CN118377147A - A high contrast star point target light source - Google Patents

Abstract

The invention relates to the technical field of space optics, in particular to a high-contrast star point target light source, which comprises: the optical fiber beam splitter is used for splitting the emergent light of the light source into two paths of optical signals, carrying out attenuation modulation on one path of optical signals, irradiating the two paths of optical signals on two surfaces of the spectroscope, and transmitting and reflecting the two paths of optical signals by the spectroscope according to the light transmittance and the reflectivity of the spectroscope, so that 2 star point targets with different light intensities can be obtained on one side of the spectroscope. The invention can simulate two star point targets with different light intensities at the same time, the light intensity ratio of the two star point targets can cover 10 ⁰~10¹², the requirement on the light intensity ratio of the star point targets when the planetary crown instrument is tested in the ground development stage is completely met, and the light intensity ratio of the two star point targets can be adjusted according to the requirement.

Description

A high contrast star point target light source

Technical Field

The invention relates to the technical field of space optics, and in particular provides a high-contrast star point target light source.

Background technique

Since habitable Earth-like planets must be located near stars, and the light intensity contrast between planets and stars is very different, the weak photon signals from planets are submerged in the extremely strong stellar background. In order to directly image planets, special technical means are needed.

Coronagraphs are the mainstream means of direct imaging observation of habitable terrestrial planets outside the solar system at home and abroad. The core indicator of a coronagraph is the imaging contrast, which is required to be at least 10 ^8. In order to measure the imaging contrast of a coronagraph during the ground development phase and confirm whether it meets the indicator requirements, it is necessary to develop a high-contrast star point target light source. In order to achieve the above purpose, the target light source is required to meet the following requirements: First, the target light source can generate two star point targets at the same time, and both can be imaged on the focal plane of the coronagraph; second, the light intensity ratio of these two star point targets is required to be ≥10 ⁸ .

However, the current high-contrast star point target solution usually consists of a pinhole and an attenuation sheet. The pinhole is used to generate the star point target, and the attenuation sheet is used to form a high-contrast light intensity. However, this design requires precise alignment of the pinhole and the light source, but the alignment operation has high technical difficulty. There is no effective alignment method in the prior art, which greatly reduces the reliability of the existing solution. In addition, the attenuation sheet is prone to cause ghost images, which in turn submerges the simulated dim target and affects the performance of the high-contrast star point target.

Summary of the invention

In order to solve the above problems, the present invention provides a high-contrast star point target light source, which can simulate two star point targets with different light intensities at the same time. The light intensity ratio of the two star point targets can cover 10 ⁰ ~ 10 ¹² , and can be designed and adjusted accordingly according to the contrast requirements. It has good flexibility and versatility, and avoids the problems in the prior art that the pinhole needs to be precisely aligned with the light source and the attenuation plate easily causes ghost images.

The high-contrast star point target light source provided by the present invention comprises: a light source, an optical fiber beam splitter, an optical fiber attenuation unit and a spectroscope;

The light source is connected to the optical fiber beam splitter through an optical fiber. The optical fiber beam splitter splits the output light of the light source into a first optical signal and a second optical signal according to its own splitting ratio. The first optical signal is transmitted to the optical fiber attenuation unit through the optical fiber. The optical fiber attenuation unit modulates the light intensity of the first optical signal. The modulated first optical signal is irradiated on one side surface of the beam splitter, and the second optical signal is irradiated on the other side surface of the beam splitter. The first optical signal and the second optical signal are conjugate with respect to the beam splitter. The beam splitter transmits and reflects the first optical signal and the second optical signal according to its own light transmittance and reflectivity, so as to simulate and obtain two star point targets.

Preferably, the light source is a fiber laser.

Preferably, the attenuation rate of the optical fiber attenuation unit is continuously adjustable between 1 and 10 ^b .

Preferably, the splitting ratio of the optical fiber beam splitter is 10 ^a :1, the attenuation rate of the optical fiber attenuation unit is 10 ^b , the ratio of the light transmittance and reflectivity of the beam splitter is 10 ^c :1, the light intensity ratio of the two star point targets obtained in the direction in which the first light signal is reflected by the beam splitter is 10 ^abc , and 10 ^abc ≥10 ⁸ .

