JPH07508590A - Configuration for point-like measurement of diffuse reflection on surfaces - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Configuration for point-like measurement of diffuse reflection on surfaces The present invention is applicable to multiple spectral regions (visible, near-infrared, and mid-infrared). Regarding the configuration for measuring the diffuse reflection of small surfaces of solids and liquids in the , thereby controlling the spectrum diffuse reflectance and/or object color. It is possible to detect one side distribution.

The present invention ensures color uniformity in products, detects color deviations or harmonizes colors with each other. It can be applied in various fields of industry and manufacturing to harmonize the environment. harmonize colors with each other For example, the color of the denture should match the natural color of the teeth as much as possible. It also plays a major role in denture manufacturing, which is a problem.

In the prior art, a plurality of sequentially controllable spectrally selective radiation sources and receivers are used. There are many publicly available configurations for measuring the diffuse reflectance of objects. It is knowledge. The optical portion of these configurations essentially provides radiation to the test surface. There are different ways of providing The method described in German Patent Application No. 4120749 and the In the device described in Democratic Republic of China Patent No. 99439, the test surface is directly irradiated. be done. As a result, the "punctate" surface to be measured (punktuellen"Fl aeche) is the size of the emitted light cone of the LED and the distance between the measurement object and the radiation source. Determined by required separation distance. Therefore, it is important to select the dotted surface to be small enough. I can't do it.

Due to the divergence of synchrotron radiation, it is necessary to obtain accurate measurement results on surfaces with strong absorption. requires a very high luminous intensity. In addition, excessive amounts of various LEDs on the measurement surface Radiation accuracy cannot be achieved sufficiently due to angular dispersion in the radiation characteristics of LEDs. Not possible.

German Patent No. 3,626,373 discloses that the radiation of an individual radiation source is A lens that focuses the emitted light onto the sample to be tested via a filter unit. A device is described that leads to the lens component. This radial guide device has high adjustment costs. and high mechanical stability. The surface resolution that can be achieved is as specified in the above-mentioned patents. Determined and limited by the LED radiation characteristics as well as those listed in the specification. Ru. In addition, the radiation intensity is reduced by a filter unit and the image Limited by system aperture. Federal Republic of Germany Patent Application No. 3038 No. 786 discloses a device for measuring the color of gums. With this measuring device, Light from a light source is directed to the test surface via a flexible optical waveguide bundle. against the test surface The separation pressure of the light exit surface moves slightly, and this light exit surface is auxiliary polished into a lens shape. It is possible to focus the light on a very small measurement point if Ru.

The problem with such configurations is that they do not allow enough radiant energy to be absorbed into the light. One example is collecting them into a waveguide bundle.

The object of the invention is to provide a simple means for emitting radiation from several radiation sources with different radiation characteristics. This allows the radiant energy to be concentrated on the smallest possible area of the test surface with almost no loss. Provides a configuration for point-wise measurements of diffuse reflection in different spectral regions It is to be.

This task consists of at least two radiation sources of different spectral ranges as well as at least Different spectra with receivers sensitive to different selected spectral regions Arrangement for point-wise measurement of diffuse reflection of solids or liquids in an area where the incident and expanded The angular position of the diffusely reflected light is different, and on the other hand, this angular position is on the other hand corresponds to an angle substantially different from the surface normal and surface parallel. In this configuration, the problem is solved as follows. That is, the radiation source is followed by a concentrator. This condenser has the shape of a truncated cone and is covered with a low refractive index material. By being made of a transparent material with a high refractive index, /J% of the surface is substantially reflected by total reflection. The synchrotron radiation is concentrated in minutes.

The concentrator is made of a film produced by dipping or spraying as a low refractive index outer coating. It is preferably made of any transparent material with a surface layer. Other suitable forms In this case, the condenser is made of glass, especially quartz glass, and the outer periphery of the condenser has a low refractive index. The covering portion is formed by heat treating the glass.

Preferably, when using a diverging LED, the semicone angle of the condenser made of quartz glass is , is approximately one-fifth of the numerical aperture of an optical waveguide made of the same material. In this case, the concentrator is preferably glued to the window of the LED used. In addition, the adhesive layer is for LED It is matched to the refractive index of the window material and the refractive index of the concentrator. The radiation source is a surface as an individual LED. at equal angular intervals around the receiver placed in the direction of the normal above and below the surface normal. Preferably, they are arranged at about 45°. Compensating for the divergence of the radiation source in the form of LEDs In order to achieve this, the light exit surface of the condenser is preferably formed spherically. Especially small inspection In order to realize a radiation head, it is necessary to place a radiation source at an arbitrary location away from the surface and use a light condenser. It is generally convenient to glue the optical fiber to the light exit face of the The end of the optical fiber is placed at equal angles around the receiver (ill) placed in the direction of the surface normal. They are arranged at intervals and at an angle of approximately 45° to the surface normal. in this case The radiant emittance is reduced by the spherical shape of the optical fiber's exit surface. suitable. Another preferred form of construction according to the invention is the use of tricolor LEDs. achieved by. i.e. only a single concentrator is an LED (three radiation sources in one) Following the integrated LED), a three-color LED and a condenser are arranged in the direction of the surface normal. Ru.

