KR20170058176A - Measurement Apparatus for differential spectral responsivity on photovoltaic cells - Google Patents

Measurement Apparatus for differential spectral responsivity on photovoltaic cells Download PDF

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KR20170058176A
KR20170058176A KR1020150162054A KR20150162054A KR20170058176A KR 20170058176 A KR20170058176 A KR 20170058176A KR 1020150162054 A KR1020150162054 A KR 1020150162054A KR 20150162054 A KR20150162054 A KR 20150162054A KR 20170058176 A KR20170058176 A KR 20170058176A
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current
light source
bias light
bias
output
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KR101749565B1 (en
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자이니 헬미
박성종
유재근
이동훈
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한국표준과학연구원
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G01J3/2803—Investigating the spectrum using photoelectric array detector
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/02—Details
    • G01J3/0264—Electrical interface; User interface
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/26—Testing of individual semiconductor devices
    • G01R31/2607—Circuits therefor
    • G01R31/2632—Circuits therefor for testing diodes
    • G01R31/2635—Testing light-emitting diodes, laser diodes or photodiodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/08—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors
    • H01L31/09—Devices sensitive to infrared, visible or ultraviolet radiation
    • G01J2001/4257—

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Abstract

The present invention provides a device and a method to measure a derivative of spectral responsivity. The device includes: a probe light source providing solid color probe light, of which intensity is modulated with a predetermined intensity modulation frequency, to a photoelectric device; a bias light source providing bias light, of which radiation flux is larger than the radiation flux of the probe light and of which spectrum area is wide, to the photoelectric device; a bias light source operating part operating the bias light source by providing a current to the light source; a current sink connected to an output terminal of the photoelectric device to provide a predetermined target DC current; and a control part commonly connected with the output terminal of the photoelectric device and the current sink, and receiving a difference between an output current of the photoelectric device and the target DC current to control the bias light source operating part to remove the difference.

Description

≪ Desc / Clms Page number 1 > Measurement Apparatus for Differential Spectral Responsivity on Photovoltaic Cells &

The present invention relates to an apparatus and method for evaluating a photoelectric device, and more particularly, to an apparatus for measuring photoelectric conversion efficiency of a solar cell including feedback control.

Spectral responsivity is a measure of the output of a photovoltaic conversion device or of an electrical signal to the irradiance, expressed as a function of wavelength, corresponding to an SI unit traceability spectral response characterization . Generally, the wavelength can be changed to measure the spectral sensitivity, but a reference detector that can measure the spectral light source and thus the radiation output or the radiation intensity is required, and is generally made by DC method. However, in the case of solar cells, since it is necessary to measure spectral response characteristics under a high irradiance condition of 1 kW / m 2 , direct measurement by the DC method is very difficult.

Disclosure of Invention Technical Problem [8] The present invention provides a device for measuring the spectral sensitivities of solar cells with a high signal-to-noise ratio. Specifically, when a circuit for measuring the spectral sensitivity derivative is constructed, a large direct current due to a strong bias light is induced in the solar cell. The monochromatic probe light whose intensity is modulated with a predetermined intensity modulation frequency is irradiated to the solar cell simultaneously with the bias light. In this case, the intensity-modulated monochromatic probe light induces a very small photocurrent of the modulated frequency component in the solar cell. A method is provided for efficiently and stably amplifying and measuring the induced modulated frequency component photocurrent. This extraction of the stable modulated frequency component photocurrent can be provided by stabilizing the output of the bias light with the DC component of the short circuit current of the solar cell as a control variable

A spectroscopic sensitivity derivative measurement apparatus according to an embodiment of the present invention includes: a probe light source that provides intensity-modulated monochromatic probe light with a predetermined intensity modulation frequency to an optoelectronic device; A bias light source for providing a bias light having a broad spectral range to the photoelectric device, the bias light source having a radiation flux greater than the radiation flux of the probe light; A bias light source driving unit for supplying and operating a current to the bias light source; A current sink connected to an output terminal of the photoelectric device to provide a predetermined target DC current; And a control unit connected to an output terminal of the photoelectric device and the current sink to control the bias light source driving unit to receive the difference between the output current of the photoelectric device and the target DC current, do.