Preferably, the splitting ratio of the fiber beam splitter is 100:1, the attenuation rate of the fiber attenuation unit is 10 ⁵ , the ratio of the light transmittance and reflectivity of the beam splitter is 10:1, and the light intensity ratio of the two star point targets obtained in the direction where the first light signal is reflected by the beam splitter is 10 ⁸ .

Preferably, the optical fiber attenuation unit includes at least one optical fiber attenuator.

Preferably, it also includes: a first optical fiber output end face and a second optical fiber output end face, the modulated first optical signal is transmitted to the first optical fiber output end face through the optical fiber for output, and the second optical signal is transmitted to the second optical fiber output end face through the optical fiber for output; the first optical fiber output end face and/or the second optical fiber output end face are connected to an adjustment table, and the optical path from the first optical fiber output end face and the second optical fiber output end face to the beam splitter is made equal through the adjustment table.

Compared with the prior art, the present invention can achieve the following beneficial effects:

The present invention generates two signal lights by beam splitting through an optical fiber beam splitter, attenuates the light intensity of one of the signal lights by using an optical fiber attenuator, and then reflects and transmits the two signal lights according to set transmittance and reflectivity through a beam splitter. Two star point targets with different light intensities can be simulated on one side of the beam splitter. The light intensity ratio of the two star point targets can cover 10 ⁰ ~ 10 ¹² , which fully meets the requirement for the light intensity ratio of the star point targets when the coronagraph is tested in the ground development stage. In addition, the optical fiber beam splitter, the optical fiber attenuation unit and/or the beam splitter can be adjusted according to the specific requirement for the light intensity ratio, so that the light intensity ratio of the two star point targets can be continuously adjustable, which greatly improves the flexibility of the star point target light source.

The star point target light source of the present invention is designed based on an all-fiber optical path, avoiding interference from external stray light, and the optical fiber can be selected according to the size of the star point target to be simulated, which can be either a single-mode optical fiber or a multi-mode optical fiber. In addition, the design concept of the star point target light source of the present invention is also applicable to the simulation of multiple star point targets, and the specific structural design principle is basically the same as that of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic structural diagram of a high-contrast star point target light source provided according to an embodiment of the present invention.

Reference numerals include:

Light source 1, first optical fiber 2, optical fiber splitter 3, second optical fiber 3-1, third optical fiber 3-2, optical fiber connector 4, optical fiber attenuator 5, first optical fiber output end face 6-1, second optical fiber output end face 6-2, adjustment stage 7, and beam splitter 8.

Detailed ways

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the same modules are represented by the same reference numerals. In the case of the same reference numerals, their names and functions are also the same. Therefore, the detailed description thereof will not be repeated.

In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

As shown in FIG1 , the high contrast star point target light source disclosed in the embodiment of the present invention includes: a light source 1, a first optical fiber 2, an optical fiber beam splitter 3, a second optical fiber 3-1, a third optical fiber 3-2, an optical fiber connector 4, an optical fiber attenuation unit, a first optical fiber output end face 6-1, a second optical fiber output end face 6-2, an adjustment stage 7 and a beam splitter 8, wherein the light source 1 adopts an optical fiber laser, and the light outlet of the optical fiber laser is connected to the optical fiber beam splitter 3 through the first optical fiber 2. The output light of the optical fiber laser is transmitted to the optical fiber beam splitter 3 through the first optical fiber 2. In order to simulate and generate an ideal star point target, the core diameter of the first optical fiber 2 is required to be much smaller than the Airy disk diameter of the optical system. If the Airy disk diameter of the optical system is 50 μm, in this embodiment, the first optical fiber 2 selects a single-mode optical fiber, and its core diameter is selected to be 10 μm, which is much smaller than the Airy disk diameter of the optical system, so it can be used as an ideal star point target. It should be emphasized that the first optical fiber 2 can not only use a single-mode optical fiber, but also a multi-mode optical fiber, which mainly depends on the size of the star point target to be simulated.

