CN103292902B - Dayglow temperature photometer and method thereof for detecting airglow spectrum intensity and temperature - Google Patents

Abstract

The invention provides a dayglow temperature photometer and a method thereof for detecting airglow spectrum intensity and temperature. An echelon grating and a narrow-band interference filter equipped with a micro-angle stepping motor are organically combined to serve as a core device of the dayglow temperature photometer, the high spectral resolution is obtained, the range of spectrum detection is broaden by rotating narrow-band filter, and luminous intensity and temperature of dayglows in an upper atmosphere are detected simultaneously by utilizing a high-resolution spectroscopic method and a rotational spectral-line temperature-measuring method. The dayglow temperature photometer comprises four portions including a light guide system, a telescopic system, a light splitting system and an imaging system which are sequentially arranged.

Description

A kind of method of dayglow temperature photometer and probe gas aura spectral intensity and temperature

Technical field:

The present invention relates to a kind of dayglow temperature photometer, and the method for its probe gas aura spectral intensity and temperature, belong to upper atmospheric exploration technical field.

Background technology:

The naturally luminous airglow of round-the-clock is utilized to carry out as light source the Main Means that passive remote sensing atmospheric sounding characteristic (temperature, wind speed, luminous intensity, very small quantities of particles density and abundance) is research Aeronomy.

For the luminous intensity of nightglow and the detection of temperature comparatively ripe.Usual employing rotational line thermometry, it realizes by the photometer be made up of spike interference filter and photomultiplier or CCD (Charge Coupled Device), the detection accuracy of temperature reaches 1K, can obtain volume emissivity information and the dynamic characteristic of light emitting elements simultaneously.Representative instrument has the MORTI(Mesopause Oxygen Rotational Temperature Imager of the people such as the R.H.Wiens of Canadian York university development in 1989), and the SATI(Spectral Airglow Temperature Imager after this instrument being improved in 1997).The people from Japan such as K.Shiokawa have developed the same quasi-instrument possessing 12 passages and more high detection sensitivity for 2007.China's Chinese Academy of Sciences's space science and applied research center also successfully have developed an inclination filter photometer and detect twiglow and nightglow in 1996.

Certain limitation is still had for the luminous intensity of dayglow and the detection of temperature.Due to daytime, the strength ratio airglow emissive porwer of daylight goes out greatly several magnitude, if instrument is sensitive not, then the signal of dayglow is just submerged in daylight.At present, usual by high-resolution spectral instrument in the world, daylight and clear sky are taken respectively, from the comparing result of twice shooting, extracts the illuminated message of dayglow.Representative instrument has the people such as the Narayanan of India to utilize a FP etalon (Fabry – Perot etalon) the novel photosystem of covering that is coupled to obtain daylight and clear sky spectral information simultaneously, thus is finally inversed by the luminous intensity information of dayglow.The people such as the Pallamraju of the U.S. have developed single pass ground high-resolution image spectrometer (HIRISE:a ground-based high-resolution imagingspectrograph using echelle grating) and multi channel imaging spectrometer (MISE:amultiwavelength imaging spectrograph using echelle grating) respectively in 2002 and 2012, all make use of one piece of echelon grating and diffraction light splitting is carried out to target light source, obtain the luminous intensity information that meticulous spectral information carrys out inverting dayglow.The domestic detection for dayglow is still in the starting stage.

Therefore, although nightglow detection instrument can detect luminous intensity and the temperature of airglow simultaneously, due to lower spectrally resolved ability, the detection of dayglow can not be used for; Although and dayglow detection instrument possesses very high spectrally resolved ability, this important parameter of temperature of airglow can not be detected.

Summary of the invention:

The object of this invention is to provide a kind of dayglow temperature photometer, echelon grating and spike interference filter are organically combined as core devices, utilizes high-resolution spectroscopy method and rotational line thermometry to detect the luminous intensity of dayglow in upper atmosphere and temperature simultaneously.

Another object of the present invention utilizes above-mentioned dayglow temperature photometer, and the spectral intensity of detection upper atmosphere dayglow and the method for temperature, significantly improve instrument efficiency.