In one embodiment of the present invention, the controller includes: a current-voltage converter for converting a current difference between the output current of the photoelectric element and the target DC current into a voltage signal; An inverter amplifier for changing a sign of an output signal of the current-voltage converter and outputting the sign; And an integrator for outputting an output signal of the inverter amplifier. The bias light source driving unit may provide a driving current proportional to an output signal of the integrator to the bias light source.

In one embodiment of the present invention, the bias light source may be a series-connected LED.

In one embodiment of the present invention, a lock-in amplifier for extracting an intensity-modulated frequency component from an output signal of the current-voltage converter or an output signal of the inverter amplifier; And an auxiliary controller for processing an output signal of the lock-in amplifier.

In one embodiment of the present invention, the probe light source includes a broadband light source having a wide spectral range; An intensity modulator for intensity modulating the output of the wideband light source to a predetermined intensity modulation frequency; A spectroscope for spectroscopically modulating the intensity-modulated light according to a wavelength to output monochromatic light; A beam splitter for separating the monochromatic light into two paths; And a reference photodetector disposed in one of the separated beams. And the other one of the separated beams from the beam splitter may be provided as the monochromatic probe light to the photoelectric element.

In one embodiment of the present invention, the auxiliary control unit provides a DC target current control signal to change a DC target current of the current sink, and the auxiliary control unit supplies a wavelength change control signal to the DC current source so as to change the wavelength of the monochromatic probe light. Can be provided to the probe light source.

According to an embodiment of the present invention, there is provided a spectroscopic sensitivity derivative measurement method, comprising: providing a photoelectric device with monochromatic probe light whose intensity is modulated on / off at a predetermined intensity modulation frequency; Providing a bias light having a broad spectral range to the photoelectric device with a radiation flux greater than the radiation flux of the probe light; Controlling the bias light source driving unit to generate the photocurrent by receiving the monochromatic probe light and the bias light and to remove the current difference by receiving a current difference between the photocurrent and the set target DC current of the current sink; Generating a bias light by providing a driving current of the bias light source driving unit to a bias light source; And extracting the intensity modulated frequency component from a difference in current between the photocurrent and a set target DC current of the current sink.

In one embodiment of the present invention, there is provided a method of modifying a wavelength of a monochromatic probe light, And changing the target DC current.

In one embodiment of the present invention, the step of controlling the bias light source driving unit to remove the current difference may include at least one of proportional control, integral control, proportional-integral control, or proportional-integral-differential control .

According to an embodiment of the present invention, by controlling the bias light source in a feedback manner, the intensity of the bias light can be kept constant and the DC component of the output current of the solar cell can be kept constant. The signal-to-noise ratio (SNR) of the measurement signal can be improved by sinking only the DC component current which is kept constant as the DC component of the output current of the solar cell is kept constant, and then passing the DC component current through the front-

FIG. 1 is a conceptual diagram for explaining a spectroscopic sensitivity derivative measurement apparatus according to an embodiment of the present invention.
2 is a view for explaining a feedback loop of the spectroscopic sensitivity derivative measurement apparatus of FIG.
3 is a detailed view showing a circuit of the spectroscopic sensitivity derivative measuring apparatus of FIG.
4 is a diagram showing signals of the spectroscopic sensitivity measuring apparatus of FIG.
5 is a block diagram illustrating a method for measuring spectral sensitivity according to an embodiment of the present invention.

The spectral responsivity is a function of the response current i (unit: A) with respect to the radiation flux? (Unit: W) of the incident light of a predetermined wavelength (?) In a photoelectric conversion element such as a solar cell or a photodiode When this occurs, the photoelectric conversion ratio of the photoelectric device is quantified as a function of wavelength, such as R = i / Φ (unit: A / W), which is closely related to the power generation performance.

