CN107314887B - Method for estimating absolute light response rate of photomultiplier under low light intensity condition - Google Patents

Abstract

The invention relates to the field of optical measurement, and discloses a method for estimating absolute light response rate of a photomultiplier under the condition of low light intensity, wherein a silicon photodiode is used as a reference for calibrating absolute light power of the photomultiplier to be measured, and the incident light power is 10 ^‑6 W to 10 ^‑11 Calibration of silicon photodiode nonlinearity, linearity under WWherein the method comprises the steps of Silicon photodiode output signal I _A+B (k) Is of non-linearity of (2)Output signal I of photomultiplier to be measured _C+D (k) Is of non-linearity of (2)Determination of photomultiplier at incident light power of 10 ^‑11 Absolute response under W; estimated at optical power of 10 ^‑16 Absolute light response at W; obtaining the photomultiplier to be tested at 10 ^‑11 W to 10 ^‑16 Absolute light response ratio in the W range.

Description

A method for estimating the absolute photoresponsivity of a photomultiplier tube at low light intensity

technical field

The invention relates to the field of optical measurement, in particular to a method for estimating the absolute light responsivity of a photomultiplier tube under low light intensity conditions by using nonlinear correction to estimate the absolute light responsivity of a photomultiplier tube.

Background technique

The measurement of extremely low-power light plays an important role in scientific research and industrial applications, such as astronomical observation, nuclear radiation detection, bioluminescence detection, and spectroscopy measurement. Photomultiplier tubes are used in photodetectors to measure the visible light region. Low power light; the most common method of accurately measuring absolute photoresponsivity is to compare the measurement results of the detector under test with the data of a calibrated reference light source or photodetector. The defect of the current existing technology is that the estimation of the absolute photoresponsivity and the measurement of the linearity are carried out separately, and it is only for a certain spectral range or a certain narrow optical power range, relying on these experimental results is not enough to estimate The photoresponsivity measured by the photomultiplier tube in a wide power range, and the method for estimating the absolute photoresponsivity of the photomultiplier tube under low light intensity conditions can solve the problem.

The responsivity of a photodiode refers to the ratio of its output current signal to the amount of input radiation, and the responsivity is usually a function of the wavelength of the input radiation; if the responsivity of a photodiode does not change with the amount of input radiation, it is called Linearity, linearity is one of the basic requirements for precision measurement of optical radiation, especially in the field of photometry and radiometry, in the linearity measurement method, the superposition method is a basic method, by the literature [Sanders, CLJRes.NatlBur .Stand.A1972, 76, 437] and literature [Sanders, CLAppl.Opt.1962, 1, 207] we can see that the principle of the superposition method for measuring nonlinearity is that the light emitted by two light sources is respectively in the photodiode to be tested The resulting photoresponses are N ₁ and N ₂ , the sum of the light from the two light sources produces a photoresponse in the photodiode under test of N ₁₂ , if N ₁ +N ₂ =N ₁₂ , the photodiode under test can be considered to be Linearly, if N ₁ +N ₂ ≠ -N ₁₂ , the non-linearity can be given by N ₁₂ /(N ₁ +N ₂ ). Two different light sources or one light source and two different apertures can be used in the above method.

Contents of the invention

In order to solve the above problems, the present invention uses nonlinear correction to estimate the absolute light responsivity of the photomultiplier tube, which is estimated by comparing with the result obtained by the calibrated optical attenuator. The power range in the visible light range is wide, and the minimum optical power can be close to the single photon level.

The present invention proposes a method for estimating the photoresponsivity of a photomultiplier tube under visible light irradiation with optical power at the single-photon level, based on three factors: the spectral responsivity of the calibrated silicon photodiode; the calibrated silicon photodiode Conversion of responsivity to photomultiplier tubes; nonlinearity correction for silicon photodiodes and photomultiplier tubes.