Technical solution of the present invention is as follows:

A kind of dayglow temperature photometer, comprise four parts set gradually: light-conducting system, telescopic system, beam splitting system, imaging system and shell, wherein, light-conducting system, by pointing to mirror 1 and precision rotation platform 2 forms, points to mirror 1 and is fixed on precision rotation platform 2; Telescopic system is made up of optical window 3, telephoto lens 4 and adjustable mechanical slit 5 successively; Beam splitting system is made up of plane mirror A6, concave mirror A7, spike interference filter 8, micro-angle stepper motor 9 and echelon grating 10 successively, wherein plane mirror A6 and concave mirror A7 is staggered relatively, and echelon grating 10 is also staggered relatively with concave mirror A7 simultaneously; Spike interference filter 8 and micro-angle stepper motor 9 form filter unit and are fixed between concave mirror A7 and echelon grating 10; Imaging system is made up of concave mirror B11, plane mirror B12 and area array CCD detector 13, concave mirror B11 and echelon grating 10 staggered relatively, concave mirror B11 and plane mirror B12 is also staggered relatively, plane mirror B12 and contour placement relative with area array CCD detector 13.

This dayglow temperature photometer is also provided with shell 14, and above four parts are fixed in shell 14.

Equal to the distance of concave mirror A7 reflection spot with from echelon grating 10 central point to the distance of concave mirror A7 reflection spot from described adjustable mechanical slit 5, be the focal length of concave mirror A7; From concave mirror B11 reflection spot to the distance of echelon grating 10 central point with equal to the distance of area array CCD detector 13 from concave mirror B11 reflection spot, be the focal length of concave mirror B11.

The incident angle of echelon grating 10 is 60 ° ~ 70 °.

Spike interference filter 8 is installed on micro-angle stepper motor 9 output shaft; Spike interference filter 8 halfwidth is between 0.2 ~ 0.8nm, and effective clear aperature is 48mm, and maximum micro-anglec of rotation is 15 °.

A method for dayglow temperature photometer probe gas aura spectral intensity and temperature, the method comprises the following steps:

1) shooting of solar direction:

A () controls precision rotation platform 2 and sensing mirror 1 is turned to solar direction, adjustment spike interference filter 8 plane of incidence normal is parallel with optical axis, opposite battle array ccd detector 13 chooses the time shutter (0.1 ~ 5s not etc., determine according to weather conditions on the same day), once take, obtain the first width spectrum picture;

B () controls the invariant position that sensing mirror 1 keeps solar direction, by micro-angle stepper motor 9 normal of spike interference filter 8 turned to the angle becoming 5 ° with optical axis, the time shutter of holding surface battle array ccd detector 13 and identical (same time shutter) in step 1) (a), carry out second time shooting, obtain the second width spectrum picture; Respectively the normal of spike interference filter 8 is turned to the angle becoming 10 ° and 15 ° with optical axis subsequently, repeat above-mentioned steps, carry out third time and the 4th shooting, obtain the 3rd width and the 4th width spectrum picture;

In c spectrum picture that four times are taken by (), not photosensitive region is deleted, first width spectrum picture end and the second width spectrum picture front end are spliced, second width is with the 3rd width, adopt same connecting method between the 3rd width and the 4th width, and the fourth officer spectrum picture width that permeates represents the complete spectrum figure of solar direction the most at last;

2) shooting in sky background direction:

A () controls precision rotation platform 2 and sensing mirror 1 is rotated 180 ° to sun reverse direction, adjustment spike interference filter 8 plane of incidence normal is parallel with optical axis, opposite battle array ccd detector 13 chooses the time shutter (0.1 ~ 5s not etc., determine according to weather conditions on the same day), once take, obtain spectrum picture;

B () controls the invariant position that sensing mirror 1 keeps sky background direction, by micro-angle stepper motor 9 normal of spike interference filter 8 turned to the angle becoming 5 ° with optical axis, the time shutter of holding surface battle array ccd detector 13 and step 2) identical (same time shutter) in (a), carry out second time shooting, obtain the second width spectrum picture; Respectively the normal of spike interference filter 8 is turned to the angle becoming 10 ° and 15 ° with optical axis subsequently, repeat above-mentioned steps, carry out third time and the 4th shooting, obtain the 3rd width and the 4th width spectrum picture;