The optical fiber beam splitter 3 has one input and two outputs, and the two outputs are connected to the second optical fiber 3-1 and the third optical fiber 3-2 respectively. The second optical fiber 3-1 and the third optical fiber 3-2 can be selected to have the same model and size as the first optical fiber 2. The optical fiber beam splitter 3 splits the output light in the first optical fiber 2 into the first optical signal and the second optical signal according to the set light intensity output ratio according to its own splitting ratio. The splitting ratio of the optical fiber beam splitter 3 is expressed as 10 ^a :1.

The first optical signal continues to be output along the second optical fiber 3-1 to the optical fiber attenuation unit, and the optical fiber attenuation unit attenuates and modulates the light intensity of the first optical signal according to its own attenuation rate, and the maximum attenuation rate of the optical fiber attenuation unit is expressed as 10 ^b . According to the demand for the attenuation of the light intensity of the first optical signal, the optical fiber attenuation unit may include one or more optical fiber attenuators 5 of the same or different models connected in series, and the attenuation rate of each optical fiber attenuator 5 is continuously adjustable, so the attenuation rate of the optical fiber attenuation unit to light is continuously adjustable between 1 and 10 ^b . In addition, since the high-contrast star point target light source of the present invention is based on an all-fiber optical path, the light on the optical path may involve the situation where two sections of optical fiber are connected to each other, and the optical fiber connection can be performed through the existing optical fiber connector 4. In order to illustrate the use of the optical fiber connector 4, in this embodiment, only two sections of optical fiber are used between the optical fiber splitter 3 and the optical fiber attenuator 5, and they are connected through the optical fiber connector 4.

The first optical signal is attenuated and modulated and then transmitted to the optical fiber, the end of which is provided with a first optical fiber output end face 6-1. The first optical signal is transmitted to the first optical fiber output end face 6-1 through the optical fiber and then emitted to one side surface of the beam splitter 8. The end of the third optical fiber 3-2 is provided with a second optical fiber output end face 6-2. The second optical signal is transmitted to the second optical fiber output end face 6-2 through the third optical fiber 3-2 and then emitted to the other side surface of the beam splitter 8. In order to make the two star point targets conjugate with respect to the beam splitter 8, it is necessary to install the first optical fiber output end face 6-1 or the second optical fiber output end face 6-2 on the adjustment table 7, or to connect an adjustment table 7 to the lower end of the first optical fiber output end face 6-1 and the lower end of the second optical fiber output end face 6-2 respectively. The purpose of installing the adjustment table 7 is mainly to facilitate the adjustment of the posture of the first optical fiber output end face 6-1 and the second optical fiber output end face 6-2. In this embodiment, only the first optical fiber output end face 6-1 is installed on an adjustment platform 7. In order to make the two star point targets conjugate with respect to the beam splitter 8, the posture of the first optical fiber output end face 6-1 is adjusted by the adjustment platform 7, including the adjustment of the position and the light output angle, so that the optical path from the first optical fiber output end face 6-1 and the second optical fiber output end face 6-2 to the beam splitter 8 is equal.

The first light signal and the second light signal are irradiated on both sides of the beam splitter 8 respectively, and are conjugate with respect to the beam splitter 8. The beam splitter 8 can reflect and transmit light at the same time, and its transmittance and reflectance ratio of light can be expressed as 10 ^c : 1. The specific transmittance and reflectance ratio can be designed according to the demand. After the above processing, two simulated star point targets can be obtained in the direction where the first light signal is reflected by the beam splitter 8. The light intensity ratio of the two star point targets is 10 ^abc . In order to meet the requirements of the light intensity ratio of the star point targets during the coronagraph test in the ground development stage, the light intensity ratio of the two star point targets 10 ^abc should not be less than 10 ⁸ . When the high-contrast star point target light source is used for other tests or simulations, one or more parameters of the splitting ratio of the optical fiber beam splitter 3, the attenuation rate of the optical fiber attenuation unit, and the light transmittance and reflectance ratio of the beam splitter 8 can be adjusted, so that the light intensity ratio of the two star point targets can cover 10 ⁰ ~10 ¹² .

