CN104296882A - Large-caliber and wide-dynamic-range infrared system radiometric calibration method - Google Patents

Abstract

The invention discloses a large-caliber and wide-dynamic-range infrared system radiometric calibration method and belongs to the technical field of photoelectric measurement. The large-caliber and wide-dynamic-range infrared system radiometric calibration method comprises the steps that an entrance pupil of an infrared system is covered with an opening of a high-precision surface source black body, and medium-temperature-section external radiometric calibration and low-temperature-section external radiometric calibration are conducted on the infrared system; the medium-and-high-temperature cavity type black body is placed at an equivalent position of a primary image face of the infrared system, a reflector is moved horizontally and is switched, and medium-temperature-section internal radiometric calibration and high-temperature-section internal radiometric calibration are conducted on a part of a light path; internal calibration data and external calibration data in a common temperature area are extracted and processed, so that the correction coefficient between internal calibration and external calibration is obtained, and medium-temperature-section internal radiometric calibration data and high-temperature-section internal radiometric calibration data are corrected, so that medium-temperature-section radiometric calibration data and high-temperature-section radiometric calibration data of the whole light path are obtained; whole-system and wide-dynamic-range radiometric calibration data are obtained according to an external calibration result, and then radiometric calibration is achieved. According to the large-caliber and wide-dynamic-range infrared system radiometric calibration method, wide-dynamic-range radiometric calibration of the large-caliber infrared system is achieved on the basis that no large-caliber infrared collimator is used, the radiometric calibration precision is guaranteed, the development cost of the infrared system is reduced greatly, and the motility of the infrared system is improved.

Description

Heavy caliber, wide dynamic range infrared system Calibration Method

Technical field

The invention belongs to technical field of electro-optical measurement, be specifically related to the radiation calibration of a kind of heavy caliber infrared system in wide dynamic range.

Background technology

The infrared signature measurement of target obtains one of target information, the basic technology of target being carried out to detection and identify.Infrared system will complete the detection of target and infrared signature is measured, and needs to carry out accurate radiation calibration to it before development process and line.

Present stage, the radiation calibration of heavy caliber, wide dynamic range infrared system adopts extend blackbody method and parallel light tube to expand the method for method combination: extend blackbody method uses the extend blackbody covering infrared system entrance pupil to carry out radiation calibration to infrared system, the maximum temperature that can set due to extend blackbody is less, thus extend blackbody method can only be used in, the radiation calibration of low temperature section; It is after using the infrared radiation of infrared collimator centering high temperature lumen type black matrix to expand that parallel light tube expands method, the entrance pupil projecting infrared system carries out radiation calibration, achieve the radiation calibration of heavy caliber infrared system at middle and high temperature section, but there is cycle length, high in cost of production shortcoming in the manufacture of heavy caliber infrared collimator, the method can only be carried out in indoor simultaneously, the maneuverability requirement that inapplicable range equipment is higher.

Summary of the invention

In order to solve problems of the prior art, the invention provides a kind of heavy caliber, wide dynamic range infrared system Calibration Method, the method realizes the radiation calibration of heavy caliber infrared system in wide dynamic range by the radiation calibration of inside and outside scaled correction.

The technical scheme that technical solution problem of the present invention adopts is as follows:

Heavy caliber, wide dynamic range infrared system Calibration Method, the method equipment therefor comprises: high precision extend blackbody, middle high temperature lumen type black matrix, infrared system and infrared eye; The method comprises the steps:

Step one: the bore of high precision extend blackbody is covered the entrance pupil of infrared system, introduces infrared system by the radiation of high precision extend blackbody, and in carrying out infrared system, low-temperature zone radiation calibrates outward;

Step 2: the equivalent position place middle high temperature lumen type black matrix being placed on infrared system image planes, by translation switched mirror, introduces infrared system by the radiation of middle high temperature lumen type black matrix, part light path is carried out to the radiation internal calibration of medium and high temperature section;

Step 3: extract calibration data inside and outside public temperature range by infrared eye and process to obtain the correction factor between inside and outside calibration, the internal calibration data of use correction factor centering, high temperature section carry out revising the radiation calibration data of the full light path of acquisition in medium and high temperature section;

Step 4: combine the radiation calibration data that outer the calibration results obtains total system, wide dynamic range, achieves heavy caliber, wide dynamic range infrared system Calibration Method.

