CN101477239B - Star sensor lens and its use method in large-temperature range accurate fixed star azimuth measurement - Google Patents
Star sensor lens and its use method in large-temperature range accurate fixed star azimuth measurement Download PDFInfo
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- CN101477239B CN101477239B CN2009100425119A CN200910042511A CN101477239B CN 101477239 B CN101477239 B CN 101477239B CN 2009100425119 A CN2009100425119 A CN 2009100425119A CN 200910042511 A CN200910042511 A CN 200910042511A CN 101477239 B CN101477239 B CN 101477239B
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Abstract
The invention discloses a star sensor lens and a method for large temperature range accurate measurement of azimuth angles of stars by using the same. The star sensor lens comprises a lens barrel, a base, lenses, an optoelectronic image sensor, a diaphragm and a light filter which also serves as a protective window, wherein each two lenses of the four lenses form a group, the two lens groups are arranged on the two sides of the diaphragm symmetrically, object lens expansion rings are arranged at the outer sides of the two lens groups, and a spring ring for restoring and fastening is arranged between the two lens groups. Through an expansion and contraction effect of the expansion rings, the distance between the two lens groups are finely adjusted in a passive mode, so that the focus offset caused by the amount of the fine adjustment between the lenses counteracts that caused by a thermal effect of the lenses and the lens barrel. The focus star sensor lens has excellent thermal stability. According to calculation, the thermal offset delta f/f of the lens focus f is no more than 2*10<-6> within a temperature range from 20 DEG C below zero to 60 DEG C. Under a condition of a large temperature range, the accuracy of the measurement of the azimuth angles of stars of the star sensor lens reaches arc second order.
Description
Technical field
The present invention relates to a kind of camera lens of star sensor and be used for large-temperature range accurately measure the azimuthal method of fixed star.
Background technology
Star sensor is one of photoelectric instrument commonly used of independently measuring spacecraft attitude.The residing ambient temperature range of spacecraft is-20 ℃ to+60 ℃, and the thermal stability of lens focus has tangible influence to the measuring error of star sensor.In the disclosed star sensor of document, lens focus causes star sensor that the azimuthal measured value of fixed star is occurred than mistake with the lifting generation marked change of environment temperature.Usually take following two kinds of methods, make star sensor under the condition of environment temperature lifting, keep higher measuring accuracy:
(1) common method that reduces the star sensor measuring error relevant with environment temperature is " a modified value method ", promptly on the basis of the temperature drift rule of priori knowledge lens focus value, the temperature of real-time detector lens, the thermal migration amount of deduction lens focus in the Measurement and Data Processing process
Make azimuthal calculated value more near theoretical value through revising.Above-mentioned modification method is suitable for the medium accuracy star sensor, can not satisfy the demand of high precision (for example, inferior rad level) star sensor.
(2) the another kind of method that reduces the star sensor measuring error relevant with environment temperature is real-time detector lens focal length, uses lens focus data accurately in the Measurement and Data Processing process.But the device of the additional focal length of monitoring in real time can increase the load of spacecraft, and has increased the complexity of star sensor.
The implication of " automatic focusing " is that the photosurface of imageing sensor is alignd all the time with the imaging surface of scenery, thereby obtains distinct image.For being for the digital camera, video camera of measurement target with scenery, technology of auto has good result and very high practical value.
The author of Chengdu photoelectric technology research institute delivered paper (the SPIE Vol.5874 that is entitled as " A Hybrid Athermal CCD Camera " in 2005,2005), the principle of the imaging surface displacement complementation that this article causes based on the thermal expansion amount and the optical lens thermal effect of metal lens barrel guarantees that the CCD camera is obtaining HD image in big temperature difference environment.
" airborne weapon " the 3rd periodical carried " optical system does not have the applied research of thermalization design on air-to-air missile " in 2006, proposed low thermal coefficient of expansion and the no thermalization optical imagery of high thermal expansion coefficient " thermometal is compensation " scheme.
