JP2010002598A - Optical filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical filter with which a light translucent optical plate is easy to distinguish and manufacturing cost can be reduced. <P>SOLUTION: The optical filter F1 is constituted of a quartz crystal wavelength plate 1, an infrared-absorbing glass plate 2 and a quartz crystal birefringent plate 3, and their main surfaces are stuck with an adhesive. Although it is not illustrated, an antireflection film (AR coated film) is formed on a light-emitting surface (rear surface) of the quartz crystal birefringent plate 3. Furthermore, the quartz crystal birefringent plate 3 has a profile size which differs from that of the quartz crystal wavelength plate 1 and the infrared-absorbing glass plate 2 and has an extension part 31, which extends in longitudinal directions (vertical directions). Additionally, a marking M is formed by laser, at the extension part 31 which is extended upward. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an optical filter such as an optical low-pass filter, and relates to a configuration having a marking for identifying the optical filter.

  An optical filter such as an optical low-pass filter is used for adjusting image quality in a digital camera or a digital video camera. The configuration of the optical low-pass filter is, for example, a configuration in which a quartz birefringence plate, an infrared absorption glass plate, and a quartz wavelength plate are bonded together, and has a rectangular parallelepiped shape as a whole. In such an optical low-pass filter, a chamfered portion is sometimes formed in order to clearly indicate the optical axis (crystal axis) direction of the component or to identify each product. The chamfered portion is formed on a part or all of a rectangular four-dimensional portion when the optical main surface of the optical low-pass filter is viewed in plan. See Japanese Utility Model Sho 63-109901.

  The formation of such a chamfered part requires a machining process for forming a chamfered part in addition to a normal cutting process, and in some cases, a machining apparatus having an expensive NC control may be required. This was a factor that significantly increased the manufacturing cost of the optical filter.

In addition, the optical plate that constitutes the optical filter, such as an optical plate such as a quartz birefringent plate, has different ray separation directions and separation widths depending on the customer's required specifications. It was difficult to clarify only. For example, quartz birefringent plates with the same light separation direction and different separation widths have a slightly different plate thickness and have almost the same outer shape, which makes it difficult to distinguish parts during production. Had.
Japanese Utility Model Publication No. 63-109901

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an optical filter that can easily distinguish between translucent optical plates and can reduce manufacturing costs.

The present invention provides an optical filter comprising one or a plurality of translucent optical plates, wherein the surface of the translucent optical plate is engraved or marked inside. It is characterized by being.

The marking may be any mark that can visually recognize characters, symbols, patterns, and the like. Further, the marking may have a configuration (engraved configuration) engraved from the surface of the translucent optical plate or a configuration formed inside the optical plate. The optical surface characteristic information can be clearly shown without marking the optical surface by marking as in the case of printing with ink due to the engraving structure or the like.

According to a second aspect of the present invention, the marking may be formed by a laser beam.

For example, a carbon dioxide laser is used as the laser beam. When the laser beam is engraved from the surface of the optical plate, the marking may be performed by condensing the laser beam with a focusing lens near the surface. When marking is performed only inside the optical plate, the marking process may be performed by condensing the laser beam with a converging lens in a marking area inside the optical plate. Other types of laser beams may be used.

By processing with a laser beam, it is possible to mark characters, symbols, designs, etc. at any position on the optical plate. In particular, by using a laser marker having a three-dimensional control mechanism, three-dimensional marking is also possible, and more information can be clearly shown about the characteristic information of the optical plate.

In addition, as shown in claim 3, it is preferable that the marking region is formed in a depth region of 5 μm or more from the surface of the translucent optical plate. For example, when marking is performed using a laser beam, the gap between the galvano scanner part of the laser marker and the marking target area of the optical plate may vary, and this difference in the gap becomes the difference in laser power. Is related to marking quality. In practice, a variation in depth of about 2 to 3 μm may occur. By making the marking area a depth of 5 μm or more, a variation in marking quality due to the aforementioned variation is absorbed to obtain a stable marking. be able to.

In addition, it is preferable that the depth of a marking area | region is 15 micrometers or less from a practical viewpoint. This is because, when marking is performed by engraving from the surface, visibility (clarity) of the marking is improved by engraving deeply. However, it has been found that the visibility hardly changes when the depth is 15 μm or more.

