CN100498426C - Optical low-pass filter - Google Patents
Optical low-pass filter Download PDFInfo
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- CN100498426C CN100498426C CNB038015099A CN03801509A CN100498426C CN 100498426 C CN100498426 C CN 100498426C CN B038015099 A CNB038015099 A CN B038015099A CN 03801509 A CN03801509 A CN 03801509A CN 100498426 C CN100498426 C CN 100498426C
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
- G02B5/3083—Birefringent or phase retarding elements
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
- G02B1/08—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of polarising materials
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
- G02B27/288—Filters employing polarising elements, e.g. Lyot or Solc filters
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/42—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect
- G02B27/46—Systems using spatial filters
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Abstract
An optical low-pass filter (1) comprising birefringent wafers (31, 32, 33) formed by cutting a quartz ingot (2) and laid in layers. The birefringent wafer (31) is formed by cutting the quartz ingot (2) at an angle of 44.8 DEG. with respect to its optical axis A and separates an incident light in the horizontal direction. The birefringent wafer (32) is formed by cutting the quartz ingot (2) at an angle of 69 DEG. with respect to its optical axis A and separates the incident light in the direction of +45 DEG. with respect to the horizontal direction. The birefringent wafer (33) is formed by cutting the quartz ingot (2) at an angle of 69 DEG. with respect to its optical axis A and separates the incident light in the direction of -45 DEG. with respect to the horizontal direction.
Description
Technical field
The present invention relates to adopt the optical low-pass filter of birefringent plate.
Background technology
The radio-frequency component that optical low-pass filter filters the image frequency of light in order to be suppressed at imaging apparatus and to be subjected to the simulating signal that the light time produces, its characteristic is determined by the separation grating that light is separated.
For example, in optical low-pass filter in the past, disclosed optical low-pass filter in TOHKEMY 2000-56268 communique is arranged.
This optical low-pass filter is overlapping and constitute by 3 mutually different birefringent plates of optic axis.These 3 overlapping birefringent plates are cut apart, formed a plurality of low-pass filters.
Specifically, 3 birefringent plates are optic axis with respect to quartzy piece to block quartzy piece with 44.8 degree formed.These 3 birefringent plates be by the light with institute's incident be separated into horizontal direction the horizontal direction birefringent plate, make institute's incident light with respect to the detaching direction of horizontal direction birefringent plate to+45 degree directions separate+45 degree direction birefringent plates and the light that makes institute's incident separates-45 degree direction birefringent plates with respect to the detaching direction of horizontal direction birefringent plate to-45 degree directions and constituted, with these horizontal direction birefringent plates ,+45 spend direction birefringent plates ,-45 and spend the overlapping in order optical low-pass filter that forms of direction birefringent plates.
Incide the light in this optical low-pass filter, be separated into ordinary ray and extraordinary light, by ± 45 degree direction birefringent plates separated ordinary ray and extraordinary light are separated into 4 points respectively by the horizontal direction birefringent plate.
Like this, by adopting optical low-pass filter incident light is separated into 4 points, will the input light of the imaging apparatus of CCD etc. be separated, make image fog, decay causes the simulating signal of Moire fringe picture.
But the unit interval of imaging apparatus is in the trend that diminishes at present.Promptly in the CCD of manufacturing in recent years, the design of useful size same diminishes its unit interval increases the trend of pixel count (for example, being increased to 3,000,000 pixels etc. from 2,000,000 pixels).Therefore, be accompanied by the shortening of the unit interval of CCD, just the light of optical low-pass filter need be separated reduced width.
But,, just need make the thickness attenuation of each birefringent plate that constitutes optical low-pass filter in order to dwindle the separation width of optical low-pass filter.And, need make ± therefore 1/ √ 2 that the thickness of 45 degree direction birefringent plates become the horizontal direction birefringent plate realize thinner thickness with ± 45 degree direction birefringent plates, its attrition process is very difficult, has become the main cause that cost increases.
In addition, in the combined aspects of birefringent plate, because in fact quartzy piece can't be grown so greatly, thereby large-scale ± 45 degree direction birefringent plates are difficult to obtain.And in general, ± 45 degree direction birefringent plates are to have optic axis rectangular-shaped along limit that 45 degree directions are extended, and an angle has lacked very big one.In this case, obtain in the operation being divided into a plurality of rectangular-shaped a plurality of of optical low-pass filter by birefringent plate, will produce the loss of material, its poor efficiency.
