CN111521264B - A fast calculation method and device for pulse energy measurement - Google Patents

Abstract

The invention discloses a fast calculation method and device for pulse energy measurement, which are suitable for use when a thermopile detector performs pulse energy measurement. Among them, by obtaining the starting threshold point ( T _s , V _s ), the maximum value point ( T _m , V _m ), and the ending threshold value point ( T _e , V _e ) from the voltage response curve measured by the detector, the voltage The response curve is divided into four stages according to the time points T _s , T _m , and T _e , and then the areas S _m and S _e under the corresponding curves of T _s ~ T _m and T _m ~ T _e stages are calculated according to the actual sampling data, and The areas under the curves S _s and S _t corresponding to the 0 ~ T _s and Te ~ ∞ _stages are estimated, and finally the sum of the areas under the curves corresponding to the four stages is calculated, and the optical energy measurements are calculated. Through the above calculation method, the test speed can be improved, the change of the incident signal can be quickly measured, the energy value of the incident light can be quickly calculated, and the relative deviation of the measurement can be small, which meets the needs of high precision and fast response to the detection object in practical applications.

Description

A fast calculation method and device for pulse energy measurement

technical field

The invention relates to a fast calculation method for pulse energy measurement, in particular to a fast calculation method used for pulse energy measurement of a thermopile detector, and a device for realizing the above fast calculation method.

Background technique

At present, lasers are more and more widely used in communication, medical, industrial manufacturing and other fields. In the process of laser development, production and application, measuring and calibrating the power of the laser is an essential step. In the prior art, a laser detector is usually used to test the power of a continuous laser or the average power of a pulsed laser in a certain period of time.

According to different measurement principles, laser detectors mainly include two categories: photoelectric laser detectors and pyroelectric laser detectors. Compared with photoelectric detectors, pyroelectric detectors have the advantages of flat spectral response and wide spectral range, and have a wide range of applications in optoelectronic testing and metrology.

Pyroelectric detectors (also known as thermopile detectors) use a thermopile structure and, based on the Seebeck effect, convert thermal energy into electrical energy to detect laser power. Thermopile detectors measure relevant energy data using the thermal effects of the detected object. According to the principle of energy conversion, the thermopile detector absorbs the incident light energy and converts it into its own thermodynamic energy, converts the light signal into an electrical signal, and uses a single-chip microcomputer and an A/D conversion device to collect a voltage signal proportional to the input light pulse energy. Quantity calibration to complete the energy measurement. Thermopile detectors have the advantages of flat spectral response and wide spectral range, and can be applied to the measurement of multi-wavelength or non-monochromatic light, as well as the energy measurement of a single pulse. Using thermopile detectors for pulse energy measurement, in practical applications, due to the influence of heat loss, thermocouple noise and other factors, the response time of thermopile detectors is long, and it takes several seconds or even ten seconds to reach equilibrium, which cannot be performed quickly. In addition, the real performance of the incident light cannot be output in real time, which affects the test efficiency.

SUMMARY OF THE INVENTION

The primary technical problem to be solved by the present invention is to provide a fast calculation method for pulse energy measurement, which is suitable for use in thermopile detectors for pulse energy measurement, and has fast response speed and high accuracy.

Another technical problem to be solved by the present invention is to provide a device for implementing the above fast calculation method.

In order to realize above-mentioned technical purpose, the present invention adopts following technical scheme:

According to a first aspect of the embodiments of the present invention, a fast calculation method for pulse energy measurement is provided, which is used when a thermopile detector performs pulse energy measurement, including the following steps:

S1, use a thermopile detector to measure the light pulse to obtain a voltage response curve;

S2, obtain the starting threshold point ( T _s , V _s ), the maximum value point ( T _m , V _m ) and the ending threshold point ( T _e , V _e ) from the voltage response curve, where V _s , V _m , V _e represents the starting threshold voltage, the maximum voltage and the ending threshold voltage, respectively, T _s , T _m , and Te _represent the time point corresponding to the starting threshold voltage, the time point corresponding to the maximum voltage, and the time corresponding to the ending threshold voltage, respectively point; the voltage response curve is divided into four stages according to the time points T _s , T _m , and Te , which are: 0 ~ T _s , T _s ~ T _m , T _m ~ T _e , T _e ~∞ _;

S3, according to the shape of the corresponding curve in the 0~ T _s stage, estimate the area S _s under the corresponding curve in the 0~ T _s stage;

S4, according to the actual sampling data, calculate the area S _m under the corresponding curve in the stage T _s ~ T _m ;

S5, according to the actual sampling data, calculate the area S _e under the corresponding curve in the stage T _m ~ T _e ;

S6, according to the shape of the corresponding curve in the T _e ~ ∞ stage, estimate the area S _t under the corresponding curve in the T _e ~∞ stage;

S7, calculate the area S under the entire curve from 0 to ∞, S=S _s +S _m +S _e +S _t ;

S8, calculate the optical energy measurement value E of the incident light, E=a×S ; wherein, a is the energy correction coefficient calibrated with the standard light source.

