JPH0442749Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to an optical measuring device, and relates to a structure for measuring temperature using, for example, a material in which the amount of light transmitted changes depending on the temperature.

[Conventional technology]

Figure 4 shows an example of a temperature measuring device using light. In the figure, 1 is an LED as a light emitting element for reference light, 2 is an LED for signal light, and 3 is LED 1, 2.
4 is a half-mirror that combines LEDs 1 and 2, 5 is a detection element (hereinafter referred to as PD) for monitoring the light intensity of LEDs 1 and 2, 6 is an optical fiber for transmission, and 7 is for detecting temperature. 8 is the optical fiber for reception, 9 is the sensor 7
10 is a PD for signals that detects the light transmitted through the
A conversion section drives 5 and 9 to convert detected light into electricity, 11 is a signal processing section, and 12 is a display section.

Next, the operation will be explained.

In a device that measures temperature using a sensor 7 in which the amount of transmitted light changes depending on the temperature, there is an LED 1 that emits a reference light of a wavelength that does not change due to the temperature change of the sensor 7, and an LED 1 that emits a reference light whose transmitted light does not change depending on the temperature change of the sensor 7. The driving unit 3 causes the LED 2, which emits signal light of a wavelength that changes with each pulse, to be turned on alternately in a pulsed manner. The light multiplexed by the half mirror 4 is guided to the sensor 7 through the optical fiber 6. Sensor 7 has two LEDs 1,
Among the lights of 2, only the light intensity of LED 2 for signal light is transmitted in a light intensity corresponding to the temperature amount, and the light intensity of LED 2 for signal light is transmitted.
The light from LED1 passes through as is. Both lights are guided to the PD 9 via the optical fiber 8 and the conversion unit 1
0 and converted to voltage. In order to prevent errors in light intensity reduction due to deterioration of LEDs 1 and 2, the light intensity is monitored by a monitor PD5. This signal is also converted into voltage and subjected to signal processing such as division in the signal processing section 11 to estimate and detect the temperature and display it on the display section 12.

[Problem that the invention attempts to solve]

Since the conventional optical temperature measuring device is configured as described above, the half mirror 4 for combining lights of different wavelengths and monitoring the light amount is essential. For this reason, it became expensive and large.

This invention aims to eliminate the half-mirror and make it cheaper and smaller in order to solve the above problem.

[Means for solving problems]

The optical measurement device according to this invention has an LED and a monitoring PD arranged close to each other on the same plane with the light emitting side and the light receiving side facing the same direction, and the input side of the optical fiber for transmission. The end face of the ferrule is formed into a reflective surface, and each of the LEDs arranged close to each other,
A PD and a ferrule are arranged opposite to each other with a predetermined distance therebetween.

[Effect]

In this idea, each LED, PD for monitor
Since the ferrules of the optical fibers are arranged at predetermined positions, the light emitted from each LED directly enters the optical fiber for transmission, and also reflects from the ferrules and enters the PD for monitoring.

[Example of idea]

An embodiment of this invention will be described below.
In Fig. 1, 1 is an LED for reference light, 2 is an LED for signal light, 3 is a drive unit for driving LEDs 1 and 2, 5 is a monitor PD that monitors the amount of light,
6 is an optical fiber for transmission, 7 is a sensor for detecting temperature, 8 is an optical fiber for reception, 9 is a PD for a signal that detects the light transmitted through the sensor 7, and 10 is a PD
11 is a signal processing unit, 12 is a display unit that displays the detected temperature, and 13 and 14 are the input side ends of the optical fiber 6 for transmission. and an optical fiber ferrule provided at the output side end of the receiving optical fiber 8, respectively.

Next, the operation will be explained.

