JP5712454B2 - Measuring method and processing method of semi-finished blank - Google Patents

Description

  The present invention is a processing method for measuring whether or not processing is performed under processing conditions according to a prescription when a lens is manufactured by processing either the front or back surface of a semi-finished blank, and processing based on the measurement result It is about the method.

  When processing plastic lenses according to the wearer's prescription, if it is a very general prescription pattern, use a glass mold with a shape according to the prescription to shape the lens in advance and secure it as a permanent item. In general, it is generally provided as appropriate. However, if special prescriptions are required according to the wearer's fine prescription, lenses corresponding to these prescriptions must be produced individually. In such a case, a semi-finished blank is prepared, and either the concave side or the convex side is processed to produce a lens in a semi-customized manner. A semi-finished blank is a precursor of a lens that is preliminarily molded with a glass mold in the same manner as a regular product, and is generally processed on either the concave side or the convex side by a processing apparatus. Patent document 1 is shown as an example as a prior art which processes such a semi-finished blank and produces a lens in a semi-custom-made manner.

When machining a semi-finished blank whose concave surface is the machining surface, the semi-finished blank must be fixed to the machining apparatus so as to face the concave surface to be machined in the cutting tool or grinding tool direction. Therefore, it is necessary to mount a block piece as a connecting member for fixing to the processing apparatus on the convex surface side of the semifinished blank. The block piece is a kind of connector that is attached to a processing apparatus and fixes the semi-finished blank at a predetermined position. At this time, the block piece should not damage the lens and must be firmly mounted on the convex surface. As a fixing means for that purpose, the block piece is generally fixed to the semifinished blank via a low melting point alloy (alloy), a thermoplastic resin, wax or the like. Such a fixing means is generally called blocking. Patent Document 2 is given as an example of the prior art for explaining a state in which a block piece is blocked by a blocked semi-finished blank. It is also possible to grip the periphery of the semi-finished blank with a kind of clamp at a predetermined interval and arrange the block piece on the clamp. Such a fixing means is generally called chucking.
The semi-finished blank must be blocked or chucked, and when processing is complete, it must be checked whether the finished lens meets certain processing conditions. For example, optical characteristics such as prism and lens power are measured by a measuring device, and it is checked whether or not optical characteristics corresponding to processing conditions are obtained. In this case, since the optical characteristics are measured based on the amount of refraction of the light beam that passes through the lens, it is necessary to measure in the state of the lens alone by removing a part related to blocking or chucking that once disturbs the measurement. .

Japanese Patent Laid-Open No. 10-175149 JP 2004-202679 A

However, there are cases where the measured machining conditions do not become the planned machining conditions, and it is necessary to correct them by cutting a little more. In that case, it is necessary to perform blocking or chucking again to fix the lens to the processing apparatus, but in the case of blocking, the convex surface of the lens is again covered with alloy or resin as described above. The convex curve changes slightly due to heat. That is, the lens is slightly deformed, and the block pieces are connected under conditions different from the initial conditions, and there is a problem that the correction amount is not correctly reflected in the re-processing. Also, once blocking is performed, if this is canceled and performed again, there will be a slight error in the position and inclination of connecting the block pieces. Become. This also occurs in chucking for gripping the lens edge, and the amount of deformation of the lens changes from the original due to subtle differences in gripping position and strength. For this reason, once a part related to blocking or chucking is removed, it has been difficult to process the processing conditions to the prescribed values. Especially in an outer surface progressive addition lens with a progressive surface on the convex side, the lens surface is not uniform, so the contact condition between the block piece and the convex surface is not constant and it is very difficult to fix it in the same state as the original, so it is realistic. It was difficult to correct.
In addition to the means of blocking and chucking to fix the semi-finished blank to the processing equipment, it may be gripped so as to cover one side for transporting and transporting the semi-finished blank (lens). In such a case, the same problem as described above occurs.
The present invention has been made paying attention to such problems. The purpose is to calculate the value of the predetermined optical characteristics without removing the covering member in the semi-finished blank with the covering member mounted on either the front or back side, and the processing conditions can be determined based on the calculation result. It is an object of the present invention to provide a measuring method and a processing method of a semi-finished blank capable of checking whether or not it is satisfied.

In order to achieve the above object, the invention according to claim 1 is a semi-finished blank having a convex surface and a concave front and back surfaces, and the first surface is disposed on the first surface of either the front or back surface. The semi-finished blank is provided with a covering member to be covered, and an antireflection film for preventing reflection on the second surface is formed without mounting the covering member on the other second surface. Irradiating light from the second surface side toward the first surface side and calculating a value of a predetermined optical characteristic based on a measured value of the reflected light acquired on the second surface side. The gist.
Further, in the invention of claim 2, a semi-finished blank having a convex surface and a concave front and back surfaces, and a covering member that covers the first surface is mounted on either the first surface or the first surface. For the semi-finished blank on which the covering member is not mounted on the other second surface, a reflective film is formed on the second surface, and the second surface is irradiated with light. While calculating the value of the first curve of the second surface based on the reflected light acquired from the second surface, the light with respect to the second surface without a reflective film on the second surface The second curve value of the first surface is calculated based on the reflected light acquired from the first surface and predetermined optical characteristics are obtained based on the values of the first and second curves. The gist is to calculate.
Moreover, in invention of Claim 3, it is a semi-finished blank which has a convex surface and a concave-convex front and back surface, Comprising: The coating | coated member which covers the 1st surface is attached to the 1st surface of either the front and back , For the semi-finished blank not provided with the covering member on the other second surface, the shape of the first surface for specularly reflecting the irradiation light on the first surface is met. A reflecting means is formed, and light is irradiated from the second surface side toward the first surface side, and a value of a predetermined optical characteristic is determined based on a measured value of the reflected light acquired on the second surface side. The gist is to calculate.
In addition, in the invention of claim 4, in addition to the configuration of the invention of claim 2, when calculating the value of the second curve of the first surface, the second surface of the semifinished blank is on the second surface. The gist of the invention is that an antireflection film for preventing the irradiation light from reflecting on the second surface is formed.
Further, the gist of the invention of claim 5 is that, in addition to the configuration of the invention of any of claims 1 to 4, the predetermined optical characteristic is a prism.
Further, the invention of claim 6 is characterized in that, in addition to the configuration of the invention of any one of claims 1 to 4, the predetermined optical characteristic is a lens power.