Preferably, in step S2, the initial threshold point ( T _s , V _s ) is set, the maximum value point ( T _m , V _m ) is obtained from the voltage response curve, and calculated according to the maximum voltage V _m The end threshold voltage Ve , and then the end threshold point ( T _e , _{Ve )} is determined.

Preferably, the end threshold voltage Ve =0.368V _m , or the end threshold voltage _Ve =0.5V _{m .}

Preferably, in step S3, according to the starting threshold point ( T _s , V _s ) and 1.2 times the starting threshold point ( T _{s 1} , V _{s 1} ), the following formula is used to calculate the time period from 0 to T _s Area under the inner curve S _s : S _s = ( V _s ×T _{s 1} )/0.4,

Among them, V _s is the starting threshold voltage, V _{s 1} is set to 1.2 times the starting threshold voltage, T _s is the time point corresponding to the starting threshold voltage, recorded as the zero point of the collected data, and T _{s 1} is 1.2 times the starting threshold voltage. The time point corresponding to the initial threshold voltage.

Preferably, in step S4, the following formula is used to calculate the area under the curve S _m in the time period from T _s to T _m :

；

;

Among them, f(t _i ) is the voltage value corresponding to the sampling point, Δt is the sampling time, and the sampling number n=( T _m −T _s )/ Δt .

Preferably, in step S5, the following formula is used to calculate the area under the curve S _e in the time period T _m ~ T _e :

；

;

Among them, y(t _i ) is the voltage value corresponding to the sampling point, Δt is the sampling time, and the sampling number w=( T _e −T _m )/ Δt .

Preferably, in step S6, the area under the curve of T _e ~∞ time period S _t is estimated by the following formula: S _t =V _e ×τ , where τ is the decay of the voltage value in the voltage response curve from the maximum value to Time at 1/ e times the maximum value.

According to a second aspect of the embodiments of the present invention, a fast calculation device for pulse energy measurement is provided, which is used to implement the above-mentioned fast calculation method for pulse energy measurement, including a control module, a storage module, a feature point calculation module, an area calculation module and power calculation module; wherein,

The control module is used to coordinate the work of other modules;

The feature point calculation module is used to obtain the starting threshold point ( T _s , V _s ), the maximum value point ( T _m , V _m ) and the ending threshold value point ( Te , _{Ve )} ;

The area calculation module is used to calculate the areas S _m and S _e under the corresponding curves of the T _s ~ T _m and T _m ~ T _e stages according to the actual sampling data, and estimate the 0 ~ T _s and T _e ~ ∞ stages Corresponding to the area under the curve S _s and S _t , and calculate the sum S of S _{s ,} S _m , Se and S _t ;

The power calculation module is used to calculate the optical energy measurement value E of the incident light according to the area S under the entire curve from 0 to ∞;

The storage module is used for storing the voltage response curve measured by the thermopile detector and all the calculation results of the feature point calculation module, the area calculation module and the power calculation module.

Preferably, the feature point calculation module is used to set the initial threshold point ( T _s , V _s ), and to obtain the maximum value point ( T _m , V _m ) from the voltage response curve, and according to the maximum value The end threshold voltage V _e is calculated from the voltage V _m , and then the end threshold point ( T _e , V _e ) is determined.

Preferably, the area calculation module is used to estimate 0~ T according to the starting threshold point ( T _s , V _s ) and 1.2 times the starting threshold point ( T _{s 1} , V _{s 1} ) using the following formula The time period _s corresponds to the area under the curve S _s :

S _s = ( V _s ×T _{s 1} )/0.4,

Among them, V _s is the starting threshold voltage, V _{s 1} is set to 1.2 times the starting threshold voltage, T _s is the time point corresponding to the starting threshold voltage, recorded as the zero point of the collected data, and T _{s 1} is 1.2 times the starting threshold voltage The time point corresponding to the threshold voltage;

The area calculation module is used to calculate the area under the curve S _m in the time period from T _s to T _m using the following formula:

；

;

Among them, f(t _i ) is the voltage value corresponding to the sampling point, Δt is the sampling time, and the sampling number n=( T _m -T _s )/ Δt ;

The area calculation module is used to calculate the area under the curve S _e in the time period T _m ~ T _e using the following formula:

；

;

Among them, y(t _i ) is the voltage value corresponding to the sampling point, Δt is the sampling time, and the sampling number w=( T _e −T _m )/ Δt ;

The area calculation module is also used for estimating the area S _t under the T _e ~∞ time period curve by the following formula:

；

;

where τ is the time for the voltage value in the voltage response curve to decay from the maximum value to 1/ e times the maximum value.

The fast calculation method for pulse energy measurement provided by the present invention is suitable for use when a thermopile detector performs pulse energy measurement. Among them, by obtaining the starting threshold point ( T _s , V _s ), the maximum value point ( T _m , V _m ) and the ending threshold point ( T _e , V _e ) from the voltage response curve measured by the thermopile detector, The voltage response curve is divided into four stages according to the time points T _s , T _m , and _Te , and then the areas S _m and S _e under the corresponding curves of the stages T _s ~ T _m and T _m ~ Te are calculated according to the actual sampling data _. , and estimate the areas S _s and S _t under the curves corresponding to the 0~ T _s and Te ~∞ _stages , and finally calculate the sum of the areas under the curves corresponding to the four stages, and finally calculate the measured value of the optical energy. Through the above calculation method, the test speed can be improved, the change of the incident signal can be quickly measured, the energy value of the incident light can be quickly calculated, and the relative deviation of the measurement can be small, which meets the needs of high precision and fast response to the detection object in practical applications.

