A high-precision modeling method for calculating the detection capability of a broadband photoelectric telescope

Abstract

The application discloses a kind of wide-band photoelectric telescope detection ability high-precision calculation modeling methods, belong to photoelectric measurement technical field.The method is by the spectral integration of target photon flux density, system response and noise source in the whole detection waveband, accurately calculate signal electron number, background electron number and total noise, and then solve system signal-to-noise ratio (SNR).Specifically include: based on target apparent magnitude and blackbody radiation model calculation photon flux density;Integral calculation signal electron number and background electron number;Comprehensively consider photon noise, dark current noise and readout noise, integral solution total noise;Finally, based on the integral result, calculate signal-to-noise ratio.The application overcomes the deficiency of traditional average wavelength approximation method, significantly improves the signal-to-noise ratio calculation precision, and is suitable for the design and performance evaluation of different photoelectric systems.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of photoelectric measurement, and particularly relates to a high-precision calculation modeling method for detection capability of a wide-band photoelectric telescope. BACKGROUND

[0002] The system detection capability of a photoelectric telescope is a core performance index, and directly determines the detection limit of the system on a weak target and the reliability of observation data. In system design, performance estimation and observation task planning, a high-precision detection capability calculation model is an indispensable theoretical basis. However, the actual detection process is affected by a variety of internal and external factors, including the coupling of a variety of wavelength-dependent parameters such as target radiation characteristics, optical system aperture and transmittance, detector spectral response, atmospheric attenuation, and sky background radiation.

[0003] The traditional detection capability calculation model is usually based on the average wavelength or the segmented approximation method, and the wavelength dependence of factors such as target spectral distribution, camera quantum efficiency curve, film system spectral characteristics and atmospheric transmittance function is not considered. This kind of method simplifies the continuous spectral response to a single wavelength point processing, ignores the actual wide-band integral effect, and leads to significant systematic deviation in calculating signal electrons and various noises. Especially in the detection of weak targets, high background conditions or complex atmospheric environment, there is a large error between the theoretical prediction results of the traditional model and the measured data, which is difficult to meet the needs of modern high-precision photoelectric observation tasks.

[0004] Therefore, there is an urgent need in the prior art for a high-precision modeling method of wide-band and multi-parameter coupling. It is urgently needed to provide a theoretical model which can fully consider the spectral characteristics, accurately calculate the signal and noise by integration in the full waveband range, and thus more truly reflect the actual detection performance of the photoelectric system, so as to improve the accuracy and reliability of system design and evaluation. SUMMARY

[0005] To solve the above technical problems, the application provides a high-precision calculation modeling method for detection capability of a wide-band photoelectric telescope, which accurately calculates signal electrons, background electrons and total noise by spectral integration of target photon flux density, system response and noise source in the entire detection waveband, and then solves the signal-to-noise ratio (SNR) of the system.

[0006] To achieve the above purpose, the application adopts the following technical scheme:

[0007] A high-precision calculation modeling method for detection capability of a wide-band photoelectric telescope, the method comprising:

[0008] Step 1, based on the target-based apparent magnitude, the photon flux density is determined, and the target signal electrons generated by a single target pixel in the exposure time and the background signal electrons generated by a single background pixel in the exposure time are calculated by integrating the wavelength in the entire working waveband range of the telescope;

[0009] Step 2, in the working waveband, the total noise composed of target photon noise, background photon noise, dark current noise and readout noise during the observation of the target by the photodetector telescope is calculated;

[0010] Step 3, based on the target signal electrons, the background signal electrons and the total noise, the signal-to-noise ratio of the photodetector telescope for the observed target is calculated by applying definite integral.

[0011] In a second aspect, the present application provides an electronic device, comprising: one or more processors; a memory for storing one or more programs; wherein when the one or more programs are executed by the one or more processors, the one or more processors implement the aforementioned wide-band photoelectric telescope detection capability high-precision calculation modeling method.

[0012] In a third aspect, the present application provides a computer-readable storage medium having stored executable instructions, which, when executed by a processor, can enable the processor to implement the aforementioned wide-band photoelectric telescope detection capability high-precision calculation modeling method.

