1. The utility model provides a latent rail spectral radiance calibration equipment under spectral imaging equipment which characterized in that: including broadband standard lamp and diffuse reflection board combination, diffuse reflection board combination includes telescopic bracket and adjustable rotating shaft, the last centre bore that is provided with of telescopic bracket, the position that lies in the centre bore both sides on the telescopic bracket is provided with polytetrafluoroethylene standard diffuse reflection board and doping rare earth element's polytetrafluoroethylene diffuse reflection board respectively, adjustable rotating shaft is connected with telescopic bracket's centre bore department, and is the slope structure between adjustable rotating shaft and the telescopic bracket, telescopic bracket sets up at spectral imaging equipment front end, broadband standard lamp sets up in telescopic bracket top.

2. An underwater on-orbit spectral radiance calibration method for a spectral imaging device is characterized by comprising the following steps: the method comprises the following steps:

1) radiation calibration:

obtaining the corresponding absolute spectral radiance L (lambda) of the underwater target from the digital output DN value of the underwater spectral imaging equipment; setting the radiance L (lambda) of the spectrum of the underwater target and the radiance L of the reference spectrum of the underwater target radiometric calibration reference standard during the on-orbit operation of the underwater spectral imaging equipment as L_c(λ), the corresponding numerical outputs are:

DN(i，j)＝C(i，j)L(λ)+b(i，j) (1)

DN_c(i，j)＝C(i，j)L_c(λ)+b(i，j) (2)

in the formula, C (i, j) is the radiation responsivity of the pixel of the ith row and the jth column of the detector of the underwater spectral imaging equipment; b (i, j) is the dark current output of the pixel of the ith row and the jth column of the underwater spectral imaging equipment;

the spectral radiance of the underwater target obtained by the formulas (1) and (2) is as follows:

periodically measuring electronic output DN corresponding to on-orbit calibration reference standard during potential orbit operation under underwater spectral imaging equipment_c(i，j)，L_c(lambda) is precisely known in advance, and the potential rail radiation calibration under the underwater spectral imaging equipment can be completed by using a formula (3);

2) spectrum calibration:

s1: the diffuse reflection plate combination is not cut into the light path, and the dark current value D of each pixel of the CCD of the spectral imaging equipment is recorded_ij；

S2: doping dilute through adjustable rotating shaftCutting a polytetrafluoroethylene standard diffuse reflection plate of the soil element into the light path, namely cutting a spectrum calibration diffuse reflection plate into the light path, and recording DN response value A of each pixel of a CCD of the spectrum imaging equipment_ij；

S3: cutting a polytetrafluoroethylene standard diffuse reflection plate into a light path through an adjustable rotating shaft, namely cutting a radiation calibration diffuse reflection plate into the light path, and recording DN response value B of each pixel of a CCD (charge coupled device) of the spectral imaging equipment_ij；

S4: substituting the measured spectral response data into the formula (1) for normalization to obtain a spectral response normalization value result C of the spectral calibration diffuse reflection plate after dark current noise is removed_ij；

Wherein i represents a row and represents a spectrum dimension pixel number, j represents a column and represents a space dimension pixel number, and each value is acquired and measured for multiple times to obtain an average value so as to reduce errors;

s5: fixing the direction of the field of view, selecting a central field of view, namely selecting a specific J-J value, obtaining the corresponding relation between the spectrum dimension pixel number and the normalization value in the direction of the single field of view, namely fixing the J-J value, giving an i value, and obtaining a C value_iJObtaining a data graph with the abscissa as a pixel number and the ordinate as a normalization value;

s6: adopting a Gaussian fitting method to carry out peak searching processing and determining a peak value center pixel number X_ijAnd absorption peak position wavelength Y_ijData set namely [ X ]_ij，Y_ij]If the spectrum calibration diffuse reflection plate has m absorption peaks, m data sets are obtained;

s7: based on approximate linear arrangement of imaging detectors CCD of the spectral imaging equipment, a spectral calibration equation is established by the data set obtained in the last step, and regression analysis is carried out by adopting a least square method, which is shown as the following formula:

in the formula a_jb_jConstant terms and first-order term coefficients representing a spectrum calibration equation are used as parameters to be estimated; m is the number of absorption peaks,when j is fixed for the spatial dimension in the j-th column, X_ij，Y_ijThe formula (2) can give a spectrum calibration equation function under a fixed field of view, namely, the spectrum calibration is realized.