Summary of the invention
In order to address the above problem, the objective of the invention is to: the optical low-pass filter that carries out the attrition process of birefringent plate easily is provided; In addition, the objective of the invention is to: provide make to lack part be zero with respect to the ratio of birefringent plate integral body or diminish, by in a production run, producing a plurality of optical low-pass filters that reduce production costs.
In order to reach above-mentioned purpose, the invention provides a kind of optical low-pass filter, by make quartzy piece relatively its optic axis have that angle is cut and the birefringent plate that forms constitutes, the light of incident is separated, wherein:
Described birefringent plate is to spend big and cut described quartzy piece than the little angle of 70.0 degree than 44.8 to form with the optic axis of described relatively quartzy piece.
Be more preferably, overlapping a plurality of described birefringent plates also cut and form a plurality of optical low-pass filters,
At least one described birefringent plate in a plurality of described birefringent plates is to spend big and cut described quartzy piece than the little angle of 70.0 degree than 44.8 to form with the optic axis of described relatively quartzy piece.
Be more preferably, form a plurality of described birefringent plates, and these a plurality of birefringent plates are cut apart form a plurality of birefringent plates respectively, will be overlapping by a plurality of birefringent plates that each birefringent plate forms,
At least one described birefringent plate in a plurality of described birefringent plates is to spend big and cut described quartzy piece than the little angle of 70.0 degree than 44.8 to form with the optic axis of described relatively quartzy piece.
Be more preferably, comprise at least in the overlapping a plurality of described birefringent plate:
With the optic axis of described relatively quartzy piece is that the angles of 44.8 degree are cut described quartzy piece and formed, and the light of incident is separated into the 1st birefringent plate of horizontal direction or vertical direction; With
With the optic axis of described relatively quartzy piece is bigger and cut described quartzy piece than the little angle of 70.0 degree and form than 44.8 degree, and the 2nd birefringent plate that separates to 45 degree directions with respect to horizontal direction or vertical direction of the light that makes incident.
Be more preferably, overlapping described birefringent plate constitute by one the 1st birefringent plate and two the 2nd birefringent plates, described the 1st birefringent plate is formed rectangular-shaped parallel with optic axis in opposed both sides, and, described the 2nd birefringent plate is 5 angular shapes, promptly when 3 adjacent angles are formed approximate right angle, also be formed with relative with the angle of centre in these 3 angles and with the limit of optic axis quadrature.
According to the present invention, owing to be that optic axis with described relatively quartzy piece is bigger and cut described quartzy piece and the form dielectric grid sheet than the little angle of 70.0 degree than 44.8 degree, so can simultaneously keep with in the past block quartzy piece and the identical light of the birefringent plate that obtains separates width with 44.8 degree, one side is controlled at 2 times to the variation in thickness of birefringent plate with interior (accompanying drawing 3,5), when grinding birefringent plate, can consider the loss of materials such as birefringent plate breakage, carry out process operation at an easy rate, can reduce production costs.
In addition, according to the present invention, owing to be that optic axis with described relatively quartzy piece is bigger and cut described quartzy piece and the form dielectric grid sheet than the little angle of 70.0 degree than 44.8 degree, so birefringent plate that obtains with respect to blocking quartzy piece with 44.8 degree, be arranged under the situation of camera head, can change its light path (example light path 1 as shown in Figure 6) hardly and only at random change light separation width (accompanying drawing 3,4), thereby can reduce production costs.
In addition, cutting angle by making birefringent plate to the optic axis of quartzy piece for than the big angle of 44.8 degree, even quartzy piece does not grow up to for so big, also can increase the area of birefringent plate, its result is even lack at birefringent plate under the situation at an angle, because the ratio that institute lacks partly with respect to birefringent plate integral body diminishes, so also can be suppressed at the quantity of formed defective optical low-pass filter when being divided into a plurality of optical low-pass filter, reduce production costs.
