JPS6279332A - Optical sensor - Google Patents

Abstract

PURPOSE:To make it possible to directly measure absorbing characteristics, by providing a vetreous transparent body uniformly dispersing emitting light and incident light at the leading end of the optical fiber inserted in a blood vessel to measure the light absorbing characteristic of blood and forming the leading end part of said transparent body into a prism shape having a minute gap for permitting the penetration of blood. CONSTITUTION:The side surface of an optical fiber 1 constituting an optical sensor is surrounded by a stainless steel sleeve 6 and the leading end of the opening of the sleeve 6 is filled with the vitreous transparent body 2 contacted with the end surface of the fiber 1. This transparent body 2 has action for uniformly diffusing the light projected to the fiber 1 with in the cross-section of said fiber 1. Further, the leading end part of the transparent body 2 is formed into a prism 3 having a minute gap 4 for permitting the penetration of blood 5 and light is allowed to be projected to said gap 4 and reflected. By this method, even when blood is thick and light scattering absorption is too large, the blood absorbing characteristic of a living body can be directly measured without diluting blood.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an optical sensor that uses an optical fiber to directly measure the light absorption characteristics of a liquid to be measured in real time. The present invention relates to an optical sensor suitable for measuring the light absorption characteristics of blood in real time.

(Prior Art and Its Disadvantages) Blood flowing in the blood vessels of a living body contains extremely concentrated pigment hemoglobin. Therefore, when trying to measure the light absorption characteristics of blood, such as the absorption spectrum, the optical path length at which absorption occurs must be around 0.1 mm or less; in the wavelength region where absorption is strong, the transmitted light is Since almost everyone is in a state of near ignorance, it is impossible to measure absorption characteristics over a wide wavelength range unless a particularly high-performance light receiving system is used. In ordinary absorption spectrum measurement,
Although measurements can be made by diluting such highly absorbent substances several times, this method cannot be applied to direct measurements within living blood vessels. For this direct measurement, it is necessary and essential to keep the blood absorption path extremely short in order to absorb as little light as possible.

Conventionally, as an optical sensor that directly measures the light absorption characteristics of blood using an optical fiber, a microgap was provided at the tip of a light transmitting fiber and a light receiving fiber arranged in parallel to allow blood to enter. Optical sensors are known in which an extremely short blood absorption optical path is formed at the tip of a fiber by mounting opposed prisms. However, the light that passes through the blood and returns after being transmitted, absorbed, or scattered is mostly omnidirectional, and may not be efficiently received by a receiving fiber placed at a specific location. In addition, the conventional optical sensor has the disadvantage that the light transmitting fiber and the light receiving fiber must be separately attached to the prisms arranged opposite each other, which makes the fiber attachment structure complicated and the manufacturing cost high. In other words, the light transmitting and receiving fiber bundles used in this type of optical sensor are often arranged randomly due to manufacturing reasons, and in actual use, they are often used as both light transmitting and light receiving fibers. However, it is troublesome to separate fiber bundles arranged randomly or without consideration into the transmitting fiber and the receiving fiber and attach them to the prism, which greatly increases manufacturing costs. urge

In this case, if the light-transmitting fiber bundle and the light-receiving fiber bundle are randomly arranged or directly attached to the prism, only the light that has passed through a specific optical path will enter the light-receiving fiber, resulting in extremely low light-receiving efficiency. In addition, if a fiber bundle for transmitting light and a fiber bundle for light receiving that were separated from the beginning were used, the tip of the sensor would not be integrated (the result would be thick, making it unsuitable for use as a sensor to be inserted into a narrow space within a blood vessel). be.

(Means for Solving the Problems) The present invention is intended to eliminate the above-mentioned conventional drawbacks.
For this reason, the optical sensor according to the present invention uses optical fibers for transmitting measurement light between the measurement system and the liquid to be measured, and a group of fibers for transmitting light and a group of fibers for receiving light that are arranged randomly or without considering the arrangement. Rather than attaching a prism directly to the tip of the optical fiber, an optical fiber consisting of a group of fibers is used, and instead of attaching a prism directly to the tip of the optical fiber, the output light is directed from the light transmitting fiber group to the prism and from the prism to the light receiving fiber group. A glass-like transparent body having the same cross-section as the optical fiber that uniformly disperses incident light within the cross-section is provided, and the glass-like transparent body is arranged facing each other with a minute gap that allows the liquid to be measured to enter the front end of the glass-like transparent body. A pair of prisms are provided.