On the other hand, there is a case where an optical plate having a predetermined thickness is prepared as an optical filter component, and for this reason, the thickness of the optical plate needs to be changed for some reason. In such a case, the optical plate is polished and thinned, and the marking is also removed by polishing. However, when the above-described marking area is deep, it is necessary to polish more than necessary, and in some cases, the marking may not disappear unless the thickness is reduced beyond the design change (thinning). From the above, the depth of the marking region is preferably 5 μm or more and 15 μm or less.

Furthermore, as shown in claim 4, the marking may be formed in a region 0.5 mm or more inside from the outer periphery of the translucent optical plate. For example, a quartz birefringent plate may be obtained by dividing and cutting a large quartz wafer by dicing or the like to obtain individual quartz birefringent plates. In such a case, the split cut surface, that is, the outer peripheral end surface may be microscopically damaged such as cracks, burrs, cracks, etc., and is formed when marking is formed in a region very close to such an outer peripheral end surface. Due to the stress at the time, cracks and the like may expand from the damaged area as a starting point.

By forming the marking in the area 0.5mm or more inside from the outer periphery of the translucent optical plate, the marking is formed with high accuracy in a good yield state without being affected by the damage of the outer peripheral end face. can do. In addition, it is not preferable to form the inner side more than necessary because the effective area for imaging is narrowed.

Further, as shown in claim 5, the marking may be configured such that no intersection is formed. The marking is a structure in which the surface of the translucent optical plate is engraved or formed inside, and the optical plate may be damaged by the formation of the marking. In this case, the intersection formed by the intersection of the markings may intensify the damage. However, by adopting a configuration in which no intersection is formed in the marking, damage to the optical plate can be suppressed, and high quality marking can be achieved. It can be carried out.

Further, according to a sixth aspect of the present invention, the translucent optical plate may be made of a crystal body, and the marking may have a configuration in which a crystal axis of the translucent optical plate is clearly shown. For example, the quartz birefringent plate is a transparent light-transmitting optical plate made of a single crystal, and the light beam separation direction cannot be visually recognized from the quartz birefringent plate itself. In such a case, a configuration may be adopted in which a marking formation position with respect to the light beam separation direction is determined in advance and the light beam separation direction can be determined at the marking formation position.

ADVANTAGE OF THE INVENTION According to this invention, the optical filter which can distinguish a translucent optical board easily and can reduce manufacturing cost can be obtained.

  The first embodiment of the present invention will be described with reference to the drawings, taking an optical filter having three optical plates as an example. FIG. 1 is a perspective view of an optical filter according to the present invention, and shows a state where an optical surface (light incident / exit surface) is directed in the vertical direction. 2 is a plan view of FIG. 1, and FIG. 3 is a diagram showing a marking example.

  The optical filter F1 is disposed between an image pickup element including an optical lens and a C-MOS element in the image pickup system, and plays a role as an optical low-pass filter that removes an optical signal unnecessary for an image.

  The optical filter F1 includes a quartz wavelength plate 1, an infrared absorption glass plate 2, and a quartz birefringence plate 3, and has a configuration in which main surfaces are bonded together with an adhesive (not shown). The quartz wavelength plate 1 is a plate-like quartz plate having a rectangular shape in plan view, and has front and back main surfaces that transmit light. Although not shown in the figure, an antireflection film (AR coating film) is formed on the light incident surface (front surface) of the quartz wavelength plate 1. The quartz wavelength plate 1 has a function of converting linearly polarized light into circularly polarized light, and transmits the circularly polarized light from the back surface to the infrared absorbing glass plate side.

The infrared absorbing glass 2 is a glass plate having a rectangular shape in plan view having sides of the same size as the quartz wavelength plate 1, and has front and back main surfaces that transmit light. The infrared absorbing glass has a function of absorbing the infrared rays.

The quartz birefringent plate 3 is a plate-like quartz plate having a rectangular shape in plan view, and has front and back main surfaces that transmit light, and acts to separate light rays incident on the front surface into ordinary light and abnormal light and emit them from the back surface. have. Although not shown in the drawing, the antireflection film (AR coating film) is formed on the light emitting surface (back surface) of the quartz birefringent plate 3. The quartz crystal birefringent plate 3 is different in external dimensions from the quartz wavelength plate 1 and the infrared absorbing glass plate 2 and has an elongated portion 31 extending in the vertical direction (vertical direction) as shown in FIG. is doing. Although the extending portion 31 has chamfered portions 3a, 3b, 3c, and 3d, these chamfered portions need not be formed. A marking M is formed on the extending portion 31 extending upward. In FIG. 2, the imaging area of the optical filter is indicated by 31, and even if marking is performed on the outside thereof, the filter characteristics of the optical filter are not adversely affected.

