Optical sensing device

Abstract

To provide an optical sensing device that can be implemented with a simple configuration and can accurately measure the distance to an object.SOLUTION: An optical sensing device 100 includes a pulse generation unit 101 that generates a first electrical signal S1e, and an electro-optical converter 102 that converts the first electrical signal S1e into a first optical signal S1o. The optical sensing device 100 includes a branching unit 110 that branches the first optical signal S1o into a second optical signal S2o and a third optical signal S3o, and a circulator 103 that transmits the second optical signal S2o and receives a fourth optical signal S4o. The optical sensing device 100 includes a coupling unit 120 that couples the third optical signal S3o to the fourth optical signal S4o to generate a fifth optical signal S5o, and a photoelectric converter 104 that converts the fifth optical signal S5o into a second electrical signal S2e. The optical sensing device 100 includes a signal analysis unit 105 that measures the distance to an object based on time difference information of the frequency-selective fading of the second electrical signal S2e.SELECTED DRAWING: Figure 4A

Description

[Technical Field]

[0001] The present invention relates to an optical sensing device. [Background technology]

[0002] Optical distance measuring devices that measure the distance to an object using optical signals have been proposed. Patent Document 1 discloses an optical distance measuring device that measures the distance to an object by transmitting and receiving optical pulse signals. The optical distance measuring device disclosed in Patent Document 1 calculates the distance to the object based on the phase change points of the transmitted and received optical pulses. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2021 / 044534 Summary of the Invention [Problem to be solved by the invention]

[0004] The optical distance measuring device disclosed in Patent Document 1 generates and transmits an optical pulse having a first phase modulation portion with a phase change point and a second phase modulation portion in an optical pulse generation unit. The optical distance measuring device also calculates the distance from the optical distance measuring device to a measurement target based on the phase change point of the received optical pulse. Therefore, the optical distance measuring device requires the optical pulse generation unit to generate a specific optical pulse having a phase change point in advance, which poses problems of increased processing and circuit scale.

[0005] The present invention has been made in view of the problems inherent in the conventional technology, and an object of the present invention is to provide an optical sensing device that can be realized with a simple configuration and that can accurately measure the distance to an object. [Means for solving the problem]

[0006] An optical sensing device according to an embodiment of the present invention includes a pulse generating unit that generates a first electrical signal by upconverting a pulse signal at the carrier frequency of a carrier wave, an electrical-to-optical converter that converts the first electrical signal into a first optical signal, a branching unit that branches the first optical signal into a second optical signal and a third optical signal, a circulator that transmits the second optical signal to an optical transmitting unit and receives a fourth optical signal that is reflected by an object and received by an optical receiving unit, a combining unit that combines the third optical signal and the fourth optical signal to generate a fifth optical signal, an optical-to-electrical converter that converts the fifth optical signal into a second electrical signal, and a signal analyzing unit that measures the distance to the object using time difference information of frequency selective fading contained in the second electrical signal.