(Function) The light incident on the glass-like transparent body from the light-transmitting fiber group is dispersed so as to spread over the entire cross section of the glass-like transparent body, and then enters the prism. The light incident on the prism is reflected by the outer surface of the prism, passes through a minute gap into which the liquid to be measured has entered, and then is reflected by the outer surface of one of the opposing prisms and enters the glass-like transparent body again. The light that has entered the glass-like transparent body and passed through the liquid to be measured is again dispersed so as to spread over the entire cross section of the glass-like transparent body, and is received by the light-receiving fiber group. The light received by the light-receiving fiber group is uniformly distributed in the incident position and angle of incidence within the entire cross-section of the optical fiber, so that the light can be received evenly over the entire light-receiving fiber.

(Example) Examples of the present invention will be described in detail below with reference to the drawings.

FIGS. 1 to 6 are diagrams showing an embodiment of the present invention as an optical sensor for insertion into a blood vessel.

In the figure, 1 is an optical fiber consisting of a group of light transmitting fibers and a group of light receiving fibers, 2 is attached to the tip of the optical fiber 1, and the incident light from the optical fiber 1 to a prism, which will be described later, and from the prism to the optical fiber 1. A glass-like transparent body 6.6 for uniformly diffusing incident light within the cross section of the glass-like transparent body 2 is formed integrally with the transparent body at the tip of the glass-like transparent body 2, and is arranged facing each other with a minute gap 4. The prisms 3.6 are a pair of 45° prisms, and the outer surfaces of the prisms 3.6 are at an angle of 90° to each other and serve as reflective surfaces. The optical fiber 1 has the following structure as shown in FIG.
It consists of a fiber bundle in which a light transmitting fiber group 1a and a light receiving fiber group 1b are arranged randomly within the cross section and integrated. Reference numeral 5 designates blood to be measured that has entered the minute gap 4 between the pair of prisms 6.3, and 6 is a sleeve made of stainless steel or the like that covers and supports the optical fiber 1 and the glass-like transparent body 2. The blood 5 filling the minute gap 4 forms an extremely short absorption optical path for measurement. This blood to be measured 5 can be naturally exchanged with blood outside the minute gap 4 due to the blood flow within the blood vessel.

Note that a reflector is deposited on the outer surface of the glass-like transparent body 2, and the outer side of the reflector is further coated with silicone resin. In addition, it is desirable that the axial length L of the glass-like transparent body 2, excluding the prism portion, be a length expressed by the following formula (see FIG. 7).

NA L = Dcot (sin”-)...Song------
- (1) However, D: diameter of the optical fiber NA: numerical aperture of the optical fiber n refractive index of the glass-like transparent body. Therefore, when light is input from the light source to the light transmitting fiber bundle, 1. This light passes through the transparent body 2 and is reflected by one reflective surface of the facing prism 6.6, as shown by the broken line in the figure. The reflected light passes through the blood #5 in the minute gap 4, and the scattered light enters one of the opposing prisms and is reflected by its reflective surface, and passes through the transparent body 2 again to the light receiving fiber bundle. and is transmitted to the light receiving system. At this time, the light transmitting fiber group 1
As shown in FIG. Therefore, the incident position and incident angle of the light incident on the light-receiving fiber group 1b from the glass-like transparent body 2 are made uniform within the cross section of the optical fiber 1 regardless of its arrangement.
Light can be uniformly received throughout the light receiving fiber. Therefore, the light receiving efficiency and sensor stability (
It is possible to greatly improve the characteristics of small variations in sensitivity between sensors. Since this light is transmitted or scattered in the blood, it contains information regarding the absorption characteristics of blood, which is the liquid to be measured.

Therefore, by spectroscopically analyzing this light with a light receiving system, the absorption characteristics of the blood to be measured can be measured directly and in real time. This means that it satisfies the most necessary requirements when measuring the absorption characteristics of blood in living organisms.

FIGS. 9 and 10 respectively show other embodiments of the sensor for intravascular insertion according to the present invention, and these embodiments differ only in the form of the facing prism 6.6 and other configurations. It is exactly the same as that of the previous embodiment.

FIG. 11 to FIG. 15 show still another embodiment of the sensor for insertion into a blood vessel according to the present invention, and the same reference numerals as in the previous embodiment indicate the same elements. In this embodiment, the facing prism 6.6 is separated from the transparent body 2;
This is supported by a pair of protruding pieces 7.7 extending from the tip of the prism 3.6, thereby creating a minute distance 8 between the facing prism 3.6 and the transparent body 2, which allows blood to be measured 5 of a desired thickness to further enter. It was formed. The minute separation distance 8 is thicker than the minute gap 4 between the opposing prisms (therefore, the optical path length of the blood to be measured 5 can be made larger, thereby increasing the sensitivity of the absorption characteristic and Effective measurement is possible even when the liquid is thin.