In addition, according to the present invention, owing to be that optic axis with described relatively quartzy piece is to cut described quartzy piece and the form dielectric grid sheet than the big angle of 44.8 degree, thereby can thicken the thickness of birefringent plate, can at an easy rate thickness be adjusted to the thickness that sets in advance.For example, in the past, pixel count at the CCD that digital camera (camera head) is adopted is increased under the situation of 3,000,000 pixels from 2,000,000 pixels, change the thickness of optical low-pass filter, according to this change, just need carry out the design alteration of the digital cameras such as optical path length self of changed number camera, but according to optical low-pass filter of the present invention, owing to can adjust the cutting angle of birefringent plate, make its thickness the same with in the past, thereby can only set the size of birefringent plate, the optical path length that does not need the changed number camera, thus can reduce production costs.
In addition, as mentioned above, adopt under the situation of optical low-pass filter,, preestablish the thickness of optical low-pass filter for the increase of the production cost of the design alteration that prevents camera head self at the camera head of the digital camera with CCD etc.Therefore, if camera head adopts optical low-pass filter of the present invention, because quartzy piece is being come the form dielectric grid sheet to its optic axis than the big angle cutting of 44.8 degree, thereby the thickness that need not change optical low-pass filter just can dwindle it and separate width, the increase of pixel count that can corresponding CCD.
Specifically, in above-mentioned structure, also can in overlapping a plurality of above-mentioned birefringent plates, cut apart, form a plurality of above-mentioned birefringent plates, in the middle of they are a plurality of, have at least an above-mentioned birefringent plate that quartzy piece is being formed than the big angle cutting of 44.8 degree its optic axis.In addition, in above-mentioned structure, also can be when forming a plurality of above-mentioned birefringent plates, the birefringent plates that these are a plurality of are cut apart, form a plurality of birefringent plates respectively, to be undertaken by the formed a plurality of birefringent plate of different birefringent plates overlapping, in the middle of they are a plurality of, have at least an above-mentioned birefringent plate with above-mentioned quartzy piece to its optic axis than 44.8 the degree big angle cutting forming.
In addition, in above-mentioned structure, in superimposed a plurality of above-mentioned birefringent plate, at least can comprise above-mentioned quartzy piece cut at 44.8 degree its optic axis form, the light of incident is separated into the 1st birefringent plate of horizontal direction or vertical direction and with above-mentioned quartzy piece to its optic axis at the 2nd birefringent plates that form, the light of incident is separated into horizontal direction or vertical direction 45 degree directions than the big angle cutting of 44.8 degree.
In this case, owing to make horizontal direction or vertical direction are separated into 45 the 2nd birefringent plate thickenings of spending directions, thereby just can will be usually than the thickness thickening of the 2nd birefringent plate of the thin thickness of the 1st birefringent plate, when grinding the 2nd birefringent plate, do not worry that process operation is carried out in the breakage of material of the breakage etc. of birefringent plate at an easy rate.
In above-mentioned structure, superimposed above-mentioned birefringent plate also can be made of one the 1st birefringent plate and two the 2nd birefringent plates, above-mentioned the 1st birefringent plate forms rectangular-shaped parallel with optic axis in opposed both sides, and above-mentioned the 2nd birefringent plate is forming 5 angular shapes, 3 adjacent dihedrals become approximate right angle, and in these 3 angles, form with middle angle opposed, and with the limit of optic axis quadrature.
In addition, in above-mentioned structure, be than the big angle of 44.8 degree with respect to the optic axis of above-mentioned quartzy piece, being more preferably the optic axis that is set at above-mentioned relatively quartzy piece is below 80 degree, particularly be set at 69 degree, desirable more on easy formation optical low-pass filter this point.
Description of drawings
Fig. 1 (a) is cutting angle embodiments of the present invention, that be used to form birefringent plate with respect to optic axis is the skeleton diagram of the quartzy pieces of 44.8 degree, and Fig. 1 (b) is the cutting angle that is used to form birefringent plate for being the skeleton diagram of the quartzy pieces of 69 degree with respect to optic axis.
Fig. 2 (a) is the planimetric map that the incident light of embodiments of the present invention is separated into the birefringent plate of horizontal direction, Fig. 2 (b) is for being separated into the incident light of embodiments of the present invention+planimetric map of the birefringent plate of 45 degree directions to horizontal direction, Fig. 2 (c) is separated into-45 birefringent plates of spending directions for the incident light with embodiments of the present invention to horizontal direction, and Fig. 2 (d) is 3 planimetric maps that birefringent plate is overlapping with embodiments of the present invention.