The technical scheme adopted in the present invention is:

The method for estimating the absolute photoresponsivity of a photomultiplier tube under low light intensity conditions, the device mainly includes a laser, an attenuator I, a dark box, a beam splitter I, an attenuator II, a plane mirror I, a shutter I, a shutter II, and a plane mirror II, beam splitter II, cassette, silicon photodiode, photomultiplier tube to be tested, said beam splitter I, attenuator II, plane mirror I, shutter I, shutter II, plane mirror II, beam splitter II, cassette, silicon The photodiode and the photomultiplier tube to be tested are all located in the dark box, the silicon photodiode and the photomultiplier tube to be tested are located in the dark box, and the laser emits laser light through the attenuator 1 to the beam splitter 1, and the Laser, attenuator I, beam splitter I, shutter I, plane mirror II, beam splitter II, and silicon photodiode form an optical path I. The laser, attenuator I, beam splitter I, attenuator II, plane mirror I, The shutter II, the beam splitter II, and the silicon photodiode form the optical path II. The attenuator I, the attenuator II and the optical axis of the measurement system all have a certain angle of inclination to avoid interference. The responsivity under the ^-6 W condition is known, and the linearity under different optical power conditions is measured by adjusting the parameters of the attenuator I and the attenuator II. There are n sets of attenuator parameters in total, so that the incident silicon photoelectric The optical power of the diode can be varied from 10 ^-6 W to 10 ^-16 W.

The steps of the method for estimating the absolute photoresponsivity of the photomultiplier tube under low light intensity conditions are:

1. Use the silicon photodiode as a reference for calibrating the absolute optical power of the photomultiplier tube to be tested, and calibrate the silicon photodiode under the condition that the incident light power is in the range of 10 ^-6 W to 10 ^-11 W Non-linear, the method is as follows: adjust the plane mirror I, plane mirror II and beam splitter II to collimate the two beams of light and overlap at the same point in the center of the optical sensor. In the initial state, both the shutter I and the shutter II are closed, and then , open the shutter I, measure the output signal I _A of the silicon photodiode at this time, then open the shutter II, measure the output signal I _A+B of the silicon photodiode at this time, then close the shutter I, and measure the When the output signal I _B of the silicon photodiode is opened, the shutter I is opened to measure the output signal I′ _B+A of the silicon photodiode at this time, and then the shutter II is closed to measure the output signal of the silicon photodiode at this time. Output signal I′ _A , the linearity is obtained by the following formula where /> k represents a group of conditions in the above n groups, the method for calculating the linearity can eliminate the laser drift effect produced by the attenuator in the linearity measurement experiment, and finally, the linearity under each optical power condition is multiplied, Obtain the nonlinearity of the silicon photodiode output signal I _A+B (k)

2. Calibrate the nonlinearity of the photomultiplier tube to be tested under the condition that the incident light power is in the range of 10 ^-6 W to 10 ^-11 W, the method is as follows: remove the silicon photodiode, and place the photoelectric tube to be tested The multiplier tube is placed at the position of the original silicon photodiode. By adjusting the plane mirror I, plane mirror II and beam splitter II, the two beams of light are collimated and overlapped at the same point in the center of the optical sensor. In the initial state, the shutters I and II are both Close, next, open the shutter I, measure the output signal I _C of the photomultiplier tube to be tested at this time, then open the shutter II, measure the output signal I _C+D of the photomultiplier tube to be tested at this time, and then close the shutter I , measure the output signal ID of the photomultiplier tube to be tested at this time, then open the shutter I, measure the output signal I′ _D+C of the photomultiplier tube to be tested at this _time , then close the shutter II, and measure the The output signal I′ _C of the photomultiplier tube, the linearity is obtained by the following formula where /> By adjusting the parameters of attenuator I and attenuator II to measure the linearity under different optical power conditions, there are n groups of attenuator parameters, so that the optical power incident on the silicon photodiode can be from 10 ^-6 W to Change within the range of 10 ^-16 W, k represents a group of conditions in the above n groups, the method for calculating the linearity can eliminate the laser drift effect produced by the attenuator in the linearity measurement experiment, and finally, each optical power The linearity under the condition is multiplied, obtains the non-linearity of described photomultiplier tube output signal I _C+D (k) to be measured