[0013] The present application has the following beneficial effects:

[0014] The calculation accuracy is significantly improved: the wide-band spectral integration method is adopted, the traditional average wavelength approximation strategy is completely abandoned, the spectral dependence of key parameters such as target radiation, atmospheric transmittance, optical system efficiency and detector response is fully taken into account, systematic deviation caused by simplified wavelength processing is effectively avoided, and the accuracy of signal-to-noise ratio (SNR) and detection capability prediction is greatly improved.

[0015] The model is more consistent with the actual observation: by strictly integrating the signal and noise in the entire detection waveband, the present model more truly reflects the actual working state of the photoelectric system, especially in the detection of weak targets, high background noise and complex atmospheric conditions, the consistency of the calculation results with the measured data is substantially improved, providing a more reliable basis for system design, performance evaluation and observation plan.

[0016] The method is universal and adaptable: the method has clear structure and high parameterization degree, and is suitable for various photoelectric systems of different wavebands, different optical structures and different detector types. Users only need to substitute the corresponding system parameters and spectral curves to realize high-precision modeling, which has good engineering applicability and popularization value. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 This is a flowchart of a high-precision calculation and modeling method for the detection capability of a wide-band photoelectric telescope according to the present invention;

[0018] Figure 2 This is an atmospheric transmittance curve from an example embodiment;

[0019] Figure 3 This is a transmittance curve of the optical system in the embodiment;

[0020] Figure 4 The graph shows the quantum efficiency of the detector used in the embodiment.

[0021] Figure 5 The above is a graph showing the background radiation curve of the skylight in the embodiment. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] like Figure 1 As shown, this invention provides a high-precision calculation and modeling method for the detection capability of a wide-band photoelectric telescope, the method comprising the following steps:

[0024] Step 1: Determine the photon flux density based on the apparent magnitude of the target. Within the entire operating wavelength range of the telescope, calculate the number of target signal electrons generated by a single target pixel during the exposure time, as well as the number of background signal electrons generated by a single background pixel during the exposure time by integrating the wavelength.

[0025] Step 2: Within the operating band, apply integral calculation to determine the total noise consisting of target photon noise, background photon noise, dark current noise, and readout noise during the observation of the target by the photoelectric detection telescope;

[0026] Step 3: Based on the number of target signal electrons, the number of background signal electrons, and the total noise, the signal-to-noise ratio of the photoelectric detection telescope to the observed target is calculated using definite integral.

[0027] Furthermore, in step 1, the exposure time of a single target pixel... Number of target signal electrons generated internally The calculation method is as follows:

[0028] ,

[0029] in, The number of signal electrons generated on a single target pixel of the image sensor during the exposure time, and its unit is _____. ; The number of photons incident on the surface of a single target pixel on the image sensor during the exposure time; This is the gain factor for the image sensor; The photon flux density corresponding to the target; The exposure time of the image sensor; The entrance pupil area of ​​the telescope's optical system; The aperture of the telescope's optical system; For example, the atmospheric transmittance function, Figure 2 As shown; Let transmittance be a function of the optical system, such as Figure 3 As shown; Let the quantum efficiency function of the image sensor be, such as Figure 4 As shown; The obstruction ratio of the telescope's optical system; The number of pixels occupied by the observed target on the image sensor; and This indicates the range of wavelengths that the telescope can detect.

[0030] For a single background pixel in an image sensor, its exposure time The number of background signal electrons generated internally for:

[0031] ,

[0032] in, The number of electrons generated on a single background pixel of the image sensor during the exposure time, expressed in units of . The number of photons from the sky background incident on the surface of a single pixel of the image sensor during the exposure time; The radiance of the sky background is given by the unit . The sky background radiance curve is as follows: Figure 5 As shown; and These are Planck's constant and the speed of light, respectively. The pixel area of ​​a single pixel in the image sensor; It is the reciprocal of the relative aperture of the telescope's optical system; and All parameters have the same meaning as those in step 1.

[0033] Furthermore, the method for calculating the total noise N during the target observation process of the photoelectric detection telescope in step 2 is as follows:

[0034] ,

[0035] in, , which represents the target photon noise; , which is background photon noise; This is the dark current noise of the image sensor; This refers to the dark current generated by the thermal effect in the image sensor. To read out noise for the imaging system; This represents the super-noise factor of the image sensor.