Further, in the invention of claim 7 in addition to the configuration of the invention according to any one of claims 1 to 6, the connecting member of the first surface by a fixing means to said the object to be covered member coupled to the processing device the connecting member der Rukoto fixed so as to cover the central region as its gist.
Further, in the invention of claim 8 in addition to the configuration of the invention according to claim 7, wherein the connecting member is a gist that you have been attached to the convex side of the semi-finished blank.
Further, in the invention of claim 9, in addition to the configuration of the invention of any one of claims 1 to 8, a plurality of light beams are irradiated from the second surface side over a wide range of the lens, and reflected light for each light beam. acquires and is referred to as its gist that you calculate the value of predetermined optical characteristics based on the measured value.
Further, in the invention of claim 10, in addition to the configuration of the invention of any one of claims 1 to 9 , the wavefront is measured in the measurement of the reflected light, and the predetermined optical characteristic is calculated based on the measurement result. This is the gist .

The gist of the invention of claim 11 is that the second surface side is processed based on the value of the predetermined optical characteristic calculated by the measurement method of any of claims 1 to 10.
Further, it is the invention of claim 12 which is a so that addition of any of the required correction according to check the value of the predetermined optical characteristic calculated processing condition in the measurement method according to claim 1 to 1 0 The gist.
Further, in the invention of claim 13 wherein the semi-finished blank in the processing method according to claim 1 1 or 12 is progressive refractive surface is formed on the convex surface side, the lens thus manufactured was so that der outer surface progressive-power lens This is the gist.
The gist of the invention of claim 14 is that, in the processing method of claims 11 to 13 , the measurement of the reflected light is performed after processing the concave surface side of the semi-finished blank .
State also, in the invention of claim 15 in any of the processing method according to claim 1 1-14, wherein the temporarily stopped processing of concave side before the thickness of the appointment, the covering member at that stage is mounted The semi-finished blank is irradiated with light from the concave side toward the convex side, and predetermined optical characteristics are calculated based on the measured value of the reflected light acquired on the concave side, and the calculation result is checked. The gist is that processing is performed again with necessary corrections according to the processing conditions .

In such a configuration, when the concave surface side is processed with respect to the semifinished blank in a state where the covering member covering the first surface is mounted, the second is performed at any stage before processing, during processing, or after processing. The light is irradiated from the surface side toward the first surface side. Then, the reflected light acquired on the second surface side is measured to calculate a value of a predetermined optical characteristic. Furthermore, it is possible to check the calculated value of the optical characteristics and add necessary corrections according to the processing conditions.
The reflected light passes through the semi-finished blank through the second surface → first surface → second surface along the second surface side (hereinafter referred to as main reflected light) and the semi-finished blank. Without including both components of the light beam reflected on the second surface (hereinafter referred to as sub-reflected light). In the present invention, a place where the light beam that originally passes through the two interfaces of the second surface → the first surface is measured and analyzed is replaced by a path of the second surface → the first surface → the second surface instead. Main reflected light passing through the three interfaces is measured on the irradiation side to calculate a value of a predetermined optical characteristic, and the second surface side can be processed based on the calculated value. It is also possible to check the value of the predetermined optical characteristic and add necessary correction according to the processing conditions. Although only the main reflected light may be measured or the light including the sub reflected light may be measured, it is preferable that the sub reflected light is not generated as much as possible when only the main reflected light is measured.
When the prism is simply measured as the type of light beam, a single light beam may be used, but more complex measurement is possible with a plurality of light beams. For example, when measuring the astigmatism power, at least four are required. Furthermore, if the light beam intersects the surface in a ring shape, that is, the light beam irradiates in a cylindrical shape, it is possible to measure with higher accuracy and fill the entire region that intersects the surface in a circular shape. If the luminous flux is used, the measurement accuracy is further improved.
Further, a plurality of light beams may be irradiated from the second surface side over a wide range of the lens, and reflected light is obtained for each light beam, and a predetermined optical characteristic value is calculated based on the measured value. .
Typical examples of the predetermined optical characteristics to be measured include a prism and a lens power.

Reflecting means is preferably formed on the first surface of the semifinished blank along the shape of the first surface for reflecting the irradiation light. If possible, it is preferable to use a mirror surface in order to grasp the accurate shape of the first surface and increase the reflectance. As the reflecting means, it is conceivable to use an alloy as a fixing means in contact with the first surface as a smooth surface or attach a reflective film.
It is preferable that an antireflection film for preventing reflection of irradiated light on the concave surface is stuck on the second surface of the semifinished blank. As a result, light can be incident on the semifinished blank with high transmittance without reflecting light on the second surface. This is particularly effective when sub-reflected light is not required. In general, it is conceivable that the antireflection film is formed by attaching a film body to a transparent film, and in this case, the film side needs to be disposed and adhered to the outside (that is, the irradiation side). The refractive index of the transparent film is desirably the same as or close to the refractive index of the base material of the semifinished blank.

  A reflection film is formed on the second surface of the semifinished blank, and the second surface is irradiated with light, and the first curve of the second surface is obtained based on the reflected light acquired from the second surface. While calculating the value, the second surface is irradiated with light with no reflective film on the second surface, and the second surface of the first surface is reflected based on the reflected light acquired from the first surface. It is conceivable to calculate the value of the curve and calculate the lens power based on the values of the first and second curves. That is, the value of the first curve of the second surface and the value of the second curve of the first surface are acquired separately, and the lens power is calculated based on the values. Here, in order to obtain the value of the second curve of the first surface, it is necessary to measure at least the second surface without a reflective film. In that case, in order to transmit the emitted light in the first surface direction with higher efficiency, it is preferable to form an antireflection film for preventing the irradiation light from reflecting on the second surface on the second surface.