3. Under the condition that the incident light power is 10 ^-11 W, measure the incident light with the calibrated silicon photodiode and the photomultiplier tube to be tested respectively, and measure in the optical path II, and measure the calibrated silicon photoelectric The optical power data of the diode is compared with the optical power data of the photomultiplier tube to be tested. The method is as follows: first, the silicon photodiode is placed in the optical path II, and the absolute incident laser power is measured using the calibrated silicon photodiode , secondly, remove the silicon photodiode, place the photomultiplier tube to be tested at the position of the original silicon photodiode, and measure the photomultiplier tube’s photoresponse to the incident laser light, wherein the position of the laser irradiation is adjusted to be linear with the above step 1 Consistent in the degree measurement, so repeated ten times, finally, calculate the ratio of the incident light power measured by the photomultiplier tube to be tested and the incident light power measured by the silicon photodiode, and determine the photomultiplier tube in the Absolute responsivity under the condition of incident light power of 10 ^-11 W;

4. Estimate the nonlinear characteristics of the photomultiplier tube to be tested under the condition of incident light power ^10-16 W, and combine the responsivity-incident light power curve obtained in the above step 3, by fitting method, estimate with this Absolute photoresponsivity when the optical power is 10 ^-16 W;

5. Finally, obtain the absolute photoresponsivity of the photomultiplier tube to be tested in the range of 10 ⁻¹¹ W to 10 ⁻¹⁶ W.

The beneficial effects of the present invention are:

The invention can estimate the photoresponsivity of the photomultiplier tube in the range of visible light power from 10 ^-11 W to 10 ^-16 W, and the method for calculating the linearity can eliminate the laser drift effect produced by the attenuator in the linearity measurement experiment , which eliminates the wavelength and time dependence of the attenuator transmittance in a series of linearity measurements.

Description of drawings

Below in conjunction with figure of the present invention further illustrate:

Figure 1 is a schematic diagram of the present invention.

In the figure, 1. Laser, 2. Attenuator I, 3. Obscura, 4. Beam splitter I, 5. Attenuator II, 6. Plane mirror I, 7. Shutter I, 8. Shutter II, 9. Plane mirror II, 10. Beam splitter II, 11. Cassette, 12. Silicon photodiode, 13. Photomultiplier tube to be tested.

Detailed ways

Figure 1 is a schematic diagram of the present invention, the device mainly includes a laser 1, an attenuator I2, a dark box 3, a beam splitter I4, an attenuator II5, a plane mirror I6, a shutter I7, a shutter II8, a plane mirror II9, a beam splitter II10, a cassette 11, Silicon photodiode 12, photomultiplier tube 13 to be tested, beam splitter I4, attenuator II5, plane mirror I6, shutter I7, shutter II8, plane mirror II9, beam splitter II10, cassette 11, silicon photodiode 12, to be tested The photomultiplier tubes 13 are all located in the dark box 3, the silicon photodiode 12 and the photomultiplier tube 13 to be tested are located in the dark box 11, and the laser 1 emits laser light through the attenuator I2 to the beam splitter I4, and the Said laser 1, attenuator I2, beam splitter I4, shutter I7, plane mirror II9, beam splitter II10, silicon photodiode 12 form optical path I, by said laser 1, attenuator I2, beam splitter I4, attenuator II5 , plane mirror I6, shutter II8, beam splitter II10, and silicon photodiode 12 form optical path II, and the optical axis of the attenuator I2, attenuator II5 and the measurement system all has a certain angle of inclination to avoid interference, and the silicon photodiode 12 The responsivity under the condition of incident optical power 10 ^-6 W is known, and the linearity under different optical power conditions is measured by adjusting the parameters of attenuator I2 and attenuator II5. There are n sets of attenuator parameters in total, so that The optical power incident on the silicon photodiode 12 can range from 10 ⁻⁶ W to 10 ⁻¹⁶ W.