[0036] Furthermore, the method for calculating the signal-to-noise ratio (SNR) of the photoelectric detection telescope for the observed target in step 3 is as follows:

[0037] ,

[0038] Where M is the pixel merging factor in the pixel mode, and the other parameters are defined in the same way as in steps 2 and 3.

[0039] Example

[0040] This embodiment takes the photoelectric system of a certain experiment as an example, and includes the following steps:

[0041] Step 1: Using integration, calculate the target's position during the exposure time for a single target pixel of the image sensor in the imaging system. Number of target signal electrons generated internally And the exposure time of a single background pixel The number of background signal electrons generated internally :

[0042] Assuming stellar radiation is blackbody radiation, according to Planck's law of radiation, for an effective temperature of... Stars with wavelengths of Spectral radiative exitance at for:

[0043] ,

[0044] in, is Planck's constant, and c is the speed of light in a vacuum, and ; It is the Boltzmann constant, and ;wavelength The unit is (Angle); Effective temperature The unit is K (Kelvin).

[0045] According to the Stefan-Boltzmann law, for Integrating over the entire wavelength range yields the effective temperature. Total radiative output of stars :

[0046] ,

[0047] The spectral photon flux density of each type of star with apparent magnitude at the top of the Earth's atmosphere can be obtained by using the relationship between apparent magnitude and irradiance :

[0048] ,

[0049] The effective temperature of the Sun = 5780 K, and the spectral photon flux density function of a 0 magnitude Sun can be obtained as

[0050] ,

[0051] where is in units of ; the wavelength λ is in units of Å; and the effective temperature of the star Te is in units of K.

[0052] The photon flux density corresponding to a target with apparent magnitude is:

[0053] ,

[0054] where is in units of nm.

[0055] The number of target signal electrons produced by the target in the exposure time is:

[0056] ,

[0057] where is the number of photons incident on the surface of a single target pixel of the image sensor from the target in the exposure time; is the quantum efficiency function of the image sensor; is the gain factor of the image sensor; is the photon flux density corresponding to the target; is the exposure time of the image sensor; is the entrance pupil area of the telescope optical system; is the clear aperture of the telescope optical system; is the atmospheric transmittance function; is the optical system transmittance function; is the obscuration ratio of the telescope optical system; is the number of pixels occupied by the observation target on the image sensor; and represent the wavelength range detected by the telescope.

[0058] For a single background pixel in the image sensor, the number of background signal electrons generated in the exposure time

[0059]

[0060] where, is the number of electrons generated on a single background pixel of the image sensor in the exposure time, with the unit of is the number of sky background photons incident to the surface of a single pixel of the image sensor in the exposure time; is the sky background radiation luminosity function, with the unit of are the Planck constant and the speed of light, respectively; is the pixel area of a single pixel of the image sensor; is the reciprocal of the relative aperture of the optical system of the telescope; have the same meaning of the parameters in step 1.

[0061] Step 2, the total noise N of the photoelectric detection telescope in observing the target is calculated by integration:

[0062]

[0063] where, is the target photon noise; is the background photon noise; is the dark current noise of the image sensor; is the dark current of the image sensor due to thermal effects; is the readout noise of the imaging system; is the super noise factor of the image sensor.

[0064] Step 3, the number of target signal electrons , the number of background signal electrons and the total noise calculated by integration are obtained, and the signal-to-noise ratio of the photoelectric detection telescope for observing the target is calculated by definite integration:

[0065]

[0066] where, M is the pixel merging factor in the binning mode, and the remaining parameters have the same meaning of the parameters in steps 1 and 2.

[0067] According to steps 1 and 2, we have: ​​​​​​​​​

[0068] ,

[0069] ,

[0070] In an embodiment, the detection efficiency of a certain photoelectric imaging system is fitted by a function :

[0071] ,

[0072] The atmospheric transmittance function of the system is fitted by a smoothing spline interpolation (B-spline) as follows:

[0073] ,

[0074] wherein is the spline coefficient; is the jth cubic B-spline basis function; 89 coefficients correspond to about 85 polynomials, and each polynomial has 4 coefficients.