The covering member may be a connecting member that is fixed so as to cover the central region of either the first or second surface by a fixing means in order to connect to the processing apparatus. As the fixing means, for example, the above blocking or chucking can be considered, but there is no particular limitation as long as the connecting member can be fixed to the convex surface side of the semi-finished blank. In a general semi-finished blank, the connecting member is often mounted on the convex surface side. In this case, the convex surface side is the first surface.
In the measurement of the reflected light, the wavefront may be measured, and the predetermined optical characteristic may be calculated based on the measurement result. By measuring the wavefront, it is possible to measure well even in a state where the main reflected light and the sub-reflected light are mixed. Further, since it is necessary to reflect the concave surface and the convex surface in order to measure the lens power, it is possible to measure the lens power by measuring a wavefront in which main reflected light and sub-reflected light are mixed. At the same time, the prism can be measured. Deviation between the ideal wavefront and the actual wavefront to be measured is recognized as wavefront aberration, and generally this wavefront aberration is the object of evaluation.

  In the present invention, the semifinished blank is particularly advantageous when a progressive refractive surface is formed on the convex surface side and the produced lens is applied to an outer surface progressive addition lens. If the convex side is a progressive refracting surface instead of a spherical or aspherical surface, the convex surface is more complex than the spherical or aspherical surface and is not uniform in shape. It is hard to become a state of wearing. Therefore, it is significant that the processing conditions can be checked without removing the covering member.

  As described above, since the covering member is not removed in the present invention, it is possible not only to check whether the processing is performed under the processing conditions planned after the processing but also to check appropriately before or during the processing. . If processing is temporarily stopped and checked before the planned thickness is reached during processing, processing can be performed until the planned thickness is reached at that stage, whether correction is necessary or not. It is possible to get a prescription lens for the wearer, of just the expected thickness.

  In the invention of each of the above claims, when a lens is manufactured by processing the front or back side of the semi-finished blank, it is reflected without removing the covering member attached to the other side of the semi-finished blank. Since the value of a predetermined optical characteristic can be calculated based on the measured value of light, it is possible to check whether the optical characteristic corresponding to the processing condition is obtained based on the calculated value. . As a result, the working efficiency is improved, and the yield rate of lenses is also improved.

Explanatory drawing explaining the state by which the block piece is adhering to the semifinished blank explaining embodiment of this invention by the alloy. (A) is a fragmentary sectional view of a block piece, (b) is a perspective view from the bottom face side. It is a figure explaining the mounting process of the block piece to a semi-finished blank, (a) is an exploded view explaining the arrangement state of each member, (b) is a state just before introducing an alloy after arranging each member. FIG. (A) And (b) is explanatory drawing explaining the measuring method of the optical characteristic of the semifinished blank to which the block piece is adhering. Explanatory drawing explaining the light trace of the irradiation light from a measuring apparatus in FIG. In Embodiment 2, (a) is an explanatory view of the side surface direction of the semi-finished blank when acquiring the reflected light on the convex surface side, and (b) is the plane direction of the semi-finished blank when acquiring the reflected light on the concave surface side. Illustration. Explanatory drawing explaining the measuring method of the curve of a concave surface in Embodiment 2. FIG. Explanatory drawing explaining the measuring method of the curve of a convex surface in Embodiment 2. FIG. Explanatory drawing explaining the state which the light from a light source in Embodiment 3 reflects on the convex surface and concave surface of a semifinished blank, and is acquired by the measuring apparatus. Explanatory drawing explaining the state which has arrange | positioned the wavefront measuring apparatus in the concave surface side of a semifinished blank in Embodiment 4. FIG. FIG. 9 is a block diagram illustrating an electrical configuration in Embodiment 4. The color code map figure which showed the wavefront aberration by each aberration component. Explanatory drawing explaining a three-dimensional high-order aberration in wavefront aberration. Explanatory drawing explaining three-dimensional high-order aberration in wavefront aberration. Explanatory drawing explaining the state which has arrange | positioned the frequency distribution measuring apparatus in the concave surface side of a semifinished blank in Embodiment 5. FIG. FIG. 10 is a block diagram illustrating an electrical configuration in Embodiment 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying a method for measuring processing conditions and a processing method for a semifinished blank according to the present invention will be described below with reference to the drawings.
(Embodiment 1)
FIG. 1 shows a state in which a block piece 13 as a connecting member is mounted on the convex surface side of a semi-finished blank (hereinafter referred to as a blank) 11 using an alloy 12 as a fixing means. The blank 11 is a plastic transparent body configured in a planar circular shape, and has a meniscus lens shape having a large thickness in appearance. The diameter of the blank 11 is 70 mm in the first embodiment. The convex surface (front surface) of the blank 11 is a spherical surface, an aspherical surface, or a progressive refractive surface, and is not subjected to cutting, and the concave surface (back surface) is a processed surface. Since the concave surface is not intended to have a specific curve, it is a spherical surface having an appropriate curve here.
On the convex surface side of the blank 11, a reflective film 14 in which a metal oxide is deposited on a transparent film is attached. The reflective film 14 is a circular thin film body having a diameter of 15 mm, and the center thereof coincides with the geometric center 0 of the blank 11. An alloy 12 is disposed so as to cover the reflective film 14, and a block piece 13 is welded to the center position of the alloy 12. In a state where the alloy 12 is solidified, the deposition surface side of the reflective film 14 is visually observed from the concave surface side in a region having a radius of 15 mm including the geometric center 0 of the blank 11 with the alloy 12 as a background. In order to increase the measurement accuracy, it is preferable that the reflective film 14 is attached so that the vapor deposition surface side faces the blank 11 side.
Further, an antireflection film 15 obtained by depositing a dielectric multilayer film on a transparent film is attached to the concave surface side of the blank 11. The antireflection film 15 is a circular thin film body having a diameter of 15 mm, and the center thereof coincides with the geometric center 0 of the blank 11. Similarly, in order to increase the measurement accuracy, it is preferable that the antireflection film 15 is adhered with the dielectric multilayer film side facing outward (that is, the irradiation side).