The steps of the method for estimating the absolute photoresponsivity of the photomultiplier tube under low light intensity conditions are:

1. Use the silicon photodiode 12 as a reference for calibrating the absolute optical power of the photomultiplier tube 13 to be tested, and calibrate the silicon photoelectric under the condition that the incident light power is in the range of 10 ⁻⁶ W to 10 ⁻¹¹ W The nonlinearity of the diode 12, the method is as follows: by adjusting the plane mirror I6, the plane mirror II9 and the beam splitter II10 to collimate the two beams of light and overlap at the same point in the center of the optical sensor, in the initial state, the shutter I7 and the shutter II8 are closed , Next, open the shutter I7, measure the output signal I _A of the silicon photodiode 12 at this time, then open the shutter II8, measure the output signal I _A+B of the silicon photodiode 12 at this time, and then close the shutter I7, measure the output signal I _B of the silicon photodiode 12 at this time, then open the shutter I7, measure the output signal I′ _B+A of the silicon photodiode 12 at this time, then close the shutter II8, and measure this When the output signal I' _A of the silicon photodiode 12 is obtained, the linearity is obtained by the following formula where /> k represents a group of conditions in the above n groups, the method for calculating the linearity can eliminate the laser drift effect produced by the attenuator in the linearity measurement experiment, and finally, the linearity under each optical power condition is multiplied, Obtain the nonlinearity of the silicon photodiode 12 output signal I _A+B (k)

2. Calibrate the non-linearity of the photomultiplier tube 13 to be tested under the condition that the incident light power is in the range of 10 ^-6 W to 10 ^-11 W, the method is as follows: remove the silicon photodiode 12, and place the photomultiplier tube to be tested The photomultiplier tube 13 is placed at the position of the original silicon photodiode 12, and the two beams of light are collimated by adjusting the plane mirror I6, the plane mirror II9 and the beam splitter II10 and overlap at the same point in the center of the optical sensor. In the initial state, the shutter I7 and the shutter II8 are all closed, and then the shutter I7 is opened to measure the output signal _IC of the photomultiplier tube 13 to be tested at this time, and then the shutter II8 is opened to measure the output signal IC ₊ of the photomultiplier tube 13 to be tested at this time _D , then close the shutter I7, measure the output signal ID of the photomultiplier tube ₁₃ to be tested at this time, then open the shutter I7, measure the output signal I′ _D+C of the photomultiplier tube 13 to be tested at this time, and then close the shutter II8, measured the output signal I′ _C of the photomultiplier tube 13 to be tested at this time, obtained the linearity by the following formula where /> The linearity under different optical power conditions is measured by adjusting the parameters of the attenuator I2 and the attenuator II5. It is assumed that there are n groups of attenuator parameters, so that the optical power incident on the silicon photodiode 12 can be from 10 ^-6 W to 10 ^-16 W range, k represents a group of conditions in the above n groups, the method for calculating linearity can eliminate the laser drift effect produced by the attenuator in the linearity measurement experiment, and finally, each light The linearity under power conditions is multiplied to obtain the nonlinearity of the photomultiplier tube 13 output signal I _C+D (k) to be tested

