Measuring device for light

Abstract

The utility model discloses a measuring device for light, and relates to the technical field of optical instruments. The system comprises a variable attenuator, a single-photon detector, a data acquisition unit and a controller, the variable attenuator, the single-photon detector, the data acquisition unit and the controller form a measuring unit, the variable attenuator is used for being connected with light to be measured, the variable attenuator is connected with the single-photon detector, the single-photon detector is electrically connected with the data acquisition unit, and the controller is electrically connected with the data acquisition unit. The data acquisition unit is electrically connected with the controller, and the controller is electrically connected with a control port of the variable attenuator. The attenuation value of the variable attenuator is correspondingly adjusted according to needs, and the measurement work efficiency is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to optical instrument technical field especially, relate to a kind of for light measuring device. BACKGROUND

[0002] Optical power meter and optical energy meter are the instruments for measuring light intensity, wherein the optical power meter measures the average power of light, and the energy meter measures the optical pulse energy, many instruments can measure optical power and energy, which is called optical power and energy meter.

[0003] The current optical power meter and optical energy meter have the following technical problems:

[0004] Because the optical attenuation value of the attenuator used in current measurement cannot be adjusted, the applicability is poor; replacing attenuators with different optical attenuation values leads to low measurement efficiency. Moreover, the sensitivity is not high.

[0005] Because the optical fiber coupling light path structure of wide-spectrum achromatic is relatively complex, the cost performance is poor. INVENTION CONTENTS

[0006] The utility model provides a kind of for light measuring device, solves the technical problem of low measurement efficiency.

[0007] To solve the above technical problems, the technical solution adopted by the utility model is as follows:

[0008] A kind of for light measuring device, including variable attenuator, single photon detector, data acquisition unit and controller, variable attenuator, single photon detector, data acquisition unit and controller form measurement unit, variable attenuator is used to connect with the light to be measured, variable attenuator is connected with single photon detector, single photon detector is electrically connected with data acquisition unit, data acquisition unit is electrically connected with controller, controller is electrically connected with the control port of variable attenuator.

[0009] Further technical solutions are as follows: the variable attenuator comprises a box body, a motor side control port fixed on the box body, an input optical fiber interface and an output optical fiber interface, a variable attenuator drive unit fixed in the box body, a stepping motor, a concave mirror, a mirror fixing frame, an optical fiber fixing frame, an input optical fiber and an output optical fiber, and an optical attenuation sheet rotating wheel located in the box body; the variable attenuator drive unit, the stepping motor, the mirror fixing frame and the optical fiber fixing frame are fixedly connected with the box body; the concave mirror is fixedly connected with the mirror fixing frame; the input optical fiber and the output optical fiber are fixedly connected with the optical fiber fixing frame; the optical attenuation sheet rotating wheel is fixedly connected with a rotating shaft of the stepping motor; a plurality of optical attenuation sheets are arranged on the optical attenuation sheet rotating wheel; one end of the input optical fiber is connected with the input optical fiber interface, and the other end of the input optical fiber is an optical output port; one end of the output optical fiber is connected with the output optical fiber interface, and the other end of the output optical fiber is an optical input port; the optical output port of the input optical fiber and the optical input port of the output optical fiber are located on the same side of the optical attenuation sheets of the optical attenuation sheet rotating wheel, the concave mirror is located on the other side of the optical attenuation sheets of the optical attenuation sheet rotating wheel, the optical output port of the input optical fiber is located on one side of a normal line of the concave mirror, and the optical input port of the output optical fiber is located on the other side of the normal line of the concave mirror; the input optical fiber is used for connecting a to-be-measured light; the output optical fiber interface of the variable attenuator is connected with an input end of the single photon detector through the output optical fiber; a control end of the controller is connected with the motor side control port of the variable attenuator; the motor side control port is electrically connected with a control end of the variable attenuator drive unit; and an output end of the variable attenuator drive unit is electrically connected with the stepping motor.