Description of drawings

Fig. 1 is the flow chart of the fast calculation method for pulse energy measurement provided by the present invention;

Figure 2 is a schematic diagram of a voltage response curve obtained when a thermopile detector is used for pulse energy measurement;

3 is a schematic diagram of a voltage response curve divided by an end threshold point obtained based on the first calculation method;

4 is a schematic diagram of a voltage response curve divided by an end threshold point obtained based on the second calculation method;

Figure 5 is an example of a real voltage response curve obtained by a thermopile detector for pulse energy measurement;

FIG. 6 is a schematic block diagram of a module of a fast computing device for pulse energy measurement provided by the present invention.

Detailed ways

The technical solutions of the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

Aiming at the defects of slow response speed and difficult to guarantee detection accuracy of thermopile detectors for energy measurement, an efficient, fast and accurate calculation method is proposed. The algorithm can improve the test speed, quickly measure the change of the incident signal, and quickly calculate the energy value of the incident light.

As shown in FIG. 1 , the fast calculation method for pulse energy measurement disclosed in the present invention, which is used when a thermopile detector performs pulse energy measurement, includes the following steps:

S1, use a thermopile detector to measure the light pulse to obtain a voltage response curve;

S2, obtain the starting threshold point ( T _s , V _s ), the maximum value point ( T _m , V _m ) and the ending threshold point ( T _e , V _e ) from the voltage response curve, where V _s , V _m , V _e represents the starting threshold voltage, the maximum voltage and the ending threshold voltage, respectively, T _s , T _m , and Te _represent the time point corresponding to the starting threshold voltage, the time point corresponding to the maximum voltage, and the time corresponding to the ending threshold voltage, respectively point; the voltage response curve is divided into four stages according to the time points T _s , T _m , and Te , which are: 0 ~ T _s , T _s ~ T _m , T _m ~ T _e , T _e ~∞ _;

S3, according to the shape of the corresponding curve in the 0~ T _s stage, estimate the area S _s under the corresponding curve in the 0~ T _s stage;

S4, according to the actual sampling data, calculate the area S _m under the corresponding curve in the stage T _s ~ T _m ;

S5, according to the actual sampling data, calculate the area S _e under the corresponding curve in the stage T _m ~ T _e ;

S6, according to the shape of the corresponding curve in the T _e ~ ∞ stage, estimate the area S _t under the corresponding curve in the T _e ~∞ stage;

S7, calculate the area S under the entire curve from 0 to ∞, S=S _s +S _m +S _e +S _t ; (1)

S8, calculate the optical energy measurement value E of the incident light, E=a×S ; wherein, a is the energy correction coefficient calibrated with the standard light source.

Among them, in step S2, in order to simplify the calculation of the subsequent steps, the initial threshold point ( T _s , V _s ) is set, and then the maximum value point ( T _m , V _m ) is obtained from the voltage response curve, and according to the maximum value The end threshold voltage V _e is calculated from the voltage V _m , and then the end threshold point ( T _e , V _e ) is determined. According to different calculation methods, the fitting function of the stage T _m ~ T _e is processed, it can be inferred that the end threshold voltage is set to V _e =0.368V _m , or the end threshold voltage is set to V _e =0.5V _m , the area under the descending curve of T _e ~∞ can be quickly obtained while ensuring the calculation accuracy.

In step S3, according to the starting threshold point ( T _s , V _s ) and 1.2 times the starting threshold point ( T _{s 1} , V _{s 1} ), use formula (2) to estimate the area under the corresponding curve in the 0~ T _s stage S _s :

S _s = ( V _s ×T _{s 1} )/0.4, (2)

Among them, V _s is the starting threshold voltage, V _{s 1} is set to 1.2 times the starting threshold voltage, T _s is the time point corresponding to the starting threshold voltage, recorded as the zero point of the collected data, and T _{s 1} is 1.2 times the starting threshold voltage The time point corresponding to the threshold voltage.

In step S4, the area under the curve S _m in the time period T _s ~ T _m is calculated using the following formula:

； （3）

; (3)

Where f(t _i ) is the voltage value corresponding to the sampling point, Δt is the sampling time, and the sampling number n=( T _m -T _s )/ Δt .

In step S5, the area under the curve S _e in the time period T _m ~ T _e is calculated using the following formula:

； （4）

; (4)

Among them, y(t _i ) is the voltage value corresponding to the sampling point T _m ~ T _e , Δt is the sampling time, and the sampling number w=( T _e -T _m )/ Δt .

In step S6, the area under the curve T _e ~∞ time period S _t is estimated by the following formula:

（5）

(5)

where τ is the time for the voltage value in the voltage response curve to decay from the maximum value to 1/ e times the maximum value.