3. Under the condition that the incident light power is ^10-11 W, measure the incident light with the silicon photodiode 12 after calibration and the photomultiplier tube 13 to be measured respectively, and measure in the described optical path II, and measure the calibrated The optical power data of the silicon photodiode 12 is compared with the optical power data of the photomultiplier tube 13 to be tested. The method is as follows: first, the silicon photodiode 12 is placed in the optical path II, and the silicon photodiode 12 after calibration is used. 12 Measure the absolute incident laser power. Secondly, remove the silicon photodiode 12, place the photomultiplier tube 13 to be tested at the position of the original silicon photodiode 12, and measure the photomultiplier tube’s photoresponse to the incident laser light, wherein the laser irradiation The position is adjusted to be consistent with the linearity measurement of the above-mentioned step 1, and this is repeated ten times. Finally, the ratio of the incident light power measured by the photomultiplier tube 13 to be tested and the incident light power measured by the silicon photodiode 12 is calculated. Ratio, and use this to determine the absolute responsivity of the photomultiplier tube under the condition that the incident light power is 10 ^-11 W;

Four. Estimate the nonlinear characteristics of the photomultiplier tube 13 to be measured under the condition of incident light power ^10-16 W, and in conjunction with the responsivity-incident light power curve obtained in the above step 3, by fitting method, with this Estimation of the absolute photoresponsivity at an optical power of 10 ^{- 16} W;

5. Finally, obtain the absolute photoresponsivity of the photomultiplier tube 13 to be tested in the range of 10 ⁻¹¹ W to 10 ⁻¹⁶ W.

The method for estimating the absolute photoresponsivity of the photomultiplier tube under low light intensity conditions uses nonlinear correction to estimate the absolute photoresponsivity of the photomultiplier tube, which can estimate the responsivity of incident light in a wide power range, and the lowest light strong close to the single-photon level.

Claims (1)

