CN106358443A - Polarization imaging filter and method for manufacturing same - Google Patents

Abstract

A polarization imaging filter (1) provided with a polarizer array (2), wherein the polarizer array (2) is formed by arranging a plurality of polarizer units (3) having different transmission axis directions (4) two-dimensionally in two rows and two columns, the transmission axis directions (4) of the plurality of polarizer units (3) arranged in the polarizer array (2) are regular, the polarizer unit (3) has a periodic structure of high refractive index portions (11) and low refractive index portions (12), and the periodic structure is a refractive index change region formed in a cover glass due to oxygen excess and oxygen defect.

Description

Polarization imaging filter and manufacturing method thereof

technical field

The invention relates to a polarization imaging filter and a manufacturing method thereof.

Background technique

The polarization imaging filter is used in the polarization imaging sensor, and transmits only polarized light in a predetermined direction from input light to the polarization imaging sensor. Thus, the polarization imaging sensor can obtain the polarization information of the input light. Therefore, the polarization imaging filter includes a polarizing plate array that does not transmit unnecessary polarized light among input lights. As such a polarizing plate array, the use of a photonic crystal polarizing plate produced by a self-replication method (self-cloning method) is disclosed (for example, refer to Patent Document 1).

As shown in Figure 4 of Patent Document 2 and Figure 4 of Non-Patent Document 1 (Figure 17 of the present application), the photonic crystal polarizer mentioned above can transmit TM polarized light at a specific wavelength, but obviously cannot polarize TE. light through. That is, the photonic crystal polarizer works as a polarizer for the input light of the above-mentioned specific wavelength.

prior art literature

patent documents

Patent Document 1: Japanese Patent No. 4274543

Patent Document 2: Japanese Patent No. 4294264

Patent Document 3: Japanese Patent Laid-Open No. 2009-168795

Patent Document 4: Japanese Patent Laid-Open No. 2004-310009

non-patent literature

Non-Patent Document 1: Kawakami Shojiro et al. "Development of a Polarization Imaging Camera Using a Photonic Crystal Polarizer", Journal of the Society for Electronics, Information and Communication ”Journal of the Society for Electronics, Information and Communications, General Social Organization, Society for Electronics, Information and Communications) January 1, 2007 J90-C(1)p.17-24

Contents of the invention

(1) Technical problems to be solved

However, in other words, the photonic crystal polarizers in the above-mentioned Patent Documents 1 and 2 and Non-Patent Document 1 do not work as polarizers for input light other than the above-mentioned specific wavelength. Specifically, as shown in FIG. 18 , the above-mentioned photonic crystal polarizer can transmit both TE polarized light and TM polarized light at a wavelength (symbol T) of about 550 nm to 700 nm or less.

Here, since the wavelength of visible light is 400nm-800nm, the photonic crystal polarizer does not work as a polarizer in the entire wavelength range of visible light. Therefore, as described in Non-Patent Document 1 "Because both polarized lights are transmitted in light above 550 nm, a multilayer film filter is formed on the back of the polarizer to intercept light in this wavelength range". Thus, the polarization imaging filter including the photonic crystal polarizer functions only within a limited wavelength band of visible light.

In addition, the above-mentioned photonic crystal polarizer, that is, the photonic crystal polarizer manufactured by the self-replication method, can also change the wavelength band that operates as a polarizer by adjusting its structure or material. However, in order to operate as a polarizing plate in the entire wavelength band of visible light, it is necessary to optimize the structure and material, and there is a problem that it cannot be easily manufactured.

On the other hand, a wire grid polarizing plate can also operate as a polarizing plate in the entire wavelength band of visible light (for example, refer to Patent Document 3). However, since the wire grid polarizing film is made of metal (without transmission), there is a problem of low transmission.

In addition, Patent Document 4 discloses an optical structure formed by irradiating glass with femtosecond laser light. However, Patent Document 4 does not disclose whether or not the optical structure works as a polarizing plate in the entire wavelength band of visible light.

Therefore, an object of the present invention is to provide a polarization imaging filter having high transparency and capable of effectively functioning in the entire wavelength band of visible light, and a method for manufacturing the same.

(2) Technical solution

In order to solve the above technical problems, the polarization imaging filter of the first invention is a polarization imaging filter with a polarizer array,

The polarizer array is formed by arranging two-dimensionally a plurality of polarizer units with different transmission axis directions,

The transmission axis directions of the plurality of polarizer units arranged in the polarizer array are regular,

The polarizer unit has a periodic structure of high refractive index parts and low refractive index parts,

The periodic structure is a refractive index change region formed by oxygen excess and oxygen deficiency on the substrate through which laser light is transmitted.