On the other hand, a fiber bundle consisting of optical waveguides (LWL) arranged concentrically is This fiber bundle receives the diffusely reflected light at an angle of approximately 45°. , and each color of the three-color LED is then switched on in sequence. In this case, There are two suitable variations of LWL configurations to accommodate diffusely reflected light. on the other hand The LWL (with end faces perpendicular to the LWL axis) is simply about 45 However, on the other hand, the light entrance face and light output face of the detection head Mouth surface has a consistent smooth surface. Therefore, the end face of LWL is cut at an angle. There are several advantages if you do. Here too, it was diffusely reflected at an angle of about 45″. In order to guide the light to the receiver, the LWL/air refractive index ratio (here, quartz glass/air The angle between the LWL and the surface normal of the object surface is reduced based on the refractive index ratio of .

As a result, the plane method for LWL is based on the light refraction during air-silica glass transition. The angular position relative to the line will be approximately 30''.

It is further preferred to firmly connect the light collector to the tricolor LED via an adhesive layer. It is. In this case, the adhesive layer is mutually matched to the refractive index of the LED window and the concentrator.

Preferably, the light exit surface of the condenser is further formed into a flat surface. This basic The idea is to detect multiple radiation sources using a simple truncated cone made of a transparent material that undergoes total internal reflection. , especially the various radiation characteristics of LEDs and concentrating the divergent radiation, thereby reducing the diffuse reflection. To be able to give sufficient radiant intensity to a point area on the surface of the object to be measured. That is. In this case, the principles of dark-field illumination, which are known per se, are used. this The principle is also known as the 0'/45° geometric measuring arrangement, and the point according to the invention It has been adapted and modified according to the particularities of diffuse reflectance measurements. Configuration according to the invention Accordingly, it is possible to accurately measure diffuse reflection on the most seven surfaces of an object. Together, they provide a nodal output diverging light source for accurate diffuse reflectance measurements with little radiation loss. can be used. Particularly suitable is the industrial use of diffuse reflectance measurements for color matching. It is applied in various fields of industry.

First of all, the special form of construction according to the present invention is short and compact, and the critical surface is Easily kept sterile, it can be used in dentistry (denture making) and forensic medicine (e.g. blood This proves to be advantageous and suitable for use in the chronological assessment of

Next, a more detailed explanation will be given using two examples. The drawings show:

1 shows a principle diagram of the arrangement according to the invention in an (incomplete) m-plane, and FIG. 1 shows a top view of 3 shows a principle view of another configuration according to the invention in side view, and FIG. 4 shows a top view of FIG. The figure shows.

It is shaped like a truncated cone. If the outer covering surface of this truncated cone totally reflects the synchrotron radiation, Concentrate on both at the same time.

Depending on the number of spectral regions, V- They are distributed at equal angular intervals.

form one of the In this embodiment, this component group is as shown in FIG. , are arranged around the receiver 5 with a phase difference of 120°.

Test surface 1 is activated by red, green and blue LEDs 3.1.3.2 and 3.3. The irradiation is performed sequentially in pulses at a qualitative angle of 45°. At that time, each The light concentrator 2 captures the emitted light from the LED and directs it to a narrow area on the test surface 1. Concentrate on the part. In that case, the size of this limited part is different for different LEDs. The parameters of the condenser 2 (cone angle, high refraction) The refractive index ratio of the truncated cone having a refractive index and the outer peripheral covering part having a low refractive index) and the surface 1 It is determined by the distance between the light exit surface of the light condenser 2 and the light exit surface of the light condenser 2. For the refractive index ratio , the relationship regarding the generally known semi-closed angle regarding light waveguides (LWL) is It is valid: sin u” (nK” nM”)”, where nK and nu are the truncated cone body and the refractive index of the outer peripheral coating. Therefore, the refractive index ratio of the condenser 2 is lower than that of the conventional LWL. is similar to the refractive index ratio of , the value of nK is about 1.45 and the value of nM is about 1.43. . Thereby, the material of the condenser 2 is essentially Ensign Bickford. Ensign-Bickford Optic Compatible with the LWL of s Company) (USA). Same at the light exit of condenser 2. Based on the slightly larger synchrotron radiation divergence than the conventional LWL, which appears as The separation distance therebetween is chosen to be absolutely small. In the opposite condition, all The light cone of the radiation source 3 leaves the light outlet of the condenser 2 and reaches the receiver 5 as reliably as possible. Therefore, the separation distance must always be large so that surface 1 to be detected is completely illuminated. The fact is that there is no. The receiver I15 is placed in a metal sleeve 7 to avoid external incident light. It is convenient to receive the diffusely reflected light guided through the buried LWL6. Therefore, for surface 1, the distance should be almost no less than the distance of 2 machinings. At that time This separation distance is achieved with respect to the metal sleeve 7, while the inlet face of LWL6 is It is moved slightly backward in order to avoid the incidence of emitted light that is diffusely reflected by sources other than 1.