The form of the relation of the coefficient (with reference to Fig. 4) when Fig. 3 is expression cutting angle of embodiments of the present invention and d=589.3 (nm).
The curve map of the relation of the coefficient when Fig. 4 is expression cutting angle of embodiments of the present invention and d=589.3 (nm).
Fig. 5 is that cutting angle and the cutting angle of expression embodiments of the present invention is 44.8 the curve maps of relation of thickness ratio of birefringent plate 32,33 when spending.
Fig. 6 (a) is the arrangement plan of structure member of light path of camera head that is provided with the optical low-pass filter of embodiments of the present invention, and Fig. 6 (b) is the arrangement plan of structure member of light path of camera head that is provided with the optical low-pass filter of other embodiments.
Fig. 7 is the figure of separation grating of the light of the expression optical low-pass filter that passed through embodiments of the present invention.
Fig. 8 (a), Fig. 8 (b) are for the optical low-pass filter of embodiments of the present invention and in the past optical low-pass filter are compared, and have represented the thickness of each quartzy piece of forming respectively and the figure of effective length.
Fig. 9 is that expression has been passed through to separate the figure of grating with other of the light of the optical low-pass filter that separates the different embodiment of the present invention of grating shown in Figure 7.
Embodiment
Below, in conjunction with the accompanying drawings embodiments of the present invention are described.
The optical low-pass filter 1 of embodiments of the present invention is that 3 birefringent plates 31,32,33 of forming by quartzy piece 2 shown in Figure 1 is cut are piled up institute and constitute.
These birefringent plates 32,33 are called the 2nd birefringent plate in the present invention, and the cutting angle that forms these birefringent plates 32,33 is set at 69 degree to optic axis A, and this 69 degree is to calculate according to computing formula shown below 1.In addition, the characteristic of in Fig. 3～Fig. 5, having represented the cutting angle of calculating according to this computing formula.The form of the relation of the coefficient (with reference to Fig. 4) when Fig. 3 is expression cutting angle and d=589.3 (nm) has been represented this curve map in Fig. 4.In addition, Fig. 5 is that expression cutting angle and cutting angle are 44.8 the curve maps of relation of thickness ratio of birefringent plate 32,33 when spending.
＜computing formula 1 〉
(d: separate width, ne=1.5534: the refractive index of extraordinary light, no=1.5443: the refractive index of ordinary ray, θ: cutting angle, t: the thickness of birefringent plate)
Can know that according to this computing formula 1 the separation width d (with reference to Fig. 7) of birefringent plate 31,32,33 has substantial connection with the thickness t of cutting angle θ and birefringent plate.In embodiments of the present invention because the cutting angle of form dielectric grid sheet 32,33 is 69 degree to optic axis A, thereby and compare in the situation that 44.8 degree cut, it is reduced that it separates width d.
Below, in conjunction with Fig. 2 the production process of this optical low-pass filter 1 is carried out following detailed explanation.
Incide the light of formed optical low-pass filter 1, by being separated into ordinary ray and extraordinary light by birefringent plate 31 formed horizontal direction birefringent plates (diagram is omitted), by by each birefringent plate 32,33 formed ± 45 degree direction birefringent plates (diagram is omitted), separated ordinary ray and extraordinary light are separated into 4 points.
By the optical low-pass filter 1 that above-mentioned production process is produced, for example be used to the camera head of digital camera shown in Fig. 6 (a) etc.
Be provided with in this camera head: shown in Fig. 6 (a), the light that is taken into during with photography carries out the camera lens 7 of optically focused; With reception in a plurality of photo detectors (diagram omit) by the light of 7 optically focused of camera lens, and be the CCD8 of numerical data with the information conversion of this light.Then, optical low-pass filter 1 is arranged in the light path (length 1) between these camera lenses 7 and the CCD8.In addition, in order to prevent the irregular reference of light, on the plane of incidence 1a of the light of this optical low-pass filter 1 and outgoing plane 1b, be formed with AR coating (diagram is omitted).