Specifically, assuming that the pulse width of the measured laser pulse is much smaller than the thermal response period of the thermopile, the temperature difference model of the thermopile is established; according to the Seebeck effect of the thermopile, the induced electromotive force is proportional to the temperature difference, and the induced electromotive force V _t is calculated.

According to the theoretical and practical data collection, as shown in Figure 2, the voltage response curve of the thermopile first rises rapidly and steeply to the maximum value V _m (the time point is recorded as T _m ), and then slowly decreases according to the exponential function curve. It is very long, and the end point cannot be detected in a limited time. Through reasonable calculation, the time point _Te corresponding to the end threshold voltage can be determined by setting the end threshold voltage Ve , and the end threshold point ( T _e , _{Ve )} As the end point of the recording; in addition, because it is a passive detection, the thermopile does not know the time starting point T _s of the detection in advance. At this time, by setting the time point T _s corresponding to the fixed starting threshold voltage V _s as the recording zero point, Take the starting threshold point ( T _s , V _s ) as the starting point of the recording to start recording the voltage and time data; thus, in the case that the starting zero point and the end point are not available, set the time point T _s corresponding to the starting threshold voltage and the The time point T _e corresponding to the end threshold voltage is used as the time point for segment calculation, and then the area under the curve between the start threshold point and the end threshold point is calculated respectively, and the area under the curve before the start threshold point and after the end threshold point is estimated. area, the power of the pulse can be quickly calculated and measured.

Since the energy value is proportional to the area of the curve, the corresponding energy value can be derived by accurately calculating the area under the entire curve from 0 to ∞.

As shown in Figure 2, the time points T _s , T _m , and Te are known, and the corresponding voltage values are V _s , V _m , and V _e respectively _; in order to calculate the area under the entire curve from 0 to ∞, this method uses the voltage response curve It is divided into four stages according to time points, which are: 0~ T _s , T _s ~ T _m , T _m ~ T _e , T _e ~∞ ; the time periods T _s ~ T _m and T _m ~ T _e can be passed through The area is calculated from the sampled data; the time periods 0~ T _s and T _e ~∞ are both unmeasurable time periods, but the area generated by this time period belongs to the energy response process. If it is not included, a large measurement error will occur. In the algorithm, the area between 0~ T _s and T _e ~∞ time period is estimated to eliminate the error.

In other words, the area under the voltage response curve consists of four parts S _s , S _m , Se and S _{t .} Among them, V(t) of all time periods from T _s to T _m and T _m to Te can be captured and recorded by the control system; the core of this algorithm is to record V(t) _of all time periods from T _s to T _e , Calculate the areas S _m and S _e , and estimate the areas S _s and S _t , and then calculate the sum of the four areas to obtain the area below the entire curve from 0 to ∞. This area is corrected by a certain linear coefficient with the standard light source, A measurement of the optical energy is obtained.

The specific calculation process is described below.

1. Estimate the curve function of the 0~ T _s time period in the rising curve

To get the area from 0 to T _s , you first need to get the function of the rising curve.

In the 0~ T _s time period of the rising curve, the data in the 0~ T _s time period before the starting threshold point ( T _s , V _s ) cannot be collected by the control system. Because the voltage response curve of the thermopile rises rapidly and steeply first, the initial threshold voltage V _s can be set to a lower voltage (for example, V _s is 5mV), and the area under the curve in the 0~ T _s time period is It can be estimated as the area of a small triangle. Take two points on this curve and calculate the function coefficients. Using the starting threshold point ( T _s , V _s ) and 1.2 times the starting threshold point ( T _{s 1} , V _{s 1} ), V _{s 1} =1.2× V _s , calculate the coefficient of the linear function in the time period of 0~ T _s , thereby estimating the area under the curve for the time period 0~ T _s . The choice of V _s should consider the detection accuracy of the thermopile detector, and at the same time should avoid the interference of other factors. The smaller the V _s is, the higher the accuracy will be, but if the V _s is too small, there will be interference factors.

The 0~ T _s time period curve is estimated to conform to the formula: V _t = k × t ; (6)

where t is the time, V _t is the real-time output voltage at time t , and k is the coefficient of the proportional function; the proportional coefficient of this linear function is calculated as follows:

； （7）

; (7)

Among them, V _s is the starting threshold voltage, V _{s 1} is set to 1.2 times the starting threshold voltage, T _s is the time point corresponding to the starting threshold voltage, recorded as the zero point of the collected data, and T _{s 1} is 1.2 times the starting threshold voltage The time point corresponding to the threshold voltage.

。 （8） So the rising curve proportional function is:

. (8)

2. Calculate the area under the rising curve 0~ T _m ;

The area under the curve of the ascending segment is divided into two parts, namely the area under the curve of the 0~ T _s time period S _s and the area under the curve of the T _s ~ T _m time period S _m ; the area under the curve of the 0~ T _s time period is estimated by the proportional function To solve, the area under the curve in the time period T _s ~ T _m is calculated from the sampled data.