In c spectrum picture that four times are taken by (), not photosensitive region is deleted, first width spectrum picture end and the second width spectrum picture front end are spliced, second width is with the 3rd width, adopt same connecting method between the 3rd width and the 4th width, and the fourth officer spectrum picture width that permeates represents the complete spectrum figure in sky background direction the most at last;

3) respective pixel between step 1 (c) and two width complete spectrum figure of step 2 (c) is carried out subtraction calculations one by one, the difference spectrum image obtained is the spectral intensity of the dayglow spectral line that will detect; The variation relation of luminous intensity and temperature can be derived from HITRAN08 molecular spectrum database, temperature resolution is 1K, therefore, the curve of above-mentioned difference spectrum image and HITRAN08 molecular spectrum database is utilized to carry out least square fitting, when theoretical curve and actual detection curve difference minimum time, just uniquely can determine temperature, be the airglow temperature that will detect required for the present invention.

Beneficial effect of the present invention is as follows:

1. by one piece of echelon grating and spike interference filter coupling, obtain the high-resolution spectroscopy of dayglow and the information of rotational line intensity rate simultaneously, realize detection while the spectral intensity of dayglow in upper atmosphere and temperature.

2. adopt rotational line thermometry, than conventional dopplerbroadening method, possess higher detection accuracy and reliability.

3. system all adopts reflection type optical path, compared with transmission-type light path, possesses the higher efficiency of light energy utilization and thermal stability, lower dispersive power, less difference, thus makes instrument space compacter, has very high shock resistance and repeats reliability.

Accompanying drawing explanation

Fig. 1 is the photometric structural representation of dayglow temperature of the present invention;

In figure, 1. point to mirror, 2. precision rotation platform, 3. optical window, 4. telephoto lens, 5. adjustable mechanical slit, 6. plane mirror A, 7. concave mirror A, 8. spike interference filter, 9. micro-angle stepper motor, 10. echelon grating, 11. concave mirror B, 12. plane mirror B, 13. area array CCD detectors, 14. shells, 15-optical axis.

Embodiment

Below in conjunction with the drawings and specific embodiments, the present invention is described in detail.

As shown in Figure 1, the photometric structure of dayglow temperature of the present invention is, the structure description order in figure, comprises five main parts: light-conducting system, telescopic system, beam splitting system, imaging system and shell along optical axis from top to bottom.Wherein, light-conducting system, by pointing to mirror 1 and precision rotation platform 2 forms, points to mirror 1 and is fixed on precision rotation platform 2, can carry out the rotation of 0-90 ° in the vertical direction, then can carry out 0-360 ° of all-directional rotation in the horizontal direction; Telescopic system is made up of optical window 3, telephoto lens 4 and adjustable mechanical slit 5 successively, the light that dayglow sends can be converged to instrument; Beam splitting system is made up of plane mirror A6, concave mirror A7, spike interference filter 8, micro-angle stepper motor 9 and echelon grating 10 successively, wherein the effect of plane mirror A6 is folded optical path, it is with concave mirror A7 staggered relatively horizontal by miter angle, echelon grating 10 is also staggered relatively with concave mirror A7 simultaneously, this structure can make instrument space compacter, and spike interference filter 8 and micro-angle stepper motor 9 form filter unit and be fixed between concave mirror A7 and echelon grating 10; Imaging system is made up of concave mirror B11, plane mirror B12 and area array CCD detector 13, concave mirror B11 and echelon grating 10 staggered relatively, concave mirror B11 and plane mirror B12 is also staggered relatively, plane mirror B12 and contour placement relative with area array CCD detector 13; All devices are fixed in shell 14, form solid and compact light channel structure.

Equal to the distance of concave mirror A7 reflection spot with from echelon grating 10 central point to the distance of concave mirror A7 reflection spot from adjustable mechanical slit 5, be the focal length of concave mirror A7; From concave mirror B11 reflection spot to the distance of echelon grating 10 central point with equal to the distance of area array CCD detector 13 from concave mirror B11 reflection spot, be the focal length of concave mirror B11.

Echelon grating 10 is Primary Components for instrument of the present invention, and the incident angle arrived on echelon grating 10 by the light of spike interference filter 8 outgoing is 60 ° to 70 °; Spike interference filter 8 and micro-angle stepper motor 9 form another Primary Component that filter unit is instrument of the present invention, optical filter halfwidth is between 0.2 to 0.8nm, effective clear aperature is 48mm, maximum micro-anglec of rotation is 15 °, it act as and changes the normal of spike interference filter and the angle of optical axis, thus leaches the spectral line of different wave length section.