(Effects of the Invention) As an effect of the present invention, it is possible to measure the absorption characteristics of blood without diluting it, even though the absorption characteristics of blood could not be measured without dilution due to the concentration of blood, which causes too much scattering and absorption of light. The sensor structure allows blood inside the sensor to be exchanged with blood outside the sensor, so the changing absorption characteristics of blood can be measured in real time. The sensor can be easily manufactured and provided at low cost because an optical fiber in which a group of light transmitting fibers and a group of light receiving fibers are randomly arranged or whose arrangement is not taken into consideration can be used as a transmitting optical fiber; Since it uses an optical fiber in which a group of light transmitting fibers and a group of light receiving fibers are integrated, it can be configured as a sensor to be inserted into a narrow place in a blood vessel, and the glass-like transparent material allows the entire cross section of the optical fiber to be Since light can be uniformly received at the sensor, there is an advantage that the sensitivity stability of the light receiving efficiency sensor can be greatly improved.

The present invention can be applied to a wide range of fields such as measuring blood in living blood vessels, measuring lymph fluid, gastric fluid, etc. in living bodies, and monitoring industrial wastewater.

[Brief explanation of drawings]

FIG. 1 is a perspective view of one embodiment of the present invention, FIG. 2 is a top view of the same, FIG. 3 is a front view of the same, FIG. 4 is a side view of the same, and FIG.
FIG. 6 is a cross-sectional view showing an example of the arrangement of the transmitting and receiving optical fibers of the optical fiber used in the sensor of the present invention, and FIG. A diagram showing the relationship between length and diameter, etc., FIG. 8 is an enlarged sectional view of the main part of the present invention, FIGS. 9 and 10 are perspective views of other embodiments of the present invention, and FIG. 11 is an illustration of the present invention. Furthermore, a perspective view of another embodiment, FIG. 12 is a top view of the same, FIG. 16 is a front view of the same, FIG. 14 is a side view of the same, and FIG. 15 is a line 13-B of FIG. 14.
It is a figure shown with blood in KG5 sectional view. 1... Optical fiber, 2... Glass-like transparent body, 3...
・・・Prism, 4...Minute gap, 5...Blood,
8...Small separation distance. Patent issue: Sumitomo Electric Industries, Ltd. (5 others) Figure 1-Figure 9 Figure 10 Figure 11 B=

Claims (7)

[Claims] (1) Optical sensor equipped with a pair of prisms facing each other with a minute gap that allows the liquid to be measured to enter the end of an optical fiber that transmits measurement light between the measurement system and the liquid to be measured. In this method, an optical fiber consisting of a group of light-transmitting fibers and a group of light-receiving fibers arranged randomly or without considering the arrangement is used as the optical fiber, and a tip of the optical fiber is connected to a group of light-transmitting fibers from the group of light-transmitting fibers at the tip of the optical fiber. A glass-like transparent body having substantially the same cross-section as the optical fiber is provided, which uniformly disperses within the cross-section the emitted light toward the prism and the incident light from the prism toward the light-receiving fiber group; An optical sensor characterized in that the prism is provided on the front side. (2) The optical sensor according to claim 1, wherein the pair of prisms is formed integrally with the glass-like transparent body. (3) In the optical sensor according to claim 2, the axial length L of the glassy transparent body is approximately L=Dcot(
sin^-^1NA/n) However, D: diameter NA of the optical fiber: numerical aperture n of the optical fiber: refractive index of the glass-like transparent body. (4) In the optical sensor according to claim 1, the pair of prisms are arranged opposite to the glass-like transparent body with a small distance between them, and the liquid to be measured is located within the small gap and the small distance. An optical sensor characterized by being able to be penetrated. (5) An optical sensor according to any one of claims 1 to 4, characterized in that a reflector is deposited on the outer surface of the glass-like transparent body. (6) The optical sensor according to claim 5, characterized in that the outer surface of the reflector is coated with silicone resin. (7) In the optical sensor according to any one of claims 1 to 4, the sensor is an optical sensor for insertion into a blood vessel, and blood is exchanged within the minute gap or within the minute gap and a minute separation distance. An optical sensor characterized by being able to be penetrated.