[0007] An optical sensing device according to another aspect of the present invention includes a pulse generating unit that generates a first electrical signal by upconverting a pulse signal at the carrier frequency of a carrier wave, a first circulator that branches the first electrical signal into a second electrical signal and a third electrical signal, an electrical-to-optical converter that converts the second electrical signal into a first optical signal, a second circulator that transmits the first optical signal to an optical transmitting unit and receives the second optical signal that is reflected by an object and received by an optical receiving unit, an optical-to-electrical converter that converts the second optical signal into a fourth electrical signal, a third circulator that combines the third electrical signal and the fourth electrical signal to generate a fifth electrical signal, and a signal analysis unit that measures the distance to the object using time difference information of frequency selective fading contained in the fifth electrical signal. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide an optical sensing device that can be realized with a simple configuration and that can measure the distance to an object with high accuracy. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing the configuration of a distance measuring system to which an optical sensing device according to an embodiment of the present invention is applied. [Figure 2A] FIG. 10 is a diagram illustrating a frequency spectrum. [Figure 2B] FIG. 2 is a diagram for explaining a pulse waveform. [Figure 3A] FIG. 10 is a diagram illustrating a frequency spectrum after upconversion. [Figure 3B] FIG. 10 is a diagram for explaining a pulse waveform after upconversion. [Figure 4A] 1 is a block diagram showing a configuration of a light-sensing device according to an embodiment of the present invention. [Figure 4B] FIG. 10 is a block diagram showing another configuration of the light-sensing device according to the present embodiment. [Figure 5] FIG. 10 is a diagram illustrating frequency selective fading with respect to a time difference ΔT. [Figure 6] FIG. 1 is a diagram illustrating a signal affected by frequency selective fading. [Figure 7A] FIG. 10 is a diagram for explaining an image of the resolution of a pulse waveform. [Figure 7B] FIG. 10 is a diagram for explaining an image of the resolution of a pulse waveform. [Figure 8A] 10A and 10B are diagrams for explaining an image of the resolution of a pulse waveform in the light-sensing device according to the embodiment. [Figure 8B] 10A and 10B are diagrams for explaining an image of the resolution of a pulse waveform in the light-sensing device according to the embodiment. [Figure 8C] 10A and 10B are diagrams for explaining an image of the resolution of a pulse waveform in the light-sensing device according to the embodiment. [Figure 9A] FIG. 1 is a diagram illustrating an image of frequency selective fading and the bandwidth of pulse width T. [Figure 9B] FIG. 1 is a diagram illustrating an image of frequency selective fading and the bandwidth of pulse width T. [Figure 9C] FIG. 1 is a diagram illustrating an image of frequency selective fading and the bandwidth of pulse width T. [Figure 10] 10A and 10B are diagrams for explaining a frequency spectrum affected by fading in the optical sensing device according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] The optical sensing device 100 according to this embodiment will be described in detail below with reference to the drawings. Note that the dimensional proportions in the drawings are exaggerated for the sake of explanation and may differ from the actual proportions. In addition, in the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

[0011] (Ranging system) Fig. 1 is a diagram showing the configuration of a ranging system to which an optical sensing device 100 according to this embodiment is applied. As shown in Fig. 1, the ranging system uses pulses having flat frequency characteristics such that the frequency spectrum has a rectangular shape, unlike pulses used in general TOF (Time Of Flight) methods.

[0012] For example, if the distance from the optical sensing device 100 to the target object 200 is d, the speed of light is c, and the time difference between the transmission time of the transmitted wave and the reception time of the received wave is ΔT, then d is expressed by the following equation (1).

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[0013] Generally, the Fourier transform between the time domain and the frequency domain has the relationship of the following equations (2) and (3). The waveform of a pulse whose frequency power spectrum is rectangular is as shown in Fig. 2A and Fig. 2B. Fig. 2A is a diagram for explaining the frequency spectrum. Fig. 2B is a diagram for explaining the pulse waveform.

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[0014] In this embodiment, the pulses shown in Figures 2A and 2B are up-converted at a carrier frequency fc, resulting in a pulse signal with a waveform as shown in Figures 3A and 3B. Figure 3A is a diagram for explaining the frequency spectrum after up-conversion. Also, Figure 3B is a diagram for explaining the pulse waveform after up-conversion.

[0015] The upconverted pulses shown in Figures 3A and 3B can utilize frequency domain information that was not available in conventional pulse baseband signals. Furthermore, the upconverted pulses can obtain peaks by adjusting the phase so that the amplitudes of the upconverted carriers and the carrier frequency fc of the carrier wave are not canceled out. Therefore, in the optical sensing device 100 according to this embodiment, the bandwidth of the upconverted pulses is equal to or greater than the carrier frequency fc.

[0016] Next, the light-sensing device 100 according to this embodiment will be described in detail.

[0017] (Optical sensing device 100) 4A is a block diagram showing the configuration of the optical sensing device 100 according to this embodiment. In the example shown in FIG. 4A, the optical sensing device 100 includes a pulse generating unit 101, an electro-optical converter 102, a branching unit 110, a circulator 103, a coupling unit 120, an optical-electrical converter 104, and a signal analyzing unit 105.

[0018] The pulse generating unit 101 generates a first electrical signal S1e by up-converting a pulse signal with a carrier wave. Specifically, the pulse generating unit 101 up-converts a waveform such as that shown in Figures 2A and 2B with the carrier frequency fc of the carrier wave to generate a signal such as that shown in Figures 3A and 3B.

[0019] The electro-optical converter 102 converts the first electrical signal S1e into a first optical signal S1o. The electro-optical converter 102 uses a light-emitting element, or a light-emitting element and an external optical modulator, and applies a light-emitting element or an external optical modulator that can track the carrier frequency fc.