More than the technical scheme that proposed of two documents, focus on and eliminate of the influence of image planes displacement image definition.For the digital camera that uses tight shot, in " focusing " process, the focal length of tight shot is constant.When variation of ambient temperature, focal length changes with environment temperature.Make the focal length value of common tight shot not equal the nominal focal length value all the time.
In sum, the space flight optical system reported of domestic literature does not take measures to restrain the hot bias of focal length that temperature variation causes specially
Summary of the invention
The object of the present invention is to provide a kind of in-20 ℃ to+60 ℃ scopes, the hot bias of objective focal length is reduced to MIN lens of star sensor, and provides the described camera lens of a kind of utilization accurately to measure the method for fixed star image patch centroid position (thereby calculating the fixed star position angle).
The camera lens of star sensor of the present invention; comprise lens barrel, base, lens, electro-optical imaging sensors; the optical filter and the diaphragm of double as protection window; it is characterized in that described lens are four, per two are combined into one group; two groups of lens symmetries are placed on the both sides formation spherical lens group of diaphragm; lay the expansion ring that is used to finely tune the eyeglass interval two groups of lens both sides, be provided with the fastening resilient ring that resets in the centre of two groups of lens, expansion ring and resilient ring constitute focal length thermal migration amount automaton.
Demarcate the position of electro-optical imaging sensors, make photosurface be positioned at best out of focus face position.Described out of focus face is characterised in that: represent the difference of same fixed star at the image patch point range figure root mean square radius value of center, visual field and field of view edge with Δ R, point range figure root mean square radius value is about 20 microns, and Δ R value is not more than 0.2 micron.
The thermomechanical effect of expansion ring in-20 ℃ to+60 ℃ temperature ranges finely tuned two groups of spacings between the lens, the lens focus side-play amount that this spacing amount trimmed causes is offset the thermal migration amount of lens focus, and the thermal migration amount Δ f/f of controls lens focal distance f is not more than 2 * 10 in-20 ℃ to+60 ℃ temperature ranges
-6
Be provided with the supporting base of fine setting electro-optical imaging sensors position between electro-optical imaging sensors and base, by the thermal deformation effect of supporting base and base, the photosurface of fine setting imageing sensor makes it to overlap with the out of focus face in large-temperature range.
The major parameter of described eyeglass is:
The material of described eyeglass, spherical shape and thickness parameter are:
Curved surface 1: radius-of-curvature 19.05510mm, thickness 3.32860mm, material trademark: LAK3, refractive index 1.74693, thermal refractive index coefficient 0 * 10
-6/ ℃, thermal expansivity 5.2 * 10
-6/ ℃;
Curved surface 2: radius-of-curvature-76.73780mm; Interval 1:0.80190mm;
Curved surface 3: radius-of-curvature-37.25010mm, thickness 0.85480mm, material trademark: F13, refractive index 1.62588, thermal refractive index coefficient 2.4 * 10
-6/ ℃, thermal expansivity 9.6 * 10
-6/ ℃;
Curved surface 4: radius-of-curvature 22.10300mm;
Interval 2:1.49406mm;
Diaphragm: radius-of-curvature ∞;
Interval 2:1.49406mm;
Curved surface 6: radius-of-curvature-34.60840mm, thickness 0.85480mm material trademark: F13;
Curved surface 7: radius-of-curvature 27.54970mm;
Interval 3:0.85480mm;
Curved surface 8: radius-of-curvature 44.65530mm, thickness 3.32850mm, material trademark: LAK3;
Curved surface 9: radius-of-curvature-22.83450mm.
Accurately measure the azimuthal method of fixed star with camera lens of the present invention, it is characterized in that, may further comprise the steps:
(1) at the focal length value f ' that demarcates (for example 20 ℃) mensuration optical system under the temperature
Demarcate
(2), utilize arc tangent angle measurement formula θ=arctan (S/f) to calculate the fixed star azimuth angle theta at-20 ℃ to+60 ℃.In the formula, the focal distance f value of imaging system is got calibration value f '
DemarcateThat is, make the thermal migration amount of imaging system focal distance f be zero at-20 ℃ to+60 ℃;
In tangent angle measurement formula, the center-of-mass coordinate S of fixed star image patch is the actual measured value of imageing sensor on the out of focus face;
Described out of focus face is characterised in that: represent the difference of same fixed star at the image patch point range figure root mean square radius value of center, visual field and field of view edge with Δ R, point range figure root mean square radius value is about 20 microns, and Δ R value is not more than 0.2 micron.