In this embodiment, the goal is to meet the test requirements of the coronagraph in the ground development stage. It is necessary to simulate and obtain two star point targets with a light intensity ratio of 10 ^8. Therefore, the splitting ratio of the optical fiber beam splitter 3 is selected to be 100:1, that is, the light intensity of the second light signal is 100 times the light intensity of the first light signal. The optical fiber attenuation unit only includes one optical fiber attenuator 5, and the attenuation rate of the optical fiber attenuator 5 to light is set to 10 ^5. If the light intensity ratio of the two star point targets is required to be higher, that is, the contrast is higher, more optical fiber attenuators 5 can be connected in series after the optical fiber attenuator 5 or an optical fiber attenuator 5 with a higher maximum attenuation rate can be selected. The ratio of the transmittance and reflectance of the beam splitter 8 is 10:1, then the light intensity ratio of the two star point targets obtained in the direction where the first light signal is reflected by the beam splitter 8 is 10 ⁸ , that is, in the direction where the first light signal is reflected by the beam splitter 8, the light intensity of the light output by the second optical fiber output end face 6-2 is 10 ⁸ times the light intensity of the light output by the first optical fiber output end face 6-1.

Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and cannot be understood as limiting the present invention. Those skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

The above specific implementations of the present invention do not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims (7)

1. A high contrast star point target light source, characterized by comprising: a light source, a fiber beam splitter, a fiber attenuation unit and a beam splitter; The light source is connected to the optical fiber beam splitter through an optical fiber. The optical fiber beam splitter splits the output light of the light source into a first optical signal and a second optical signal according to its own splitting ratio. The first optical signal is transmitted to the optical fiber attenuation unit through the optical fiber. The optical fiber attenuation unit modulates the light intensity of the first optical signal. The modulated first optical signal is irradiated on one side surface of the beam splitter, and the second optical signal is irradiated on the other side surface of the beam splitter. The first optical signal and the second optical signal are conjugate with respect to the beam splitter. The beam splitter transmits and reflects the first optical signal and the second optical signal according to its own light transmittance and reflectivity, so as to simulate and obtain two star point targets. 2. The high-contrast star point target light source as described in claim 1, characterized in that the light source is a fiber laser. 3. The high-contrast star point target light source according to claim 1, wherein the attenuation rate of the optical fiber attenuation unit is continuously adjustable between 1 and 10 ^b . 4. The high-contrast star point target light source according to claim 3, characterized in that the splitting ratio of the fiber beam splitter is 10 ^a :1, the attenuation rate of the fiber attenuation unit is 10 ^b , the ratio of the light transmittance and reflectivity of the beam splitter is 10 ^c :1, the light intensity ratio of the two star point targets obtained in the direction in which the first light signal is reflected by the beam splitter is 10 ^abc , and 10 ^abc ≥10 ⁸ . 5. The high-contrast star point target light source according to claim 1, characterized in that the splitting ratio of the fiber beam splitter is 100:1, the attenuation rate of the fiber attenuation unit is 10 ⁵ , the ratio of the light transmittance and reflectivity of the beam splitter is 10:1, and the light intensity ratio of the two star point targets obtained in the direction in which the first light signal is reflected by the beam splitter is 10 ⁸ . 6 . The high-contrast star point target light source according to claim 1 , wherein the optical fiber attenuation unit comprises at least one optical fiber attenuator. 7. The high-contrast star point target light source as described in claim 1 is characterized in that it also includes: a first optical fiber output end face and a second optical fiber output end face, the modulated first optical signal is transmitted to the first optical fiber output end face through the optical fiber for output, and the second optical signal is transmitted to the second optical fiber output end face through the optical fiber for output; the first optical fiber output end face and/or the second optical fiber output end face are connected to an adjustment table, and the optical path from the first optical fiber output end face and the second optical fiber output end face to the beam splitter is made equal through the adjustment table.