Be below the present invention simultaneously to the spectral intensity of dayglow in upper atmosphere and the detection method of temperature, utilize above-mentioned dayglow temperature photometer, be described in detail from detection light path, detection principle, detection steps three aspects:

Detection method of the present invention, detection light path is: with reference to Fig. 1, the directed mirror 1 of incident light from upper atmosphere dayglow light source and optical window 3 import telephoto lens 4, then converged in by telephoto lens 4 on the adjustable mechanical slit 5 being positioned over camera lens focus place, the diverging light of outgoing arrives on concave mirror A and is collimated after the turnover of plane mirror 6, the directional light be collimated subsequently needs the filter action through spike interference filter 8, carry a small amount of mixed spectra information and enter echelon grating 10 with larger incident angle (60 ° to 70 °), under the diffraction of echelon grating 10, the directional light that multi beam carries different spectral information is incident to concave mirror B11 with different angles, become converged light again and effect through plane mirror 12 is imaged on the target surface of area array CCD detector 13, data message under final entry.

Detection method of the present invention, detection principle mainly realizes with the characteristic that angle changes by the high spectral resolution ability of echelon grating and spike interference filter centre wavelength.Conventional grating is all improve linear dispersion and resolution by increasing every millimeter of groove number, echelon grating is then utilize larger angle of diffraction to obtain high diffracting grade, by increase by two ruling spans from method develop, therefore grating line number is less, has the outstanding advantages such as angle dispersive power is large, resolution is high.From grating equation:

nλ＝d(sinα+sinβ) （1）

Wherein, n is the order of diffraction time, and λ is wavelength, and d is the spacing of adjacent two grooves, α and β is respectively incident angle and angle of diffraction.Angle dispersive power d β/d λ can be obtained to (1) formula two ends differentiate:

dβ/dλ＝n/(dcosβ) （2）

Then (1) formula and (2) formula are combined and can obtain:

dβ/dλ＝(sinα+sinβ)/(λcosβ) （3）

Can find out from (3) formula when setted wavelength λ, angle dispersive power only has relation with incident angle α and angle of diffraction β, when incident angle α and angle of diffraction β is very large, angle dispersive power also can correspondingly be enhanced, namely this is the reason place of echelon grating high dispersion characteristics, and the present invention also utilizes this point.But echelon grating also has an obvious shortcoming, namely after angle dispersive power d β/d λ increases, the spectral range that the detector target surface of limited areal presents will be shortened greatly, and this is unfavorable for the detection to broadband light source.And the temperature of airglow exactly needs even multiple the shaking of detection one to turn the intensity rate of many spectral lines that can be with, general required spectrum span will reach more than 5-10nm, and echelon grating is in order to ensure 10 ^-2the resolution of magnitude makes spectral range generally be only about 1nm.For this contradiction, the Dominant Facies of the characteristic with echelon grating that utilize spike interference filter is combined by the present invention, reaches the more broadband object of detection.Spike interference filter is normally based on the principle that Fabry-Perot is interfered, and its transmitance formula can be expressed as:

${\mathrm{\τ}}_f(\mathrm{\λ},\mathrm{\θ})=\frac{{\mathrm{\τ}}_c}{1+{[\frac{2(\mathrm{\λ}-{\mathrm{\λ}}_c)}{{\mathrm{\Δ\λ}}_c}+\frac{\mathrm{\λ}}{{\mathrm{\Δ\λ}}_c}\frac{{\mathrm{\θ}}^2}{n_e^2}]}^2}---\left(4\right)$

Wherein, τ _ffor transmitance, τ _cfor peak transmittance, λ _cfor centre wavelength during normal incidence, θ is the incident angle of light beam, n _efor the effective refractive index of interference filter, Δ λ _ccentered by wavelength through halfwidth.Once selected optical filter, so its λ _c, n _e, τ _c, Δ λ _cbe known quantity, so can be known by inference by (4) formula, along with the change of incident angle, the halfwidth of transmitance profile can increase, and centre wavelength moves to shortwave direction simultaneously.And the overall characteristic with incident angle change to the movement of shortwave direction of this transmitance profile can make up the narrower shortcoming of echelon grating detection spectral coverage just, this is also dayglow temperature of the present invention the most basic photometric detection principle.