Since the spectroscopic sensitivity varies depending on the radiation flux (?) Or intensity of incident light, it is generally expressed as R = R (?;?). Normally, the spectral sensitivity is obtained by measuring the output current of the photoelectric conversion element after the monochromatic light whose intensity is known is made incident on the photoelectric conversion element. In general, since the light output of a monochromatic light source is limited, measurements can only be made under the condition that monochromatic light of about WW or less is irradiated.

It is not appropriate to use the spectral sensitivity measured at several μW to measure the power generation performance of the solar cell operating under the condition of irradiating light of 100 mW or more.

In order to quantify the power generation performance of a photoelectric conversion element under a condition where a strong light such as a solar cell is irradiated using the spectral sensitivity, the spectral sensitivity should be measured as monochromatic light with high output. However, it is practically impossible to raise the output of a monochromatic light source to several tens mW or more. To solve this problem, the measured amount is the spectral sensitivity. The spectral sensitivity derivative can be defined as:

When the incident light of an arbitrary spectrum enters the photoelectric conversion element (or the photoelectric element) with the radiation ray flux?, The output current of the photoelectric element is represented by i and the radiation ray flux of the light of the wavelength? Let ΔΦi be the output current when the sum Φ + ΔΦ is added. The differential spectral responsivity (DSR; R '(?;?)) At the wavelength? And the radiation flux? Of the incident light is given as follows.

Figure pat00001

At this time, the light output by the radiation flux? Of the incident light does not need to be monochromatic light, but monochromatic light may be added by ?? only. Therefore, it is possible to measure the spectral responsivity derivative even with monochromatic light having a weak intensity of about μW. The spectral responsivity derivative is measured in turn while increasing the radiation flux (?) Of the incident light.

In this way, the functional relationship of R '(Φ; λ) is determined by measuring the spectral responsivity derivative against the photocathode generation (Φ) of incident light of several intensities, The efficiency (or sensitivity) can be calculated. Since the efficiency of a solar cell is generally evaluated under a standardized solar light spectrum (AM1.5 spectrum), it is generalized so that light known as a relative spectrum S (?) Is irradiated on the solar cell, out , calculate the sensitivity as a function of the output current i out .

First, the sensitivity derivative R '(i) for the bias light having the relative spectrum S (λ) from the spectral sensitivity derivative (R' (φ) of the solar cell) is calculated. That is, this sensitivity derivative means an increase in current when the bias light of the S (?) Relative spectrum (S (?)) Slightly increases the output. The spectral sensitivity derivative can be expressed both as a function of Φ or as a function of i.

Figure pat00002

When the output current of the solar cell is represented by i out, copy bias light that is incident on the solar cell in this case in flux Φ is given by:

Figure pat00003

Therefore, the sensitivity (R) for the output current i out to be obtained is given as follows.

Figure pat00004

(A weak intensity of monochromatic light) of a monochromatic probe light modulated with a predetermined intensity modulation frequency is superimposed on a radiation beam? (Strong intensity bias light) of a bias light having a constant DC light output, . It is also assumed that the radiant flux DELTA phi of the monochromatic probe light can be modulated by using a chopper.

If the photocurrent given to the solar cell by i = 100 mA and the photocurrent given by the photocathode of the monochromatic probe light to the solar cell is Δi = 0.1 μA, the photocurrent given to the solar cell by the photocathode The photocurrent flowing through the photodiode has a value of 100 mA + 0.1 μA and a current of 100 mA.

At this time, if the current difference Δi = 0.1 μA flowing in the solar cell depending on the presence or absence of the monochromatic probe light can be measured and the radiation flux (ΔΦ) of the incident monochromatic probe light can be measured with the reference detector already calibrated, R '(?;?)) Can be measured.