The marking M may be any mark that can be visually recognized, such as letters, symbols, patterns, and the like. For example, the model name of a product composed of a combination of alphabets and numbers may be described. Further, the marking M may be configured to be engraved inside including the surface of the translucent optical plate, or the marking M may be performed only inside the optical plate.

The marking M is formed by a laser beam, for example, by a three-dimensional simultaneous control laser marker using a carbon dioxide laser. Specific processing examples for forming the marking are shown below. First, an optical filter for forming a marking is placed on the processing stage. The optical filter has a configuration shown in FIGS. 1 and 2, for example, and is in a state before the marking M is formed on the elongated portion 31. In the processing stage, the optical filter is first positioned to identify the marking formation region. In this state, the laser irradiation port of the laser marker is opposed to the marking formation region. Thereafter, the laser beam is irradiated onto the marking formation region by the operation of the galvano scanner portion of the laser marker to form predetermined characters, symbols, pictures, and the like. Thereafter, the optical filter is discharged from the processing stage.

In addition, you may form marking in the state of the optical plate before assembling to an optical filter. For example, the quartz birefringent plate 3 shown in FIG. 1 is positioned in a single plate state by holding the outer periphery with a holding jig. In this state, the laser irradiation port of the laser marker is opposed to the marking formation region. Thereafter, the laser beam is irradiated to the marking formation region by the operation of the galvano scanner unit to form predetermined characters, symbols, pictures, and the like. Thereafter, the optical plate is removed from the holding jig, and the process proceeds to the next bonding step.

FIG. 3 shows an example of marking. FIG. 3 is a diagram showing a state in which the letters “KD” in the alphabet are engraved on the quartz plate Q by laser marking. The marking example has a configuration in which the engraved lines do not intersect each other and no intersection is formed. That is, as illustrated by A in the figure, the engraved lines do not intersect each other. Thus, by setting it as the structure which does not form an intersection in the said marking, damage to an optical plate can be suppressed and high quality marking can be performed.

In the above embodiment, the depth of the marking M is set to about 5 μm from the surface of the optical plate. With such a depth setting, even if the distance between the laser irradiation port and the marking formation region varies during processing, the marking can be reliably formed. In addition, it is preferable that the depth of a marking area | region is 5 micrometers or more and 15 micrometers or less. As described above, when marking is performed by engraving from the surface, the visibility (clarity) of the marking is improved by engraving deeply, but when the depth becomes 15 μm or more, the visibility changes substantially. It turns out not to. On the other hand, an optical plate having a predetermined thickness may be prepared as an optical filter component, and this may require a change in the thickness of the optical plate for some reason. In such a case, the optical plate is polished and thinned, and the marking is also removed by polishing. However, when the above-mentioned marking area is deep, it is necessary to polish more than necessary, and in some cases, the marking may not disappear unless the thickness after the design change is increased (thinning). For the above reasons, the depth of the marking region is preferably 5 μm or more and 15 μm or less.

Moreover, in the said embodiment, the position of the marking M is formed in the area | region which entered 0.5 mm inside from the outer periphery of the quartz crystal birefringent plate. As a result, even if damage such as cracks, burrs, cracks, etc. occurs on the outer peripheral end face of the crystal birefringent plate microscopically, marking can be formed without being affected by this damage. The formation yield of can be improved.

In the present embodiment, the marking M indicates the model name of the crystal birefringent plate and simultaneously indicates the crystal axis direction. By clearly indicating the crystal axis direction, the light beam separation direction due to the birefringence effect can be determined, thereby preventing the occurrence of misplacement during installation on equipment to which an optical filter is applied or when bonding optical plates together. . Specifically, as shown in FIG. 2, the marking M is formed at the central portion in the width direction of the elongated portion. In such a case, for example, it is determined that the crystal axis of the crystal birefringent plate is applied to the crystal M that has a crystal axis in the direction perpendicular to the marking M, or when the marking is formed at the left end in the width direction. By defining that the light beam is separated in the direction of 45 degrees from the left to the upper left corner, the crystal axis direction, that is, the light beam separation direction can be specified. As described above, the manufacturing operation can be performed efficiently and accurately.