In camera head, light is incided camera lens 7 from the outside, by camera lens 7 optically focused.Then, will be separated by the light of optically focused, and incide each photo detector of CCD8 by optical low-pass filter 1.
But the unit interval of CCD8 presents the trend that diminishes at present.Promptly, in the CCD8 of manufacturing in recent years, the design of useful size same makes that its unit interval diminishes, pixel count increases the trend of (for example, being increased to 3,000,000 pixels etc. from 2,000,000 pixels).Therefore, the unit interval that is accompanied by CCD8 shortens, and the separation width d of the light of optical low-pass filter need be dwindled, but can know according to above-mentioned computing formula 1, by adopting the birefringent plate 32,33 of embodiments of the present invention, just can dwindle and separate width d.
In addition, in optical low-pass filter in the past,, adopt and dwindle the birefringent plate that separates width d in order to increase the pixel count of CCD8.Therefore, the thickness of optical low-pass filter is with regard to attenuation, and its result is variable just at the optical path length shown in Fig. 6 (a) 1.Therefore, in optical low-pass filter in the past, path glass is overlapped onto the thickness of adjusting optical low-pass filter on the birefringent plate.But, optical low-pass filter according to the embodiment of the present invention because the thickness of ± 45 degree direction birefringent plate 32a, 33b is very thick, thereby can with these ± thickness of 45 degree direction birefringent plate 32a, 33b adjust to the thickness that sets in advance.Therefore, need not change optical path length 1 and just can dwindle and separate width d, the increase of the pixel count of corresponding CCD8, and, can also need not adopt other medium such as birefringent plate path glass in addition, thereby reduce cost.Promptly, for example, be increased under the situation of 3,000,000 pixels from 2,000,000 pixels at pixel count with CCD8, need carry out the design alteration of digital camera self of optical path length 1 grade of changed number camera, but according to this optical low-pass filter 1, only the thickness of ± 45 degree direction birefringent plate 32a, 33b are adjusted to the thickness that sets in advance and get final product, thereby can reduce cost.
As mentioned above, according to this optical low-pass filter 1, owing to horizontal direction is separated into ± birefringent plate the 32, the 33rd of 45 degree directions, quartzy piece 2 is cut and forms at 69 degree its optic axis A, thereby for obtain with cutting angle 44.8 degree in the past same separate width d (with reference to Fig. 7), with the thickness thickening of the birefringent plate 32,33 of common thickness attenuation, ground birefringent plate at 32,33 o'clock, just can not worry the breakage of the materials such as breakage of birefringent plate 32,33, carry out process operation at an easy rate, can reduce production costs.
In addition, in embodiments of the present invention, because birefringent plate the 32, the 33rd, quartzy piece cut at 69 degree its optic axis A form, thereby can be with the thickness attenuation of the crystal that made according to raw material crystal 21.For example, from quartzy 21 aspects of raw material, the thickness that makes the quartzy piece 2 of the birefringent plate 32,33 shown in the embodiments of the present invention is decided to be t.Then, quartzy piece is being formed under the situation of coming these birefringent plates 32,33 its optic axis basis such cutting at 44.8 degree in the past, shown in Fig. 8 (b), from raw material crystal 21 ' aspect, the thickness of quartzy piece 2 ' is t ' just.Can know according to this Fig. 8 (b), cut under the situation about forming, the thickness of quartzy piece 2 ' need be t ' from the t thickening according to such spending in the past 44.8.Therefore, to compare by the situation of the quartzy piece 2 form dielectric grid sheets 32,33 of the thickness t shown in the embodiments of the present invention with by quartzy piece 21 ' form dielectric grid sheet 32 ' in the past, 33 ' situation, the one-tenth that just can shorten quartzy piece 2 is long-time, reduces production costs.In addition, quartzy piece 2,2 ' as shown in Figure 8, along with being bred, the length of effective length Y, Y ' shortens.Therefore, will be from of embodiments of the present invention quartzy piece 2 cut and the birefringent plate 32,33 that forms and cut and the birefringent plate that forms 32 ', 33 ' situation compare at 44.8 degree at 69 degree from the past a quartzy piece 2 ', the aspect of embodiments of the present invention is many by the number of quartzy piece 2 formed birefringent plates 32,33, is very desirable on the production cost this point.And, cut under the situation of form dielectric grid sheet 34 at 44.8 degree at 2 couples of optic axis A of quartzy piece thickness t, shown in Fig. 8 (a), when its area diminishes, because one jiao of birefringent plate 34 has lacked very big one, thereby just can not form a lot of birefringent plates by birefringent plate 34, on the production efficiency this point, be unfavorable.