1. A method for estimating the absolute photoresponsivity of a photomultiplier tube under low light intensity conditions. The device mainly includes a laser (1), an attenuator I (2), a dark box (3), a beam splitter I (4), and an attenuator II (5), plane mirror I (6), shutter I (7), shutter II (8), plane mirror II (9), beam splitter II (10), cassette (11), silicon photodiode (12), waiting Measuring photomultiplier tube (13), the beam splitter I (4), attenuator II (5), plane mirror I (6), shutter I (7), shutter II (8), plane mirror II (9), splitter Beamer II (10), cassette (11), silicon photodiode (12), photomultiplier tube to be tested (13) are all positioned in described dark box (3), described silicon photodiode (12), photomultiplier to be tested The tube (13) is located in the cassette (11), the laser (1) emits laser light through the attenuator I (2) to the beam splitter I (4), and the laser (1), attenuator I (2 ), beam splitter I (4), shutter I (7), plane mirror II (9), beam splitter II (10), silicon photodiode (12) form optical path I, by said laser (1), attenuator I (2), beam splitter I (4), attenuator II (5), plane mirror I (6), shutter II (8), beam splitter II (10), silicon photodiode (12) form the optical path II, The attenuator I (2), the attenuator II (5) and the optical axis of the measurement system all have a certain angle of inclination to avoid interference, and the silicon photodiode (12) under the condition of incident light power of 10 ^-6 W The responsivity is known, and the linearity under different optical power conditions is measured by adjusting the parameters of the attenuator I (2) and the attenuator II (5). There are n sets of attenuator parameters in total, so that the incident silicon photoelectric The optical power of the diode (12) can vary from 10 ^-6 W to 10 ^-16 W, It is characterized in that: the steps of the method for estimating the absolute photoresponsivity of the photomultiplier tube under the condition of low light intensity are: One. Use the silicon photodiode (12) as a reference for calibrating the absolute optical power of the photomultiplier tube (13) to be measured, and calibrate under the condition that the incident optical power is 10 ^-6 W to 10 ^-11 W range The non-linearity of the silicon photodiode (12), the method is as follows: by adjusting the plane mirror I (6), the plane mirror II (9) and the beam splitter II (10) to collimate the two beams of light and in the center of the optical sensor The same point overlaps, and in the initial state, the shutter I (7) and the shutter II (8) are both closed, and then the shutter I (7) is opened, and the output signal I _A of the silicon photodiode (12) is measured at this time, Open the shutter II (8) again to measure the output signal I _A+B of the silicon photodiode (12) at this time, then close the shutter I (7) to measure the output of the silicon photodiode (12) at this time Signal I _B , then open the shutter I (7), measure the output signal I′ _B+A of the silicon photodiode (12) at this time, then close the shutter II (8), measure the silicon photodiode at this time The output signal I' _A of (12), the linearity is obtained by the following formula where /> k represents a group of conditions in the above n groups, the method for calculating the linearity can eliminate the laser drift effect produced by the attenuator in the linearity measurement experiment, and finally, the linearity under each optical power condition is multiplied, Obtain the nonlinearity of the silicon photodiode (12) output signal I _A+B (k) 2. Calibrate the nonlinearity of the photomultiplier tube to be tested (13) under the condition that the incident light power is in the range of ^10-6 W to ^10-11 W, the method is as follows: remove the silicon photodiode (12), The photomultiplier tube (13) to be tested is placed at the position of the original silicon photodiode (12), and the two beams of light are collimated by adjusting the plane mirror I (6), the plane mirror II (9) and the beam splitter II (10) And overlap at the same point in the center of the optical sensor. In the initial state, both the shutter I (7) and the shutter II (8) are closed. Next, the shutter I (7) is opened, and it is measured that the photomultiplier tube (13 ) output signal I _C , then open the shutter II (8), measure the output signal I _C+D of the photomultiplier tube (13) to be tested at this time, and then close the shutter I (7), measure the photoelectric The output signal ID of the multiplier tube ( ₁₃ ), then open the shutter I (7), measure the output signal I′ _D+C of the photomultiplier tube (13) to be tested at this time, then close the shutter II (8), measure At this moment, the output signal I′ _C of the photomultiplier tube (13) to be measured obtains the linearity by the following formula in Measure the linearity under different optical power conditions by adjusting the parameters of attenuator I (2) and attenuator II (5), assuming a total of n groups of attenuator parameters, so that the light incident on the silicon photodiode (12) The power can vary from 10 ^-6 W to 10 ^-16 W, k represents a group of conditions in the above n groups, and the method for calculating the linearity can eliminate the laser drift produced by the attenuator in the linearity measurement experiment effect, at last, multiply the linearity under each light power condition, obtain the nonlinearity of the photomultiplier tube (13) output signal I _C+D (k) to be tested 3. Under the condition that the incident light power is ^10-11 W, measure the incident light with the calibrated silicon photodiode (12) and the photomultiplier tube (13) to be measured respectively, and measure in the optical path II, measure The optical power data of the silicon photodiode (12) obtained after calibration is compared with the optical power data of the photomultiplier tube (13) to be measured, and the method is as follows: first, the silicon photodiode (12) is placed in the optical path In II, use the calibrated silicon photodiode (12) to measure the absolute incident laser power, secondly, remove the silicon photodiode (12), and place the photomultiplier tube (13) to be tested at the position of the original silicon photodiode (12) , and measured the photoresponse of the photomultiplier tube to the incident laser, wherein the position of the laser irradiation was adjusted to be consistent with the linearity measurement of the above step 1, so repeated ten times, and finally, the photomultiplier tube to be tested (13) was calculated The ratio of the incident light power measured and the incident light power measured by the silicon photodiode (12) is used to determine the absolute responsivity of the photomultiplier tube under the condition of ^10-11 W of incident light power; Four. Estimate the nonlinear characteristics of the photomultiplier tube to be tested (13) under the condition of incident light power ^10-16 W, and in conjunction with the responsivity-incident light power curve obtained in the above-mentioned step 3, by fitting method, with This estimates the absolute photoresponsivity at an optical power of 10 ^-16 W; 5. Finally, obtain the absolute photoresponsivity of the photomultiplier tube (13) to be tested in the range of 10 ⁻¹¹ W to 10 ⁻¹⁶ W.