Combined wavefront sensor

Abstract

The invention discloses a combined wavefront sensor. The sensor is composed of a rectangular pyramid device, a Hartmann wavefront sensor and a corresponding relay system. A pupil of an optical system is divided through a rectangular pyramid device, and a relay system transmits a light beam to a corresponding Hartmann sensor to detect wavefront aberrations at different pupil plane positions. According to the invention, aberration of different pupil positions is detected by using a plurality of Hartmann sensors, so that high-speed and high-resolution measurement effects are achieved. The method is suitable for the field of solar adaptive optical wavefront detection, and is particularly suitable for the real-time high-resolution wavefront detection process of a large-aperture wide-field solar adaptive optical system on an observed target.

Description

Technical Field

[0001] The present invention belongs to the field of wavefront detection in solar adaptive optical systems, in particular to the wavefront detection technology of large-aperture and wide-field solar adaptive optical systems, and specifically relates to a combined wavefront sensor. Background Art

[0002] In the field of modern ground-based astronomical telescope research, researchers mainly pursue larger apertures and wider fields of view. This is because the light-gathering ability of a telescope is proportional to the square of its aperture, while the spatial resolution is linearly related to the aperture. On the other hand, a wider field of view can cover a larger area of ​​the sky in a single observation, significantly improving observation efficiency, which is especially important in the observation of targets with large extensions, such as the sun.

[0003] Large-aperture ground-based telescopes have greatly reduced spatial resolution due to dynamic interference caused by factors such as atmospheric turbulence, so they rely on adaptive optics (AO) systems to correct distorted wavefronts in real time. However, due to the limitations of atmospheric anisotropy, the correction field of view of traditional adaptive optics systems is only on the order of arc seconds, which cannot meet the needs of high-resolution imaging observations of solar active regions at the diagonal component level in solar physics. With the introduction of a series of large-field adaptive optics technologies represented by ground-level adaptive optics (GLAO), this problem has been solved.

[0004] Surface adaptive optics abandons the concept of diffraction-limited imaging and only corrects for surface turbulence, instead obtaining improved system imaging quality in a relatively wide field of view. This method, which is between traditional AO and seeing-limited observations, benefits many astronomical observations in the visible and near-infrared bands, especially for observations of extended targets such as the sun. Since both GLAO and traditional AO use a single deformable mirror, the two can be shared, so the current research focus is on developing a wide-field wavefront sensor that meets the needs of GLAO.

[0005] As an important component of the GLAO system, the wavefront sensor is mainly responsible for real-time measurement of the dynamic distortion wavefront and providing effective information for subsequent wavefront control. The most widely used Shack-Hartmann wavefront sensor has an increasing number of subapertures as the telescope aperture increases. In the observation of point source targets, in order to ensure that the Hartmann sensor has sufficient dynamic range, each subaperture should contain an appropriate number of pixels, otherwise it may cause crosstalk between adjacent subapertures, thereby affecting the accuracy of wavefront reconstruction. When observing extended targets, each subaperture requires a corresponding detection field of view to obtain an image with a certain degree of extension, so that the wavefront slope can be calculated using the relevant algorithm. Therefore, the pixel resolution in each subaperture is crucial, which directly affects the observation quality of the extended target and the acquisition of wavefront information. Maintaining an appropriate pixel resolution can ensure the accurate calculation of the wavefront slope, thereby achieving effective compensation for the wavefront distortion in the AO system. As the telescope aperture increases and the detection field of view expands, the camera target surface of the sensor will also expand rapidly. The large target surface of the camera is limited by the detector technology, and the detection frame rate cannot meet the requirements of the AO system. On the other hand, it also brings huge computing burden and performance challenges to the data processing of the system's real-time controller. Summary of the invention

[0006] The technical problem to be solved by the present invention is: in view of the above-mentioned shortcomings of a single Shack-Hartmann wavefront sensor, a combined wavefront sensor consisting of a pyramid device and a Shack-Hartmann sensor is provided. The sensor is aimed at a solar adaptive optical system with a large aperture and a wide field of view, and uses a pyramid device to divide the pupil, and then uses multiple detection cameras to image each divided sub-pupil. A combined wavefront sensor proposed by the present invention uses a wavefront sensor with a small target surface to detect the sub-pupil divided by the pyramid, which is more in line with the wavefront detection requirements of a solar adaptive optical system with a large aperture and a large field of view.