In addition, in the polarization imaging filter of the second invention, in the polarization imaging filter of the first invention, the substrate through which the laser light passes is the cover glass of the polarization imaging sensor.

Furthermore, the method for manufacturing a polarization imaging filter of the third invention is the method for manufacturing a polarization imaging filter of the first invention or the second invention,

It includes a step of forming a refractive index change region at a converging position of the femtosecond laser light by irradiating a substrate through which the laser light passes.

In addition, the manufacturing method of the polarization imaging filter of the fourth invention is in the manufacturing method of the polarization imaging filter of the third invention,

The polarizer array is stacked while adjusting the parameters of the femtosecond laser according to the desired phase difference in the polarization imaging filter.

(3) Beneficial effects

According to the above-mentioned polarization imaging filter and its manufacturing method, it is possible to achieve high transmittance and effectively function in the entire wavelength band of visible light.

Description of drawings

FIG. 1 is a schematic perspective view showing the structure of a polarization imaging sensor using a polarization imaging filter according to an embodiment of the present invention.

FIG. 2 is a plan view schematically showing the above polarization imaging filter, wherein FIG. 2A is a diagram showing a transmission axis with double arrows, and FIG. 2B is a diagram showing a high refractive index portion with lines.

3 is a perspective view schematically showing a polarizer array of the same polarization imaging filter, wherein FIG. 3A is a diagram showing a transmission axis with double arrows, and FIG. 3B is a diagram showing a cylindrical region.

FIG. 4 is a three-layered perspective view of the above polarizer array, wherein FIG. 4A is a diagram corresponding to FIG. 3A , and FIG. 4B is a diagram corresponding to FIG. 3B .

Fig. 5 is a graph showing the additivity of retardation in the same polarizing plate array.

Fig. 6 is a Mueller matrix of polarizer units constituting the above polarizer array, wherein the left side is a graph showing its matrix components, and the right side is a determinant showing the graph.

Fig. 7 is a diagram showing an experiment in which four polarized lights are input and photographed in the same polarizer array, wherein Fig. 7A is a top view schematically showing the polarizer array, and Fig. 7B is a photograph of inputting polarized light in a 0° direction , FIG. 7C is a photo of polarized light input in a 45° direction, FIG. 7D is a photo of a polarized light input in a 90° direction, and FIG. 7E is a photo of a polarized light input in a 135° direction.

Fig. 8 is a view showing the manufacturing device of the polarized imaging filter as above, wherein Fig. 8A is a schematic structural view, and Fig. 8B is an enlarged view of the cover glass and the femtosecond laser irradiated thereto.

FIG. 9 is a view corresponding to FIG. 8 showing a state in which the same cylindrical region is formed.

FIG. 10 is a diagram corresponding to FIG. 8 , showing a state in which the direction of the magnetic field of the femtosecond laser is rotated by 45°.

Fig. 11 is a diagram corresponding to Fig. 8 showing the state where the magnetic field direction of the same femtosecond laser is rotated by 45° to form a cylindrical region

FIG. 12 is a plan view schematically showing the polarizing plate array as above, and is a diagram for explaining the transmission axis angle.

FIG. 13 is a plan view schematically showing a polarizing plate array according to another embodiment, and is a diagram for explaining the angle of the transmission axis.

FIG. 14 is a diagram showing a method of manufacturing a polarization imaging filter according to another embodiment.

FIG. 15 is a diagram showing a polarizing plate array according to another embodiment, FIG. 15A is a perspective view of a laminated polarizing plate array, and FIG. 15B is a plan view of each layer of the polarizing plate array.

Fig. 16 is a perspective view showing a polarization imaging filter according to another embodiment.

FIG. 17 is a graph showing the relationship between the wavelength of input light and the transmittance for a conventional photonic crystal polarizer (produced by the self-replication method), and is FIG. 4 in the non-patent literature.

Fig. 18 is a diagram showing a manufacturing method of another embodiment of the above polarization imaging filter.

detailed description

Next, a polarization imaging filter according to an embodiment of the present invention will be described based on the drawings.

First, a schematic description will be given of a polarization imaging sensor using the above polarization imaging filter.