The first step is to estimate the area under the curve of the 0~ T _s time period. The curve of this time period conforms to a linear function, and the area is as follows:

S _{s =} V _s × ΔT _s /2 (9)

Among them, ΔT _s is the time difference from the actual starting point of the curve to the starting threshold point, ΔT _s= V _s /k , k=0.2×V _s /T _{s 1} ,

。 （10） so,

. (10)

In the second step, the area under the curve S _m in the time period T _s ~ T _m is calculated by summing the sampled data;

It is known that the rising curve function f(t) is continuous on the interval [ T _s , T _m ], and the interval [ T _s , T _m ] is divided into n sub-intervals [ T ₀ , T ₁ ], [ T ₁ , T ₂ ], [ T ₂ , T ₃ ], ... [ T _n-1 , T _n ], where T ₀ = T _s , T _n = T _m ;

During the sampling process, the length of each interval is kept the same, which is Δt , and the sampling number n=( T _m -T _s )/ Δt during this period is obtained; (11)

Sum the curve sampling data in the time period T _s ~ T _m to obtain the curve area S _m in this time period:

； （12）

; (12)

Among them, f(t _i ) is the voltage value corresponding to the sampling point in the time period from T _s to T _m , Δt is the sampling time, and the number of samples n=( T _m - T _s )/ Δt . The smaller the Δt , the higher the calculation accuracy.

3. Find the descending curve function.

。 The first step is to collect the voltage V _m ~ V _e in the time period T _m ~ T _e to verify the descending curve function. The falling curve of the output voltage of the thermopile detector is in the form of a negative exponential function:

.

Among them, t is time; V _t is the real-time output voltage at time t ; a is the coefficient of the exponential function; τ is the time constant, which is the inherent parameter of the thermopile detector, which means that the physical quantity decays from the maximum value to the maximum value of 1/ The time required for e times (about 0.368 times).

There are two methods to calculate the exponential function coefficient a and the time constant τ :

In the first method, the end threshold voltage Ve is set to 0.368V _{m ,} and at this time, the voltage response curve is divided into four stages as shown in FIG. 3 .

)中的a取任何值，函数都过 某个具体的点。y=e ^x 过(0,1)点，

过(0,a)点，对于热电堆探测器输出电压的下 降曲线，t ₀对应的输出电压为V _m ，得到下降曲线指数函数的系数a=V _m 。τ是电压值从最大值衰 减到最大值的1/e倍时的时间，此时的输出电压V _τ =0.368V _m ，因此，实时输出电压的数据采 集，只需采集到最大值V _m 的0.368倍，所以将结束阈值电压设置为V _e =0.368V _m ，就可得到时间 常数τ=T _e ，从而得到下降曲线的指数函数

。 （13） According to the properties of the exponential function, regardless of the exponential function y=a ^x ( a > 0 and

) in any value of a , the function passes through a specific point. y=e ^x passes (0,1) point,

Passing the (0, a ) point, for the falling curve of the output voltage of the thermopile detector, the output voltage corresponding to t ₀ is V _m , and the coefficient a=V _m of the exponential function of the falling curve is obtained. τ is the time when the voltage value decays from the maximum value to 1/ e times the maximum value. The output voltage at this time is V _τ =0.368V _m . Therefore, for real-time output voltage data acquisition, it is only necessary to collect the maximum value of V _m . 0.368 times, so the end threshold voltage is set to V _e =0.368V _m , the time constant τ = T _e can be obtained, and the exponential function of the falling curve can be obtained

. (13)

Therefore, this method is to set the end threshold voltage V _e to V _e =0.368V _m , and record the voltage and time data in the time period T _m ~ T _e through the data acquisition of the control system to obtain T _e , that is, to obtain the time constant τ .

In the second method, the least squares method is used to fit the curve, and at this time, the end threshold voltage Ve is set to 0.5V _{m .}

Least squares is a mathematical optimization algorithm. It finds the best functional match for the data by minimizing the sum of squared errors. Using the least squares method, the unknown data can be obtained through samples, and the sum of squares of the errors between the obtained data and the actual data can be minimized.

，令系数b =1/τ，x=t，y=V _t ，则得到函数

。对函数

两边取对数，得到lny=lna-bx，令，a ₀ =lna，a ₁ =-b，就得到线性模型

。通过控制系统采集到的V _m ~V _e 标本数 据，利用最小二乘法，可以解得a ₀、a ₁。由a ₀ =lna，得到

；由a ₁ =-b，得到b=-a ₁；从而得到 拟合函数

。 The falling curve of the output voltage of the thermopile detector is in the form of a negative exponential function:

, let the coefficient b =1/ τ , x=t , y= V _t , then the function

. pair function

Take the logarithm of both sides to get ln y =ln a - bx , let, a ₀ =lna , a ₁ =-b , then a linear model is obtained

. A ₀ and a ₁ can be obtained by using the least squares method from the V _m ~ V _e specimen data collected by the control system. From a ₀ =lna , we get

; From a ₁ =-b , get b=-a ₁ ; thus get the fitting function

.

Using the least squares method, the end threshold voltage V _e can be set to 0.5V _m , and the control system only needs to collect and record the voltage and time data in the range of V _m ~ 0.5V _m , and then the exponential function of the falling curve can be fitted, The end threshold point in method 1 is represented by ( T _τ , V _τ ). At this time, the voltage response curve is divided into four stages as shown in FIG. 4 . It can be seen from Fig. 4 that, compared with method 1 _{, setting the end threshold Ve} to 0.5V _m improves the test speed.