Background art:

in the real use process of the underwater spectral imaging device, the parameters of optical, mechanical and electronic parts of the underwater spectral imaging device are slightly changed under the influence of unavoidable factors such as a submarine distribution stage and an on-orbit operation period, such as ocean dynamic environment (impact and vibration), so that the responsivity of the spectral imaging device is reduced. Meanwhile, when the underwater spectral imaging equipment is really used, the factors of the underwater background environment of the ocean are not completely the same as the calibration background environment of a laboratory. In consideration of the above situation, the laboratory calibration response function before submerging will generate difference, the data inversion result will not be applicable any more, and it is necessary to supplement the submerged spectrum radiometric calibration of the underwater spectrum imaging device on the basis of laboratory calibration.

The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

The invention content is as follows:

the invention aims to provide a potential rail spectrum radiation calibration device and a calibration method thereof under an underwater spectrum imaging device, thereby overcoming the defects in the prior art.

In order to achieve the purpose, the invention provides a potential rail spectral radiation calibration device under an underwater spectral imaging device, which comprises a broadband standard lamp and a diffuse reflection plate combination, wherein the diffuse reflection plate combination comprises a telescopic support frame and an adjustable rotating shaft, the telescopic support frame is provided with a central hole, polytetrafluoroethylene standard diffuse reflection plates and polytetrafluoroethylene diffuse reflection plates doped with rare earth elements are respectively arranged at the positions on two sides of the central hole on the telescopic support frame, the adjustable rotating shaft is connected with the central hole of the telescopic support frame, an inclined structure is formed between the adjustable rotating shaft and the telescopic support frame, the telescopic support frame is arranged at the front end of the spectral imaging device, and the broadband standard lamp is arranged above the telescopic support frame.

A method for calibrating underwater on-orbit spectral radiation of a spectral imaging device comprises the following steps:

1) radiation calibration:

obtaining the corresponding absolute spectral radiance L (lambda) of the underwater target from the digital output DN value of the underwater spectral imaging equipment; under water spectral analysisDuring the on-orbit operation of the image equipment, the spectral radiance L (lambda) of the underwater target and the spectral radiance L of the reference standard of the underwater latent orbit radiometric calibration_c(λ), the corresponding numerical outputs are:

DN(i，j)＝C(i，j)L(λ)+b(i，j) (1)

DN_c(i，j)＝C(i，j)L_c(λ)+b(i，j) (2)

in the formula, C (i, j) is the radiation responsivity of the pixel of the ith row and the jth column of the detector of the underwater spectral imaging equipment; b (i, j) is the dark current output of the pixel of the ith row and the jth column of the underwater spectral imaging equipment;

the spectral radiance of the underwater target obtained by the formulas (1) and (2) is as follows:

periodically measuring electronic output DN corresponding to on-orbit calibration reference standard during potential orbit operation under underwater spectral imaging equipment_c(i，j)，L_c(lambda) is precisely known in advance, and the potential rail radiation calibration under the underwater spectral imaging equipment can be completed by using a formula (3);

2) spectrum calibration:

s1: the diffuse reflection plate combination is not cut into the light path, and the dark current value D of each pixel of the CCD of the spectral imaging equipment is recorded_ij；

S2: cutting a polytetrafluoroethylene standard diffuse reflection plate doped with rare earth elements into a light path through an adjustable rotating shaft, namely cutting a spectrum calibration diffuse reflection plate into the light path, and recording DN response value A of each pixel of a CCD (charge coupled device) of a spectrum imaging device_ij；

S3: cutting a polytetrafluoroethylene standard diffuse reflection plate into a light path through an adjustable rotating shaft, namely cutting a radiation calibration diffuse reflection plate into the light path, and recording DN response value B of each pixel of a CCD (charge coupled device) of the spectral imaging equipment_ij；