[0010] Further technical solutions are as follows: six rotating wheel holes are formed in the optical attenuation sheet rotating wheel, and the six rotating wheel holes are uniformly distributed on the optical attenuation sheet rotating wheel; no optical attenuation sheet is fixed on the first rotating wheel hole; one first optical attenuation sheet is clamped and fixed on the second rotating wheel hole to form a first group of optical attenuation sheets; one first optical attenuation sheet and one second optical attenuation sheet are clamped and fixed on the third rotating wheel hole to form a second group of optical attenuation sheets; one first optical attenuation sheet and one third optical attenuation sheet are clamped and fixed on the fourth rotating wheel hole to form a third group of optical attenuation sheets; one first optical attenuation sheet and one fourth optical attenuation sheet are clamped and fixed on the fifth rotating wheel hole to form a fourth group of optical attenuation sheets; and two first optical attenuation sheets and one fourth optical attenuation sheet are clamped and fixed on the sixth rotating wheel hole to form a fifth group of optical attenuation sheets.

[0011] Further technical solutions are as follows: the variable attenuator is a rotating wheel type variable attenuator.

[0012] Further technical solutions are as follows: the single photon detector is a silicon avalanche photodiode single photon detector.

[0013] The above technical solutions have the following beneficial effects:

[0014] First, a kind of measuring device for light, including variable attenuator, single photon detector, data acquisition unit and controller, variable attenuator, single photon detector, data acquisition unit and controller form measuring unit, variable attenuator is used to connect with the light to be measured, variable attenuator is connected with single photon detector, single photon detector is electrically connected with data acquisition unit, data acquisition unit is electrically connected with controller, controller is electrically connected with the control port of variable attenuator.According to the attenuation value of the corresponding adjustment variable attenuator as required, improve the measurement efficiency.

[0015] Second, compared with the traditional transmission lens, only one device can realize wide-spectrum achromatic fiber coupling of concave mirror, and the cost performance is good.

[0016] Third, in measurement, there is always a rotating hole in the light path, when the attenuation value needs to be adjusted, the light attenuation piece rotating wheel is rotated by the stepper motor, can be switched to any one set attenuation value, and then realize the light attenuation adjustment in a large range, since the light attenuation piece of each rotating hole is fixed, each adjustment is only switched between these fixed attenuation pieces, can obtain very high repeatability.

[0017] See the part of specific embodiment for details. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is the principle block diagram of the utility model;

[0019] Figure 2-1 It is the structural diagram of variable attenuator;

[0020] Figure 2-2 It is Figure 2-1 The structural diagram of light attenuation piece rotating wheel in

[0021] Figure 2-3 It is the light path distribution diagram of variable attenuator;

[0022] Figure 3 It is the time sequence diagram of data acquisition unit;

[0023] Figure 4 It is the structural diagram of the utility model.

[0024] Wherein: 1 light attenuation piece rotating wheel, 2-1 first rotating wheel hole, 2-2 second rotating wheel hole, 2-3 third rotating wheel hole, 2-4 fourth rotating wheel hole, 2-5 fifth rotating wheel hole, 2-6 sixth rotating wheel hole, 3 closed loop control stepping motor, 4 concave mirror, 5 mirror fixing frame, 6 input optical fiber interface, 7 output optical fiber interface, 8 input optical fiber, 9 output optical fiber, 10 optical fiber fixing frame, 11 box body, 12 light attenuation piece, 13 rotating wheel type variable attenuator, 14 silicon avalanche photodiode single photon detector, 15 FPGA board card, 16 notebook computer, 17 cable, 18 data line, 19 rotating wheel motor control line, 20 light to be measured. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative, but not as any limitation on the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0026] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, but the present application can also be implemented in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the connotation of the present application, therefore the present application is not limited to the specific embodiments disclosed below.

[0027] As shown in Figure 1 The utility model discloses a kind of for light measuring device, including variable attenuator, single photon detector, data acquisition unit, controller, USB3.0 interface and controller side control port, variable attenuator, single photon detector, data acquisition unit and controller form measurement unit.

[0028] As shown in Figure 2-1 Variable attenuator includes box body 11, motor side control port fixed on box body 11, input optical fiber interface 6 and output optical fiber interface 7, variable attenuator drive unit fixed in box body 11, closed loop control stepping motor 3, concave mirror 4, mirror fixing frame 5, optical fiber fixing frame 10, input optical fiber 8 and output optical fiber 9 and light attenuation piece rotating wheel 1 located in box body 11, variable attenuator drive unit, closed loop control stepping motor 3, mirror fixing frame 5 and optical fiber fixing frame 10 are all fixedly connected with box body 11, concave mirror 4 is fixedly connected with mirror fixing frame 5, input optical fiber 8 and output optical fiber 9 are all fixedly connected with optical fiber fixing frame 10, light attenuation piece rotating wheel 1 is fixedly connected with the rotating shaft of closed loop control stepping motor 3.