[0020] The branching unit 110 branches the first optical signal S1o into a second optical signal S2o and a third optical signal S3o. The branching unit 110 uses a general coupler.

[0021] The circulator 103 transmits the second optical signal S2o to an optical transmitting unit (not shown), and receives a fourth optical signal S4o that is reflected by the object 200 and received by an optical receiving unit (not shown). Note that the optical transmitting unit and the optical receiving unit may be configured by a general antenna.

[0022] The combining unit 120 combines the second optical signal S2o and the fourth optical signal S4o to generate a fifth optical signal S5o. The combining unit 120 uses a coupler with low polarization dependency.

[0023] The optical-electrical converter 104 converts the fifth optical signal S5o into a second electrical signal S2e. The optical-electrical converter 104 may be a photodiode or the like that can track the carrier frequency fc.

[0024] The signal analysis unit 105 measures the distance to the object 200 based on the time difference information of frequency selective fading included in the second electrical signal S2e. Fig. 5 is a diagram for explaining frequency selective fading with a time difference ΔT. Fig. 6 is a diagram for explaining a signal affected by frequency selective fading.

[0025] Here, frequency selective fading is a characteristic that occurs when, for example, radio signals or other signals with a time difference due to multipath are received together. In this embodiment, the optical sensing device 100 splits the first optical signal S1o into a second optical signal S2o and a third optical signal S3o, and combines a fourth optical signal S4o, which is a received wave corresponding to the transmitted second optical signal S2o, with the second optical signal S2o. As a result, in this embodiment, frequency selective fading appears as shown in FIGS. 5 and 6. The signal analysis unit 105 measures the distance to the target 200 based on ΔT that appears in this frequency selective fading. Specifically, the signal analysis unit 105 measures the distance to the target 200 based on the above equation (1).

[0026] 4B is a block diagram showing another configuration of the optical sensing device 100 according to this embodiment. In the example shown in FIG. 4B, the optical sensing device 100 includes a pulse generating unit 101, a first circulator 103a, an electrical-to-optical converter 102, a second circulator 103b, an optical-to-electrical converter 104, a third circulator 103c, and a signal analyzing unit 105.

[0027] The pulse generating unit 101 generates a first electrical signal S1e by up-converting a pulse signal with the carrier frequency of a carrier wave. Specifically, the pulse generating unit 101 up-converts a waveform such as that shown in Figures 2A and 2B with the carrier frequency fc of the carrier wave to generate a signal such as that shown in Figures 3A and 3B.

[0028] The first circulator 103a splits the first electrical signal S1e into a second electrical signal S2e and a third electrical signal S3e.

[0029] The electrical-optical converter 102 converts the second electrical signal S2e into a first optical signal S1o.

[0030] The second circulator 103b transmits the first optical signal S1o to an optical transmitting unit (not shown), and receives the second optical signal S2o reflected by the object 200 and received by an optical receiving unit (not shown). Note that the optical transmitting unit and the optical receiving unit may be configured by a general antenna.

[0031] The optical-electrical converter 104 converts the second optical signal S2o into a fourth electrical signal S4e.

[0032] The third circulator 103c combines the third electrical signal S3e and the fourth electrical signal S4e to generate a fifth electrical signal S5e.

[0033] The signal analysis unit 105 measures the distance to the object 200 based on the time difference information of frequency selective fading included in the fifth electrical signal S5e. Details of the distance measurement process in the signal analysis unit 105 are the same as those of the signal analysis unit 105 in Fig. 4A described above, and therefore will not be described here.

[0034] Figures 7A and 7B are diagrams for explaining the image of the resolution of a general pulse waveform. As shown in Figures 7A and 7B, in a conventional pulse waveform, the pulse width limits the resolution, and a decrease in the strength of the received pulse makes it difficult to detect the signal (see Figure 7B). Note that Figure 7A shows an example where ΔT is the half-width, and Figure 7B shows an example where ΔT is 0.5 × T with respect to the pulse width T.