As shown in FIG. 1 , the polarization imaging sensor S includes a polarization imaging filter 1, a light receiving module R, and an information processing unit I, wherein the polarization imaging filter 1 makes the transmission axis direction (in In Fig. 1, the polarized light represented by the double arrow 4) passes through; the light receiving module R receives the polarized light passing through the polarized imaging filter 1; information is processed. The information processing unit 1 is composed of well-known components that perform image processing and computation, and store the information as needed. In addition, the pixels P of the above-mentioned light receiving module R are arranged two-dimensionally in multiple rows and columns, and in this embodiment, they are arranged in six rows and six columns in order to simplify the description and drawings. In addition, in the above-mentioned polarization imaging filter 1 , the traveling direction of visible light V (the direction of the white hollow arrow in FIG. 1 ) will be described as the thickness direction, and the direction perpendicular to the thickness direction will be described as the width direction. Furthermore, there are various definitions of visible light, but the visible light V in this embodiment refers to light having a wavelength of 400 nm to 800 nm.

In addition, a typical polarization imaging sensor is equipped with a cover glass for protecting the light receiving module in addition to the polarization imaging filter. However, in the polarization imaging sensor S of the present embodiment, the above-mentioned polarization imaging filter 1 also serves as a cover glass, so to be precise, the cover glass has the function of a polarization imaging filter, thereby eliminating the need for an additional cover glass .

Next, the above-mentioned polarization imaging filter 1 will be described in detail.

As shown in FIG. 2A , the polarization imaging filter 1 is composed of two-dimensionally arranged polarizer units 3 in six rows and six columns (in reality, multiple rows and multiple columns). Each polarizer unit 3 is in one-to-one correspondence with the pixels P of the light receiving module R (refer to FIG. 1 ). As shown by the dotted line in FIG. 2A , one polarizer array 2 is formed by two polarizer units 3 in two rows and two columns. That is, the polarizer array 2 is formed by arranging the polarizer units 3 two-dimensionally in two rows and two columns. In addition, as shown in FIG. 2A , one polarizer unit 3 is configured such that the transmission axis 4 is in one direction. Also, the transmission axis directions 4 of four (two rows and two columns) polarizer units 3 arranged in one polarizer array 2 are regular. Specifically, as shown in FIG. 1 , in each polarizer array 2 , the transmission axes 4 of the adjacent polarizer units 3 in rows and columns are 45° to each other. The purpose of making the transmission axis direction 4 regular in this way is to send the information of the polarization direction to the light receiving module R. Specifically, if polarized light is input to the polarizer array 2, the polarizer unit 3 close to the transmission axis direction 4 of the input polarized light direction will fully transmit the polarized light, and the polarized light unit 3 far from the incident polarized light direction will be fully transmitted. The polarizer unit 3 in the cross-axis direction 4 cannot fully transmit the polarized light. Therefore, according to the polarized light passing through the polarizer array 2, the direction of the input polarized light can be clearly known.

2A is a diagram schematically showing the transmission axis 4 of the above-mentioned polarization imaging filter 1 with double arrows, but the actual transmission axis 4 passes through the refractive index change region formed on the cover glass (by the high refractive index portion and the low refractive index portion). It is determined by the role of the composition of the refractive index. When the high refractive index portion is represented by a line, parallel lines 11 can be seen in each polarizing plate unit 3 as shown in FIG. 2B . That is, the parallel lines 11 are high-refractive-index portions where the refractive index increases due to excess oxygen. On the other hand, 12 other than the above-mentioned parallel lines is a low-refractive-index portion where the refractive index decreases due to oxygen deficiency. Since the high refractive index portions 11 and the low refractive index portions 12 appear alternately, the refractive index change region composed of the high refractive index portions 11 and the low refractive index portions 12 can be called a periodic structure. In addition, as can be seen from the comparison of FIG. 2A and FIG. 2B , the direction of the transmission axis 4 is a direction perpendicular to the parallel line of the high refractive index portion 11 .

Next, a description will be given focusing on one polarizer array 2 .