[0029] like Figure 2-2 As shown, six rotating holes, 2-1 to 2-6, are evenly distributed on the optical attenuator rotating wheel 1. No optical attenuator is fixed in the first rotating hole 2-1. A first optical attenuator is fixed in the second rotating hole 2-2 to form a first group of optical attenuators. A first optical attenuator and a second optical attenuator are fixed in the third rotating hole 2-3 to form a second group of optical attenuators. A first optical attenuator and a third optical attenuator are fixed in the fourth rotating hole 2-4 to form a third group of optical attenuators. A first optical attenuator and a fourth optical attenuator are fixed in the fifth rotating hole 2-5 to form a fourth group of optical attenuators. Two first optical attenuators and a fourth optical attenuator are fixed in the sixth rotating hole 2-6 to form a fifth group of optical attenuators.

[0030] The optical attenuator is installed in six mounting holes in the rotary device.

[0031] As shown in Table 1, this application selected four types of optical attenuators.

[0032] Table 1: Attenuator Parameter Table

[0033] Attenuation sheet number Type Operating wavelength nm Diameter mm Attenuation dB ① Absorbing 300-1100 25 10 ② Reflective 350-1100 25 10 ③ Reflective 350-1100 25 20 ④ Reflective 350-1100 25 30

[0034] As shown in Table 2, 0 to 3 optical attenuators are selected for each aperture to form six attenuation values.

[0035] Table 2: Relationship between Rotor Hole Number, Attenuation Value, and Transmittance

[0036] Rotary hole number Combination case Total attenuation value dB Total transmittance 1 Empty 0 1.0 2 ① 20 1.0 x 10 -2 ]]> 3 ①+② 40 1.0 x 10 -4 ]]> 4 ①+③ 60 1.0 x 10 -6 ]] 5 ①+④ 80 1.0 x 10 -8 ]]> 6 ①+④+① 100 1.0 x 10 -10 ]]>

[0037] During measurement, one rotating wheel hole is always in the optical path, achieving the corresponding optical attenuation. When the attenuation value needs to be adjusted, the optical attenuator wheel 1 is rotated by a stepper motor. Every 60 degrees of rotation switches to a nearby hole. Based on the current attenuation value, i.e., the current rotation angle of the stepper motor, adjusting the rotation angle allows switching to any set attenuation value. A wide range of optical attenuation adjustment can be achieved, and since the optical attenuator for each hole is fixed, each adjustment only involves switching between these fixed attenuators, resulting in extremely high repeatability.

[0038] like Figure 2-1 As shown, one end of the input fiber 8 is connected to the input fiber interface 6, and the other end of the input fiber 8 is the output port. One end of the output fiber 9 is connected to the output fiber interface 7, and the other end of the output fiber 9 is the input port.

[0039] like Figure 2-3As shown, the output port of the input fiber 8 and the input port of the output fiber 9 are located on the same side of the optical attenuator 12 of the optical attenuator wheel 1, and the concave mirror 4 is located on the other side of the optical attenuator 12 of the optical attenuator wheel 1. The output port of the input fiber 8 is located on one side of the normal of the concave mirror 4, and the input port of the output fiber 9 is located on the other side of the normal of the concave mirror 4.

[0040] like Figure 1 As shown, the light under test is connected to the input fiber optic interface of the variable attenuator via an input fiber optic cable. The output fiber optic interface of the variable attenuator is connected to the input end of the single-photon detector via an output fiber optic cable. The output end of the single-photon detector is electrically connected to the input end of the data acquisition unit via a cable. The output end of the data acquisition unit is electrically connected to the input end of the controller. The controller is electrically connected to a USB 3.0 interface. The controller's control terminal is electrically connected to the controller-side control port. The controller-side control port is electrically connected to the motor-side control port of the variable attenuator via a control line. The motor-side control port is electrically connected to the control terminal of the variable attenuator drive unit. The output end of the variable attenuator drive unit is electrically connected to the stepper motor.