In addition, the optic axis A that is decided to be quartzy piece 2 by the cutting angle with birefringent plate 32,33 is 69 degree, even it is so big that quartzy piece 2 does not grow up to, in the area that can enlarge birefringent plate 32,33, even lack at the angle of birefringent plate 32,33 under one the situation, because birefringent plate 32, the 33 whole ratios that lack part are become very little, thereby also can with when being divided into 9 optical low-pass filters 1 the quantity of the defective optical low-pass filter 11 that forms (with reference to Fig. 2 (d)) be controlled at two, reduce production costs.
In addition, birefringent plate the 32, the 33rd cuts at 69 degree the optic axis A of quartzy piece 2 and to form, but can know according to Fig. 3～Fig. 5, if cutting angle is 69 degree, with cutting angle is 44.8 to compare when spending, and the thickness t of birefringent plate can be thickeied about 1.501 times.In addition, even beyond 69 degree, surpass 44.8 degree, as shown in Figure 5, if below the critical value that extremely changes for thickness 80 degree, also can at random set cutting angle, same with embodiments of the present invention, compare during with cutting angle 44.8, the thickness t thickening of birefringent plate can obtain the effect of embodiments of the present invention.
In addition, the optical low-pass filter 1 of embodiments of the present invention is formed rectangular-shaped, but is not limited thereto, and also can form shape arbitrarily according to desired shape.
In addition, in embodiments of the present invention, the light that employing will be incided birefringent plate 31 is separated into the plate of horizontal direction, but also can adopt the plate that the light of incident is separated into vertical direction.In this case, birefringent plate 32 just adopts the light of incident is separated into+plate of 45 degree directions vertical direction, and birefringent plate 33 just adopts the plates that the light of incident are separated into-45 degree directions to vertical direction.
In addition, in embodiments of the present invention, be to be undertaken overlapping formed by the order of birefringent plate 31, birefringent plate 32, birefringent plate 33, but be not limited thereto, its order for example also can be the order of birefringent plate 32, birefringent plate 33, birefringent plate 31, also can be the order of birefringent plate 31, birefringent plate 33, birefringent plate 32.
In addition, in embodiments of the present invention, be to adopt 3 birefringent plates, but be not limited to this number, for example also can its number be changed to 5 etc., change the number of the burble point of light according to purposes.In addition, birefringent plate the 32, the 33rd is separated into light ± 45 degree directions, but is not limited thereto, and for example also can its angle be changed according to light being separated into ± purposes of 30 degree directions etc.Like this, light is separated into the birefringent plate of direction arbitrarily by adopting to number arbitrarily from 1, just can be with the burble point of light from 2 points arbitrarily that change to a plurality of points, it separates grating for example also can form various gratings such shown in Fig. 9 (a)～(d).
In addition, the birefringent plate 32,33 of embodiments of the present invention is 5 angular shapes, if but be polygonal words, its shape also can be shape arbitrarily.
In addition, for easy form dielectric grid sheet, also quartzy piece 2 can be cut at 69 degree its optic axis A and form all birefringent plates.
In addition, in embodiments of the present invention, be to form 9 optical low-pass filters 1, but also can at random set the number of optical low-pass filter according to desired size by overlapping birefringent plate 31, birefringent plate 32, birefringent plate 33.
In addition, the production process of the optical low-pass filter 1 of embodiments of the present invention also can be the production process of following detailed description.According to the optical low-pass filter 1 that this production process is produced, have and action effect that the optical low-pass filter produced according to above-mentioned production process 1 is same.
In addition, in embodiments of the present invention, be the camera head that optical low-pass filter 1 is used for digital camera etc., but its configuration is not limited to the configuration shown in Fig. 6 (a), for example also can be the configuration shown in Fig. 6 (b).