However, since the difference of Δi = 0.1 μA is only about 10 -6 compared to 100 mA, it is impossible to measure with a general front-end amplifier (gain: G), a lock-in amplifier, and a digital voltmeter.

According to an embodiment of the present invention, a feedback loop is operated with respect to the optical output of the bias light source, and the solar cell detects the optical output of the bias light source to generate a photocurrent, And an error, which is the difference between the photocurrent and the target DC current, is provided to the control section. The control unit generates a control signal to control the bias light source driving unit so that the optical output of the bias light source is controlled. The photocurrent of the solar cell is converted into a voltage signal by a current-to-voltage converter and amplified. By controlling the DC input current of the current-to-voltage converter to zero, the gain of the AC input current of the current-to-voltage converter is kept high. Thus, for the AC input current of the current-to-voltage converter, the current / voltage conversion gain can be increased to 10,000 times or more. The current-voltage converter may be implemented through a current-voltage front-end amplifier.

According to an embodiment of the present invention, the DC output photocurrent of the solar cell is kept constant by feedback control so that the intensity of the bias light, which is the output light of the bias light source, is kept constant, and the DC output photocurrent flows through the precise current sink. Therefore, the current-voltage converter can amplify only the AC current signal due to the monochromatic probe light with high gain. Thus, it is possible to measure the spectral sensitivity derivative having strong signal-to-noise ratio and strong against disturbance.

According to an embodiment of the present invention, when the bias light source is a light source in which a plurality of LEDs are connected in series, it is possible to light up the current with less current than when one or several LEDs are connected in parallel, Since the optical output can be stably kept constant, the AC signal component of the solar cell due to the monochromatic probe light intensity-modulated by On / Off can be extracted with a high SNR.

Generally, when measuring the spectral sensitivity derivative (DSR), the photocurrent of the solar cell due to the bias light is about 100 mA, and the AC photocurrent of the solar cell due to the monochromatic probe light is about 1 μA maximum. Therefore, in order to well separate the AC photocurrent component due to the monochromatic probe light, the intensity of the bias light requires a stability of about 1 / 100,000. According to the feedback loop of the present invention, the stability of the bias light can be maintained at 1 / 100,000 or less.

According to an embodiment of the present invention, when an LED connected in series to a bias light source is employed, a stability of about 1/100000 can be obtained by employing a feedback loop.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments disclosed herein are being provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. In the drawings, the components have been exaggerated for clarity. Like numbers refer to like elements throughout the specification.

FIG. 1 is a conceptual diagram for explaining a spectroscopic sensitivity derivative measurement apparatus according to an embodiment of the present invention.

2 is a view for explaining a feedback loop of the spectroscopic sensitivity derivative measurement apparatus of FIG.

3 is a detailed view showing a circuit of the spectroscopic sensitivity derivative measuring apparatus of FIG.

4 is a diagram showing signals of the spectroscopic sensitivity measuring apparatus of FIG.

5 is a block diagram illustrating a method for measuring spectral sensitivity according to an embodiment of the present invention.

1 to 5, the spectroscopic sensitivity derivative measuring apparatus 100 includes a probe light source 110, a bias light source 120, a bias light source driving unit 160, a current sink 140, and a controller 150 do. The probe light source 110 provides intensity-modulated monochromatic probe light to the optoelectronic device 130 at a predetermined intensity modulation frequency f m . The bias light source 120 provides bias light having a broad spectral range to the photoelectric device 130 with a radiation flux greater than the radiation flux of the probe light. The bias light source driving unit 160 supplies a driving current to the bias light source 120 to operate the bias light source. A current sink 140 is coupled to the output of the optoelectronic device 130 to provide a predetermined target DC current. The control unit 150 is connected to the output terminal of the photoelectric device and the current sink and receives the difference between the output current of the photoelectric device and the target DC current to remove the current difference, 160).