The invention has the beneficial effects as follows: on the basis not using heavy caliber infrared collimator, achieve the radiation calibration of heavy caliber infrared system in wide dynamic range, while guarantee radiation calibration precision, dramatically saves on the development cost of infrared system, and improve the maneuverability of infrared system.

Accompanying drawing explanation

Fig. 1 is heavy caliber, wide dynamic range infrared system Calibration Method calibrates schematic diagram outward;

Fig. 2 is heavy caliber, wide dynamic range infrared system Calibration Method internal calibration schematic diagram;

Fig. 3 is heavy caliber, wide dynamic range infrared system Calibration Method workflow diagram.

In figure: 1, high precision extend blackbody, 2, infrared system, 3, image planes, 4, middle high temperature lumen type black matrix, 5, switched mirror, 6, infrared eye and 7, front system.

Embodiment

Below in conjunction with drawings and Examples, the present invention is described in further details.

As depicted in figs. 1 and 2, be placed on by middle high temperature lumen type black matrix 4 on the equivalent position of the inner image planes 3 of infrared system 2, the translation of switched mirror 5 makes the radiation of medium and high temperature lumen type black matrix 4 introduce and draw infrared system 2.The step of the method is as follows:

Step one: switched mirror 5 is moved into light path, high precision extend blackbody 1 is work black matrix, and now infrared system 2 is outer calibration state.As shown in Figure 1, the entrance pupil of the bore covering infrared system 2 of high precision extend blackbody 1 carries out radiation calibration to total system, and by covering the target surface of infrared eye 6 after infrared system 2, the mathematical model of outer calibration can be expressed as:

DN ₁＝t·(α _w·L _b+DN _stray,w)+DN _det,w (1)

In formula, DN ₁for infrared eye output gray level value, t is the integral time of infrared eye, α _wfor outer calibration radiance responsiveness, L _bfor the radiance of black matrix, DN _{stray, w}for the gray-tone response caused by system self heat radiation, scattering background radiation etc. during outer calibration, DN _{det, w}for the gray-tone response that infrared detector dark current causes.

Step 2: switched mirror 5 is shifted out light path, middle high temperature lumen type black matrix 4 is work black matrix, and now infrared system 2 is internal calibration state.As shown in Figure 2, cover the target surface of infrared eye 6 after the radiation passage spectroscopy system of middle high temperature lumen type black matrix 4, carry out internal calibration to the part light path of infrared system 2, the mathematical model of internal calibration can be expressed as:

DN ₂＝t·(α _n·L _b+DN _stray,n)+DN _det,n (2)

In formula, DN ₂for infrared eye output gray level value, t is the integral time of infrared eye, α _nfor internal calibration radiance responsiveness, L _bfor the radiance of black matrix, DN _{stray, n}for the gray-tone response caused by system self heat radiation, scattering background radiation etc. during internal calibration, DN _{det, n}for the gray-tone response that infrared detector dark current causes.

Step 3: according to Fig. 1 and Fig. 2, in the optical system applied during inside and outside calibration, difference totally 6 camera lenses, by these 6 camera lenses as an entirety, be called " front system 7 ", according to internal calibration mathematical model (2), outer calibration can also be expressed as:

$\begin{array}{c}{\mathrm{DN}}_1=t\·({\mathrm{\α}}_n\·({\mathrm{\τ}}_{\mathrm{ps}}\·L_b+B_{\mathrm{ps}})+{\mathrm{DN}}_{\mathrm{stray},n})+{\mathrm{DN}}_{\det ,n}\\ =t\·{\mathrm{\α}}_n\·{\mathrm{\τ}}_{\mathrm{ps}}\·L_b+(t\·{\mathrm{\α}}_n\·B_{\mathrm{ps}}+t\·{\mathrm{DN}}_{\mathrm{stray},n}+{\mathrm{DN}}_{\det ,n})\end{array}---\left(3\right)$

In formula, τ _psfor the gain of front system 7, B _psfor being biased of front system 7.