Regarding the condenser 2 that concentrates the LEDs with a diameter of 3 mm on the exit surface of the 1.4 order, a semicircle Under the condition that the cone angle is about 2.5', the length will be less than 2 am. At that time, a semicircle The cone angle should be no more than 10% greater than one-fifth of the numerical aperture. Light collector 2 is relatively short in length and is at a suitable position of 45@ with respect to the surface normal to surface 1, so Rather than placing the light source 3 directly near the surface 1, the light is transmitted to the LWL (in this configuration, (not shown) to the appropriate location can be configured according to the present invention. This is an advantage due to its compact and elongated structural form. In this case, the concentrator Preferably, the light exit surface of No. 2 is bonded to the end surface of the LWL. As LWL, preferred For more information, please contact Ensign Big 7 Ord Optics Company, Inc. Model H manufactured by gn-Bickford Optics Company (USA) CG-MO365T-10 LWL is used.

As the radiation source 3 described above, instead of the LED used in the embodiment, a special semiconductor structure or Incandescent bulb filter configurations may also be used. In this case, these alternatives Depending on the product, the concentrator 2 needs to be shaped to match its light entrance surface and length. There is.

In FIG. 3, the positions of the radiation source 3 and receiver 5 have been changed compared to the first embodiment. This is an arrangement according to the invention which is designed differently in principle. Here, the radiation source 3 is arranged in the direction of the surface normal of surface 1. A suitable example for this is three-color LE D8 (for example, Elcos (El, ωS CmbH) (Germany, Bucoahue) Mention may be made of the use of the type CMS 124) of the city of Nhoven. In that case Here again, each color division section is sequentially controlled in a pulsed manner. Three color LED8 is here is connected via an adhesive layer 9 to the condenser 2 formed in the same manner as in the first embodiment. It is preferable to In this connection, the window material of the three-color LED 8 is connected to the light condenser 2 through the adhesive layer 9. (refractive index matching).

Since light divergence occurs after the light exit surface of the condenser 2, it is different from that in the first embodiment. Similarly, the distance from surface 1 is small. With the light condensing body 2 placed above, As a result of the vertical position of the three-color LED 8, the reception of diffusely reflected light is properly performed. In this case, distances in the order of 1 to 1.6 for plane 1 can be realized. Figure 3 is the same as Figure 4 (top view). As clearly shown in connection with Figure), in this example receiver 5 is used to Diffusely reflected light is received via a fiber bundle consisting of LWL6. This fiber bundle are arranged concentrically and evenly around the radiation source/concentrator unit arranged along the surface normal. distributed.

Therefore, model HCG-M 0200 T-10 (numerical aperture: 0.22, metal Carer: Ensign Bickford Optics Company, Inc. ign-Bickford Optics Company) (USA) A step index optical fiber is used. At that time, LWL6 is diffusely reflected. The LWL6 is arranged so that the light received by the LWL6 is preferably received at an angle of 456 with respect to the surface normal. It is advantageous that it is On the one hand, the end of LWL6 is connected to the selected angle setting. (e.g. exactly 45@) and preferably cast in one piece. this In this case, the end face of LWL6 is perpendicular to the fiber axis and is practically the coupling surface. stands out from This variant is not clearly shown in the drawing. Figure 3 is another This shows the deformation of the refractive index of quartz glass as well as the surface of the measurement sensor. The often preferred situation is that it is better to be as smooth as possible. here LWL6 is adjusted at an angle of 300 with respect to the surface normal of surface 1 (e.g. note (by embedding in mold resin).