As shown in FIGS. 2A and 2B, the block piece 13 has a circular ring-shaped main body 17 formed with a communication hole 16 that communicates vertically with the center, and is formed integrally with the main body 17 and extends in the axial direction. It is comprised from the taper-shaped insertion part 18 to come out. Cutouts 19 are formed in the insertion portion 18 at two positions opposed to each other by 180 degrees.
The block piece 13 is fixed as follows. As shown in FIGS. 3A and 3B, a recess 22 is formed on the installation surface 21 configured in an oblique shape. The block piece 13 is accommodated in the recess 22, and a block ring 23 is arranged along the positioning block 24 so as to surround the recess 22 as a ring for alloy molding. An injection port 25 for injecting the alloy 12 is formed in the block ring 23, and the injection port 25 is arranged so as to be the uppermost position on the slope. Then, the blank 11 is placed on the block ring 23 so that the center of the block piece 13 and the geometric center 0 of the blank 11 coincide. In this embodiment, the reflection film 14 and the antireflection film 15 are already attached to the blank 11 on the convex surface side and the concave surface side, respectively, before the placement. In this state, the molten alloy 12 is injected from the injection port 25. The inner space surrounded by the blank 11, the block ring 23, and the block piece 13 is filled with the alloy 12, and the alloy 12 is allowed to cool down and solidify in a state where it reaches the inlet 24 at the highest position. The block piece 13 is fixed to 11.

For the blank 11 to which the block piece 13 is fixed, prism measurement is performed by applying the present invention at any stage before processing, during processing, or after processing. In the first embodiment, the blank 11 is attached to a processing apparatus (not shown) via the block piece 13, and is temporarily removed from the processing apparatus just before reaching a predetermined lens thickness, and the blank 11 is measured.
In the first embodiment, a reflection type measuring device 28 as shown in FIG. 4A is used. The reflection type measuring device 28 is a measuring device that measures the curve or inclination of the surface by reflecting the irradiated light on the opposite surface of the lens and measuring the reflected light based on the angle shift with respect to the incident light. The reflection type measuring device 28 reflects the irradiated light only on one certain surface and measures the reflected light to measure the curve or inclination of the surface.
As shown in FIG. 4A, the blank 11 is arranged on the measurement terminal 29 of the reflective measurement device 28 so that the irradiation light is incident perpendicular to the concave surface. In the first embodiment, the measurement position is made to coincide with the geometric center 0 of the blank 11. Then, as shown in FIG. 4B with the blank 11 placed on the measurement terminal 29, the block piece 13 and the measurement terminal 29 are sandwiched by the clamp 30 and fixed so that the blank 11 does not move. Run.

Next, the theory of prism measurement will be described.
The prism is evaluated by the inclination of the convex surface with respect to the concave surface. For this reason, in the first embodiment, the position of the concave geometric center 0 is regarded as a horizontal plane, and it is checked whether the prism amount is in accordance with the processing condition with the inclination of the convex surface at the geometric center 0. Therefore, the reflective measuring device 28 is used to measure the inclination of the convex surface of the blank 11 with the irradiation light from the concave surface side.
For this purpose, the irradiation light incident on the blank 11 is made to be incident on the concave surface without being reflected as much as possible, and reaches the convex surface without being refracted and orthogonal to the concave surface which is the interface through which the incident irradiation light first transmits. It is necessary. In the first embodiment, the light beam that has passed through the interface without being reflected by the anti-reflection film 15 and entered the blank 11 is incident on the incident direction according to the inclination of the convex surface by the reflective film 14 adhered along the convex surface. And reflected with a predetermined reflection angle. The prism can be measured by calculating the angle of the reflected light. However, since the reflected light is refracted according to Snell's law when exiting from the concave surface, it is necessary to calculate it in consideration thereof. As shown in FIG. 5, the refracted light emitted from the concave surface has a predetermined inclination corresponding to the material refractive index with respect to the direction (dashed arrow) assumed not to be refracted (note that the reflection angle in FIG. 5 is slightly exaggerated). As shown).

Specific examples implemented in the first embodiment having the above-described configuration will be described. (1) Lens conditions: Outer surface progressive addition lens (progressive band length 13m, material refractive index 1.6, distance power 0.00D, addition 2.00D)
-Setting the down prism to 0.8 prism diopter (2) Measurement result and correction Measurement was performed on the blank 11 under such conditions. As described above, the refracted light emitted from the concave surface in accordance with Snell's law is inclined at an inclination angle corresponding to the material refractive index with respect to the direction in which the obtained value is assumed not to be refracted (here, since the material refractive index is 1.6, 1 Therefore, if a measurement result of 0.8 × 1.6 = 1.28 prism diopter (Δ) is obtained in the down direction, the blank 11 has a predetermined prism. However, as a result of actual measurement, measurement results of 1.12Δ down and 0.32Δ in were obtained.
It can be seen that the actual characteristic of the blank 11 is 0.70Δ in the down direction and 0.20Δ in, by dividing by 1.6. That is, there is an error of 0.20Δ for an unnecessary prism in the in direction, which is less than 0.10Δ in the down direction.
Therefore, in order to obtain the required conditions of 0.80Δ in the down direction and 0.00Δ in, the blank 11 is again mounted on the processing apparatus, and the processing conditions of the apparatus are 0.90Δ in the down direction and 0.20Δ in the out direction. This lens is set so as to be manufactured, and is processed again to a predetermined thickness so as to obtain the required prism characteristics.

With the above configuration, the following effects are achieved in the first embodiment.
(1) About the blank 11 which cannot transmit irradiation light because the block piece 13 is fixed, the reflected light which reflected on the convex surface the light irradiated toward the convex surface side from the concave surface side with the block piece 13 attached Since the prism amount is measured using the prism, the prism measurement can be performed by applying the present invention at any stage before, during or after the processing.
(2) Since the antireflection film 15 is adhered to the concave surface side of the blank 11, the incident irradiation light is not reflected and does not interfere with the measurement. In addition, since the reflective film 14 that is specularly reflected is attached to the convex surface side, the irradiation light that reaches the convex surface is relatively attenuated and is reflected accurately according to the convex surface shape.
(3) Since the irradiation light is irradiated so as to be orthogonal to the concave surface that is the first transmitting interface, the reflected light data can be obtained without being affected by the angle of the concave surface that is the first interface. Is easy.

