A wavefront detection system and a phase detection system

Abstract

The present application provides a wavefront detection system and a phase detection system, wherein the wavefront detection system is provided with a target light source, and the target light source is used to emit a target laser in a target band; along the propagation direction of the target laser, the wavefront detection system is also provided with a grating, a 4f lens group and a camera in sequence; wherein the 4f lens group includes a front lens and a rear lens arranged in sequence along the propagation direction of the target laser; the rear focal plane of the front lens in the target band coincides with the front focal plane of the rear lens in the target band; the image sensor of the camera is used to sense the target laser, and the image sensor is arranged at the rear focal plane of the rear lens in the target band; the grating is arranged in front of the front focal plane of the front lens in the target band; between the target light source and the grating, a sample to be detected is arranged. The wavefront detection system provided by the present application reduces the difficulty of building the optical path of the system.

Description

Technical Field

[0001] The present application relates to the field of optics, and in particular to a wavefront detection system and a phase detection system. Background Art

[0002] In the field of optics, in order to determine the phase distribution of a sample in a specific band, a grating is often set on the light-emitting side of the sample, and an image sensor is set behind the grating. In this way, the laser light of a specific band passing through the sample will interfere when passing through the grating, and the image sensor can capture the corresponding interference image. According to the interference image captured by the image sensor, the laser light of a specific band passing through the sample can be wavefront detected, and the phase distribution of the sample in the specific band can be determined. To this end, it is necessary to provide a wavefront detection system that can smoothly perform wavefront detection on the sample, and the wavefront detection system provided by the related technology has great difficulty in construction. Utility Model Content

[0003] One purpose of the present application is to provide a wavefront detection system and a phase detection system. The wavefront detection system provided by the present application reduces the difficulty of building the system optical path.

[0004] According to one aspect of an embodiment of the present application, a wavefront detection system is disclosed, wherein the wavefront detection system is provided with a target light source, and the target light source is used to emit a target laser of a target wavelength band; along the propagation direction of the target laser, the wavefront detection system is also provided with a grating, a 4f lens group and a camera in sequence;

[0005] The 4f lens group includes a front lens and a rear lens sequentially arranged along the propagation direction of the target laser; the rear focal plane of the front lens in the target band coincides with the front focal plane of the rear lens in the target band;

[0006] The image sensor of the camera is used to sense the target laser, and the image sensor is arranged at the rear focal plane of the rear lens under the target wavelength band;

[0007] The grating is arranged in front of the front focal plane of the front lens in the target band; and is used to arrange the sample to be detected between the target light source and the grating.

[0008] In an exemplary embodiment of the present application, the target light source is used to emit a target laser in the far-infrared band; the rear focal plane of the front lens in the far-infrared band coincides with the front focal plane of the rear lens in the far-infrared band; the image sensor is used to sense a light beam in the far-infrared band; the image sensor is arranged at the rear focal plane of the rear lens in the far-infrared band; the grating is arranged in front of the front focal plane of the front lens in the far-infrared band; and the sample operates in the far-infrared band.

[0009] In an exemplary embodiment of the present application, the target laser is at least perpendicular to the front lens and the rear lens, and the target laser passes through at least the center of the front lens and the center of the rear lens.

[0010] In an exemplary embodiment of the present application, the distance between the grating and the front focal plane of the front lens in the target band is positively correlated with the period of the grating, and is inversely correlated with the numerical aperture of the sample.

[0011] In an exemplary embodiment of the present application, the period of the grating is 72 μm ± 3 μm;

[0012] When the numerical aperture of the sample is 0.04, the distance between the grating and the front focal plane of the front lens in the target band is 0.4 mm to 0.8 mm;

[0013] When the numerical aperture of the sample is 0.1, the distance between the grating and the front focal plane of the front lens in the target band is 0.3 mm to 0.45 mm;

[0014] When the numerical aperture of the sample is 0.15, the distance between the grating and the front focal plane of the front lens in the target band is 0.15 mm to 0.25 mm.

[0015] In an exemplary embodiment of the present application, the period of the grating is 144 μm ± 3 μm;

[0016] When the numerical aperture of the sample is 0.04, the distance between the grating and the front focal plane of the front lens in the target band is 0.3 mm to 1.8 mm;

[0017] When the numerical aperture of the sample is 0.1, the distance between the grating and the front focal plane of the front lens in the target band is 0.2 mm to 0.75 mm;

[0018] When the numerical aperture of the sample is 0.15, the distance between the grating and the front focal plane of the front lens in the target band is 0.2 mm to 0.45 mm.

[0019] In an exemplary embodiment of the present application, the period of the grating is 180 μm ± 3 μm;

[0020] When the numerical aperture of the sample is 0.04, the distance between the grating and the front focal plane of the front lens in the target band is 0.2 mm to 2.3 mm;

[0021] When the numerical aperture of the sample is 0.1, the distance between the grating and the front focal plane of the front lens in the target band is 0.2 mm to 0.9 mm;

[0022] When the numerical aperture of the sample is 0.15, the distance between the grating and the front focal plane of the front lens in the target band is 0.5 mm to 0.6 mm.

[0023] In an exemplary embodiment of the present application, the value of f1 / f2 is positively correlated with the size of the sample; wherein f1 is the focal length of the front lens in the target band, and f2 is the focal length of the rear lens in the target band.

[0024] In an exemplary embodiment of the present application, the period of the grating is positively correlated with the value of f1 / f2; wherein f1 is the focal length of the front lens in the target band, and f2 is the focal length of the rear lens in the target band.