The spectroscopic sensitivity derivative measurement device must stably extract the intensity modulated frequency component from the photocurrent of the optoelectronic device 130 due to the intensity modulated monochromatic probe light with a predetermined intensity modulation frequency f m . For this purpose, the bias light source 120 is feedback-controlled to maintain the radiation flux of the bias light at a constant value.

In the feedback control, the opto-electronic device 130 functions as a measuring device, and the current sink 140 can flow a target DC current set to a target value for the control amount. The DC component of the photocurrent of the optoelectronic device 130 may be set to flow to the ground through the current sink 140. [

In the absence of the monochromatic probe light, the DC photocurrent of the photoelectric element is decomposed into the target DC current and the error DC component, and the error DC component is provided to the controller 150. The error DC component may be converted into a voltage signal by the controller 150, amplified, and then integrated to generate a bias power control signal CTRL_V. The bias power control signal CTRL_V may be provided to the bias light source driving unit 160 so that the bias light source driving unit 160 may control the driving current to change the intensity of the bias light. Thus, the error DC component is removed over time. The controller 150 may perform at least one of a proportional control, an integral control, a proportional-integral control, and a proportional-integral-differential control. Preferably, the control method may be an integral control.

On the other hand, in the case of monochromatic probe light, monochromatic probe light whose intensity is modulated with a predetermined intensity modulation frequency (f m ) corresponding to the signal is provided to the photoelectric element in the control circuit. The optoelectronic device 130 additionally outputs an alternating current component having a predetermined intensity modulation frequency f m . The photocurrent of the photoelectric element is decomposed into a target DC current component, an error DC component, and an AC signal component. The target DC current component is provided to the current sink, and the error DC component and AC signal component are provided to the control unit 150. [ The controller 150 removes the error DC component through a feedback loop.

The controller 150 includes a current-to-voltage converter 151 for converting a current difference between the output current of the photoelectric element and the target DC current into a voltage signal; An inverter amplifier 152 for changing the sign of the output signal of the current-voltage converter 151 and outputting the same; And an integrator 153 for integrating the output signal of the inverter amplifier. The bias light source driving unit 160 provides a driving current proportional to the bias power source control signal CTRL_V, which is an output signal of the integrator, to the bias light source 120.

The current-to-voltage converter 151 converts the difference between the output current of the optoelectronic device and the current of the target DC current into a voltage signal and amplifies the voltage signal. The current-voltage converter may be an inverting trans-impedance amplifier. The current-to-voltage converter 151 functions as a pre-amplifier, and the gain of the current-voltage converter may be 10 5 to 10 6 . The AC signal component of the photoelectric device can be amplified to a voltage signal of several hundreds mV to several V levels in the case of 1 μA level.

The current flowing through the current sink 140 is set to flow a target DC current set to a precise current source. The current stability of the current sink 140 may be 1 / 100,000 or less.

When the bias light source starts operating in the unlit state, the light output of the bias light source gradually increases, so that the magnitude of the photocurrent of the photoelectric device is smaller than the target DC current of the current sink. Therefore, if the sign of the current value of the current sink is set negative, the net current input to the current-voltage converter 151 becomes negative, and the error DC component can have a positive value. In order to change the sign of the error DC component, an inverting amplifier operating as an inverter is disposed at the output terminal of the current-voltage converter. The gain of the inverting amplifier is set at 0.1 to 10 levels.

The current-voltage converter 151 may include an operational amplifier OP3. The positive input of the operational amplifier OP3 is grounded and the negative input of the operational amplifier OP3 can be connected to the output of the operational amplifier OP3 via a capacitor C2 and a resistor R5 connected in parallel to each other have.

Inverter amplifier 152 includes an operational amplifier OP4 that operates to change the sign of the input signal and the operational amplifier OP4 outputs the output of the current-voltage converter 151 through a resistor R6 to a negative Input. The positive input of the operational amplifier OP4 is grounded. The negative input of the operational amplifier OP4 is connected to the output of the operational amplifier OP4 via a resistor R7,

The output of the operational amplifier OP4 has an AC signal component and an error DC component. The output of the operational amplifier OP4 is branched and connected to a lock-in amplifier 170 and an integrator 153 for generating a control signal. Respectively.