  A second embodiment according to the present invention will be described with reference to the drawings, taking an optical filter having four optical plates as an example. FIG. 4 is a perspective view of an optical filter according to the present invention, showing a state in which the optical surface is directed in the left-right direction.

The optical filter F2 is composed of an optical plate of a quartz birefringent plate 4, a quartz wave plate 5, an infrared absorbing glass plate 6, and a quartz birefringent plate 7, and has an optical structure in which the principal surfaces are bonded together with an adhesive. It is a low-pass filter. In the present embodiment, the shape and size of each optical plate in plan view are set to be the same.

The quartz birefringent plate 4 is a plate-like quartz plate having a rectangular shape in plan view, and has front and back main surfaces that transmit light. Although not shown in the drawing, the infrared ray reflection film (IR cut coat film) is formed on the light incident surface (surface) of the quartz birefringent plate 4. The quartz crystal birefringent plate 4 separates incident light into ordinary light and extraordinary light and emits the light from the back surface. A marking M1 is formed inside the upper right side of the crystal birefringent plate main surface. The marking on the inside of the optical plate is formed by using the above-mentioned laser marker, and can be formed by setting the focal position of the laser beam inside the optical plate. The marking M1 describes the model name of the optical filter and indicates the light beam separation direction. In this example, the crystal birefringent plate has a characteristic of separating light from the lower left to the upper right at an angle of 45 degrees. Note that the imaging area of the optical filter is indicated by 41, and even if marking is performed on the outside thereof, the filter characteristics of the optical filter are not adversely affected.

The quartz wavelength plate 5 is a plate-like quartz plate having a rectangular shape in plan view, and has front and back main surfaces that transmit light. The quartz wavelength plate 5 has a function of converting linearly polarized light into circularly polarized light, and each separated light beam incident from the surface of the quartz wavelength plate from the side of the quartz birefringent plate 4 is circularly polarized, and from the back side. It is transmitted to the infrared absorbing glass plate side.

The infrared absorption glass 6 is a glass plate having a rectangular shape in plan view having sides of the same size as the quartz wavelength plate 5, and has front and back main surfaces that transmit light. The infrared absorbing glass has a function of absorbing the infrared rays.

The quartz birefringent plate 7 is a plate-like quartz plate having a rectangular shape in plan view, and has front and back main surfaces that transmit light. Although not shown in the drawing, the antireflection film (AR coating film) is formed on the light emitting surface (back surface) of the quartz wavelength plate 6. Although not shown, a marking M2 is formed on the upper left side of the main surface of the crystal birefringent plate. The marking M2 describes the model name of the optical filter and indicates the light beam separation direction. In this example, the crystal birefringent plate has a characteristic of separating light from the lower right to the upper left at 45 degrees obliquely. The marking M2 may be a mark indicating only the direction of light separation, for example, a symbol consisting only of a black circle (dot).

  It should be noted that the present invention can be implemented in various other forms without departing from the spirit, gist, or main features. For this reason, the above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. The scope of the present invention is indicated by the claims, and is not restricted by the text of the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

  The present invention is effective for production of an optical filter such as an optical low-pass filter.

It is a perspective view which shows 1st Embodiment. It is a top view which shows 1st Embodiment. It is a figure which shows 1st Embodiment and shows the example of marking. It is a perspective view which shows 2nd Embodiment.

Explanation of symbols

1, 5 Quartz wave plate 2, 6 Infrared absorbing glass plate 3, 4, 7 Quartz birefringence plate F1, F2 Optical filter

Claims (6)

An optical filter comprising one or a plurality of light-transmitting optical plates, wherein a marking formed on or in the surface of the light-transmitting optical plate is provided. The optical filter according to claim 1, wherein the marking is formed by a laser beam. The optical filter according to claim 1, wherein the marking is formed in a depth region of 5 μm or more from the surface of the translucent optical plate. 4. The optical filter according to claim 1, wherein the marking is formed in a region 0.5 mm or more inside from the outer periphery of the translucent optical plate. The optical filter according to claim 1, wherein the marking has a configuration in which no intersection is formed. The optical filter according to claim 1, wherein the translucent optical plate is made of a crystal, and the marking clearly indicates a crystal axis of the translucent optical plate.

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