S4: substituting the measured spectral response data into the formula (1), and normalizing to obtain the spectral response of the spectral calibration diffuse reflection plate after dark current noise is removedNormalized value result C_ij；

Wherein i represents a row and represents a spectrum dimension pixel number, j represents a column and represents a space dimension pixel number, and each value is acquired and measured for multiple times to obtain an average value so as to reduce errors;

s5: fixing the direction of the field of view, selecting a central field of view, namely selecting a specific J-J value, obtaining the corresponding relation between the spectrum dimension pixel number and the normalization value in the direction of the single field of view, namely fixing the J-J value, giving an i value, and obtaining a C value_iJObtaining a two-dimensional data graph with the abscissa as a pixel number and the ordinate as a normalization value;

s6: adopting a Gaussian fitting method to carry out peak searching processing and determining a peak value center pixel number X_ijAnd absorption peak position wavelength Y_ijData set namely [ X ]_ij,Y_ij]If the spectrum calibration diffuse reflection plate has m absorption peaks, m data sets are obtained;

s7: based on approximate linear arrangement of imaging detectors CCD of the spectral imaging equipment, a spectral calibration equation is established by the data set obtained in the last step, and regression analysis is carried out by adopting a least square method, which is shown as the following formula:

in the formula a_j b_jConstant terms and first-order term coefficients representing a spectrum calibration equation are used as parameters to be estimated; m is the number of absorption peaks,when j is fixed for the spatial dimension in the j-th column, X_ij，Y_ijThe formula (2) can give a spectrum calibration equation function under a fixed field of view, namely, the spectrum calibration is realized.

Compared with the prior art, the invention has the following beneficial effects:

the invention adopts the combination of the polytetrafluoroethylene standard diffuse reflection plate and the polytetrafluoroethylene diffuse reflection plate doped with rare earth elements to establish the spectral radiation standard, can realize the spectral calibration and the radiation calibration of the underwater spectral imaging equipment during the in-orbit operation, makes up the inaccuracy of the laboratory calibration result caused by the submerged arrangement of the instrument and the tiny change of the optical-mechanical structure during the in-orbit operation, and can improve the spectral radiation calibration precision.

Description of the drawings:

FIG. 1 is a schematic diagram of a potential rail spectral radiance scaling apparatus under an underwater spectral imaging device of the present invention;

the reference signs are: 1-broadband standard lamp, 2-diffuse reflection plate combination, 21-telescopic support frame, 22-adjustable rotating shaft, 23-center hole, 24-polytetrafluoroethylene standard diffuse reflection, 25-rare earth element doped polytetrafluoroethylene diffuse reflection plate and 3-spectral imaging equipment.

The specific implementation mode is as follows:

the following detailed description of specific embodiments of the invention is provided, but it should be understood that the scope of the invention is not limited to the specific embodiments.

Throughout the specification and claims, unless explicitly stated otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element or component but not the exclusion of any other element or component.

As shown in fig. 1, a latent rail spectral radiance calibration device under spectral imaging equipment under water, including broadband standard lamp 1 and diffuse reflection board combination 2, diffuse reflection board combination 2 includes telescopic support frame 21 and adjustable pivot 22, be provided with centre bore 23 on the telescopic support frame 21, the position that lies in centre bore 23 both sides on the telescopic support frame 21 is provided with polytetrafluoroethylene standard diffuse reflection 24 board and doping rare earth element's polytetrafluoroethylene diffuse reflection board 25 respectively, adjustable pivot 22 is connected with telescopic support frame 21's centre bore 23 department, and is the slope structure between adjustable pivot 22 and the telescopic support frame 21, telescopic support frame 21 sets up at spectral imaging equipment 3 front end, broadband standard lamp 1 sets up in telescopic support frame 21 top.