FIG. 3A is a perspective view schematically showing one polarizer array 2, and FIG. 3B is a perspective view actually showing the polarizer array 2 of FIG. 3A. As shown in FIG. 3B , the polarizer array 2 is formed by a plurality of cylindrical refractive index changing regions (hereinafter simply referred to as cylindrical regions 5 ) juxtaposed on the same plane (that is, in a raft shape). Each cylindrical region 5 is formed by connecting spherical refractive index changing regions in a straight line. This spherical refractive index change region is obtained by irradiating a femtosecond laser (a pulsed laser with a pulse time of ^10-12 seconds to ^10-15 seconds) on a cover glass (an example of a substrate through which a laser beam passes). formed at the spotlight position. Therefore, each of the above-mentioned cylindrical regions 5 is formed by irradiating the femtosecond laser to the above-mentioned cover glass while relatively moving the cover glass and the femtosecond laser in the same direction, so as to be on the track of the converging position of the femtosecond laser. Forming. In addition, the parallel lines of the high refractive index portion 11 in each cylindrical region 5 are formed in the same direction as the magnetic field direction of the above-mentioned femtosecond laser.

In addition, what represented among Fig. 3 is the example of forming one deck polarizer array 2 on the cover glass, but if the retardation of polarizer array 2 is not enough (if not satisfying desired retardation), then can be as shown in Fig. 4 As shown, the polarizer array 2 is arranged in multiple layers (shown in FIG. 4 is an example of three layers). By providing the polarizer arrays 2 in multiple layers, the phase difference of the polarization imaging filter 1 including these multilayer polarizer arrays 2 is set to a value obtained by multiplying the phase difference of each polarizer array 2 by the number of layers. For example, as shown in the graph of FIG. 5 , when the retardation of the polarizing plate array 2 is about 0.3πrad, it has been confirmed through experiments that a retardation of about 0.3πrad can be obtained if there are one layer, and a retardation of about 0.3πrad can be obtained if there are two layers. A phase difference of 0.3πrad×2 can be obtained, and if there are three layers, a phase difference of 0.3πrad×3 can be obtained. That is, in the polarization imaging filter 1 described above, it can be said that the retardation of the stacked polarizing plate array 2 is additive. In addition, by changing the parameters of the irradiated femtosecond laser light, the phase difference of the single-layer polarizing plate array 2 is changed in the range of 0 to 0.367πrad (100nm).

Next, the function of the polarization imaging filter 1 will be described.

If the visible light V is input to the polarization imaging filter 1, the polarized light in the same direction as the transmission axis direction 4 of each polarizer unit 3 will pass through, and the transmitted polarized light will be transmitted by each pixel corresponding to the light receiving module R P receives. In addition, the transmission axis directions 4 of the four polarizer units 3 arranged in the polarizer array 2 are set regularly, so that the information of the polarized light direction will be sent to the light receiving module R, so the transmitted polarized light can be Accuracy improved. In addition, the light receiving module R that receives these polarized lights will send information such as the direction of the polarized light, brightness and color to the information processing unit I.

Here, in order to know the characteristics of the polarizing plate unit 3 with respect to the entire wavelength range of the visible light V, various wavelengths of the above-mentioned visible light V are injected into the sample, and the light output from the sample is measured. Find the matrix components of the Muller matrix. The apparatus used for this measurement was a spectropolarimeter Poxi-spectra (manufactured by Tokyo Instruments Co., Ltd.), and the above-mentioned sample formed a refractive index change region on a 2 mm square quartz glass. The refractive index change region is a periodic structure in which linear high-refractive-index portions with a line width of 1.5 μm are formed at a pitch of 2.0 μm, and low-refractive-index portions are formed between these high-refractive-index portions. That is, the sample has the same structure as the polarizer unit 3 . In addition, the change of the said wavelength is specifically 400 nm - 800 nm. The reason is that, in the visible light V of this embodiment, 400nm is the shortest wavelength (the color is purple), and 800nm is the longest wavelength (the color is red), so it can be known that the entire wavelength range of the polarizer unit 3 for the visible light V of the characteristics. As a result, the matrix components of the Mueller matrix of the polarizer unit 3 are as shown in the 16 graphs shown on the left side of FIG. 6 . On the other hand, these theoretical formulas expressed numerically are represented by the determinant shown on the right side of FIG. 6 . Here, θ in FIG. 6 is the transmission axis direction of the sample, and δ is the phase difference of the sample. In addition, E=0° in Figure 6 (E is the electric field direction) is linearly polarized light parallel to the transmission axis (called TM polarized light), and E=90° is linearly polarized light perpendicular to the transmission axis (called TM polarized light). for TE polarized light). As shown in FIG. 6 , for M23 and M32, the matrix components are greatly different between E=0° and E=90° in the wavelength range of 400 nm to 800 nm. Specifically, for M23, within a wavelength of 400 nm to 800 nm, the matrix component of E=0° is 1.0 to 0.5, and the matrix component of E=90° is -1.0 to -0.5. In addition, for M32, within a wavelength of 400 nm to 800 nm, the matrix component of E=0° is -1.0 to -0.5, and the matrix component of E=90° is 1.0 to 0.5. Therefore, according to the matrix component of M23 above, that is, the component that converts circularly polarized light into 45° polarized light, in the wavelength range of 400nm to 800nm, the polarized light (TM polarized light) parallel to the transmission axis direction will be transmitted as it is. , and the polarized light (TE polarized light) perpendicular to the transmission axis direction will be reversed and transmitted. In other words, according to the matrix composition of M23, TM polarized light will be transmitted at 45°, and TE polarized light will be transmitted at -45°. In addition, according to the above-mentioned matrix component of M32, that is, the component that converts circularly polarized light into 45° polarized light, within the wavelength of 400nm to 800nm, the polarized light (TM polarized light) parallel to the transmission axis direction will be reversed and transmitted. The polarized light (TE polarized light) perpendicular to the transmission axis direction will be transmitted as it is. In other words, according to the matrix composition of M32, TM polarized light is transmitted clockwise, and TE polarized light is transmitted counterclockwise. That is, within a wavelength of 400 nm to 800 nm, the polarization states of TM polarized light and TE polarized light output from the sample are different. From this, it can be known that the polarizer unit 3 works as a wavelength plate.