[0035] In the case of the pulse waveform of the optical sensing device 100 according to this embodiment, separation is possible even when ΔT is T / 2 with respect to the pulse width T, as shown in the image of the resolution of the pulse waveform shown in Figures 8A to 8C. Furthermore, because the optical sensing device 100 has flat frequency characteristics as shown in Figure 3A, it is possible to determine the time difference by analyzing the period based on the frequency spectrum of the pulse waveform affected by frequency selective fading on the frequency axis as shown in Figure 9A.

[0036] For example, if the frequency at which the first dip occurs in Figure 9B is the dip frequency fd, then since fd = 1 / (2 x ΔT), it is possible to calculate the time difference ΔT from the dip frequency fd. Furthermore, by adjusting the upconverting frequency to the desired resolution (first dip frequency), analysis with a resolution higher than the pulse width is possible. Figure 9C shows a waveform when ΔT is 0.25 x T and the upconverting carrier frequency fc is 1.5 / 2T. Furthermore, Figure 10 shows a waveform of a frequency spectrum affected by fading.

[0037] In conventional optical distance measuring devices, the pulse width limits the detection resolution. On the other hand, the optical sensing device 100 according to this embodiment uses frequency-upconverted pulses to detect the interference frequency of the signal, thereby enabling the detection resolution limit to be doubled compared to the case of a pulse width of T. Furthermore, by adjusting the upconverted frequency, the optical sensing device 100 is also capable of analysis beyond the resolution of the pulse width. Furthermore, by adjusting the upconverted frequency, interference with the sensor signal can be suppressed even when another device uses a light source with the same wavelength, thereby enabling high sensitivity.

[0038] As described above, the optical sensing device 100 includes a pulse generating unit 101 that generates a first electrical signal S1e by up-converting a pulse signal with a carrier frequency of a carrier wave. The optical sensing device 100 also includes an electro-optical converter 102 that converts the first electrical signal S1e into a first optical signal S1o. The optical sensing device 100 also includes a branching unit 110 that branches the first optical signal S1o into a second optical signal S2o and a third optical signal S3o. The optical sensing device 100 also includes a circulator 103 that transmits the second optical signal S2o to an optical transmitting unit and receives a fourth optical signal S4o that is reflected by the object 200 and received by an optical receiving unit. The optical sensing device 100 also includes a combining unit 120 that combines the third optical signal S3o and the fourth optical signal S4o to generate a fifth optical signal S5o. The optical sensing device 100 also includes an optical-electrical converter 104 that converts the fifth optical signal S5o into a second electrical signal S2e. The optical sensing device 100 also includes a signal analysis unit 105 that measures the distance to the target object 200 based on time difference information of frequency selective fading included in the second electrical signal S2e.

[0039] As a result, the optical sensing device 100 performs analysis in the frequency domain when measuring the distance to the object 200, and is therefore only affected by noise components in the frequency band of the pulse signal, making it possible to suppress noise compared to methods that perform analysis in the time domain. Furthermore, the optical sensing device 100 does not need to include a phase change point in the pulse signal, and can be implemented with a simple configuration, making it possible to measure the distance to the object 200 with high accuracy.

[0040] In another configuration, the optical sensing device 100 includes a pulse generating unit 101 that generates a first electrical signal S1e by up-converting a pulse signal at the carrier frequency of a carrier wave. The optical sensing device 100 also includes a first circulator 103a that branches the first electrical signal S1e into a second electrical signal S2e and a third electrical signal S3e. The optical sensing device 100 also includes an electro-optical converter 102 that converts the second electrical signal S2e into a first optical signal S1o. The optical sensing device 100 also includes a second circulator 103b that transmits the first optical signal S1o to an optical transmitting unit and receives a second optical signal S2o that is reflected by the object 200 and received by an optical receiving unit. The optical sensing device 100 also includes an optical-electrical converter 104 that converts the second optical signal S2o into a fourth electrical signal S4e. The optical sensing device 100 also includes a third circulator 103c that combines the third electrical signal S3e and the fourth electrical signal S4e to generate a fifth electrical signal S5e. The optical sensing device 100 also includes a signal analyzer 105 that measures the distance to the target 200 based on time difference information of frequency selective fading included in the fifth electrical signal S5e.

[0041] As a result, the optical sensing device 100 performs analysis in the frequency domain when measuring the distance to the object 200, and is therefore only affected by noise components in the frequency band of the pulse signal, making it possible to suppress noise compared to methods that perform analysis in the time domain. Furthermore, the optical sensing device 100 does not need to include a phase change point in the pulse signal, and can be implemented with a simple configuration, making it possible to measure the distance to the object 200 with high accuracy.

