CN101165544A - A High Precision Star Simulator - Google Patents

Abstract

The invention relates to a high-precision star simulator, which includes a light source, an infrared reflector, frosted glass, a condenser lens A, a glued prism, an attenuation sheet group, a filter, a condenser lens B, a star point plate and a collimator, which are sequentially arranged on the optical path ; In order to stabilize the light source, the present invention may also include a light source brightness control circuit, a cemented prism arranged behind the condenser A and a photodiode arranged on the transmitted light path of the cemented prism. The present invention solves the shortcomings of low precision and high cost of existing star simulators, and has the advantages of direct simulation of seventeen magnitudes, simulation precision of up to ±0.05, single star parallelism simulation precision of up to ±1", low cost, and systematic It has the advantages of high stability and convenient operation.

Description

A High Precision Star Simulator

technical field

The invention relates to a star simulator.

Background technique

With the development of my country's space technology, satellites, manned spacecraft and other spacecraft need longer life, higher control accuracy and reliability. In the spacecraft attitude control system, the star sensor (hereinafter referred to as the star sensor) is the attitude sensor with the highest measurement accuracy. It has no mechanical moving parts itself, which is conducive to long life and miniaturization, so it is the most promising in the spacecraft. and one of the most accurate attitude sensors. The reference object of the star sensor to determine the attitude is the star, and the star simulator (hereinafter referred to as the star simulator) is mainly used for ground detection. The function of the star simulator is mainly to simulate the characteristics of infinite stars such as spectrum, illuminance, parallelism and color temperature. Therefore, the quality of the simulated starlight of the star simulator is very important, and its performance directly determines the reliability of the measurement results of the star sensor.

One of the technical schemes of the star simulator is to use the skydome optical fiber scheme, and fix the star sensor on the turntable under the sky for testing. This solution is very realistic, but the cost is high. The second technical solution of the star simulator is to use the computer as a star map generator to generate a sky star map on the LCD screen, and then use a wide-angle objective lens to convert the spherical light waves emitted by the stars in the display screen into parallel light to simulate infinite distance. astral body. But its accuracy is poor. The third technical solution of the star simulator is to use liquid crystal light valves instead of liquid crystal display screens to generate sky star maps. The current liquid crystal light valves are 1024×768 pixels, with a contrast ratio of more than 1000:1, and simulated magnitudes of +2 to +6.5. Magnitude accuracy ±0.3 magnitude. However, at present, the liquid crystal light valve cannot meet the requirement of covering -2 to +6 magnitudes, and the indicators such as the parallelism of starlight cannot meet the requirements. For this reason, an alternative to the first solution must be found to simulate the sky dome with high quality and high fidelity.

Contents of the invention

The object of the present invention is to provide a star simulator with high quality, high fidelity and low cost, which solves the shortcomings of low precision and high cost of existing star simulators.

The technical solution of the present invention is: a kind of high-precision star simulator, comprises light source 1 and collimator 12, and its special feature is, described star simulator also comprises that is arranged between light source 1 and collimator 12 Condenser lens system, attenuation film group 7 and star point plate 10.

The above condenser lens system includes a condenser lens A4 and a condenser lens B9; the attenuation sheet group 7 is arranged between the condenser lens A4 and the condenser lens B9, and the star point plate 10 is arranged behind the condenser lens B9.

The above-mentioned star simulator also includes a filter 8; the filter 8 is arranged before or after the attenuation film group 7.

The condenser lens system includes a condenser lens A4 and a condenser lens B9; the attenuation sheet group 7 and the filter 8 are arranged between the condenser lens A4 and the condenser lens B9, and the star point plate 10 is arranged behind the condenser lens B9.

The above-mentioned star simulator also includes a light source brightness control circuit, a cemented prism 5 arranged behind the condenser A4, and a photodiode 6 on the transmission light path of the cemented prism 5; First power amplifier 15, low-pass filter 16, analog-to-digital converter 17, single-chip microcomputer 18, digital-to-analog converter 19 and the second power amplifier 20; Described attenuation sheet group 7 and condenser lens B9 are arranged on cemented prism 5 reflected light paths ; The output terminal of the second power amplifier 20 is connected to the power supply terminal of the light source 1 .