Here, the polarizer unit 3 is made to work as a polarizer by shielding the part of the output of the TE polarized light (polarized light perpendicular to the transmission axis direction 4 ) from the polarizer unit 3 . Its reason is, because the polarized light state that TM polarized light and TE polarized light are output from sample is different, therefore even shield the TE polarized light part that is output from described polarizer unit 3, also can not be to TM polarized light. The light is partially shielded, that is, TM polarized light (polarized light parallel to the transmission axis direction 4 ) is transmitted while TE polarized light (polarized light perpendicular to the transmission axis direction 4 ) is not transmitted. In addition, in order to partially shield the TE polarized light (polarized light perpendicular to the transmission axis direction 4) output from the polarizer unit 3, that is, in order to increase the extinction ratio to a desired value, it is necessary to increase the layer of the polarizer array 2 number, or install another wavelength plate on the cover glass 30. Thus, the polarized imaging filter 1 transmits the polarized light in the transmission axis direction 4 in the entire wavelength range of the visible light V, while preventing the polarized light in the non-transmission axis direction 4 from being transmitted. In summary, it can be said that the polarization imaging filter 1 works as a polarizer in the entire wavelength band of visible light V (400nm-800nm).

As to whether or not the polarizing plate unit 3 that increases the extinction ratio to a desired value works as a polarizing plate, experiments were actually conducted. In this experiment, the four polarized lights were respectively input to the polarizer array 2 formed by arranging the polarizer units 3 in two dimensions in two rows and two columns, that is, the polarizer array 2 shown in FIG. 7A Photography was performed, and the intensity of transmitted polarized light was confirmed visually. The photographs taken are shown in FIGS. 7B to 7E respectively. As shown in Figure 7B, if the input polarized light is in the direction of 0° (E=0°), then there is the polarizer unit 3 with the transmission axis 4 in the same direction as the polarized light direction, that is, the polarizer array in Figure 7B The lower left polarizer unit 3 in 2 is the brightest. Similarly, as shown in FIG. 7C , if the input polarized light is in the direction of 45° (E=45°), the upper left polarizer unit 3 in the polarizer array 2 is the brightest. Similarly, as shown in FIG. 7D , if the input polarized light is in the direction of 90° (E=90°), the upper right polarizer unit 3 in the polarizer array 2 is the brightest. Similarly, as shown in FIG. 7E , if the input polarized light is in the direction of 135° (E=135°), the bottom right polarizer unit 3 in the polarizer array 2 is the brightest. From these results, it can be seen that the polarizing plate unit 3 having an increased extinction ratio transmits the polarized light in the transmission axis direction 4 and does not transmit the polarized light in the non-transmission axis direction 4 . That is, it can be said that the extinction ratio is increased to a desired value, and the polarizing plate unit 3 operates as a polarizing plate.

Next, a method of manufacturing the above-mentioned polarization imaging filter 1 will be described with reference to the drawings.