[0041] When in use, the USB 3.0 interface is connected to the computer via a data cable.

[0042] The variable attenuator is described in detail below.

[0043] like Figure 2-1 As shown, the optical path structure principle is that the input fiber interface 6 and the input fiber 8 guide the light to be tested into the variable attenuator.

[0044] like Figure 2-3 As shown, the numerical aperture of the optical fiber determines the divergence angle of the light emitted from the fiber end face. The output light at the output port of the input fiber 8 propagates in a gradually diverging state, passes through the optical attenuator 12, and then illuminates the concave mirror 4. After reflection, the light begins to propagate in a gradually converging state, passes through the optical attenuator again, and finally converges at the input port of the output fiber 9. The output port of the input fiber 8 and the input port of the output fiber 9 are located on opposite sides of the optical axis of the concave mirror 4, both 1 mm away from the optical axis (normal). The input fiber 8 uses a 105 μm core diameter multimode fiber with a numerical aperture NA = 0.22; the output fiber 9 uses a 200 μm core diameter multimode fiber with a numerical aperture NA = 0.22; the concave mirror 4 uses a silver-coated film with a focal length f = 38.1 mm; the distance from the output port of the input fiber 8 and the input port of the output fiber 9 to the central front surface of the concave mirror 4 is 76.2 mm. The optical fiber-concave mirror-optical fiber form an imaging structure with an object distance and image distance of 2f. Compared with traditional transmission lenses, the concave mirror 4 only requires one device to achieve broadband achromatic optical fiber coupling.

[0045] The single photon detector is a silicon avalanche photodiode single photon detector (Si-SPAD), which is described in detail as follows.

[0046] The single photon detector is a kind of photoelectric detector capable of detecting single photons, and the photon is the basic energy unit of light. The single photon detector outputs in the form of an electric pulse when detecting a photon. The Si-SPAD works in a continuous detection mode, has a wavelength response range of 400 nm to 1100 nm, a peak wavelength detection efficiency of ~ 65%, a dark count rate of ~ 200 cps (counts per second), and a saturation count rate of ~ 15 Mcps. When the linear detection maximum count rate is ≤ 10 Mcps, the nonlinear fitting coefficient β is ≤ 1.2.

[0047] The data acquisition unit and the controller are based on an FPGA board 15, which is described in detail as follows.

[0048] The controller is an xc7A-75T chip, and the data acquisition unit supports two working modes: a counter mode and a timer mode.

[0049] As shown in Figure 3 , in the counter mode, all the electric pulse signals output by the single photon detector SPAD are accumulated within the measurement time, and finally a total count value N of the measurement is obtained. In the timer mode, the time points of all the single photon detector SPAD output signals are recorded from the start time of the measurement, and finally the time point information T1, T2, …, T n .

[0050] As shown in Figure 1 , the controller is responsible for communication with the computer, uploading the collected data to the computer, and receiving the control instructions from the computer to adjust the working parameters of the counter or the timer, or to control the attenuation value of the variable attenuator.

[0051] The program module of the computer is a prior art, which is described in detail as follows.

[0052] The computer provides a human-computer interface, through which the user can control the operation of the ultra-high sensitivity optical power and energy meter, process data, and output the measurement results. The measurement results of continuous light include optical power and photon count rate; the measurement results of pulsed light include single pulse energy, average photon number per pulse, optical pulse width, and optical pulse repetition frequency. When the light to be measured is a mixed light of pulsed light and continuous light, the measurement results of the two kinds of light are output simultaneously.

[0053] As shown in Figure 4As shown, the variable attenuator is a rotating wheel variable attenuator 13, the single photon detector is a silicon avalanche photodiode single photon detector 14, the English abbreviation is Si-SPAD; the data acquisition unit, the controller, the USB3.0 interface and the controller side control port form an FPGA board card 15; the computer is a notebook computer 16; the optical signal: the measured light 20 is connected to the rotating wheel variable attenuator 13 through the input optical fiber 8, and the attenuated measured light is guided into the silicon avalanche photodiode single photon detector 14 for detection by the output optical fiber 9. The electrical signal: the output signal of the silicon avalanche photodiode single photon detector 14 is connected into the FPGA board card 15 by the cable 17, and the data collected by the FPGA board card 15 is uploaded to the notebook computer 16 by the USB data line 18. The control signal: the computer control instruction is downloaded to the FPGA board card 15 through the USB data line 18, then the FPGA board card 15 interprets the computer control instruction, and transmits the control signal to control the motor through the rotating wheel motor control line 19.