4. Calculate the area of T _m ~∞ under the descending curve

The area of the curve in the descending segment is divided into two parts, namely, the area under the curve of the time period T _m ~ T _e , Se and the area under the curve of the time period T _e ~ ∞ , S _{t ;} the area under the curve of the time period T _m ~ T _e is determined by sampling data. The summation is calculated, and the area under the curve of the T _e ~∞ time period is estimated by integrating the fitting function.

In the first step, the area under the curve in the time period T _m ~ T _e is calculated by summing the sampled data;

It is known that the descending curve function y(t) is continuous on the interval [ T _m , T _e ], and the interval [ T _m , T _e ] is divided into w sub-intervals [ T ₀ , T ₁ ], [ T ₁ , T ₂ ], [ T ₂ , T ₃ ], ... [ Tw - ₁ , Tw ], where T ₀ = T _m , _Tw = T _{e ;}

During the sampling process, the length of each interval is kept the same, which is Δt , and the sampling number w = ( T _e -T _m )/ Δt during this period is obtained; (14)

Sum up the curve sampling data in the time period T _m ~ T _e to obtain the curve area S _e in this time period:

； （15）

; (15)

Among them, y(t _i ) is the voltage value corresponding to the sampling point in the time period T _m ~ T _e , Δt is the sampling time, and the sampling number w=( T _e - T _m )/ Δt .

In the second step, the area under the curve S _t in the time period T _e ~∞ is estimated by integrating the fitting function;

； （16） The integral formula of the area under the curve of the T _e ~∞ time period S _t is as follows:

; (16)

where S _t is the area , T _e =0 , a = V _e , b =1/ τ ;

（17）

(17)

For the same voltage response curve, the area under T _m ~ ∞ is calculated by setting different end threshold voltages, and the calculation errors of the two calculation methods are compared.

Take the waveform shown in Figure 5 as an example, where the maximum voltage V _m =1.072(V), the time T _m corresponding to the maximum voltage is set to 0, and then the calculation is performed to obtain the curve formula of the falling process: y= 1.072e ^-1.2576x , τ = 1/1.2576.

1) Using method 1, take V _e =0.368V _m =0.3945(V), corresponding to time T _e =0.785(s), calculate the area under the curve in the time period T _m ~ T _e , and obtain the integral value: 0.5334, calculate The area under the curve for the time period T _e ~∞ : S _t =0.3945÷1.2576=0.3137. The area of the descending curve is obtained by summing the areas of the two sections: 0.8471(J).

2) Using method 2, take V _e =0.5V _m =0.536(V), corresponding to time T _e =0.54(s), calculate the area of T _m ~ T _e integrally, get the integral value: 0.42107, calculate T _e ~∞ The area of : S _t =0.536÷1.2576=0.426201. The area of the descending curve is obtained by summing the areas of the two sections: 0.847271(J).

The error of the two calculation methods is about: 0.02%. It can be seen that the error caused by the two calculation methods to the calculation results is very small, and the measurement value of the optical energy can be measured faster by determining the end threshold point in the second method.

5. Calculate the area under the entire curve from 0 to ∞;

The area under the entire curve from 0 to ∞ is the sum of the areas of the four segments: S=S _s +S _m +S _e +S _t . This area is corrected by a certain linear coefficient with the standard light source, and the measured value of the optical energy can be obtained. The optical energy measurement value of the incident light is: E=a×S ; where a is the energy correction coefficient calibrated with the standard light source.

As shown in FIG. 6 , the present invention also provides a fast calculation device for pulse energy measurement, which is used to implement the above-mentioned fast calculation method for pulse energy measurement, including a control module 101, a storage module 102, a feature point calculation module 103, Area calculation module 104 and power calculation module 105; wherein,

The control module 101 is used to coordinate the work of other modules;

The feature point calculation module 103 is used to obtain the starting threshold point ( T _s , V _s ), the maximum value point ( T _m , V _m ) and the ending threshold value point ( T ) from the voltage response curve measured by the thermopile detector _e , V _e );

The area calculation module 104 is used to calculate the areas S _m and S _e under the corresponding curves of the stages T _s ~ T _m and T _m ~ T _e according to the actual sampling data, and estimate the corresponding stages of 0 ~ T _s and T _e ~ ∞ the area under the curve S _s and S _t and calculate the sum S of S _{s ,} S _m , Se and S _t ;

The power calculation module 105 is used to calculate the optical energy measurement value E of the incident light according to the area S under the entire curve from 0 to ∞;

The storage module 102 is used to store the voltage response curve measured by the thermopile detector and all the calculation results of the feature point calculation module 103 , the area calculation module 104 and the power calculation module 105 .

Specifically, the feature point calculation module 103 is used to set the initial threshold point ( T _s , V _s ), and to obtain the maximum point ( T _m , V _m ) from the voltage response curve, and according to the maximum voltage V _m calculates the end threshold voltage Ve , and further determines the end threshold point ( T _e , _{Ve )} . Preferably, the feature point calculation module 103 is configured to calculate the end threshold voltage Ve according to the following formula, _Ve =0.368V _{m ,} or _{, Ve} = 0.5V m _.

