at 40°C.
It was left in a water bath whose temperature was adjusted to allow crystal growth as a single crystal. At this time, the evaporation rate is set to b per day.
Adjust to 1.4 cc and grow crystals for 30 days.
I was able to explore a single crystal measuring 25mm x 231111mm x 20mm.

The single crystal thus obtained has a thickness of 1 m+a.

Two types of polarizing elements of the type shown in FIG. 1 were explained by cutting out a 3 mm single crystal thin layer. That is, the thickness of the thin layer 10 is 1 mm, 2 mm, and 3 mm. Note that the translucent optical members 12 and 14 have a refractive index of 1.
It was made of 92 optical glass.

The angle θl of the first factor is 47°, θ2 is 69°, θ3=47°
, θ4 is 430.

Table 1 shows the results of determining the extinction ratio as a characteristic of these three types of polarizing elements. □ Table 1 (Experimental Example 2) The evaporation rate in Experimental Example 1 was set to Q, 7 cc/day, and crystal growth was performed for 70 days to form a 24 mm x 24
A single crystal of mm x 21 mm was obtained, and from this, the thickness was 1 m and 1 m.
2 Tnm.

Three types of polarizing elements similar to those in Experiment 1 were prepared by cutting out three thin layers, and their extinction ratios and crystal states were examined.

The results are shown in Table 2.

Compared to the case of Experiment 1 in Table 2, the extinction ratio of each polarizing element is improved by one step.

In the embodiment shown in FIG. 2, reference numeral 16 represents KH2As
h, showing a thin layer of single crystal. Reference numeral 18°20 indicates a translucent optical member. Even in this embodiment, the side shape of the polarizing element is rectangular, and the translucent optical member 18
．． 20 has a rectangular prism shape.

The thin layer 16 is cut out so that the difference between the principal refractive indexes is maximized with respect to the incident angle θ5 of the incident light.

)G(2As04 single crystal has a refractive index of 1.57 for ordinary light O and a refractive index of 1.47 for extraordinary light e, so if the refractive index of the transparent optical member 18.20 is 1.92 , incident light having an incident angle θr in the range of 50.9° to 54.90° can be separated into total reflection and transmission.

A specific experimental example for this example will be described below.

(Experiment Example 3) Pour 2250 cc of water into a beaker, maintain the temperature at 50°C, and then accurately weigh it to make 100 ml of 9KH2ASO4.
0? The dissolved solution was left in a water bath kept at a temperature of 42±0.2° C. for 24 hours to precipitate supersaturated KH2ASO4. Next, the supernatant liquid in the beaker was transferred to another beaker, and one of the precipitated microcrystals, which was unnecessary and transparent, was placed in the other beaker as a seed crystal, and the evaporation rate was set at a constant rate per day. 1.2cc
Crystal growth was performed for 200 days in a water bath at 40°C under the control of 4Q 11+1 x 4Q uX20.
A single crystal with a thickness of 111 was obtained.

From this single crystal, thickness 11m, 2mm, 3iit
Three types of polarizing elements of the type shown in Fig. 2 were created by cutting out thin layers of three types. Translucent optical member 18.
No. 20 was made of optical glass with a refractive index of 1.92.

The angle θ5 in Figure 2 is 51°, θ6 is 71.9', θ
7 is 51°, θ8 is 39°, and θ9 is 23.5°.

Note that the thickness direction of each thin layer is perpendicular to the C axis of the crystal.

As in Experimental Example 1, the extinction ratio and single crystal state of each polarizing element were investigated. The results are shown in Table 3.

Table 3 (Experimental Example 4) In Experimental Example 3, the evaporation rate excluding crystal growth was controlled to 90.8 cc per day, and after 320 days of crystal growth,
A single crystal of 381III11×33III×16 ml was obtained. Results for experiments similar to Experimental Example 3 are shown in Table 4.