The integrator 153 may be implemented as an operational amplifier in the form of an inverting amplifier using an active amplifier. Among the input signals of the integrator 153, the AC signal components are removed by integration, and the error DC components are integrated over time to provide the bias light source control signal CTRL_V. The RC time of the integrator 153 may typically be set to several hundreds of seconds. Specifically, the input resistance of the integrator is set to several tens to several hundreds of MOhm, and the capacitance of the feedback capacitor (C1) of the integrator can be set to several mu F or more. Accordingly, the integrator 153 integrates the error DC component and outputs a bias light source control signal. The integrator may include an operational amplifier OP2. The negative input of the operational amplifier OP2 is connected to the output of the inverter amplifier 152 through a resistor R4. The negative input of the operational amplifier OP2 is connected to the output of the operational amplifier OP2 through the feedback capacitor C1. The positive input of the operational amplifier OP2 is grounded.

The bias light source control signal CTRL_V is provided to the bias light source driving unit 160. The bias light source driver 160 may be a voltage controlled current source. Specifically, the bias light source driving unit 160 may include an operational amplifier OP1 and an NMOS FET M1. The positive input of the operational amplifier OP1 may be connected to the output of the integrator 153 via a resistor R3. In addition, the positive input of the operational amplifier OP1 may be connected to the ground through another resistor R3. The negative input of the operational amplifier OP1 is connected to the source of the NMOS FET M1 and the source of the NMOS FET M1 can be grounded via the resistor R1. The gate of the NMOS FET M1 may be connected to the output terminal of the non-inverting amplifier OP1. A drain of the NMOS FET Ml may be connected to the bias light source 120. [

The bias light source driving unit 160 may provide a driving current i_BS for driving the bias light source. The bias light source driver 160 may operate the bias light source 120 with a high operation voltage and a low operation current. The operating voltage of the bias light source 120 may be several volts to several tens volts. The operating current may be from a few mA to a few hundred mA.

The current sink 140 may provide a target DC current of a short-circuit output current value level to the optoelectronic device 130. The current sink 140 may include an operational amplifier OP5 and an NMOS FET M2. The positive input of the operational amplifier OP5 is branched into three branches, one connected to ground through a resistor R10, the other grounded via a capacitor C3 and the other connected to a variable resistor R9 To the cathode power source Vee. The negative input of the operational amplifier OP5 is connected to the source of the NMOS FET M2 and the source of the NMOS FET M2 is connected to the negative power source Vee through the resistor R8. The gate of the NMOS FET M2 may be connected to the output terminal of the operational amplifier OP5. The drain of the NMOS FET M2 may be connected to one end of the opto-electronic device 130 and to the input terminal of the current-voltage converter 151. [ And the other end of the photoelectric element may be grounded.

The photoelectric element 130 may be a solar cell, but may be a device capable of generating a photocurrent, not limited to a solar cell. The photoelectric device may be a photodiode or a solar cell.

The probe light source 110 includes a broadband light source 111 having a wide spectral range; An intensity modulation unit (112) for intensity-modulating the output of the broadband light source to a predetermined intensity modulation frequency; A light splitting unit 113 for splitting the intensity-modulated light according to a wavelength to output monochromatic light; A beam splitter 114 separating the monochromatic light into two paths; And a reference photodetector 115 disposed in one of the separated beams. The other one of the separated beams from the beam splitter 114 may be provided to the optoelectronic device 130 as the monochromatic probe light.

The broadband light source 111 may be a tungsten lamp or a xenon lamp. The broadband light source may provide a continuous or discontinuous spectrum ranging from 300 nm to 1100 nm.