Detection method of the present invention, detection steps is:

1. the shooting of solar direction:

A () controls precision rotation platform 2 and sensing mirror 1 is turned to solar direction, adjustment spike interference filter 8 plane of incidence normal is parallel with optical axis, opposite battle array ccd detector 13 chooses the time shutter (0.1 ~ 5s not etc., determine according to weather conditions on the same day), once take, obtain the first width spectrum picture;

B () controls to point to mirror 1 and keeps towards the invariant position of solar direction, by micro-angle stepper motor 9 normal of spike interference filter 8 turned to the angle becoming 5 ° with optical axis, the time shutter of holding surface battle array ccd detector 13 and identical (same time shutter) in step 1) (a), carry out second time shooting, obtain the second width spectrum picture; Respectively the normal of spike interference filter 8 is turned to the angle becoming 10 ° and 15 ° with optical axis subsequently, repeat above-mentioned steps, carry out third time and the 4th shooting, obtain the 3rd width and the 4th width spectrum picture;

C spectrum picture that four times are taken by () is by after the process such as flat field, denoising, normalization, region not photosensitive in deleted image, first width spectrum picture end and the second width spectrum picture front end are spliced, second width is with the 3rd width, adopt same connecting method between the 3rd width and the 4th width, and the fourth officer spectrum picture width that permeates represents the complete spectrum figure of solar direction the most at last;

2. the shooting in sky background direction:

A () controls precision rotation platform 2 and sensing mirror 1 is rotated 180 ° to sun reverse direction, i.e. sky background direction, adjustment spike interference filter 8 plane of incidence normal is parallel with optical axis, opposite battle array ccd detector 13 chooses the time shutter (0.1 ~ 5s not etc., determine according to weather conditions on the same day), once take, obtain spectrum picture;

B () controls the invariant position that sensing mirror 1 keeps sky background direction, by micro-angle stepper motor 9 normal of spike interference filter 8 turned to the angle becoming 5 ° with optical axis, the time shutter of holding surface battle array ccd detector 13 and step 2) identical (same time shutter) in (a), carry out second time shooting, obtain the second width spectrum picture; Respectively the normal of spike interference filter 8 is turned to the angle becoming 10 ° and 15 ° with optical axis subsequently, repeat above-mentioned steps, carry out third time and the 4th shooting, obtain the 3rd width and the 4th width spectrum picture;

C spectrum picture that four times are taken by () is by after the process such as flat field, denoising, normalization, region not photosensitive in deleted image, first width spectrum picture end and the second width spectrum picture front end are spliced, second width is with the 3rd width, adopt same connecting method between the 3rd width and the 4th width, and the fourth officer spectrum picture width that permeates represents the complete spectrum figure in sky background direction the most at last;

3. the respective pixel between step 1 (c) and two width complete spectrum figure of step 2 (c) is carried out subtraction calculations one by one, the difference spectrum image obtained is the spectral intensity of the dayglow spectral line that will detect; The variation relation of luminous intensity and temperature can be derived from HITRAN08 molecular spectrum database, temperature resolution is 1K, therefore, the curve of above-mentioned difference spectrum image and HITRAN08 molecular spectrum database is utilized to carry out least square fitting, when theoretical curve and actual detection curve difference minimum time, just uniquely can determine temperature, be the airglow temperature that will detect required for the present invention.

Claims (6)

1. a dayglow temperature photometer, it is characterized in that: comprise four parts set gradually: light-conducting system, telescopic system, beam splitting system and imaging system, wherein, light-conducting system, by pointing to mirror (1) and precision rotation platform (2) forms, points to mirror (1) and is fixed on precision rotation platform (2); Telescopic system is made up of optical window (3), telephoto lens (4) and adjustable mechanical slit (5) successively; Beam splitting system is made up of plane mirror (A6), concave mirror (A7), spike interference filter (8), micro-angle stepper motor (9) and echelon grating (10) successively, wherein plane mirror (A6) and vertical direction are that 45° angle is placed, and plane mirror (A6) is staggered relatively with concave mirror (A7), echelon grating (10) is also staggered relatively with concave mirror (A7) simultaneously; Spike interference filter (8) and micro-angle stepper motor (9) form filter unit and are fixed between concave mirror (A7) and echelon grating (10); Imaging system is made up of concave mirror (B11), plane mirror (B12) and area array CCD detector (13), concave mirror (B11) is staggered relatively with echelon grating (10), concave mirror (B11) and plane mirror (B12) also staggered relatively, plane mirror (B12) and contour placement relative with area array CCD detector (13).