The above-mentioned attenuating sheet group 7 is composed of four attenuating sheets selected from the following five kinds of attenuating sheets with fixed transmittance: No. 0 attenuating sheet with a transmittance of 99.8%, No. 1 attenuating sheet with a transmittance of 63.00%, Attenuator No. 2 with a transmittance of 39.73%, No. 4 attenuator with a transmittance of 15.82%, and No. 8 attenuator with a transmittance of 2.51%.

The above-mentioned attenuating sheet group 7 is combined in the following four kinds of attenuating sheets with fixed transmittance: No. 1 attenuating sheet with a transmittance of 63.00%, No. 2 attenuating sheet with a transmittance of 39.73%, and a transmittance of 15.82 % of the No. 4 attenuation film, and the No. 8 attenuation film with a transmittance of 2.51%.

The above-mentioned star simulator also includes a ground glass 3 and an infrared reflector 2 arranged between the light source 1 and the condenser lens system.

The diameter of the small hole of the above-mentioned star point plate 10 is 8-20um.

The advantages of the present invention are:

1. It can directly simulate the starry sky. Multiple star simulators at different heights are placed in different spatial orientations. Each star simulator allows precise adjustment of azimuth and pitch angle. Each star simulator can simulate 500nm~650nm, 600nm~750nm and 650nm~850nm -2, -1.5, -1, -0.5, 0, +0.5, +1, +1.5, +2, +2.5, +3, +3.5, +4, +4.5, +5, + 5.5, +6 seventeen magnitudes.

2. High simulation accuracy. By consciously selecting any attenuator for precision adjustment, the cost of attenuator coating and the harsh requirements for coating accuracy are greatly reduced; through the selection of attenuators, high-precision transmittance requirements can be achieved; the simulation accuracy can reach ±0.05, etc. , the performance has been greatly improved compared with the star map simulator.

3. The simulation accuracy of single star parallelism is high. Since the present invention adopts a brand-new design idea, a small hole with a star point plate diameter of 20um is used to simulate a star light source at infinity. Compared with an optical fiber or a liquid crystal light valve with a light-emitting point diameter of about 100um, the single star parallelism simulation of the present invention Accuracy can be as high as ±1″.

4. Wide application range. Can simulate -2, -1.5, -1, -0.5, 0, +0.5, +1, +1.5, +2, +2.5, +3, +3.5, +4, +4.5, +5, +5.5, +6 seventeen magnitudes.

5. Low cost. The coating of the attenuation sheet used in the star simulator of the present invention only needs five times, and each attenuation sheet is used multiple times when combining 17 kinds of magnitudes, which greatly reduces the coating accuracy requirement of the attenuation sheet. Because although the transmittance of each coated attenuator will fluctuate around the ideal value, it may happen that the overall transmittance of the three selected attenuators is larger than the ideal value (or slightly higher than the ideal value). Small), when selecting the fourth attenuator, consciously choose an attenuator that is smaller (or larger) than the ideal value. In this way, compared with the ideal value, the attenuation sheet whose original attenuation rate deviates greatly from the theoretical attenuation rate can also be adjusted and used.

6. The system has a high stability of 24 hours x 7 days. The invention splits the light beam by setting a glued prism in the light path, uses a photodiode to sample, and controls the stability of the light source automatically in a closed-loop control manner through a light source brightness control circuit.

7. Easy to operate. Both the optical filter and the attenuating sheet group in the present invention can be replaced in real time as required, and only need to insert the corresponding optical filter or attenuating sheet group into the corresponding position when replacing.

Description of drawings

Fig. 1 is a structural representation of the present invention;

Fig. 2 is a schematic diagram of the best optical structure of the present invention;

Fig. 3 is a schematic diagram of the connection relationship between the photodiode and the brightness control circuit of the light source;

Among them: 1-light source, 2-infrared reflector, 3-ground glass, 4-condenser A, 5-glued prism, 6-photodiode, 7-attenuation film group, 8-filter, 9-condenser B, 10- Star point plate, 11-collimator objective lens, 12-collimator, 13-two-dimensional adjustment mechanism, 14-base, 15-first power amplifier, 16-low-pass filter, 17-analog-to-digital converter, 18 -Single-chip microcomputer, 19-digital-to-analog converter, 20-second power amplifier.