(Embodiment 2)
In the second embodiment, a case where the lens power is measured using the same reflection type measuring device 28 as described above will be described. As shown in FIG. 6 (a), the blank 11 in the middle of processing to be measured has a block piece 13 fixed to the convex surface side by an alloy 12 as in the first embodiment. Similarly to the first embodiment, the reflective film 14 is attached to the convex surface, and the antireflection film 15 is attached to the concave surface. In the second embodiment, similarly to the first embodiment, the blank 11 is attached to the processing apparatus (not shown) via the block piece 13 and once removed from the processing apparatus before reaching the slightly planned lens thickness. Shall be measured. As in the first embodiment, the blank 11 is placed on the measurement terminal 29 of the reflection type measurement device 28, fixed so that the blank 11 does not move by the clamp 30, and the first measurement is executed.
Next, after the measurement is completed, the clamp 30 is once released, the blank 11 is taken out, the antireflection film 15 is peeled off as shown in FIG. 6B, and the reflection film 14 is adhered to the position. At this time, the reflective film 14 is attached so that the vapor deposition surface side faces the blank 11 side. In this way, the blank 11 with the reflective film 14 attached on both sides is placed on the measurement terminal 29 of the reflective measurement device 28 in the same manner as described above, and the blank 11 is fixed by the clamp 30 so that it does not move. Execute.

Next, the theory of lens power measurement will be described.
Since the lens power is the degree of convergence or divergence of the light transmitted through the lens, it cannot be evaluated unless the state of both the front and back surfaces of the lens is known. That is, here, it is necessary to measure the state of both convex and concave lenses. Therefore, in the second embodiment, the value of the curve on the convex surface side is calculated based on the reflected light from the convex surface in the first measurement, and the value of the curve on the concave surface side is calculated based on the reflected light from the concave surface in the second measurement. To do. In order to calculate the value of the curve, the curve must be calculated not only from the inclination but also from the inclination of at least two points on a certain surface. Since the reflected light of the convex surface is refracted according to Snell's law as in the first embodiment, it is necessary to calculate it in consideration thereof. Next, the lens power is calculated from the values of the obtained concave curve and convex curve.
An example of a specific curve measurement method will be described. In the case where there is an astigmatism power or a progressive surface, complicated calculation with a plurality of light beams is necessary, and therefore a spherical lens that can be described with one light beam will be described as an example here. First, the calculation of the concave side curve will be described.
As shown in FIG. 7, one light beam (measurement light) is irradiated on the concave surface parallel to the axis passing through the geometric center at a position deviated from the geometric center, and the reflected light reflected by the concave surface is measured. Here, A is a distance from the geometric center to the irradiation position. This value A is a known value as a basic device design value. Now, assuming that the radius of curvature of the concave surface is R2, the measuring apparatus measures θ2 in FIG. That is, R2 can be obtained from the relationship sin θ2 = A / R2. Further, in the actual calculation, sin θ2 = A / R2 is set to θ2 = A / R2 particularly when the distance from the lens to the measurement unit (sensor) and the radius of curvature of the surface are sufficiently larger than the lens thickness and A. It is also possible to approximate to Here, the calculation is performed by approximation. Note that the reflection angle in FIG. 7 is expressed slightly larger for convenience of explanation.

Next, calculation of the convex curve will be described.
As shown in FIG. 8, the light is first refracted according to Snell's law at the incident position on the concave surface. Here, for example, when the material refractive index is 1.6, the refraction angle is α = θ2−θ2 / 1.6 (1).
It is said. Since θ2 is known in the calculation on the concave surface side, α can be obtained. Next, consider the case where this light beam is reflected by a convex surface. As shown in FIG. 8, straight lines parallel to the incident light are drawn as auxiliary lines (broken lines in the figure) P and Q at the convex reflection position and the concave emission position, respectively.
Since the complex angles formed when one straight line crosses diagonally with respect to two parallel straight lines are equal, α + 2β = γ + θ2 (2)
Holds. Here, α + β is an angle between the normal line R1 at the convex reflection position and a straight line parallel to the incident light beam, which is θ1. That means
α + β = θ1 (3)
Assuming that the distance A from the geometric center to the irradiation position is sufficiently large, θ1 = A / R1 (θ1 and R1 are unknown).
From (2) above, γ = α + 2β−θ2, and from (3) above, β = θ1−α.
γ = α + 2 (θ1-α) −θ2 = 2θ1-θ2-α (4-1)
Holds.
Further, from (1), since α = θ2-θ2 / 1.6, γ = 2θ1-θ2- (θ2-θ2 / 1.6) = 2θ1-2θ2 + θ2 / 1.6 (4-2)
When Snell's law is applied at the concave exit position, the slope of the exit ray is found to be 1.6γ + θ2.
From (4-2)
1.6γ + θ2 = 1.6 (2θ1-2θ2 + θ2 / 1.6) + θ2 = 3.2θ1-1.2θ2
That is, since the value of “3.2θ1−1.2θ2” can be obtained by the measuring apparatus, θ1 and R1 can be obtained as a result. Note that the reflection angle in FIG. 8 is expressed slightly larger for convenience of explanation. In FIG. 8, for the convenience of drawing, the normal lines R1 and R2 show only the vicinity of the lens.