[0042] Furthermore, in the optical sensing device 100, the carrier frequency for upconverting the pulse signal may be equal to or less than the pulse bandwidth of the pulse signal. This makes it possible to obtain a signal peak by adjusting the phase of the upconverted pulse so that the upconversion frequency and amplitude do not cancel each other out.

[0043] (Other embodiments) Although the embodiments have been described in detail with reference to the drawings, the present embodiments are not limited to the contents described in the above embodiments. Furthermore, the components described above include those that can be easily imagined by a person skilled in the art and those that are substantially the same. Furthermore, the configurations described above can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the configurations can be made without departing from the spirit of the embodiments.

[0044] The features of the optical sensing device 100 are described below.

[0045] The optical sensing device 100 according to the first aspect includes a pulse generating unit 101 that generates a first electrical signal S1e by up-converting a pulse signal at the carrier frequency of a carrier wave. The optical sensing device 100 also includes an electro-optical converter 102 that converts the first electrical signal S1e into a first optical signal S1o. The optical sensing device 100 also includes a branching unit 110 that branches the first optical signal S1o into a second optical signal S2o and a third optical signal S3o. The optical sensing device 100 also includes a circulator 103 that transmits the second optical signal S2o to an optical transmitting unit and receives a fourth optical signal S4o that is reflected by the object 200 and received by an optical receiving unit. The optical sensing device 100 also includes a combining unit 120 that combines the third optical signal S3o and the fourth optical signal S4o to generate a fifth optical signal S5o. The optical sensing device 100 also includes an optical-electrical converter 104 that converts the fifth optical signal S5o into a second electrical signal S2e. The optical sensing device 100 also includes a signal analysis unit 105 that measures the distance to the target object 200 based on time difference information of frequency selective fading included in the second electrical signal S2e.

[0046] According to the above configuration, the optical sensing device 100 performs analysis in the frequency domain when measuring the distance to the object 200, so that it is only affected by noise components in the frequency band of the pulse signal, making it possible to suppress noise compared to methods that perform analysis in the time domain. Furthermore, the optical sensing device 100 does not need to include a phase change point in the pulse signal, and can be implemented with a simple configuration, making it possible to accurately measure the distance to the object 200.

[0047] The optical sensing device 100 according to the second aspect includes a pulse generating unit 101 that generates a first electrical signal S1e by up-converting a pulse signal at the carrier frequency of a carrier wave. The optical sensing device 100 also includes a first circulator 103a that branches the first electrical signal S1e into a second electrical signal S2e and a third electrical signal S3e. The optical sensing device 100 also includes an electro-optical converter 102 that converts the second electrical signal S2e into a first optical signal S1o. The optical sensing device 100 also includes a second circulator 103b that transmits the first optical signal S1o to an optical transmitting unit and receives a second optical signal S2o that is reflected by the object 200 and received by an optical receiving unit. The optical sensing device 100 also includes an optical-electrical converter 104 that converts the second optical signal S2o into a fourth electrical signal S4e. The optical sensing device 100 also includes a third circulator 103c that combines the third electrical signal S3e and the fourth electrical signal S4e to generate a fifth electrical signal S5e. The optical sensing device 100 also includes a signal analyzer 105 that measures the distance to the target 200 based on time difference information of frequency selective fading included in the fifth electrical signal S5e.

[0048] According to the above configuration, the optical sensing device 100 performs analysis in the frequency domain when measuring the distance to the object 200, so that it is only affected by noise components in the frequency band of the pulse signal, making it possible to suppress noise compared to methods that perform analysis in the time domain. Furthermore, the optical sensing device 100 does not need to include a phase change point in the pulse signal, and can be implemented with a simple configuration, making it possible to accurately measure the distance to the object 200.

[0049] The pulse signal of the optical-sensing device 100 according to the third embodiment may have a bandwidth equal to or greater than the carrier frequency.

[0050] According to the above configuration, in the optical sensing device 100, the upconverted pulse can obtain a signal peak by adjusting the phase so that the frequency and amplitude for upconversion do not cancel each other out.

[0051] The pulse signal of the optical sensing device 100 according to the fourth embodiment may be resolvable even if the half width is half the pulse width.