[0075] The optical system transmittance function of the system is fitted as follows:

[0076] ,

[0077] The sky background radiation brightness function of the system is as follows:

[0078] ,

[0079] Substituting , into the SNR formula, the signal-to-noise ratio of the system for the observed target is obtained as follows:

[0080] ,

[0081] wherein

[0082] ,

[0083] ,

[0084] ,

[0085] The coefficient of the signal term is :

[0086] ,

[0087] The coefficient of the background term is :

[0088] ​​​​ ,

[0089] In practical applications, the person skilled in the art can substitute the specific parameters into the above formula according to the working waveband of the specific photoelectric detection system, the selected detector model (its gain G, dark current De, read noise and other parameters), the transmittance of the optical system and the background radiation environment faced, so as to accurately calculate the total noise level of the system, thereby laying a foundation for system performance evaluation and optimization.

[0090] In a second aspect, the present application provides an electronic device, comprising: one or more processors; a memory for storing one or more programs; wherein when the one or more programs are executed by the one or more processors, the one or more processors implement the aforementioned wide-band photoelectric telescope detection capability high-precision calculation modeling method.

[0091] In a third aspect, the present application provides a computer-readable storage medium having stored executable instructions, which when executed by a processor, enable the processor to implement the aforementioned wide-band photoelectric telescope detection capability high-precision calculation modeling method.

[0092] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only for specific embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for high-precision calculation and modeling of the detection capability of a wide-band photoelectric telescope, characterized in that, The method comprises: Step 1, based on the apparent magnitude of the target, the photon flux density of the target is determined, and the target signal electrons generated by a single target pixel in the exposure time and the background signal electrons generated by a single background pixel in the exposure time are calculated by integrating the wavelength in the entire working waveband range of the telescope; Step 2, in the working waveband, the total noise composed of target photon noise, background photon noise, dark current noise and readout noise during the observation of the target by the photodetector telescope is calculated; Step 3, based on the target signal electrons, the background signal electrons and the total noise, the signal-to-noise ratio of the photodetector telescope for the observed target is calculated by applying definite integral; wherein, In step 1, the calculation of the target signal electrons comprises: determining the photon flux density function of the target according to the quantitative relationship between the apparent magnitude of the target and the reference star spectrum; spectrally weighting and fusing the photon flux density function with the atmospheric transmittance function, the optical system transmittance function and the detector quantum efficiency function in sequence; integrating the fusion result in the working waveband, and comprehensively considering the exposure time, the telescope entrance pupil area and the obscuration ratio parameters to calculate the target signal electrons; The calculation of the background signal electrons comprises: obtaining the sky background radiation brightness function; spectrally dependent step-by-step coupling the brightness function with the pixel area, the relative aperture of the optical system, the atmospheric transmittance function, the optical system transmittance function and the detector quantum efficiency function; integrating the coupling result in the working waveband, and comprehensively considering the exposure time and the gain factor to calculate the background signal electrons.

2. The method of claim 1, wherein, In step 2, the calculation of the total noise comprises: first, spectrally integrating the sum of the target photon noise power spectral density and the background photon noise power spectral density in the effective working waveband range of the optical system to obtain the total contribution of the photon noise covering the entire working waveband; then, algebraically adding the integral result with the square of the dark current noise and the square of the readout circuit noise represented in the full waveband range, and finally taking the square root operation of the sum.

3. The method of claim 2, wherein, The target photon noise is derived from the target signal electrons, and the background photon noise is derived from the background signal electrons.

4. The method of claim 1, wherein, In step 3, the calculation of the signal-to-noise ratio considers the influence of the pixel binning mode, and the pixel binning mode participates in the signal-to-noise ratio calculation through a pixel binning factor.

5. The method of claim 1, wherein, In step 3, the signal-to-noise ratio calculation process also considers the gain and the super noise factor of the image sensor, which is used to accurately quantify the influence of the electronic signal amplification process on the noise and the signal-to-noise ratio.

6. The method of claim 1, wherein, The method is suitable for various photodetector systems from ultraviolet, visible light to near-infrared waveband, and can adapt to the detection capability calculation under different telescope apertures, different detector models and different observation environments.

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