[0054] The application provides a kind of for light measuring device, is a kind of super high sensitivity optical power and energy meter, its characteristics include:

[0055] (1) high sensitivity, compared with the optical power and energy meter of traditional photodiode probe, the sensitivity of the application is improved by about five orders of magnitude.

[0056] (2) have the function of measuring light pulse width.

[0057] (3) have the function of measuring unknown light of mixed continuous light and pulse light.

Claims

1. A device for measuring light, characterized in that: It includes a variable attenuator, a single-photon detector, a data acquisition unit, and a controller. The variable attenuator, single-photon detector, data acquisition unit, and controller form a measurement unit. The variable attenuator is used to connect to the light under test. The variable attenuator is connected to the single-photon detector. The single-photon detector is electrically connected to the data acquisition unit. The data acquisition unit is electrically connected to the controller. The controller is electrically connected to the control port of the variable attenuator. The variable attenuator includes a housing (11), a motor-side control port fixed on the housing (11), an input fiber optic interface (6) and an output fiber optic interface (7), a variable attenuator drive unit fixed inside the housing (11), a stepper motor, a concave reflector (4), a reflector mounting bracket (5), a fiber optic mounting bracket (10), an input fiber optic cable (8) and an output fiber optic cable (9), and an optical attenuator wheel (1) located inside the housing (11). The variable attenuator drive unit, the stepper motor, the reflector mounting bracket (5) and the fiber optic mounting bracket (10) are all fixedly connected to the housing (11). The concave reflector (4) is fixedly connected to the reflector mounting bracket (5). The input fiber optic cable (8) and the output fiber optic cable (9) are both fixedly connected to the fiber optic mounting bracket (10). The optical attenuator wheel (1) is fixedly connected to the shaft of the stepper motor. Multiple optical attenuators are provided on the optical attenuator wheel (1). One end of the input fiber optic cable (8) is connected to the input fiber optic interface (6). The input fiber (8) is connected to the output fiber interface (7) at one end, and the output fiber (9) is connected to the output fiber interface (7) at the other end. The output fiber (9) is connected to the input fiber interface (7) at the other end. The output fiber (8) and the input fiber (9) are located on the same side of the optical attenuator of the optical attenuator wheel (1). The concave mirror (4) is located on the other side of the optical attenuator of the optical attenuator wheel (1). The output fiber (8) is located on one side of the normal of the concave mirror (4), and the input fiber (9) is located on the other side of the normal of the concave mirror (4). The input fiber (8) is used to connect the light to be measured. The output fiber interface (7) of the variable attenuator is connected to the input end of the single photon detector through the output fiber (9). The control end of the controller is connected to the motor side control port of the variable attenuator. The motor side control port is electrically connected to the control end of the variable attenuator drive unit. The output end of the variable attenuator drive unit is electrically connected to the stepper motor. The optical attenuator wheel (1) has six rotating holes, from the first to the sixth (2-1) to (2-6), which are evenly distributed on the optical attenuator wheel (1). No optical attenuator is fixed in the first rotating hole (2-1). A first optical attenuator is fixed in the second rotating hole (2-2) to form a first group of optical attenuators. A first optical attenuator and a second optical attenuator are fixed in the third rotating hole (2-3) to form a second group of optical attenuators. A first optical attenuator and a third optical attenuator are fixed in the fourth rotating hole (2-4) to form a third group of optical attenuators. A first optical attenuator and a fourth optical attenuator are fixed in the fifth rotating hole (2-5) to form a fourth group of optical attenuators. Two first optical attenuators and a fourth optical attenuator are fixed in the sixth rotating hole (2-6) to form a fifth group of optical attenuators.

2. The light measuring device according to claim 1, characterized in that: The variable attenuator is a rotary variable attenuator (13).

3. The light measuring device according to claim 1, characterized in that: The single-photon detector is a silicon avalanche photodiode single-photon detector (14).

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