In the optical low-pass filter 1 shown in this Fig. 6 (b),-45 degree direction birefringent plate 33a are set to join with the plane of incidence of the light of CCD8, and horizontal direction birefringent plate 31a and+45 degree direction birefringent plate 32a are set on the position about centre in the light path (length 1) of CCD8 and camera lens 7.And, the plane of incidence 31b of plane of incidence 33a, the horizontal direction birefringent plate 31a of-45 degree direction birefringent plate 33a and+be formed with AR coating (diagram is omitted) on the outgoing plane 32c of 45 degree direction birefringent plate 32a.
Like this, shown in Fig. 6 (b), also can form, shorten and separate width d by a plurality of birefringent plate devices spaced apart that will constitute optical low-pass filter 1.
In addition, in the optical low-pass filter 1 shown in this Fig. 6 (b),-45 degree direction birefringent plate 33a are set to join with the plane of incidence of the light of CCD8, horizontal direction birefringent plate 31a and+45 degree direction birefringent plate 32a are set on the position about centre in the light path of CCD8 and camera lens 7, but be not limited thereto, as long as in light path,, also can be set in arbitrarily on the position, set quantity arbitrarily light being separated into arbitrarily the birefringent plate of direction according to purposes.
More than, such as described, according to optical low-pass filter of the present invention, just can easily carry out the attrition process of birefringent plate, and eliminate or reduce ratio the defect part of birefringent plate integral body, in once producing, produce a plurality ofly, reduce production costs.
Promptly, according to the present invention, owing to birefringent plate is that quartzy piece is being formed than the big angle cutting of 44.8 degree its optic axis, thereby for obtain with cutting angle 44.8 degree in the past same separate width, with the thickening of the thickness of birefringent plate, when grinding birefringent plate, just can not worry the loss of materials such as birefringent plate breakage, carry out process operation at an easy rate, can reduce production costs.In addition, be decided to be the optic axis of quartzy piece than the big angle of 44.8 degree by cutting angle birefringent plate, even quartzy piece does not grow up to so big, also can increase the area of quartzy piece, its result is even lack at the angle of birefringent plate under one the situation, because the ratio of the part that birefringent plate integral body is lacked diminishes, thereby just can be controlled at the quantity of formed defective optical low-pass filter when being divided into a plurality of optical low-pass filter, reduce production costs.
In addition,,, thereby the thickness of birefringent plate can be thickeied, the thickness that sets in advance can be at an easy rate thickness adjusted to owing to birefringent plate is that quartzy piece is being formed than the big angle cutting of 44.8 degree its optic axis according to the present invention.For example, in the past, pixel count at the CCD that digital camera (camera head) is adopted is increased under the situation of 3,000,000 pixels from 2,000,000 pixels, the thickness of change optical low-pass filter, according to this change, just need carry out the design alteration of digital camera self of the optical path length etc. of changed number camera, but according to optical low-pass filter of the present invention, owing to can adjust the cutting angle of birefringent plate, make its thickness with identical in the past, thereby can only set the size of birefringent plate, do not need the optical path length of changed number camera just can reduce production costs.
And, as mentioned above, in having the camera heads such as digital camera of CCD, adopting under the situation of optical low-pass filter, the production cost that causes for the design alteration that prevents camera head self increases, and has preestablished the thickness of optical low-pass filter.Therefore, if camera head adopts optical low-pass filter of the present invention, then owing to birefringent plate is to make relative its optic axis of quartzy piece for forming than the big angle cutting of 44.8 degree, just can dwindle it and separate width so need not change the thickness of optical low-pass filter, pixel count that can corresponding CCD increases.
Claims (5)
1. optical low-pass filter, by make quartzy piece relatively its optic axis have that angle is cut and the birefringent plate that forms constitutes, the light of incident is separated, it is characterized in that:
Described birefringent plate is to spend big and cut described quartzy piece than the little angle of 70.0 degree than 44.8 to form with the optic axis of described relatively quartzy piece.
2. optical low-pass filter according to claim 1 is characterized in that:
Overlapping a plurality of described birefringent plate also cuts and forms a plurality of optical low-pass filters,
At least one described birefringent plate in a plurality of described birefringent plates is to spend big and cut described quartzy piece than the little angle of 70.0 degree than 44.8 to form with the optic axis of described relatively quartzy piece.