The sensor 7, which is made of semiconductor or the like and whose light transmission amount changes depending on the temperature, is configured so that the transmission/absorption amount (hereinafter referred to as the absorption side) changes with the wavelength, as shown in Figure 2a, and this absorption edge changes as the temperature rises. and move to the long wavelength band. The LED consists of a reference light LED 1 that transmits a constant amount regardless of sensor temperature changes, and a signal light LED 2 that transmits a constant amount of light depending on the sensor temperature. The lighting is repeated alternately by the drive unit 3. The absorption edge at a certain temperature and each wavelength waveform of LEDs 1 and 2 are shown in FIG. 2b, and the amount of transmission at that time is shown in FIG. 2c. Since the LEDs 1, 2 and PD5 are arranged close to each other on the same chip 15 as shown in Fig. 3a and b, the reflective surface 1 as shown in Fig. 3c
By bringing the ferrule 13 for the optical fiber in which the optical fiber 3a is formed close to each other, it becomes possible to perform monitoring using the PD 5 for monitoring due to multiplexing and reflection at the end of the ferrule. The light that has been multiplexed and entered the optical fiber 6 is
The light passes through the sensor 7 and becomes an appropriate amount of light, and is guided to the PD 9 via the optical fiber 8 for reception. The converter 10 converts the amount of light from the monitor PD 5 and the signal PD 9 into an amount of electricity, which is sent to the signal processor 11 . The signal processing unit 11 generates a reference light whose transmission amount is constant regardless of the temperature of the sensor 7, a signal light whose transmission amount corresponds to the temperature of the sensor 7, and a signal light from the PD 5 for monitoring.
The temperature of the sensor 7 is estimated and detected by performing calculations such as division using the reference light and a total of four signals. With the above configuration, it is possible to eliminate errors such as a decrease in light intensity due to deterioration of the LEDs 1 and 2 and a change in light intensity due to bending of the optical fibers 6 and 8, and to display an accurate temperature on the display section 12.

Furthermore, since the conventionally used half mirror 4 is no longer necessary, the device becomes inexpensive and compact.

In addition, this idea uses light to generate wavelengths of two or more wavelengths.
Similar effects can be achieved in measurements that require LEDs, such as optical measurement devices such as optical pressure measurement devices that utilize the photoelastic effect.

[Effect of idea]

As described above, according to this invention, each LED, a monitor PD, and an optical fiber ferrule are arranged facing each other at predetermined positions, so there is no need for any special equipment to combine light. It has the effect of being inexpensive and compact.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram showing an embodiment of this invention, Figure 2 a shows the temperature shift of the absorption edge wavelength, and Figure 2 b shows the LED
Figure 3 shows the wavelength waveform and absorption edge wavelength of , Figure c shows the transmitted light intensity in figure b, Figure 3 shows the reference light LED, signal light LED, and monitor light arranged on the same chip.
In the layout diagram of the PD, a and b are side views, respectively.
FIG. 4 is a front view, FIG. In the figure, 1 and 2 are LEDs as light emitting elements,
5 is a PD as a detection element for monitoring, 6 and 8 are optical fibers for transmission and reception, respectively, 7 is a sensor as a material, 9 is a PD for signals, 11 is a signal processing unit, and 13 and 14 are ferrules. It is. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims for Utility Model Registration] (1) A light-emitting element, a material whose transmission characteristics for light of a specific wavelength change as a function of a measured quantity, and a transmission optical fiber that guides the light emitted from the light-emitting element to the material. , a signal detection element that receives the light transmitted through the material via a receiving optical fiber and converts it into an electrical quantity, and a signal detection element that monitors the light emitted from the light emitting element without passing the emitted light through the material. In the apparatus, the light emitting element and the monitoring detecting element are connected to each other on the light emitting side. , are arranged close to each other on the same plane with their light receiving sides in the same direction, and the end face of the input side ferrule of the transmitting optical fiber is formed as a reflective surface, so that each of the elements disposed close to each other and the transmitting An optical measurement device characterized in that a reliable optical fiber and an input side ferrule are arranged opposite to each other with a predetermined distance therebetween. (2) A light-emitting element is a light-emitting element for signal light that emits signal light of a specific wavelength whose light transmission characteristics change as a function of the measured quantity; The optical measuring device according to claim 1, which is a utility model, and comprises a reference light emitting element that emits a reference light having a constant wavelength regardless of changes. (3) The optical measurement device according to claim 1 or 2 of the utility model registration claim, wherein the measured quantity is temperature.