Above formula and formula (1) simultaneous also arrange and can obtain:

${\mathrm{\τ}}_{\mathrm{ps}}=\frac{{\mathrm{\α}}_w}{{\mathrm{\α}}_n}---\left(4\right)$

$B_{\mathrm{ps}}=\frac{t\·({\mathrm{DN}}_{\mathrm{stary},w}-{\mathrm{DN}}_{\mathrm{stray},n})+({\mathrm{DN}}_{\det ,w}-{\mathrm{DN}}_{\det ,n})}{t\·{\mathrm{\α}}_n}---\left(5\right)$

The gray-tone response caused due to the inner dark current of infrared eye is approximately a constant, and institute with the formula (5) can be reduced to:

$B_{\mathrm{ps}}=\frac{{\mathrm{DN}}_{\mathrm{stary},w}-{\mathrm{DN}}_{\mathrm{srray},n}}{{\mathrm{\α}}_n}---\left(6\right)$

Suppose that outer temperature range of calibrating is T ₀~ T ₂, the temperature range of internal calibration is T ₁~ T ₃, extract public temperature range T ₁~ T ₂inside and outside calibration data, utilize formula (4) and (6) that the gain τ of front system 7 can be calculated _psand biased B _ps, these two parameters are the correction factor between inside and outside calibration.

Use τ _psand B _pscentering, high-temperature section (T ₁~ T ₃) internal calibration data correction, obtain:

DN＝t·α _n ^m-h·τ _ps·L _b+(t·α _n ^m-h·B _ps+t·DN _stray，n ^m-h+DN _det，n ^m-h)＝α _Q ^m-h·L _b+DN _Q ^m-h

(

7

)

In formula, α _q ^m-hand DN _q ^m-hfor total system is at middle and high temperature section (T ₁~ T ₃) radiance responsiveness and biased, can be expressed as:

α _Q ^m-h＝t·α _n ^m-h·τ _ps (8)

DN _Q ^m-h＝t·α _n ^m-h·B _ps+t·DN _stray,n ^m-h+DN _det,n ^m-h (9)

Total system just can be obtained at middle and high temperature section (T according to formula (9) ₁~ T ₃) radiation calibration result.

Step 4: combine total system that outer calibration obtains in, the radiation calibration result of low temperature section just can obtain total system, wide dynamic range (T ₀~ T ₃) radiation calibration result, operating process of the present invention is as shown in Figure 3.

Claims (1)

1. heavy caliber, wide dynamic range infrared system Calibration Method, the method equipment therefor comprises: high precision extend blackbody, middle high temperature lumen type black matrix, infrared system and infrared eye; It is characterized in that, the method comprises the steps:

Step one: the bore of high precision extend blackbody is covered the entrance pupil of infrared system, introduces infrared system by the radiation of high precision extend blackbody, and in carrying out infrared system, low-temperature zone radiation calibrates outward;

Step 2: the equivalent position place middle high temperature lumen type black matrix being placed on infrared system image planes, by translation switched mirror, introduces infrared system by the radiation of middle high temperature lumen type black matrix, part light path is carried out to the radiation internal calibration of medium and high temperature section;

Step 3: extract the inside and outside calibration data of public temperature range by infrared eye and process to obtain the correction factor between inside and outside calibration, the internal calibration data of use correction factor centering, high temperature section carry out revising the radiation calibration data of the full light path of acquisition in medium and high temperature section;

Step 4: combine the radiation calibration data that outer the calibration results obtains total system, wide dynamic range, achieves heavy caliber, wide dynamic range infrared system radiation calibration.