The intensity modulator 112 may modulate the output of the broadband light source to a predetermined intensity modulation frequency f m . The intensity modulator 112 may include a mechanical chopper and a chopper controller. The intensity modulator 112 and the wideband light source 111 may be integrated to provide an optical output in the form of a square wave with an intensity modulation frequency. Intensity modulation frequency (f m) may be a 2 Hz to 150 Hz range preferred.

The light splitting unit 113 may output the selected monochromatic light by spectrally separating the output light of the wide-band light source according to the wavelength. The light-splitting unit 113 may be a grating system, a prism system, or a filter system. The beam splitter 114 may be a plate beam splitter or a cube beam splitter. The photodetector 115 may be a silicon photodiode.

The bias light source 120 may be a broadband light source. Specifically, the bias light source may include a plurality of light emitting diodes (LEDs) connected in series with each other. The light emitting diode may be infrared, red, yellow, green, blue, white LED, or a combination thereof. The bias light source may include a plurality of organic light emitting diodes (OLEDs) connected in series.

The output of the inverter amplifier 152 includes the signal of the intensity modulated frequency component. The intensity modulated frequency component signal is demodulated by a lock-in amplifier 170. Thus, the lock-in amplifier 170 demodulates and outputs the intensity modulated frequency component. The intensity modulated frequency component is proportional to the spectral sensitivity derivative. The lock-in amplifier 170 may receive the intensity modulated frequency reference signal REF from the chopper.

The bolt meter 182 converts the output signal of the lock-in amplifier 170 into a digital signal and samples it. The bolt meter 182 transfers the intensity modulated frequency component in the form of a digital signal to the auxiliary controller 181. The auxiliary controller 181 performs a predetermined operation to calculate a derivative of spectral sensitivity.

On the other hand, a part of the monochromatic probe light is measured by the reference photodetector 115 through the beam splitter 114. The reference photodetector 115 may be a photodiode. The reference photodetector 115 can detect the radiation flux DELTA phi of the monochromatic probe light. The optical output of the monochromatic probe light is sufficiently low that the reference photodetector 115 can output a photocurrent of the level of μA. Further, since there is no DC photocurrent component, the reference current-voltage converter 183 can convert the alternating current signal into the alternating voltage signal. The reference current-voltage converter 183 may be the same as the current-voltage converter 151 described above. The reference photodetector 115 has already been calibrated.

The output signal of the reference current-to-voltage converter is provided to the auxiliary lock-in amplifier 184 and can extract the intensity-modulated driving frequency component. The output signal of the auxiliary lock-in amplifier 184 may be converted into a digital signal by the auxiliary volt meter 185 and provided to the auxiliary controller 181.

The auxiliary control unit 181 may provide the control signal CTRL_CS to the current sink to change the radial line speed of the bias light, and may sequentially change the current. In addition, the auxiliary controller may provide the control signal CTRL_PRO to change the wavelength of the monochromatic light and sequentially change the wavelength.

The auxiliary controller 181 measures the power spectral efficiency of the photoelectric device under the illumination of an arbitrary spectrum S (?) By performing the operations of Equations (2) to (4) on an arbitrary spectrum S , And the sensitivity (unit: A / W).

Referring again to FIGS. 4 and 5, the spectroscopic sensitivity measuring method provides monochromatic probe light whose intensity is modulated on / off at a predetermined intensity modulation frequency (f m ) to the photoelectric element 130 ; Providing a bias light having a broad spectral range to the photoelectric device 130 with a radiation flux greater than the radiation flux of the probe light; The photoelectric device 130 provided with the monochromatic probe light and the bias light generates a photocurrent and receives a difference between the photocurrent and a set current of the target DC current of the current sink 140 to remove the current difference. Controlling the driving unit 160; Generating a bias light by providing a driving current of the bias light source driving unit 160 to the bias light source 120; And extracting the intensity modulated frequency component from a difference in current between the photocurrent and a set target DC current of the current sink (140). The intensity modulated frequency component provides a spectral sensitivity derivative. The wavelength of the monochromatic probe light can be changed and the target DC current can be changed in order to extract the spectral sensitivity derivative according to wavelength and bias radiation speed.