Detailed ways

A specific embodiment of the present invention is shown in Fig. 2, including light source and infrared reflector, frosted glass, condenser A, cemented prism, attenuation sheet group, optical filter, condenser B, star point plate and parallel Light tube; the light source adopts a combined halogen tungsten bulb, its parameters are: voltage 12V, power 35W, luminous intensity 5000cd, average lifespan 1000h; combined halogen tungsten bulb contains a lot of infrared light, in order to reduce the temperature near the star point, infrared The reflector makes the infrared rays emitted by the bulb reflect back and dissipate heat; because most of the light energy gathered by the bulb on the frosted glass is within a diameter of 8mm, the light concentrating system focuses the light with the same angle within this range on a point on the star point plate, That is to say, each point of the light spot on the star point plate is the result of the joint action of light within 8mm of the ground glass, so the function of the ground glass is to make the distribution of the light spots that finally reach the small hole of the star point plate more uniform; the condenser lens system is the condenser A and the condenser B Composition, the magnification of condenser A and condenser B is 0.4, where condenser A is set in front of the cemented prism, and condenser B is set on the reflected light path of the cemented prism; there are 17 kinds of attenuation film groups for each spectral segment, satisfying the brightness of 17 magnitudes requirements; there are three kinds of filters, respectively through 500nm ~ 650nm, 600nm ~ 750nm and 650nm ~ 850nm of light; the attenuation film group and the filter are directly inserted in the optical path, easy to replace; the diameter of the star point plate is 20um; The objective lens of the collimator adopts the form of three mirror groups; the photodiode is arranged on the transmitted light path of the cemented prism, the output end of the photodiode is connected with the signal input end of the light source brightness control circuit, and the control output end of the light source brightness control circuit is connected with the light source brightness control circuit. The power terminal is connected; the attenuator group is a combination of four attenuators selected from the following five kinds of attenuators with fixed transmittance: No. 0 attenuator with a transmittance of 99.8%, No. 1 attenuator with a transmittance of 63.00% No. 2 attenuating sheet with a transmittance of 39.73%, No. 4 attenuating sheet with a transmittance of 15.82%, and No. 8 attenuating sheet with a transmittance of 2.51%. The attenuating sheet group can also be fixed in the following four types: Combination in attenuating sheets with high transmittance: No. 1 attenuating sheet with 63.00% transmittance, No. 2 attenuating sheet with 39.73% transmittance, No. 4 attenuating sheet with 15.82% transmittance, and 2.51% transmittance No. 8 attenuation film; the star point plate is equipped with a star point adjustment mechanism, the star point adjustment mechanism adopts fine threads, and its position accuracy is 10um; the focal length of the collimator is 1000mm, the aperture: 100mm, the resolution: 2″, the field of view : 2.4′; the objective lens group must ensure the strict concentricity of the three lenses, and ensure that the parallelism error caused by processing and assembly errors does not exceed the tolerance.

When the high-precision star simulator is used, it should also include a two-dimensional support and a base. The structure of the bracket and the base is shown in Figure 1. The two-dimensional bracket is composed of a fixed plate, a movable plate, a horizontal fine-tuning mechanism, and a vertical fine-tuning mechanism; one end of the collimator is connected with the movable plate, and the other end is in contact with the fine-tuning mechanism; Regulatory effect.

The principle of the present invention is to use a collimator to generate an infinite star point, and simulate stars with different spectra and brightness through a filter and an attenuation sheet. The diameter of the small hole of the star point plate directly determines the parallelism index of the simulated starlight: if the diameter of the small hole of the star point plate is too small, it has high requirements on the light source, and it is difficult to simulate brighter magnitudes; if the diameter of the small hole of the star point plate is too large, the simulation Astral parallelism is of poor quality. In the present invention, the diameter of the small hole is selected to be between 8-20um by weighing, and the diameter of the small hole is preferably 10um.