[0052] According to the above configuration, the optical sensing device 100 can determine the time difference by analyzing the period based on the frequency spectrum of the pulse waveform affected by frequency selective fading on the frequency axis.

[0053] The pulse signal of the optical sensing device 100 according to the fifth aspect may have a relationship of fd=1 / (2×ΔT), where fd is the frequency at which the first dip occurs in the frequency characteristic fading of the pulse signal and ΔT is the half-width.

[0054] With the above configuration, the optical sensing device 100 can obtain the time difference ΔT from the dip frequency fd. Furthermore, by adjusting the upconversion frequency to a desired resolution (first dip frequency), the optical sensing device 100 can perform analysis with a resolution higher than that of the pulse width.

[0055] The pulse generating section 101 of the light-sensing device 100 according to the sixth embodiment may generate the first electrical signal by adjusting the phase so that the wave number and amplitude for up-conversion do not cancel each other out.

[0056] According to the above configuration, in the optical sensing device 100, the first electrical signal, which is an upconverted pulse, can obtain a signal peak by adjusting the phase so that the frequency and amplitude for upconversion do not cancel each other out.

[0057] In the light-sensing device 100 according to the seventh aspect, the carrier frequency for up-converting the pulse signal may be equal to or less than the pulse bandwidth of the pulse signal.

[0058] According to the above configuration, in the optical sensing device 100, the upconverted pulse can obtain a signal peak by adjusting the phase so that the frequency and amplitude for upconversion do not cancel each other out. [Explanation of symbols]

[0059] 100 Optical sensing device 101 Pulse generation unit 102 Electrical-optical converter 103 Circulator 103a First Circulator 103b Second Circulator 103c Third Circulator 104 Optical-electrical converter 105 Signal analysis section 110 Branch 120 Joint S1e First electrical signal S2e Second electrical signal S3e Third electrical signal S4e Fourth electrical signal S5e 5th electrical signal S1o First optical signal S2o Second optical signal S3o Third optical signal S4o Fourth optical signal S5o Fifth optical signal

Claims

1. a pulse generating unit that generates a first electrical signal by up-converting a pulse signal with a carrier frequency of a carrier wave; an electrical-to-optical converter that converts the first electrical signal into a first optical signal; a branching unit that branches the first optical signal into a second optical signal and a third optical signal; a circulator that transmits the second optical signal to an optical transmitter and receives a fourth optical signal that is reflected by an object and received by an optical receiver; a combiner that combines the third optical signal and the fourth optical signal to generate a fifth optical signal; an optical-to-electrical converter that converts the fifth optical signal into a second electrical signal; a signal analysis unit that measures a distance to the object based on time difference information of frequency selective fading included in the second electrical signal; An optical sensing device comprising:

2. a pulse generating unit that generates a first electrical signal by up-converting a pulse signal with a carrier frequency of a carrier wave; a first circulator that branches the first electrical signal into a second electrical signal and a third electrical signal; an electrical-to-optical converter that converts the second electrical signal into a first optical signal; a second circulator that transmits the first optical signal to an optical transmitter and receives a second optical signal that is reflected by an object and received by an optical receiver; an optical-to-electrical converter that converts the second optical signal into a fourth electrical signal; a third circulator that combines the third electrical signal and the fourth electrical signal to generate a fifth electrical signal; a signal analysis unit that measures a distance to the object based on time difference information of frequency selective fading included in the fifth electrical signal; An optical sensing device comprising:

3. The optical sensing device according to claim 1 , wherein the pulse signal has a bandwidth equal to or greater than the carrier frequency.

4. 3. The optical sensing device according to claim 1, wherein the pulse signal can be resolved even if the half width is half the pulse width.

5. 3. The optical sensing device according to claim 1, wherein the pulse signal has a relationship of fd = 1 / (2 x ΔT), where fd is the frequency at which the first dip occurs in the frequency characteristic fading of the pulse signal and ΔT is the half-value width.

6. The optical sensing device according to claim 1 , wherein the pulse generating section generates the first electrical signal by adjusting a phase so that a wave number for up-conversion and an amplitude do not cancel each other out.

7. The optical sensing device according to claim 1 or 2, wherein the carrier frequency for up-converting the pulse signal is equal to or less than a pulse bandwidth of the pulse signal.

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