Advantage of the present invention: the Heat stability is good of (1) star sensor optical system focal length: as calculated, the thermal migration amount Δ f/f of lens focus f is not more than 2 * 10 in-20 ℃ to+60 ℃ temperature ranges
-6(2) be convenient to demarcate and calibrate.Lens focus at 20 ℃ of environment demarcation star sensors need not in the time of in orbit to calibrate in addition.(3) in environment temperature significantly under the change condition, the star sensor optical system to facula mass center locating accuracy basically identical, all reaches inferior rad level to the fixed star imaging of center, visual field and marginarium.
Description of drawings
Fig. 1 is one embodiment of the invention lens construction synoptic diagram;
Fig. 2 is the index path of embodiment 1;
Fig. 3 is the curve map that lens group spacing d and lens focus f change with temperature;
Fig. 4 is the disc of confusion point range figure RMS radius value curve map on the different out of focus faces of camera lens.
Embodiment
Embodiment 1: in conjunction with the accompanying drawings:
Eyeglass 1a, 1b, diaphragm 2 and eyeglass 1c, 1d form four lens combination of symmetrical expression object lens.3a and 3b are expansion rings, and its heat distortion amount plays fine setting effect (resilient ring 4 play reset and fastening effect) to the spacing of lens combination, and the expansion ring material is an aluminium alloy, and one-tenth-value thickness 1/10 is 4.64mm (20 ℃), its thermal expansivity=27 * 10
-6/ ℃.Imageing sensor 6 is positioned at the right side of object lens back focal plane 10.The axial location of 8 pairs of imageing sensors 6 of sustained ring plays the fine setting effect, and photosensitive 6 of sensor alignd all the time with selected out of focus face 9.
The 5th, metal lens barrel, material are titanium alloy TC 4, thermal expansivity=9.1 * 10
-6/ ℃.The 11st, optical filter (the protection window of holding concurrently).Eyeglass and imageing sensor are fixed in the lens barrel by annular fastener, and whole device possesses the performance of antidetonation and anti-acceleration.
Lens focus f:56mm, relative aperture: 1/4.0.Imaging system contains four lens (per two are combined into a group), and parameter is listed in table 1:
The spheric glass parameter of table 1 camera lens
| Sequence number | Radius-of-curvature (mm) | Thickness (mm) | Material |
| 1 | 19.05510 | 3.32860 | LAK3 |
| 2 | -76.73780 | 0.80190 | |
| 3 | -37.25010 | 0.85480 | F13 |
| 4 | 22.10300 | 1.49406 | |
| Diaphragm | ∞ | 1.49406 | |
| 6 | -34.60840 | 0.85480 | F13 |
| 7 | 27.54970 | 0.85480 |
| Sequence number | Radius-of-curvature (mm) | Thickness (mm) | Material |
| 8 | 44.65530 | 3.32850 | LAK3 |
| 9 | -22.83450 |
Lens materials and refractive index: LAK3 (n=1.74693, β=0 * 10
-6/ ℃, a=5.2 * 10
-6/ ℃); F13 (n=1.62588, β=2.4 * 10
-6/ ℃, a=9.6 * 10
-6/ ℃), the lens barrel material adopts TC4 (a=9.1 * 10
-6/ ℃).
The adjustable positions of lens combination, two lens combination are spacing d:2.9881mm (20 ℃), under temperature-20 ℃～60 ℃ condition, and variation range 3.0082mm～2.9681mm.
The structure of focus offset compensation system and effect: as Fig. 1, focal length thermal migration amount compensation system is made up of expansion ring 3 and resilient ring 4.