For this reason, a high-stable constant light source system with closed-loop feedback control is designed in the star simulator. The star simulator of the present invention selects a stable wide-spectrum light source, and then designs a color filter and an attenuation film respectively. The color filter is used to select the light with the same spectral characteristics as the simulated star, the filter in the 650-850nm band is dark red, the filter in the 600-750nm band is red, and the filter in the 500-650nm band is yellow ; The attenuation sheet is used to attenuate the filtered light at different ratios to simulate different magnitudes. The attenuation film group is composed of four attenuation films. How to form 17 magnitudes from four attenuation films is the key to this method. According to the astronomical definition, the brightness difference of every 6 integer magnitudes is 100 times, so every 2 integer magnitudes arithmetic difference $\sqrt[5]{100}=2.512$ times, every half magnitude difference $\sqrt{2.512}=1.5848$ times. Based on -2 magnitude stars, other magnitudes can be composed of different magnitudes by successively attenuating 1.5848 times. In this scheme, the attenuators are first made into the five forms shown in Table 1, and then through the combination of Table 2 or Table 3, the attenuators required for 17 magnitudes can be formed.

Table 1 Transmittance of attenuation sheet

Transmittance Attenuation sheet code value Equivalent to the attenuation number of the reference chip 99.8% No. 0 0 plate without coating 63.00% number 1 1 primary reference attenuator 39.73% number 2 2nd reference attenuator 15.82% No 4 4 reference attenuators 2.51% number 8 8 reference attenuators

Table 2 Combination Form 1 of Attenuation Sheets for 17 Magnitudes

serial number Magnitude Decay percentage Combination mode (attenuation sheet code value in Table 1) 0 -2 99.20% 0+0+0+0 1 -1.5 62.72% 1+0+0+0 2 -1 39.57% 2+0+0+0 3 -0.5 25.02% 1+2+0+0 4 0 15.75% 4+0+0+0

5 +0.5 9.96% 4+1+0+0 6 +1 6.28% 4+2+0+0 7 +1.5 3.97% 4+2+1+0 8 +2 2.50% 8+0+0+0 9 +2.5 1.58% 8+1+0+0 10 +3 1.00% 8+2+0+0 11 +3.5 0.63% 8+2+1+0 12 +4 0.397% 8+4+0+0 13 +4.5 0.251% 8+4+1+0 14 +5 0.158% 8+4+2+0 15 +5.5 0.100% 8+4+2+1 16 +6 0.063% 8+8+0+0

Table 3 Combination Form 2 of Attenuation Sheets for 17 Magnitudes

serial number Magnitude Decay percentage Combination mode (attenuation sheet code value in Table 1) 0 -2 99.20% 0+0+0+0 1 -1.5 62.72% 1+0+0+0 2 -1 39.65% 1+1+0+0 3 -0.5 25.02% 2+1+0+0 4 0 15.79% 2+2+0+0 5 +0.5 9.98% 2+2+1+0 6 +1 6.30% 2+2+2+0 7 +1.5 3.97% 4+2+1+0 8 +2 2.50% 4+4+0+0 9 +2.5 1.58% 4+4+1+0 10 +3 1.00% 4+4+2+0 11 +3.5 0.63% 8+2+1+0 12 +4 0.397% 4+4+4+0 13 +4.5 0.251% 8+4+1+0 14 +5 0.158% 8+4+2+0 15 +5.5 0.100% 8+4+2+1 16 +6 0.063% 4+4+4+4

Refer to Figure 3 for the circuit principle of the light source brightness control circuit. The tungsten-halogen bulb irradiates the photosensitive surface of the photodiode through the optical system to generate photocurrent, and the intensity of the photocurrent is proportional to the intensity of light. The photocurrent signal is amplified by the power amplifier, and then filtered by the low-pass filter to remove high-frequency impurities, and then sent to the analog-to-digital converter. The converter, after conversion, is amplified and output by the power amplifier to stabilize the halogen tungsten bulb.