First, the production apparatus used in the above-mentioned production method will be described.

As shown in FIG. 8A , the manufacturing device is provided with an output device 21, a linear polarizing plate 22, a mirror 23, and a lens 24. The output device 21 outputs a femtosecond laser 20; The linearly polarized light specified in the output femtosecond laser 20 passes through; the reflector 23 makes the femtosecond laser 20 passing through the linearly polarized light plate 22 reflect to the cover glass 30; the lens 24 is formed by the reflector 23 reflected femtosecond laser light 20 for focusing.

Next, the above-mentioned manufacturing method using the manufacturing apparatuses 21 to 24 will be described.

As shown in FIG. 8A , a cover glass 30 is placed in advance at the position where the femtosecond laser light 20 is focused, that is, at the position where the polarizer array 2 is to be formed. Furthermore, when the output unit 21 outputs the femtosecond laser light 20 , the femtosecond laser light 20 is focused inside the cover glass 30 as shown in FIGS. 8A and 8B . Here, the parameters of the femtosecond laser 20 , that is, the wavelength, the number of pulses, and the energy, etc. vary according to the periodic structure to be formed. If these parameters are changed, in the periodic structure, the distance between the high refractive index portion 11 and the low refractive index portion 12, the refractive index difference between the high refractive index portion 11 and the low refractive index portion 12, and the cross section of the formed cylindrical region 5 The surface diameter and the retardation (0 to 100 nm) of the polarizer array 2 composed of these cylindrical regions 5 vary.

After the output device 21 outputs the femtosecond laser 20 , as shown by the white hollow arrow in FIG. 9 , the femtosecond laser 20 and the cover glass 30 are relatively moved in the same direction. The direction of this relative movement is defined as the direction in which the cylindrical region 5 is to be formed, that is, the width direction of the cover glass 30 . In addition, the direction of the parallel lines of the high refractive index portion 11 formed in the cylindrical region 5 is the same as the direction of the magnetic field of the femtosecond laser 20 as shown in detail in FIG. 9B .

If the desired length of the cylindrical region 5 is obtained, as shown by the white hollow arrow in FIG. 10 , by rotating the linear polarizing plate 22 by 45°, the magnetic field direction of the femtosecond laser 20 reaching the cover glass 30 is rotated by 45°. At this time, the parallel lines of the high refractive index portion 11 in the cylindrical region 5 are also rotated by 45°. Then, as shown by white hollow arrows in FIG. 11 , by continuing the above relative movement in the same direction, the cylindrical region 5 in which the parallel lines of the high refractive index portion 11 are rotated by 45° is formed. When the cylindrical region 5 in the state where the parallel lines of the high refractive index portion 11 are rotated by 45° has a desired length, one cylindrical region 5 constituting the polarizing plate array 2 is formed.

By repeating the above steps, as shown in FIG. 2B , the polarizer units 3 are arranged in six rows and six columns in two dimensions, that is, the polarizer array 2 is arranged in three rows and three columns in two dimensions, thereby manufacturing the polarization imaging filter 1 .

In addition, if the phase difference of the arranged single-layer polarizer array 2 is not enough, another polarizer array 2 needs to be formed until the desired phase difference is satisfied. In addition, a newly formed additional polarizing plate array 2 is disposed on the upper side (arrival side of the femtosecond laser light 20 ) of the already formed polarizing plate array 2 .

In this way, according to the above-mentioned polarization imaging filter 1, since it is constituted based on oxygen excess and oxygen deficiency in the cover glass 30 (the base material through which the laser beam is transmitted), the transmittance is high, and in the entire wavelength band of visible light V By operating as a polarizer, it can effectively function in the entire wavelength band.

Furthermore, since the transmission axis direction 4 of the plurality of polarizer units 3 arranged in the polarizer array 2 is regular, the accuracy of the transmitted polarized light can be improved, and it can function more effectively.

In addition, since the cover glass 30 has the function of the polarization imaging filter 1 , when used in the polarization imaging sensor S, no additional cover glass 30 is required.

In addition, according to the manufacturing method of the polarization imaging filter 1 described above, the polarization imaging filter 1 that achieves the above effects can be easily manufactured. In particular, the above-described imaging sensor can be easily modified into the polarization imaging sensor S by simply making the existing cover glass 30 for a general imaging sensor have the function of the polarization imaging filter 1 .