A specific example implemented in the second embodiment having the above configuration will be described. (1) Lens conditions: Aspherical force lens (material refractive index 1.6, S power -1.00D, C power 0.00D)
The convex curve is 2 curves in terms of refractive index 1.6. The radius of curvature is (1.6-1) / 2 (m-1) = 0.3 m = 300 mm.
The concave curve is 1 curve in terms of refractive index 1.6. The radius of curvature is (1.6-1) / 1 (m-1) = 0.6 m = 600 mm.
Therefore, the power of this lens is -1.00D. When the concave curve was processed with the aim of the 1.00 curve, it became a 1.03 curve. Then, it turns out that the power of this lens is -1.03D.
Therefore, in order to obtain -1.00D which is the required condition, the blank 11 is newly mounted on the processing apparatus, and the processing condition of the apparatus is set so as to process a concave surface with a curve of 0.97, and is processed again to the expected thickness. Thus, the desired lens characteristics are obtained.

With the configuration as described above, the following effects are achieved in the second embodiment.
(1) For the blank 11 that cannot transmit the irradiation light because the block piece 13 is fixed, the light irradiated from the concave side toward the convex side with the block piece 13 attached is reflected on the convex surface and the concave surface, respectively. Since the lens power is measured using the reflected light, the lens power can be measured by applying the present invention at any stage before processing, during processing, or after processing.
(2) Since the antireflection film 15 is adhered to the concave surface side of the blank 11, the incident irradiation light is not reflected and does not interfere with the measurement. In addition, since the reflective film 14 that is specularly reflected is attached to the convex surface side, the irradiation light that reaches the convex surface is relatively attenuated and is reflected accurately according to the convex surface shape.

(Embodiment 3)
In the third embodiment, a case where the lens power is measured using the wavefront measuring device 31 will be described. In the third embodiment, an optical system as shown in FIG. 9 is set.
The same reflective film 14 as in the first and second embodiments is attached to the same convex surface side of the blank 11 as in the first embodiment so that the vapor deposition surface side faces the blank 11 side. An alloy 12 is disposed so as to cover the reflective film 14, and a block piece 13 is welded to the center position of the alloy 12. In the third embodiment, the block piece 13 is placed on the horizontal installation surface 32 so that the concave surface of the blank 11 faces the upper surface. A half mirror 33 is disposed above the concave surface, and a light source 35 is disposed above the half mirror 33. A wavefront measuring device 31 is disposed on the side of the half mirror 33.
In such a configuration, the light emitted from the light source 35 toward the blank 11 passes through the half mirror 33 and reaches the blank 11. Then, the light passes through the concave surface that is the interface, reaches the convex surface, is reflected, and the reflected light passes through the concave surface again, is reflected by the half mirror 33, and travels toward the wavefront measuring device 31. On the other hand, a part of the light emitted from the light source 35 toward the blank 11 is reflected by the concave surface and further reflected by the half mirror 33 toward the wavefront measuring device 31. That is, the information of the reflected light reflected by both the convex surface and the concave surface is taken into the wavefront measuring device 31. The wavefront measuring device 31 measures the convex and concave curves based on the captured light including both convex and concave components, and thereby measures the lens power and prism of the blank 11.
The wavefront measuring device 31 measures the convex and concave curves based on the captured light including both convex and concave components, and thereby measures the lens power and prism of the blank 11. That is, the prism can be measured from the difference in inclination of the wavefronts of the two reflected lights reflected by both the convex and concave surfaces, and the frequency can be measured from the difference in curvature of the wavefronts of the two reflected lights. It becomes possible.
With the above configuration, the following effects are achieved in the third embodiment.
(1) For the blank 11 that cannot transmit the irradiation light because the block piece 13 is fixed, the light irradiated from the concave side toward the convex side with the block piece 13 attached is reflected on the convex surface and the concave surface, respectively. Since the lens power is measured using the reflected light, the lens power can be measured by applying the present invention at any stage before processing, during processing, or after processing.
(2) Since both the convex and concave reflected light data can be obtained using the wavefront measuring device 31, it is possible to simultaneously measure not only the lens power but also the prism amount.

(Embodiment 4)
In the fourth embodiment, a case where a wavefront sensor is used as a more specific wavefront measuring apparatus of the third embodiment will be described. In the fourth embodiment, an optical system as shown in FIG. 10 is set.
The same reflective film 14 as in the first to third embodiments is stuck on the convex surface side of the same blank 11 as in the first embodiment so that the vapor deposition surface side faces the blank 11 side. An alloy 12 is disposed so as to cover the reflective film 14, and a block piece 13 is welded to the center position of the alloy 12.
In the fourth embodiment, the wavefront sensor 41 is arranged on the concave surface side of the blank 11. The wavefront sensor 41 includes a light source 42, a prism 43, a Hartmann plate 44 including a lens array, and a CCD camera 45 as an imaging unit. As shown in FIG. 11, the wavefront sensor 41 is connected to an analysis computer 45 to constitute a wavefront measuring apparatus. The analysis computer 45 is provided with a calculation unit 46 composed of a CPU (Central Processing Unit) and a memory 47 as storage means. The memory 47 stores various programs and analysis software for analyzing wavefront aberration. The wavefront aberration acquired from the wavefront sensor is analyzed by the calculation unit 46.
The analysis computer 45 is connected to a monitor 48 as output means and a keyboard 49 as input means. Examples of output means include output means for transferring data to a printer or another device other than the monitor 48. In addition to the keyboard 49, the input means includes a two-dimensional code such as a bar code, a means for inputting data transferred from another device such as a LAN-connected other computer or data storage device, and the like.