The end face of LWL6 has an inclined cut end face at the same 30° angle, so the measuring sensor The server has a flat, smooth surface parallel to plane l. The angle value of 30° is Selection of LWL6 made of quartz glass and acceptance angle for diffusely reflected light of 45° The result is: Therefore, the technical scope of the present invention is limited to a fixed angle value. It's not something you can do. What is important is that the diffusely reflected light at 45° is L based on the refractive index shift. into LWL6 approximately parallel to the fiber axis at the inclined light entrance face of WL6. It is preferable that it be refracted. Further advantageously, the measurement for surface 1 Since the distance between the constant sensors can be reduced to approximately 1 mm, the light output of the condenser 2 is If there are 1 or 4 groups of mouth surfaces, a measuring surface 1 having a diameter of about 2 tubes is obtained. others The smooth measuring sensor surface makes it particularly easy for medical techniques to keep sterile. meet the requirements of the art.

Claims (1)

[Claims] 1. Pointwise measurement of the diffuse reflection of a solid or liquid surface (1) in different spectral regions at least two radiation sources (3) of different spectral ranges, configured for a receiver (5) sensitive to at least selected different said spectral regions; The angular position with respect to the incident light and the diffusely reflected light is different, and the angular position is different. on the one hand, the surface normal of the surface (1), and on the other hand, the surface normal and the surface parallel line are substantially In a configuration corresponding to different angles, said radiation source (3) is provided with a concentrator (2). The condenser (2) has the shape of a truncated cone and is made of a low refractive index material. By being made of a high refractive index transparent material coated on the outer periphery with A configuration characterized in that the emitted light is concentrated on a small portion of the surface (1). 2. The light condensing body (2) is coated with a low refractive index by dipping or spraying. Any transparent material with a varnish layer produced, the transparent material being more than air. 2. According to claim 1, it has a refractive index as slightly as possible. composition. 3. the outer periphery of low refractive index, in which the light collector (2) is not made of glass, in particular quartz glass; Claim characterized in that the coating is produced by heat-treating the glass. The configuration described in Item 1. 4. Using a conventional quartz optical waveguide material and a diverging radiation source (3) in the form of an LED When used, the light concentrator (2) has a numerical aperture of about 5 of the optical waveguide made of the same material. Arrangement according to claim 3, characterized in that it has a half-cone angle of 1:1. 5. The light collector (2) is adhered to the window of the LED, and an adhesive layer is formed at this time. According to (9), the refractive index of the window material of the LED and the refractive index of the light condenser (2) are Arrangement according to claim 4, characterized in that it is adapted. 6. The radiation source (3) as individual LEDs (3.1, 3.2, 3.3) The receiver (5) is arranged at equal angular intervals around the receiver (5) in the vertical direction and parallel to the surface normal. according to claim 4, characterized in that they are arranged at an angle of approximately 45° with respect to the composition. 7. The light exit surface of the light condenser (2) is formed into a spherical shape. The configuration described in claim 6. 8. If the radiation source (3) is located at any location away from the surface, An optical fiber is glued to the light exit surface of the light condenser (2), and the end of the optical fiber are arranged at equal angular intervals around the receiver (5) arranged in the direction of the surface normal. It is characterized by being arranged at an angle of approximately 45° with respect to the surface normal. The configuration according to claim 4. 9. A claim characterized in that the light exit surface of the optical fiber is formed in a spherical shape. The configuration described in item 8. 10. The different radiation sources (3) are integrated into a tricolor LED (8), the tricolor LED A single light condenser (2) is post-connected to D, as well as a tricolor LED (8) and a light condenser ( 2) is arranged in the direction of the surface normal to the surface (1), and transmits the diffusely reflected light to the receiver. (5) from optical waveguides (6) arranged concentrically to receive and guide the A fiber bundle is provided and each color of the three color LEDs (8) is switched on sequentially. 5. Arrangement according to claim 4, characterized in that it can be 11. The end of the optical waveguide (6) is at an angle of approximately 45° to the normal to the surface (1). 11. Arrangement according to claim 10, characterized in that the arrangement is angularly arranged. 12. The end of the optical waveguide (6) is at an angle of approximately 30° to the normal to the surface (1). The end faces are arranged at an angle, and the end faces are arranged at an angle. The optical waveguide (6) is made of quartz glass and is cut obliquely. The light exit of the three-color LED (8) and the end face are in the same plane and in front. Claim 10, characterized in that it is arranged parallel to the recording surface (1). composition. 13. The light collector (2) is connected to the three-color LED (8) via an adhesive layer (9). The window of the three-color LED (8) and the light collector (2) are connected via the adhesive layer (9). Arrangement according to claim 10, characterized in that the refractive indices of are matched to each other. 14. The light exit surface of the light condenser (2) is formed in a spherical shape. The configuration according to claim 10.