2. dayglow temperature photometer according to claim 1, is characterized in that: be also provided with shell (14), above-mentioned four part parts are fixed in shell (14).

3. dayglow temperature photometer according to claim 1, it is characterized in that: equal to the distance of concave mirror (A7) reflection spot with from echelon grating (10) central point to the distance of concave mirror (A7) reflection spot from described adjustable mechanical slit (5), be the focal length of concave mirror (A7); Equal to the distance of area array CCD detector (13) with from concave mirror (B11) reflection spot to the distance of echelon grating (10) central point from concave mirror (B11) reflection spot, be the focal length of concave mirror (B11).

4. dayglow temperature photometer according to claim 1 or 3, is characterized in that: the incident angle of described echelon grating (10) is 60 ° ~ 70 °.

5. dayglow temperature photometer according to claim 1, is characterized in that: described spike interference filter (8) is installed on micro-angle stepper motor (9) output shaft; Spike interference filter (8) halfwidth is between 0.2 ~ 0.8nm, and effective clear aperature is 48mm, and maximum micro-anglec of rotation is 15 °.

6. utilize the method for dayglow temperature photometer probe gas aura spectral intensity and temperature described in claim 1, the method comprises the following steps:

1) shooting of solar direction:

A () control precision rotation platform (2) will be pointed to mirror (1) and turn to solar direction, adjustment spike interference filter (8) plane of incidence normal is parallel with optical axis, the time shutter is chosen on opposite battle array ccd detector (13), once takes, and obtains the first width spectrum picture;

B () points to mirror (1) invariant position, by micro-angle stepper motor (9) normal of spike interference filter (8) turned to the angle becoming 5 ° with optical axis, the time shutter of holding surface battle array ccd detector (13) and identical in step 1) (a), carry out second time shooting, obtain the second width spectrum picture; Respectively the normal of spike interference filter (8) is turned to the angle becoming 10 ° and 15 ° with optical axis subsequently, repeat above-mentioned steps, carry out third time and the 4th shooting, obtain the 3rd width and the 4th width spectrum picture;

In c spectrum picture that four times are taken by (), not photosensitive region is deleted, first width spectrum picture end and the second width spectrum picture front end are spliced, second width is with the 3rd width, adopt same connecting method between the 3rd width and the 4th width, and the fourth officer spectrum picture width that permeates represents the complete spectrum figure of solar direction the most at last;

2) shooting in sky background direction:

A () controls precision rotation platform (2) will point to mirror (1) rotation 180 ° to sun reverse direction, adjustment spike interference filter (8) plane of incidence normal is parallel with optical axis, the time shutter is chosen on opposite battle array ccd detector (13), once takes, and obtains spectrum picture;

B () controls the invariant position pointing to mirror (1) maintenance sky background direction, by micro-angle stepper motor (9) normal of spike interference filter (8) turned to the angle becoming 5 ° with optical axis, the time shutter of holding surface battle array ccd detector (13) and step 2) identical in (a), carry out second time shooting, obtain the second width spectrum picture; Respectively the normal of spike interference filter (8) is turned to the angle becoming 10 ° and 15 ° with optical axis subsequently, repeat above-mentioned steps, carry out third time and the 4th shooting, obtain the 3rd width and the 4th width spectrum picture;

In c spectrum picture that four times are taken by (), not photosensitive region is deleted, first width spectrum picture end and the second width spectrum picture front end are spliced, second width is with the 3rd width, adopt same connecting method between the 3rd width and the 4th width, and the fourth officer spectrum picture width that permeates represents the complete spectrum figure in sky background direction the most at last;

3) two width complete spectrum figure of step 1 (c) and step 2 (c) are normalized again, do subtraction calculations subsequently, the difference spectrum image obtained is the spectral intensity that dayglow is launched, and recycling draws the temperature of dayglow with the matching inverting of HITRAN08 molecular spectrum database.