It can be seen from the combination of the above attenuation sheets that the coating process only needs four times, at most five times. For each type of attenuator, one coating process can coat multiple pieces at the same time, and it can be used multiple times when combining 17 kinds of magnitudes. Although the transmittance of each coated attenuator will fluctuate around the ideal value, the following situations will occur when the combination is used: the overall transmittance of the three selected attenuators is larger than the ideal value (or too small). At this time, according to the illuminance corresponding to different magnitudes, the transmittance of the fourth attenuator is adjusted when selecting the fourth attenuator. The adjustment is generally made in the batch of coated products, that is, when the fourth attenuator is selected Consciously choose an attenuator that is smaller (or larger) than the ideal value. This conscious choice greatly reduces the coating accuracy requirements for the attenuator, and the attenuator that was originally a defective product can also be used during adjustment. Therefore, the combination of attenuators greatly reduces the cost of the attenuator coating and the strict requirements of coating accuracy, and can meet the high-precision transmittance requirements.

Claims (10)

1. a high precision star simulator comprises light source (1) and parallel light tube (12), it is characterized in that: described star simulator also comprises condenser system, attenuator group (7) and the star tester (10) that is arranged between light source (1) and the parallel light tube (12).

2. a kind of high precision star simulator according to claim 1 is characterized in that: described condenser system comprises condenser A (4) and condenser B (9); Described attenuator group (7) is arranged between condenser A (4) and the condenser B (9), and described star tester (10) is arranged on condenser B (9) afterwards.

3. a kind of high precision star simulator according to claim 2 is characterized in that: described star simulator also comprises the light-source brightness control circuit, be arranged on condenser A (4) afterwards cemented prism (5) and photodiode (6) on cemented prism (5) transmitted light path is set; Described light-source brightness control circuit comprises first power amplifier (15), low-pass filter (16), analog to digital converter (17), single-chip microcomputer (18), digital to analog converter (19) and second power amplifier (20) that is connected in turn after photodiode (6) output terminal; Described attenuator group (7) and condenser B (9) are arranged on cemented prism (5) reflected light path; The output terminal of described second power amplifier (20) links to each other with the power end of light source (1).

4. a kind of high precision star simulator according to claim 1 is characterized in that: described star simulator also comprises optical filter (8); Described optical filter (8) is arranged on before or after the attenuator group (7).

5. a kind of high precision star simulator according to claim 4 is characterized in that: described condenser system comprises condenser A (4) and condenser B (9); Described attenuator group (7) and optical filter (8) are arranged between condenser A (4) and the condenser B (9), and described star tester (10) is arranged on condenser B (9) afterwards.

6. a kind of high precision star simulator according to claim 5 is characterized in that: described star simulator also comprises the light-source brightness control circuit, be arranged on condenser A (4) afterwards cemented prism (5) and photodiode (6) on cemented prism (5) transmitted light path is set; Described light-source brightness control circuit comprises first power amplifier (15), low-pass filter (16), analog to digital converter (17), single-chip microcomputer (8), digital to analog converter (19) and second power amplifier (20) that is connected in turn after photodiode (6) output terminal; Described attenuator group (7) and condenser B (9) are arranged on cemented prism (5) reflected light path; The output terminal of described second power amplifier (20) links to each other with the power end of light source (1).

7. according to the described a kind of high precision star simulator of arbitrary claim of claim 1 to 6, it is characterized in that: described attenuator group (7) is fixedly to select four attenuators to make up in the attenuator of transmitance at following five kinds: transmitance is that 99.8% No. 0 attenuator, transmitance are that 63.00% No. 1 attenuator, transmitance are that 39.73% No. 2 attenuators, transmitance are that 15.82% No. 4 attenuators, transmitance are 2.51% No. 8 attenuators.

8. according to the described a kind of high precision star simulator of arbitrary claim of claim 1 to 6, it is characterized in that: described attenuator group (7) is fixedly to make up in the attenuator of transmitance at following four kinds: transmitance is that 63.00% No. 1 attenuator, transmitance are that 39.73% 2 attenuators, transmitance are that 15.82% No. 4 attenuators, transmitance are 2.51% No. 8 attenuators.

9. according to the described a kind of high precision star simulator of arbitrary claim of claim 1 to 6, it is characterized in that: described star simulator also comprises frosted glass (3) and the ir reflector (2) that is arranged between light source (1) and the condenser system.

10. a kind of high precision star simulator according to claim 9 is characterized in that: the hole diameter of described star tester (10) is 8-20um.

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