Table 4 Compared to the individual polarizing elements of Experimental Example 3, each polarizing element of Experimental Example 4 has a much improved extinction ratio.

In the embodiment shown in FIG. 3, the reference numeral 22 represents α-Hl0
．． The single crystal thin layer 24.26 indicates a translucent optical member.

The single crystal of α-HIO3 is an orthorhombic and biaxial crystal. For light incident at an incident angle of 01G, the thin layer 22
It is cut out so that the difference in principal refractive index is maximized.

α-HIO3 has α of 1.9508 and γ of 1.8123
When combined with a translucent optical member 24.26 made of optical glass having a refractive index of O and a refractive index of 1.92, if the incident angle θ1o of the incident light is 70.460 or more, Thus, the incident light can be separated into transmitted light and total reflected light.

A specific experimental example for this example will be described below.

(Experimental Example 5) Take 200 cc of water in a beaker, and while keeping it at 40°C, dissolve a weighed amount of α-Hl0a at 580F, and adjust the temperature of the resulting solution to 35 ± 0.2°C.
The mixture was left in a water bath for 24 hours to precipitate supersaturated α-HIO3. Pour the supernatant liquid in the beaker into another beaker, and put one of the precipitated microcrystals that are not in it into the beaker on the above side as a seed crystal, and control the evaporation rate to 5 cc per day. While doing so, 3
Crystal growth was performed for 12 days in a water bath at 5°C.
A single crystal of 41 mix 53 mix 20 mrs was obtained.

From Kono single crystal, thickness 1mg+, 2+im, 3
Three types of thin layers of Dragon were cut out so that the thickness direction coincided with the y-axis of the crystal, and three types of polarizing elements of the type shown in FIG. 3 were fabricated for each of the thin layers. The translucent optical members 24 and 26 were made of optical glass with a refractive index of 1.92. The angle 010 in Fig. 3 is 73°, θ11 is 70.5°, and θ12 is 73°.
°, θ131θ14 is 73°, and θ15 is 107°. Also, π:BC:DB=44:93:12
．． It is 5.

The extinction ratio and single crystal state of each of the three types of polarizing elements were investigated. The results are shown in Table 5.

Table 5 (Experimental Example 6) In Experimental Example 5, the evaporation rate during crystal growth was controlled to 2 cc per day, the crystal was grown for 20 days, and 3 g mr.
A single crystal of x x 47 mm x 20 mm was obtained. Table 6 shows the results of an experiment similar to Experimental Example 5.

Table 6 Compared to Experimental Example 5, the extinction ratio is much better.

In the embodiment shown in FIG. 4, the reference numeral 28 represents LiIO3
The single-crystal thin layers 30 and 32 indicate translucent optical members, respectively.

The single crystal thin layer 28 is cut out so that the difference in principal refractive index is maximized according to the incident angle θ16.

The crystal of Li IO3 is a hexagonal crystal, and is a uniaxial crystal whose optical axis is the C axis of the crystal axis. Regarding ordinary ray O, 1.
881, and has a refractive index of 1.736 for the extraordinary ray e. Therefore, when combined with the translucent optical member 30.32 made of optical glass with a refractive index of 1.92, the incident angle θ16
is between 64.52° and 78.00°, the incident light can be separated into totally reflected light and transmitted light depending on the polarization direction.

A specific experimental example for this example will be shown below.

(Experiment Example 7) Pour 200cc of water into a beaker, maintain it at 40°C, dissolve 3501 LiIO3 weighed out, and pour this solution into water adjusted to a temperature of 35°C ± 0.2°C. It was left in a bath for 24 hours to precipitate supersaturated LiIO3.

Next, transfer the supernatant liquid in the beaker to another beaker,
Among the precipitated microcrystals, choose one that is transparent and does not contain "I" and put it in the beaker on the above side as a seed crystal.
In a water bath at 35°C, the evaporation rate was increased by 5 times per day.
Controlled to cc, crystal growth for 15 days, 30 cities x 35j
Obtained a single crystal of deception x20.