[0007] The technical solution adopted by the present invention is: a combined wavefront sensor, including a pyramid device, multiple relay systems, and a Hartmann wavefront sensor corresponding to the relay systems. The measurement method is as follows: an incident light beam containing a wavefront to be measured is split by a pyramid device located at a pupil position, and the light beam passes through the relay system and then detects the target wavefront via the Hartmann wavefront sensor.

[0008] Furthermore, the four-sided pyramid device can be a transmission type or a reflection type, and is used to split the light beam at the pupil plane position and ensure that the split light beams do not generate aliasing.

[0009] Furthermore, the relay system can be of transmission or reflection type, and is mainly used to send the light beam split by the four-sided pyramid device into the corresponding Hartmann wavefront sensor for wavefront detection, ensuring that the entrance pupil plane of the Hartmann wavefront sensor is located at the exit pupil position of the front-end optical system and that the light beam size matches its aperture.

[0010] Compared with the prior art, the present invention has the following advantages:

[0011] The combined wavefront sensor designed by the present invention introduces a pyramid device in the pupil plane for light splitting, and uses multiple detection cameras to detect the wavefront of sub-pupils in different areas. Since multiple microlens arrays and detection cameras are used to image the divided pupils respectively, the combined wavefront sensor can realize multi-channel parallel wavefront measurement, greatly improving the real-time performance and calculation efficiency of wavefront data processing, while reducing the complexity of manufacturing and maintenance of microlens arrays. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the structure of the device in the present invention.

[0013] Figure 2 This is a light path diagram of a specific design example in the present invention.

[0014] Figure 3 This is the pupil plane image at the front end of the Hartmann wavefront sensor.

[0015] The meanings of the symbols in the accompanying drawings are: 1 is a pyramid device, 2 is a relay system, and 3 is a Hartmann wavefront sensor. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other. To achieve the above-mentioned purpose, the present invention adopts the following technical scheme.

[0017] like Figure 1As shown, the present invention includes a pyramid device 1, a plurality of relay systems 2, and a Hartmann wavefront sensor 3 corresponding to the relay systems 2. After the incident light beam enters the sensor, it first passes through the pyramid device 1 at the pupil surface position to perform pupil segmentation, and the pyramid device 1 uses a quadrangular pyramid. The incident light beam is divided into a plurality of sub-beams, each of which corresponds to a sub-pupil in an area. After passing through the relay system 2, each sub-pupil is imaged to the corresponding Hartmann wavefront sensor 3 for wavefront detection. The detection camera of the Hartmann wavefront sensor 3 transmits the detected array image to the back-end real-time controller for analysis and processing, and the wavefront phase information contained in each sub-pupil can be extracted.

[0018] Figure 2 The optical path diagram of the specific design of the combined wavefront sensor is given. Each relay system is a pair of 4f lens groups, the focus of the front lens coincides with the focus of the rear lens, and by changing the ratio of the focal lengths of the two lenses, the beam aperture after the four-sided pyramid device is split can be matched with the entrance pupil size of the rear-end Hartmann sensor.

[0019] From the imaging results of the detection plane, we can see that Figure 3 As shown, the combined wavefront sensor can perform segmented detection on the pupil plane, thus being suitable for large-aperture optical systems.

Claims

1. A combined wavefront sensor, characterized in that: The invention comprises: a pyramid device (1), a plurality of relay systems (2), and a Hartmann wavefront sensor (3) corresponding one to one with the relay systems (2); an incident light beam containing a wavefront to be measured is split by the pyramid device (1) located at the pupil plane, and the light beams are respectively passed through the relay systems (2) and then detected by the Hartmann wavefront sensor (3) on the target wavefront.

2. A combined wavefront sensor according to claim 1, characterized in that: The pyramid device (1) is a transmission or reflection type, and is used to split the light beam at the pupil plane position and ensure that the split light beams do not produce aliasing.

3. A combined wavefront sensor according to claim 1, characterized in that: The relay system (2) is of transmission or reflection type and is used to send the light beam split by the pyramid device (1) into the corresponding Hartmann wavefront sensor (3) for wavefront detection, ensuring that the entrance pupil plane of the Hartmann wavefront sensor (3) is located at the exit pupil position of the front optical system and that the light beam size matches its aperture.

4. A combined wavefront sensor according to claim 1, characterized in that: Each relay system (2) is a pair of 4f lens groups, the focus of the front lens coincides with the focus of the rear lens, and by changing the ratio of the focal lengths of the two lenses, the diameter of the light beam split by the four-sided pyramid device can be matched with the entrance pupil size of the rear-end Hartmann sensor.

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