Accordingly, it is possible to calculate the sensitivity of the photoelectric element under an arbitrary spectrum according to Equations (2) to (4).

The step of controlling the bias light source driving unit to remove the current difference may include at least one of a proportional control, an integral control, a proportional-integral control, and a proportional-integral-differential control. Preferably, integral control can be used.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, And all of the various forms of embodiments that can be practiced without departing from the technical spirit.

110: probe light source
120: bias light source
130: Photoelectric element
140: Current sink
150:
160: bias light source driver

Claims (9)

A probe light source for providing monochromatic probe light having intensity modulation with a predetermined intensity modulation frequency to the photoelectric element;
A bias light source for providing a bias light having a broad spectral range to the photoelectric device, the bias light source having a radiation flux greater than the radiation flux of the probe light;
A bias light source driving unit for supplying and operating a current to the bias light source;
A current sink connected to an output terminal of the photoelectric device to provide a predetermined target DC current; And
And a control unit that is commonly connected to the output terminal of the photoelectric device and the current sink and receives the difference between the output current of the photoelectric device and the target DC current to control the bias light source driver to remove the current difference Wherein the spectroscopic sensitivity derivative measurement device is a spectroscopic sensitivity derivative measurement device. The method according to claim 1,
The control unit includes:
A current-to-voltage converter for converting a current difference between the output current of the photoelectric element and the target DC current into a voltage signal;
An inverter amplifier for changing a sign of an output signal of the current-voltage converter and outputting the sign; And
And an integrator for integrating an output signal of the inverter amplifier,
Wherein the bias light source driving unit supplies a driving current proportional to an output signal of the integrator to the bias light source. 3. The method of claim 2,
Wherein the bias light source is a series-connected LED. 3. The method of claim 2,
A lock-in amplifier for extracting an intensity modulated frequency component from an output signal of the current-voltage converter or an output signal of the inverter amplifier; And
And an auxiliary controller for processing an output signal of the lock-in amplifier. The method according to claim 1,
Wherein the probe light source comprises:
A broadband light source having a wide spectral range;
An intensity modulator for intensity modulating the output of the wideband light source to a predetermined intensity modulation frequency;
A spectroscope for spectroscopically modulating the intensity-modulated light according to a wavelength to output monochromatic light;
A beam splitter for separating the monochromatic light into two paths; And
And a reference photodetector disposed in one of the separated beams,
And the other one of the separated beams from the beam splitter is provided as the monochromatic probe light to the photoelectric device. 5. The method of claim 4,
The auxiliary control section provides a DC target current control signal to change the DC target current of the current sink,
Wherein the auxiliary controller supplies a wavelength change control signal to the probe light source to change the wavelength of the monochromatic probe light. Providing a photoelectric device with monochromatic probe light whose intensity is modulated on / off at a predetermined intensity modulation frequency;
Providing a bias light having a broad spectral range to the photoelectric device with a radiation flux greater than the radiation flux of the probe light;
Controlling the bias light source driving unit to generate the photocurrent by receiving the monochromatic probe light and the bias light and to remove the current difference by receiving a current difference between the photocurrent and the set target DC current of the current sink;
Generating a bias light by providing a driving current of the bias light source driving unit to a bias light source; And
And extracting the intensity modulated frequency component from a difference in current between the photocurrent and a set target DC current of the current sink. 8. The method of claim 7,
Changing the wavelength of the monochromatic probe light; And
Further comprising changing the target DC current. ≪ Desc / Clms Page number 22 > 8. The method of claim 7,
Wherein the step of controlling the bias light source driving unit to remove the current difference includes at least one of a proportional control, an integral control, a proportional-integral control, and a proportional-integral-differential control.
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