3. optical low-pass filter according to claim 1 is characterized in that:
Form a plurality of described birefringent plates, and these a plurality of birefringent plates are cut apart form a plurality of birefringent plates respectively, will be overlapping by a plurality of birefringent plates that each birefringent plate forms,
At least one described birefringent plate in a plurality of described birefringent plates is to spend big and cut described quartzy piece than the little angle of 70.0 degree than 44.8 to form with the optic axis of described relatively quartzy piece.
4. according to claim 2 or 3 described optical low-pass filters, it is characterized in that:
Comprise at least in the overlapping a plurality of described birefringent plate:
With the optic axis of described relatively quartzy piece is that the angles of 44.8 degree are cut described quartzy piece and formed, and the light of incident is separated into the 1st birefringent plate of horizontal direction or vertical direction; With
With the optic axis of described relatively quartzy piece is bigger and cut described quartzy piece than the little angle of 70.0 degree and form than 44.8 degree, and the 2nd birefringent plate that separates to 45 degree directions with respect to horizontal direction or vertical direction of the light that makes incident.
5. optical low-pass filter according to claim 4 is characterized in that:
Overlapping described birefringent plate constitute by one the 1st birefringent plate and two the 2nd birefringent plates, described the 1st birefringent plate is formed rectangular-shaped parallel with optic axis in opposed both sides, and, described the 2nd birefringent plate is 5 angular shapes, promptly when 3 adjacent angles are formed approximate right angle, also be formed with relative with the angle of centre in these 3 angles and with the limit of optic axis quadrature.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP177175/2002 | 2002-06-18 | ||
| JP2002177175 | 2002-06-18 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1592865A CN1592865A (en) | 2005-03-09 |
| CN100498426C true CN100498426C (en) | 2009-06-10 |
Family
ID=29728145
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB038015099A Expired - Fee Related CN100498426C (en) | 2002-06-18 | 2003-06-05 | Optical low-pass filter |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPWO2003107073A1 (en) |
| CN (1) | CN100498426C (en) |
| AU (1) | AU2003242203A1 (en) |
| TW (1) | TWI269067B (en) |
| WO (1) | WO2003107073A1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007271900A (en) * | 2006-03-31 | 2007-10-18 | Kyocera Kinseki Corp | Quarter wave plate |
| US8514316B2 (en) | 2007-10-25 | 2013-08-20 | Nikon Corporation | Image device and optical device for providing dust removing capabilities |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001221979A (en) * | 2000-02-08 | 2001-08-17 | Daishinku Corp | Depolarlization plate for optical low-pass filter and optical low-pass filter which uses that depolarization plate |
| JP2001272632A (en) * | 2000-01-21 | 2001-10-05 | Daishinku Corp | Depolarizing member, depolarizing member for optical low pass filter and optical low pass filter using the depolarizing member |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0943542A (en) * | 1995-07-28 | 1997-02-14 | Daishinku Co | Production of optical low-pass filter |
-
2003
- 2003-06-05 AU AU2003242203A patent/AU2003242203A1/en not_active Abandoned
- 2003-06-05 WO PCT/JP2003/007167 patent/WO2003107073A1/en active Application Filing
- 2003-06-05 CN CNB038015099A patent/CN100498426C/en not_active Expired - Fee Related
- 2003-06-05 JP JP2004513829A patent/JPWO2003107073A1/en active Pending
- 2003-06-11 TW TW92115868A patent/TWI269067B/en not_active IP Right Cessation
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001272632A (en) * | 2000-01-21 | 2001-10-05 | Daishinku Corp | Depolarizing member, depolarizing member for optical low pass filter and optical low pass filter using the depolarizing member |
| JP2001221979A (en) * | 2000-02-08 | 2001-08-17 | Daishinku Corp | Depolarlization plate for optical low-pass filter and optical low-pass filter which uses that depolarization plate |
Also Published As
| Publication number | Publication date |
|---|---|
| JPWO2003107073A1 (en) | 2005-10-13 |
| WO2003107073A1 (en) | 2003-12-24 |
| AU2003242203A1 (en) | 2003-12-31 |
| CN1592865A (en) | 2005-03-09 |
| TWI269067B (en) | 2006-12-21 |
| TW200402546A (en) | 2004-02-16 |
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