Curve such as Fig. 3 that DBL d and lens focus f change with temperature.Principle with passive mode automatic fine tuning focus offset, be spacing d with Control Thermal Deformation two lens combination of expansion ring thickness, the thermal migration amount of the focal length that the side-play amount that makes the focal length that the expansion ring thermal expansion causes and eyeglass, lens barrel self thermal effect cause " positive and negative disappear mutually ".
The camera lens right-hand member, described imageing sensor 6 links to each other with base 7 (lens barrel 5) by sustained ring 8, makes the photosurface of imageing sensor overlap (as Fig. 1) with out of focus face 9.
Determine optimum out of focus image space: described out of focus face is a specific imaging position.By the material and the curved surface parameter of preferred eyeglass, make the fixed star disc of confusion radius approximately equal of large and small visual field on this image space.Thereby, fixed star image patch barycenter positioning error minimum on this out of focus face.
Fig. 4 is the Changing Pattern of image patch on the different out of focus faces of camera lens.Among the figure, the image patch disc of confusion radius of 0 degree, 2 degree, 4 degree and 6 degree visual fields has nothing in common with each other with the Changing Pattern of rear cut-off distance.The rear cut-off distance of the out of focus face that the present invention selects is 49.51mm (20 ℃), and point range figure RMS radius value is about 19.4 μ m.
Accurately measure the azimuthal method of fixed star with camera lens of the present invention, may further comprise the steps:
(1) at the focal length value f ' that demarcates (for example 20 ℃) mensuration optical system under the temperature
Demarcate
(2), utilize arc tangent angle measurement formula θ=arctan (S/f) to calculate the fixed star azimuth angle theta at-20 ℃ to+60 ℃.In the formula, the focal distance f value of imaging system is got calibration value f '
DemarcateThat is, make the thermal migration amount of imaging system focal distance f be zero at-20 ℃ to+60 ℃;
In tangent angle measurement formula, the center-of-mass coordinate S of fixed star image patch is the actual measured value of imageing sensor on the out of focus face.
The domestic star sensor of having delivered, majority are to have the centroid position of measuring the fixed star image patch under the condition of thermal migration amount at focal length.One of characteristics of the present invention are to be compensated in focal length thermal migration amount, under out of focus face and the prerequisite that photosurface aligns, to measure the centroid position of fixed star image patch.
Eyeglass of the present invention is less, and the 6-8 sheet lens combination that the bearing accuracy and the domestic literature of fixed star image patch barycenter are reported is suitable.Another characteristic is, the camera lens that eyeglass is less, and failure rate is low and be convenient to realize the lightweight of space flight optical instrument.
Claims (5)
1. lens of star sensor; comprise lens barrel; base; lens; electro-optical imaging sensors; the optical filter of diaphragm and double as protection window; it is characterized in that; described lens are four; per two are combined into one group; two groups of lens symmetries are placed on the both sides formation spherical lens group of diaphragm; lay the expansion ring that is used to finely tune the eyeglass interval two groups of lens both sides; be provided with the fastening resilient ring that resets in the centre of two groups of lens; the thermomechanical effect of described expansion ring in-20 ℃ to+60 ℃ temperature ranges finely tuned two groups of spacings between the lens; the focal length thermal migration amount that focus offset that this spacing amount trimmed causes and lens and lens barrel thermal effect are caused is cancelled out each other, and the thermal migration amount Δ f/f of controls lens focal distance f is not more than 2 * 10 in-20 ℃ to+60 ℃ temperature ranges
-6Make expansion ring and resilient ring constitute focal length thermal migration amount automaton, the photosurface of electro-optical imaging sensors is positioned at best out of focus face position.
2. lens of star sensor according to claim 1, it is characterized in that, between electro-optical imaging sensors and base, be provided with the supporting base of fine setting electro-optical imaging sensors position, thermal deformation effect by supporting base and base, the photosurface of fine setting imageing sensor makes it to overlap with the out of focus face in large-temperature range.