In addition, the phase difference of the polarization imaging filter 1 can be easily set to a desired phase difference by a simple process of laminating the polarizing plate array 2 while adjusting the parameters of the femtosecond laser 20 .

Example

Next, the polarization imaging filter 1 that more specifically shows an example of the above-mentioned embodiment will be described.

First, remove the cover glass 30 from the existing CCD camera (equipped with the cover glass 30, the light receiving module R, and the information processing unit I), and set the cover glass 30 in the manufacturing apparatuses 21 to 24 of the above-mentioned embodiment. .

In addition, the parameters of the femtosecond laser 20 are adjusted so that the cross-sectional diameter of the formed cylindrical region 5 is 2 μm. In addition, a spatial phase adjuster (not shown) is arranged between the mirror 23 and the lens 24 in the above-mentioned manufacturing apparatuses 21 to 24 to make the femtosecond laser beam 20 multi-channel reach the cover glass 30 .

Then, the plurality of femtosecond lasers 20 and the cover glass 30 are moved relative to each other, and at the same time, a plurality of cylindrical regions 5 are formed to manufacture the polarization imaging filter 1 . In addition, the speed of this relative movement was set to 2 mm/sec.

In this polarizing plate imaging filter, polarizing plate units 3 are arranged two-dimensionally in 648 rows and 488 columns, and each polarizing plate unit 3 is formed into a square of 7.4 μm square. In addition, as one polarizer unit 3, cylindrical regions 5 having a cross-sectional diameter of 2 μm are formed adjacent to each other on the same plane.

In this way, according to the polarization imaging filter 1 of this embodiment and its manufacturing method, the same effect as that of the above-mentioned embodiment can be achieved.

Furthermore, according to the manufacturing method of this embodiment, since a plurality of cylindrical regions 5 are formed at the same time, the manufacturing time of the polarization imaging filter 1 can be shortened.

In addition, in the above-mentioned embodiments and examples, in each polarizing plate array 2, as shown in FIG. 12 , an example in which the transmission axes 4 of the polarizing plate units 3 adjacent to each other in the row and column are 45° has been described. , but as shown in Figure 13, it can also be 30° or 60°, as long as it is regular.

In addition, in the above-described embodiments and examples, an example in which the cover glass 30 is easily provided with the function of the polarization imaging filter 1 has been described, but another new glass may be easily provided with the polarization imaging filter 1 function.

Furthermore, in the above embodiments and examples, the polarization imaging filter 1 used for the polarization imaging sensor S has been described, but it is not limited to the polarization imaging sensor S, and may be used for other applications such as polarized glasses.

In addition, the method of forming the columnar region 5 described in the above-mentioned embodiments and examples is only an example, and as shown in FIG. 18 , the columnar region 5 may be formed in each portion having parallel lines 11 in the same direction.

In addition, in the above-mentioned embodiments and examples, the example in which the cylindrical region 5 is formed in the width direction of the cover glass 30 has been described, but as shown in FIG. 14 , it may be formed in the thickness direction of the cover glass 30. .

In addition, in FIG. 4 of the above-mentioned embodiment, the structure in which the same polarizing plate array 2 is stacked is described, but as shown in FIG.

In addition, in the above-mentioned embodiments and examples, the stacking of the polarizing plate array 2 is not described in detail, but as shown in FIG. different.

Claims (4)

1. A polarization imaging filter, characterized in that it is a polarization imaging filter with a polarizer array, The polarizer array is formed by arranging two-dimensionally a plurality of polarizer units with different transmission axis directions; The transmission axis directions of the plurality of polarizer units arranged in the polarizer array are regular; The polarizer unit has a periodic structure of high refractive index parts and low refractive index parts; The periodic structure is a refractive index change region formed by oxygen excess and oxygen deficiency on the substrate through which laser light is transmitted. 2 . The polarization imaging filter according to claim 1 , wherein the substrate through which the laser light passes is a cover glass of a polarization imaging sensor. 3 . 3. A method for manufacturing a polarization imaging filter, characterized in that it is the method for manufacturing a polarization imaging filter according to claim 1 or 2, It includes a step of forming a refractive index change region at a condensing position of the femtosecond laser light by irradiating the substrate through which the laser light has passed. 4. The manufacturing method of the polarization imaging filter according to claim 3, characterized in that, while adjusting the parameters of the femtosecond laser according to the expected phase difference in the polarization imaging filter, stacking polarizers array.