The area calculation module 104 is used for estimating the lower part of the curve corresponding to the 0~ T _s stage by using formula (2) according to the starting threshold point ( T _s , V _s ) and the 1.2 times starting threshold point ( T _{s 1} , V _{s 1} ). The area S _s of :

S _s = ( V _s ×T _{s 1} ) / 0.4, (2)

Among them, V _s is the starting threshold voltage, V _{s 1} is set to 1.2 times the starting threshold voltage, the time point corresponding to the starting threshold voltage of T _s is recorded as the zero point of the collected data, and T _{s 1} is 1.2 times the starting threshold value. The time point corresponding to the voltage.

The area calculation module 104 is used to calculate the area under the curve S _m in the time period from T _s to T _m using the following formula:

； （3）

; (3)

Where f(t _i ) is the voltage value corresponding to the sampling point T _s ~ T _m , Δt is the sampling time, and the sampling number n=( T _m -T _s )/ Δt .

The area calculation module 104 is used to calculate the area S _e under the curve in the time period T _m ~ T _e using the following formula:

； （4）

; (4)

Among them, y(t _i ) is the voltage value corresponding to the sampling point T _m ~ T _e , Δt is the sampling time, and the sampling number w=( T _e -T _m )/ Δt .

The area calculation module 104 is used to estimate the area S _t under the curve of the T _e ~∞ time period by the following formula:

； （5）

; (5)

where τ is the time for the voltage value in the voltage response curve to decay from the maximum value to 1/ e times the maximum value.

The area calculation module 104 is also used to calculate the area S under the entire curve from 0 to ∞: S=S _s +S _m +S _e +S _t . (1)

The power calculation module 105 is configured to calculate the optical energy measurement value E of the incident light according to the following formula, E=a×S ; where a is an energy correction coefficient calibrated with a standard light source.

To sum up, the fast calculation method for pulse energy measurement provided by the present invention obtains the initial threshold point ( T _s , V _s ), the maximum value point ( T _m ) from the voltage response curve measured by the detector , V _m ), the end threshold point ( T _e , V _e ), the voltage response curve is divided into four stages according to the time points T _s , T _m , and T _e , in order: 0 ~ T _s , T _s ~ T _m , T _m ~ T _e , T _e ~∞ , and then calculate the areas S _m and Se under the corresponding curves of T _s ~ T _m and T _m ~ Te stages according to the actual _sampling data _, and according to the curve shape of the voltage response curve Features The area under the curve S _s and S _t corresponding to the 0~ T _s and Te ~∞ _stages is estimated, and the sum of the areas under the curve corresponding to the four stages is finally calculated, and the measurement value of the optical energy is finally calculated. Through the above calculation method, the measurement value of the optical energy can be quickly calculated, the test speed can be improved, the change of the incident signal can be quickly measured, the energy value of the incident light can be quickly calculated, and the relative deviation of the measurement is small, which satisfies the realization of the detection object in practical applications. High precision and fast response requirements.

The fast calculation method and device for pulse energy measurement provided by the present invention have been described in detail above. For those of ordinary skill in the art, any obvious changes made to the invention without departing from the essential spirit of the invention will constitute an infringement of the patent right of the invention and will bear corresponding legal responsibilities.

Claims (10)

1. A rapid calculation method for pulse energy measurement, which is used when a thermopile detector carries out pulse energy measurement, is characterized by comprising the following steps:

s1, measuring the light pulse by using a thermopile detector to obtain a voltage response curve;

s2, obtaining an initial threshold point from the voltage response curve (T _s ，V _s ) Maximum point of (a)T _m ，V _m ) And an end threshold point: (T _e ， V _e ) WhereinV _s 、V _m 、V _e respectively representing a starting threshold voltage, a maximum voltage and an ending threshold voltage,T _s 、T _m 、T _e respectively representing a time point corresponding to the initial threshold voltage, a time point corresponding to the maximum voltage and a time point corresponding to the ending threshold voltage; the voltage response curve is according to the time pointT _s 、T _m 、T _e The method comprises four stages in sequence: 0 toT _s 、T _s ~T _m 、T _m ~T _e 、T _e ~∞；

S3, according to the ratio of 0 toT _s The shape of the curve corresponding to the stage is estimated to be 0 toT _s Area under the phase correspondence curveS _s ；

S4, calculating according to the actual sampling dataT _s ~T _m Area under the phase correspondence curveS _m ；

S5, calculating according to the actual sampling dataT _m ~T _e Area under the phase correspondence curveS _e ；

S6, according toT _e ~∞The stage is estimated corresponding to the shape of the curveT _e ~∞Area under the phase correspondence curveS _t ；

S7, calculating the area under the whole curve of 0 to infinityS，S=S _s +S _m +S _e +S _t ；

S8, calculating the optical energy measured value of the incident lightE，E=a×S(ii) a Wherein,athe coefficients are corrected for energy calibrated to a standard light source.