A method for calibrating underwater on-orbit spectral radiation of a spectral imaging device comprises the following steps:

1) radiation calibration:

obtaining the corresponding absolute spectral radiance L (lambda) of the underwater target from the digital output DN value of the underwater spectral imaging equipment; setting the radiance L (lambda) of the spectrum of the underwater target and the radiance L of the reference spectrum of the underwater target radiometric calibration reference standard during the on-orbit operation of the underwater spectral imaging equipment as L_c(λ), the corresponding numerical outputs are:

DN(i，j)＝C(i，j)L(λ)+b(i，j) (1)

DN_c(i，j)＝C(i，j)L_c(λ)+b(i，j) (2)

in the formula, C (i, j) is the radiation responsivity of the pixel of the ith row and the jth column of the detector of the underwater spectral imaging equipment; b (i, j) is the dark current output of the pixel of the ith row and the jth column of the underwater spectral imaging equipment;

the spectral radiance of the underwater target obtained by the formulas (1) and (2) is as follows:

periodically measuring electronic output DN corresponding to on-orbit calibration reference standard during potential orbit operation under underwater spectral imaging equipment_c(i，j)，L_c(lambda) is precisely known in advance, and the potential rail radiation calibration under the underwater spectral imaging equipment can be completed by using a formula (3);

2) spectrum calibration:

s1: the diffuse reflection plate combination is not cut into the light path, and the dark current value D of each pixel of the CCD of the spectral imaging equipment is recorded_ij；

S2: cutting a polytetrafluoroethylene standard diffuse reflection plate doped with rare earth elements into a light path through an adjustable rotating shaft, namely cutting a spectrum calibration diffuse reflection plate into the light path, and recording DN response value A of each pixel of a CCD (charge coupled device) of a spectrum imaging device_ij；

S3：Cutting a polytetrafluoroethylene standard diffuse reflection plate into a light path through an adjustable rotating shaft, namely cutting a radiation calibration diffuse reflection plate into the light path, and recording DN response value B of each pixel of a CCD (charge coupled device) of the spectral imaging equipment_ij；

S4: substituting the measured spectral response data into the formula (1) for normalization to obtain a spectral response normalization value result C of the spectral calibration diffuse reflection plate after dark current noise is removed_ij；

Wherein i represents a row and represents a spectrum dimension pixel number, j represents a column and represents a space dimension pixel number, and each value is acquired and measured for multiple times to obtain an average value so as to reduce errors;

s5: fixing the direction of the field of view, selecting a central field of view, namely selecting a specific J-J value, obtaining the corresponding relation between the spectrum dimension pixel number and the normalization value in the direction of the single field of view, namely fixing the J-J value, giving an i value, and obtaining a C value_iJObtaining a two-dimensional data graph with the abscissa as a pixel number and the ordinate as a normalization value;

s6: adopting a Gaussian fitting method to carry out peak searching processing and determining a peak value center pixel number X_ijAnd absorption peak position wavelength Y_ijData set namely [ X ]_ij,Y_ij]If the spectrum calibration diffuse reflection plate has m absorption peaks, m data sets are obtained;

s7: based on approximate linear arrangement of imaging detectors CCD of the spectral imaging equipment, a spectral calibration equation is established by the data set obtained in the last step, and regression analysis is carried out by adopting a least square method, which is shown as the following formula:

in the formula a_j b_jConstant terms and first-order term coefficients representing a spectrum calibration equation are used as parameters to be estimated; m is the number of absorption peaks,when j is fixed for the spatial dimension in the j-th column, X_ij，Y_ijThe formula (2) can give a spectrum calibration equation function under a fixed field of view, namely, the spectrum calibration is realized.

The telescopic support frame with the height capable of being accurately adjusted is selected as the telescopic support frame, and the rotating shaft with the angle capable of being accurately adjusted is selected as the adjustable rotating shaft, so that two diffuse reflection plates in the diffuse reflection plate combination can be better cut into a light path.

The invention adopts the combination of the polytetrafluoroethylene standard diffuse reflection plate and the polytetrafluoroethylene diffuse reflection plate doped with rare earth elements to establish the spectral radiation standard, can realize the spectral calibration and the radiation calibration of the underwater spectral imaging equipment during the in-orbit operation, makes up the inaccuracy of the laboratory calibration result caused by the submerged arrangement of the instrument and the tiny change of the optical-mechanical structure during the in-orbit operation, and can improve the spectral radiation calibration precision.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application to enable one skilled in the art to make and use various exemplary embodiments of the invention and various alternatives and modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims and their equivalents.