The optical axis and optical elastic axis of the obtained single crystal were determined using a polarizing microscope, and three types of thin layers with thicknesses of 1, 2, and 3 were cut out. These thin layers were cut out so that the thickness direction coincided with the b-axis of the crystal. At this time, the a-axis was placed on the crystal plate plane, and the c-axis was made perpendicular to the thickness plane.

Using each of these three types of thin layers, a polarizing element 3a of the type shown in FIG. 4 was produced. Translucent optical member 30.
No. 32 was made of optical glass with a refractive index of 1.92. Fourth
In the figure, the angle θ16 is 67°, θ grave 7H70, 2o,
f) ls Id 670, θ19 + θ2G rθ
21 halo 70. θ2□ is 113° and θphantom is 67°. Also, AoBo: Bo C.

: A, Bo=36:90:7,5.

As usual, the extinction ratio and single crystal state of each polarizing element were investigated. The results are shown in Table 7.

Table 7 (Experimental Example 8) The evaporation rate for crystal growth in Experimental Example 7 was controlled to 2α per day, and crystal growth was carried out for 26 days.
A single crystal of ra x 30 mtx x 13 tj tj was obtained. An experiment similar to Experimental Example 7 was conducted. The results are shown in the 8th section.
Shown in the table.

All of the polarizing elements have better extinction ratios than the polarizing elements in Experimental Example 7 in Table 8.

In addition, in all of the above four examples, the surface polishing accuracy of the bonded surfaces was sufficiently high so that no air layer existed between the thin single crystal layer and the translucent optical member. .

In the above description, four types of embodiments have been described from FIG. 1 to FIG. 4, but as shown in FIG.
It is also possible to construct a polarizing element in which the light-transmitting optical members 36 and 38 are sandwiched between parallel plane plate-shaped light-transmitting optical members 36 and 38. Further, as is clear from the above description, the characteristics of the polarizing element of the present invention depend on the homogeneity of the single crystal, and the higher the homogeneity, the better the characteristics. Therefore, by controlling the evaporation rate during crystal growth and producing a single crystal with good homogeneity, it is possible to realize an element with characteristics equivalent to a polarizing element using natural calcite.

(Effects) As described above, according to the present invention, a novel polarizing element can be provided.

Since the single crystal used in the polarizing element of the present invention can be artificially produced, the polarizing element can be easily made into a sacred material, and the cost can be reduced.

Furthermore, since the single crystal thin layer is held between light-transmitting optical members, sufficient mechanical strength can be imparted to the element, and the element is easy to handle.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining one embodiment of the present invention, and FIG.
The figures are diagrams for explaining other embodiments of the invention, FIG. 3 is a diagram for explaining still another embodiment of the invention, and FIG. 4 is a diagram for explaining still another embodiment of the invention. FIG. 5 is a diagram for explaining still another embodiment of the present invention. 10 ・KNO3 single crystal thin layer, 16-・-KH2A
s04 single crystal thin layer, 22... α-HIO3 single crystal thin layer, 28... LiIO3 single crystal thin layer, 12
．． 14. 18°20, 24.26.30. 32・
...Translucent optical member. /徲l Diagram /Mo2 ■ Zρ Procedural Amendment December 4, 1980 - Case Indication 1982 Patent Application No. 206665 2 Name of Invention Polarizing Element 3 Person making the amendment Relationship to the case Name of patent applicant Name (+374) 4th generation Ricoh Co., Ltd.
Address: 4-5-4 Kyodo, Setagaya-ku, Tokyo "
"Detailed Description of the Invention" column and Drawing 6 Contents of amendment

Claims (1)

[Claims] KNO_3, KH_2AsO_4, LiIO_3, α-
A polarizing element made by sandwiching a thin layer of any single crystal of HIO_3 between transparent optical members.