2. The fast calculation method for pulse energy measurement according to claim 1, characterized in that: in step S2, an initial threshold point is set (T _s ，V _s ) Obtaining a maximum point from the voltage response curve (T _m ，V _m ) And according to the maximum voltageV _m Calculating an end threshold voltageV _e And further determining an end threshold point (T _e ，V _e )。

3. The fast calculation method for pulse energy measurement according to claim 2, characterized in that: the end threshold voltageV _e =0.368V _m Or, the end threshold voltageV _e =0.5V _m 。

4. The fast calculation method for pulse energy measurement according to claim 1, characterized in that: in step S3, based on the starting threshold point (S) ((T _s ，V _s ) And 1.2 times the onset threshold point (T _s1 ，V _s1) The following formula was used to calculate 0 toT _s Area under curve over time periodS _s ：S _s =(V _s ×T _s1)/0.4，

Wherein,V _s is the starting threshold valueThe voltage is applied to the surface of the substrate,V _s1set to 1.2 times the starting threshold voltage,T _s is the time point corresponding to the initial threshold voltage and is marked as the zero point of the collected data,T _s1is the time point corresponding to 1.2 times the initial threshold voltage.

5. The fast calculation method for pulse energy measurement according to claim 1, characterized in that: in step S4, the following equation is used for calculationT _s ~T _m Area under curve over time periodS _m ：

；

Wherein,f(t _i )for the sampling points to correspond to the voltage values,Δtfor the sampling time, the number of samples n ═ c (T _m －T _s )/Δt。

6. The fast calculation method for pulse energy measurement according to claim 1, characterized in that: in step S5, the following equation is used for calculationT _m ~T _e Area under curve over time periodS _e ：

；

Wherein,y(t _i )for the sampling points to correspond to the voltage values,Δtfor the sampling time, the number of samples w ═ c (c)T _e －T _m )/Δt。

7. The fast calculation method for pulse energy measurement according to claim 1, characterized in that: in the step S6, in step S6,T _e ~∞area under time period curveS _t The estimation is made by the following formula:S _t =V _e ×τwhereinτis 1 ^ or which is the decay of the voltage value from the maximum value to the maximum value in the voltage response curveeTime of the double.

8. A fast calculation apparatus for pulse energy measurement for implementing the fast calculation method for pulse energy measurement according to claim 1, characterized in that: the device comprises a control module, a storage module, a characteristic point calculation module, an area calculation module and a power calculation module; wherein,

the control module is used for coordinating the work of other modules;

the characteristic point calculating module is used for obtaining an initial threshold value point from a voltage response curve measured by the thermopile detectorT _s ，V _s ) Maximum point of (a)T _m ，V _m ) And an end threshold point: (T _e ，V _e )；

The area calculation module is used for calculating according to actual sampling dataT _s ~T _m AndT _m ~T _e area under the phase correspondence curveS _m AndS _e and estimating 0 toT _s AndT _e ~∞area under the phase correspondence curveS _s AndS _t and calculateS _s 、S _m 、S _e AndS _t sum of (2)S；

The power calculation module is used for calculating the area under the whole curve according to the range of 0 to infinitySCalculating the optical energy measurement value of the incident lightE；

The storage module is used for storing a voltage response curve measured by the thermopile detector and all calculation results of the characteristic point calculation module, the area calculation module and the power calculation module.

9. The fast calculation apparatus for pulse energy measurement according to claim 8, wherein: the feature point calculation module is used for setting an initial threshold point (T _s ，V _s ) And for obtaining a maximum point from the voltage response curve (T _m ，V _m ) And according to the maximum voltageV _m Calculating an end threshold voltageV _e And further determining an end threshold point (T _e ，V _e )。

10. The fast calculation apparatus for pulse energy measurement according to claim 8, wherein:

the area calculation module is used for calculating the area of the object according to an initial threshold point (T _s ，V _s ) And 1.2 times the onset threshold point (T _s1 ，V _s1) The following formula was used to estimate 0 toT _s Area under the time period corresponding curveS _s ：

S _s =(V _s ×T _s1)/0.4，

Wherein,V _s is the starting threshold voltage of the voltage at which,V _s1set to 1.2 times the starting threshold voltage,T _s is the time point corresponding to the initial threshold voltage and is marked as the zero point of the collected data,T _s1is 1.2 times the time point corresponding to the initial threshold voltage;

the area calculation module is used for calculating by using the following formulaT _s ~T _m Area under curve over time periodS _m ：

；

Wherein,f(t _i )for the sampling points to correspond to the voltage values,Δtfor the sampling time, the number of samples n ═ c (T _m －T _s )/Δt；

The area calculation module is used for calculating by using the following formulaT _m ~T _e Area under curve over time periodS _e ：

；

Wherein,y(t _i )for the sampling points to correspond to the voltage values,Δtfor the sampling time, the number of samples w ═ c (c)T _e －T _m )/Δt；

The area calculation module is further configured to pair through the following formulaT _e ~∞Area under time period curveS _t And (4) estimating:

；

wherein,τis 1 ^ or which is the decay of the voltage value from the maximum value to the maximum value in the voltage response curveeTime of the double.

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