4. lens of star sensor according to claim 1 is characterized in that, the major parameter of described lens is:
Curved surface 1: radius-of-curvature 19.05510mm, thickness 3.32860mm, material trademark: LAK3;
Curved surface 2: radius-of-curvature-76.73780mm;
Interval 1:0.80190mm;
Curved surface 3: radius-of-curvature-37.25010mm, thickness 0.85480mm, material trademark: F13;
Curved surface 4: radius-of-curvature 22.10300mm;
Interval 2:1.49406mm;
Diaphragm: radius-of-curvature ∞;
Interval 2:1.49406mm;
Curved surface 6: radius-of-curvature-34.60840mm, thickness 0.85480mm material trademark: F13;
Curved surface 7: radius-of-curvature 27.54970mm;
Interval 3:0.85480mm;
Curved surface 8: radius-of-curvature 44.65530mm, thickness 3.32850mm, material trademark: LAK3;
Curved surface 9: radius-of-curvature-22.83450mm.
5. lens of star sensor according to claim 1, it is characterized in that, described out of focus face is characterised in that: represent the difference of same fixed star at the image patch point range figure root mean square radius value of center, visual field and field of view edge with Δ R, point range figure root mean square radius value is about 20 microns, and Δ R value is not more than 0.2 micron.
6. the described lens of star sensor of claim 1 is used to measure the position angle of fixed star, it is characterized in that, may further comprise the steps:
Step 1: demarcate under the temperature at 20 ℃, measure lens focus value f '
Demarcate
Step 2:, utilize tangent angle measurement formula θ=arctan (S/f) to calculate the fixed star azimuth angle theta at-20 ℃ to+60 ℃;
In the described tangent angle measurement formula, lens focus f value is got calibration value f '
Demarcate, the thermal migration amount Δ f/f of described lens focus f is not more than 2 * 10
-6, the thermal migration amount is insignificant a small amount of under different temperatures; The center-of-mass coordinate S of fixed star image patch is the actual measured value on the camera lens out of focus face.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009100425119A CN101477239B (en) | 2009-01-16 | 2009-01-16 | Star sensor lens and its use method in large-temperature range accurate fixed star azimuth measurement |
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|---|---|---|---|
| CN2009100425119A CN101477239B (en) | 2009-01-16 | 2009-01-16 | Star sensor lens and its use method in large-temperature range accurate fixed star azimuth measurement |
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| CN101477239B true CN101477239B (en) | 2010-09-01 |
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| TWI413851B (en) * | 2011-04-29 | 2013-11-01 | Asia Optical Co Inc | Projector lens |
| CN103345110B (en) * | 2013-07-18 | 2015-11-18 | 中测新图(北京)遥感技术有限责任公司 | The robust structure of scalability aviation digital camera |
| JP5903079B2 (en) * | 2013-07-31 | 2016-04-13 | Ｈｏｙａ Ｃａｎｄｅｏ Ｏｐｔｒｏｎｉｃｓ株式会社 | Light irradiation device |
| CN104501805B (en) * | 2014-12-25 | 2017-07-14 | 中国科学院长春光学精密机械与物理研究所 | Object lens of large relative aperture catadioptric emitting optical system of star sensor in high precision |
| CN105450896B (en) * | 2015-11-18 | 2018-06-12 | 通富微电子股份有限公司 | Contact-type image sensor encapsulating structure |
| CN105700154B (en) * | 2016-03-23 | 2018-03-27 | 浙江东方光学眼镜有限公司 | A kind of typoscope imaging lens |
| JP6239040B1 (en) * | 2016-06-01 | 2017-11-29 | キヤノン株式会社 | Lens apparatus and imaging apparatus having the same |
| CN107193112B (en) * | 2017-07-24 | 2019-07-26 | 福建福光股份有限公司 | A kind of deep space exploration navigation lens of star sensor |
| CN111323210B (en) * | 2020-03-17 | 2021-07-09 | 北京控制工程研究所 | Device and method for testing optical axis thermal stability of optical lens |
| CN113703159A (en) * | 2021-09-08 | 2021-11-26 | 孝感华中精密仪器有限公司 | Large-view-field high-low temperature compensation method for broadband large-zoom-ratio continuous zooming camera |
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