In the measurement in such a configuration, a plurality of light beams irradiated from the light source 42 in the direction of the prism 43 are changed in direction by 90 degrees on the reflecting surface 43a and are directed in the direction of the blank 11. Then, the light passes through the concave surface, reaches the convex surface, is reflected, and the reflected light passes through the concave surface again, further passes through the prism 43 and reaches the Hartmann plate 44, and is photographed by the CCD camera 45. The blank 11 can be evaluated by analyzing the wavefront aberration acquired from the CDD camera 45. In particular, it is possible to calculate a higher order aberration component by analyzing the image, and therefore, it is effective for correcting aberrations other than the S and C degrees (lens power) and the prism amount, which are lower order aberration components.
Here, the principle of wavefront measurement will be described.
Now, a certain coordinate on the Hartmann plate 44 is set as (X, Y). When the coordinates (X, Y) are on the CCD camera 45 and the test lens (blank 11) is assumed to have no aberration (ideal wavefront), the deviation amount between the focal point and the actual arrival point is expressed as Δx, Assuming Δy and the distance between the Hartmann plate 44 and the CCD camera 45 as f, the wavefront aberration and the shift amounts Δx and Δy generally hold the relationship of the partial differential equations of the following equations 1 and 2. When the semifinished lens is an ideal planar lens, the values of Δx and Δy are zero. In the case of a semi-finished lens having a constant radius of curvature, the radius of curvature is known. Therefore, ideal Δx and Δy, which are condensing point positions for each lens array, can be easily calculated. Therefore, the wavefront aberration component can be calculated by analyzing the shift amount between Δx and Δy from the image acquired from the CCD camera 45. The shift amounts Δx and Δy are measured for each of a large number of microlenses of the lens array constituting the Hartmann plate 7, and finally, the portions other than the measurement points are subjected to interpolation calculation.

The wavefront aberration component can be evaluated by decomposing the aberration into each order using the Zernike polynomial and correcting each aberration. Here, the Zernike polynomial is a mathematical expression often used in the optical field, and is a complex function on a unit circle having a radius of 1, and has polar coordinate arguments (r, θ). Theoretically, complex functions are used, but in practice they are used as real functions. The Zernike polynomial is mainly used in the optical field to analyze the aberration component of a lens, and it is possible to know the aberration component by decomposing the wavefront aberration into a Zernike polynomial. In the following equation, W (X, Y) is a wavefront aberration, C _i ^2j-i is a Zernike polynomial, and Z _i ^2j-i is a Zernike coefficient.

Zernike polynomials have different Zernike coefficients for each term. With this Zernike coefficient, for example, a color code map showing wavefront aberrations as individual aberration components as shown in FIG. 12 is obtained (actually color, but displayed in black and white due to color limitations). The color code map is Z01, Z02 from the left in the first order, Z03, Z04, Z05 from the left in the second order, Z06, Z07, Z08, Z09 from the left in the third order, and from the left in the fourth order. Z10, Z11, Z12, Z13, Z14,... Are arranged in this order. As described above, the terms included in the third and fourth orders are aberration portions that have a great influence on the clarity of the measurement target. The prism amount, S power, and C power appear as primary and secondary aberrations, and other coma, spherical aberration, and local deformation appear as third and subsequent aberrations.
Table 1 below shows the actual measured values when there is no aberration with respect to the higher-order wavefront aberration of the lens (lower numerical value) and when some aberration occurs (upper numerical value). Here, it acquired about each term of 3rd order and 4th order Z06-Z14. The fifth and subsequent orders are not taken into account here because the amount of aberration is very small. 13 and 14 are three-dimensional diagrams of high-order aberrations created using the values in Table 1. 13 is based on the lower value of Table 1, and FIG. 14 is based on the upper value. When the three-dimensional diagram is expressed as a plane as shown in FIG. 13, there is no wavefront aberration, while when the three-dimensional diagram is shown as a three-dimensional diagram with irregularities as shown in FIG. 14, the lens has higher-order aberrations. That is. As a cause of high-order aberrations, when a concave surface is cut by a processing machine (NC lathe device) that is not very accurate, when the accuracy of the mold at the time of forming the blank 11 is not good, or a shape error occurs in the blank itself. You may have it.
When the blank 11 has high-order aberrations, it is necessary to rework the blank 11 and perform processing correction so as to produce a blank 11 having no (or few) aberrations as shown in FIG. is there. As a result of analysis by the analysis computer 45, when there is a third-order or higher order aberration component, processing data that corrects such wavefront aberration, that is, a semi-finished lens having a certain curvature, Designed by the analysis computer 45 so that the condensing point position for each lens array shown in FIG. 10 becomes ideal Δx and Δy, and based on the new machining data, the NC lathe device (not shown) is connected via the block piece 13. Then, the blank 11 is mounted and reworked. In the same manner as in the first embodiment, the lens is once processed to the thickness that is scheduled to be removed from the processing apparatus before reaching the lens thickness that is slightly planned.

By adopting such a configuration, the fourth embodiment provides the following effects in addition to the effects of the third embodiment.
(1) When a deformation derived from higher-order (third-order or higher) wavefront aberration remains, it can be determined and corrected, so that a lens (blank 11) having a better wearing feeling is provided. be able to.
(2) Since local deformation of the lens that cannot be determined by conventional evaluation can be evaluated as an objective aberration component, a lens (blank 11) with a better wearing feeling can be provided in this respect as well. it can.

(Embodiment 5)
In the fifth embodiment, a case where a large number of light beams are irradiated over a wide range of the lens (blank 11) and the reflected light is measured will be described.
As shown in FIG. 15, the same reflective film 14 as in Embodiments 1 to 4 is stuck on the convex surface side of the blank 11 as in Embodiment 1 so that the vapor deposition surface side faces the blank 11 side. An alloy 12 is disposed so as to cover the reflective film 14, and a block piece 13 is welded to the center position of the alloy 12. In the fifth embodiment, a frequency distribution measuring device (lens mapper) 51 is arranged on the concave surface side of the blank 11. As shown in FIG. 15, the lens mapper 51 includes a light source 52, a prism 53, a beam splitter 54, a screen 55, and a CCD camera 56 as an imaging means.
In measurement with such a configuration, the light beam irradiated from the light source 52 in the direction of the prism 53 is turned 90 degrees on the reflecting surface 53a and travels in the direction of the blank 11. Then, the light passes through the concave surface, reaches the convex surface, is reflected, and the reflected light passes through the concave surface again, and further passes through the prism 53 and reaches the beam splitter 54. The beam splitter 54 is formed with a large number of through-holes arranged at regular intervals in the vertical and horizontal directions, and light rays (light beams) passing through the through-holes are projected onto the screen 55. This projected light spot is used as a mapping point. The CCD camera 56 captures an image of the mapping point projected on the screen 12.
As shown in FIG. 16, the lens mapper 51 is connected to an analysis computer 57. The analysis computer 57 calculates the refractive power for all mapping points based on the positional displacement with the through hole corresponding to the light beam captured by the CCD camera 56. That is, the refractive power data (S power data, C power data, astigmatism axis data, prism amount data) of the test lens 5 can be obtained for all positions mapped on the lens. The analysis computer 57 has a memory 58 as storage means for storing refractive power data.
As shown in FIG. 16, the analysis computer 57 is connected to the evaluation computer 58. The evaluation computer 58 performs evaluation calculation of the blank 11 based on the optical characteristic data obtained from the analysis computer 57.

  With such a configuration, since the refractive power data can be obtained over a wide range of the blank 11, the lens power can be measured using the mapping point data over a wider range, for example, the entire lens surface, It becomes possible to measure a prism and a curve as in the first and second embodiments.

It should be noted that the present invention can be modified and embodied as follows.
In each of the above embodiments, the concave surface is calculated as a plane. This is because it is assumed that the position where one measurement light beam enters and exits is an area close to the center of the lens. When the lens power is calculated using one or a plurality of separated measurement light beams or a light beam having a certain area, it may be calculated in consideration of a concave curve.
-Although the block piece 13 was mentioned as an example as a coating | coated member above, another coating | coated member can also be assumed.
The material of the reflective film 14 and the antireflection film 15 is not limited to the above. In addition to adhering the tape-shaped film body as described above, a film formed so as to be mirror-coated by vapor deposition or sputtering may be used.
-You may make it stick the antireflection film 15 on the concave surface of the blank 11 in Embodiment 3-5.
In the fifth embodiment, a wide range of optical characteristics may be acquired using an interferometer instead of the lens mapper 51.
In each of the above embodiments, the case where the cutting surface is a concave surface has been described. However, the block piece 13 can be fixed to the concave surface and the convex surface side can be cut (made as a processed surface).
In the above embodiment, the concave surface of the blank 11 is a lens surface on which a predetermined power, a prism, and the like are set, and this is checked and corrected when necessary. Even if is not yet set, it is possible to apply.
-Besides, it is free to implement in a mode that does not depart from the gist of the present invention.

  DESCRIPTION OF SYMBOLS 11 ... Semi-finished blank, 12 ... Alloy as a covering member, 13 ... Block piece as a covering member

Claims (15)

A semi-finished blank having a convex surface and a concave front and back surfaces, and a covering member that covers the first surface is mounted on one of the front and back first surfaces, and on the other second surface Is directed from the second surface side to the first surface side with respect to the semifinished blank on which the antireflection film for preventing reflection on the second surface is formed without mounting the covering member. A method for measuring a semi-finished blank, wherein a value of a predetermined optical characteristic is calculated based on a measured value of reflected light obtained by irradiating light and acquired on the second surface side.   A semi-finished blank having a convex surface and a concave front and back surfaces, and a covering member that covers the first surface is attached to either the first surface or the front surface, and the other second surface is Reflected light obtained from the second surface by forming a reflective film on the second surface and irradiating the second surface with light on the semi-finished blank not equipped with a covering member On the other hand, the value of the first curve of the second surface is calculated, and the second surface is irradiated with light without the reflective film on the second surface. A semi-finished product that calculates a value of a second curve of the first surface based on the obtained reflected light and calculates predetermined optical characteristics based on the values of the first and second curves. Blank measurement method. A semi-finished blank having a convex surface and a concave front and back surfaces, and a covering member that covers the first surface is mounted on one of the front and back first surfaces, and on the other second surface Forming a reflecting means along the shape of the first surface for specularly reflecting the irradiation light on the first surface with respect to the semi-finished blank not provided with the covering member; A semi-finished product is characterized in that a value of a predetermined optical characteristic is calculated based on a measured value of reflected light obtained by irradiating light from the surface side toward the first surface side and acquired on the second surface side. Blank measurement method.   When calculating the value of the second curve of the first surface, an antireflection film is formed on the second surface of the semifinished blank to prevent reflection of irradiation light on the second surface. The method for measuring a semi-finished blank according to claim 2, wherein:   The semi-finished blank measurement method according to claim 1, wherein the predetermined optical characteristic is a prism.   The semi-finished blank measurement method according to claim 1, wherein the predetermined optical characteristic is a lens power. Any of claims 1-6, characterized in that a connecting member fixed to the connecting member covering the central region of the first surface by a fixing means for coupling the processing apparatus above a target covering member A method for measuring a semi-finished blank according to claim 1.   The method for measuring a semi-finished blank according to claim 7, wherein the connecting member is attached to the convex surface side of the semi-finished blank.   A plurality of light rays are irradiated from the second surface side over a wide range of the lens, reflected light is obtained for each light ray, and a value of a predetermined optical characteristic is calculated based on the measured value. Item 9. A method for measuring a semifinished blank according to any one of Items 1 to 8.   The method for measuring a semifinished blank according to claim 1, wherein a wavefront is measured in the measurement of the reflected light, and the predetermined optical characteristic is calculated based on the measurement result.   A method for processing a semi-finished blank, wherein the second surface side is processed based on a value of a predetermined optical characteristic calculated by the measurement method according to claim 1.   A method of processing a semi-finished blank, wherein the predetermined optical property value calculated in the measurement method according to any one of claims 1 to 10 is checked, and a necessary correction according to processing conditions is added.   13. The method of processing a semi-finished blank according to claim 11, wherein a progressive refractive surface is formed on the convex surface side of the semi-finished blank, and the produced lens is an outer surface progressive-power lens.   The method of processing a semi-finished blank according to claim 11, wherein the measurement of the reflected light is performed after processing the concave surface side of the semi-finished blank.   The processing on the concave side is temporarily stopped before reaching the predetermined thickness, and light is irradiated from the concave side to the convex side on the semi-finished blank in which the covering member is mounted at that stage. A predetermined optical characteristic is calculated based on the measured value of the reflected light acquired on the concave surface side, the calculation result is checked, and a necessary correction according to the processing condition is performed and the processing is performed again. The processing method of the semifinished blank in any one of Claims 11-14.

Images