[0025] In an exemplary embodiment of the present application, the grating is a two-dimensional grating in the shape of a chessboard, and the phase difference provided by the alternating phases of each unit cell of the grating is π.

[0026] In an exemplary embodiment of the present application, the wavefront detection system is further provided with a reflector group for adjusting the propagation direction of the target laser between the target light source and the grating, and the reflector group includes at least one reflector.

[0027] According to one aspect of an embodiment of the present application, a phase detection system is disclosed, the phase detection system comprising: a wavefront detection system as provided in any of the above embodiments; the sample disposed between the target light source and the grating, the target laser vertically incident on the sample and passing through the center of the sample; a processor;

[0028] The processor is electrically connected to the camera, and is used to receive an interference image generated by the image sensor sensing the target laser, so as to detect the phase distribution of the sample according to the interference image.

[0029] The wavefront detection system provided by the present application is provided with a target light source, which is used to emit a target laser in a target band; along the propagation direction of the target laser, the wavefront detection system is also provided with a grating, a 4f lens group and a camera in sequence; wherein the 4f lens group includes a front lens and a rear lens arranged in sequence along the propagation direction of the target laser; the rear focal plane of the front lens in the target band coincides with the front focal plane of the rear lens in the target band; the image sensor of the camera is used to sense the target laser, and the image sensor is arranged at the rear focal plane of the rear lens in the target band; the grating is arranged in front of the front focal plane of the front lens in the target band; between the target light source and the grating, a sample to be detected is arranged. The wavefront detection system provided by the present application arranges the image sensor at the rear focal plane of the rear lens in the target band, and arranges the grating in front of the front focal plane of the front lens in the target band, so that when building the system optical path, it is not necessary to accurately perceive the position of the image sensor, nor to use a device that can accurately measure the fixed distance between two points, thereby reducing the difficulty of building the system optical path.

[0030] Other features and advantages of the present application will become apparent from the following detailed description, or may be learned in part by the practice of the present application.

[0031] It should be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The above and other objects, features and advantages of the present application will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings.

[0033] Figure 1 The system architecture diagram of the wavefront detection system provided by the present application is shown.

[0034] Figure 2 A schematic diagram of the system architecture of a wavefront detection system provided in an embodiment of the present application is shown.

[0035] Figure 3 A schematic diagram of the architecture of the phase detection system provided in the present application is shown.

[0036] Figure 4 A schematic diagram of an interference image captured by an image sensor when no sample is added to the optical path of a wavefront detection system provided in an embodiment of the present application is shown.

[0037] Figure 5 Shown in Figure 4 Based on the embodiment, a schematic diagram of the interference image obtained by the image sensor after the sample is further added into the light path.

[0038] Figure 6 Shows Figure 5Schematic diagram of the theoretical phase distribution of the sample in the embodiment.

[0039] Figure 7 Shown according to Figure 5 The schematic diagram of the phase distribution obtained after the phase distribution of the sample is restored by the interference image shown in the embodiment.

[0040] Figure 8 A schematic diagram of an interference image captured by an image sensor when no sample is added to the optical path of a wavefront detection system provided in an embodiment of the present application is shown.

[0041] Fig. 9 Shown in Figure 8 Based on the embodiment, a schematic diagram of the interference image obtained by the image sensor after the sample is further added into the light path.

[0042] Fig.10 Shows Fig. 9 Schematic diagram of the theoretical phase distribution of the sample in the embodiment.

[0043] Fig.11 Shown according to Fig. 9 The schematic diagram of the phase distribution obtained after the phase distribution of the sample is restored by the interference image shown in the embodiment.

[0044] Reference numerals:

[0045] 1-target light source; 2-sample; 3-grating; 4-front lens; 4A-front focal plane of the front lens in the target band; 4B-back focal plane of the front lens in the target band; 5-rear lens; 5A-front focal plane of the rear lens in the target band; 5B-back focal plane of the rear lens in the target band; 6-camera; 61-the frontmost lens element in the camera; 62-image sensor; 7-first reflector; 8-second reflector; 9-laser attenuator; 10-processor. DETAILED DESCRIPTION

[0046] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these example embodiments are provided so that the description of the present application will be more comprehensive and complete and the concepts of the example embodiments will be fully conveyed to those skilled in the art. The accompanying drawings are only schematic illustrations of the present application and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted.

[0047] In addition, the described features, structures or characteristics may be combined in one or more example embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the example embodiments of the present application. However, those skilled in the art will appreciate that the technical solution of the present application may be practiced while omitting one or more of the specific details, or other methods, components, steps, etc. may be adopted. In other cases, known structures, methods, implementations or operations are not shown or described in detail to avoid obscuring the present application and making the various aspects of the present application obscure.

[0048] In order to enable the image sensor to collect high-quality interference images, the grating and the image sensor often need to maintain a relatively close distance L. However, since the image sensor is usually located in a camera, and in the camera, the area in front of the image sensor is usually provided with various lens elements of a certain volume (e.g., lens group, protective glass, etc.), it is difficult to set the grating to a position close enough to the image sensor.

[0049] In order to overcome this problem, a 4f lens group can be introduced between the grating and the image sensor. Specifically, the 4f lens group includes a front lens and a rear lens (in the embodiment of the present application, the relative concepts of "front" and "rear" are determined based on the direction of the optical path). The front lens and the rear lens are generally both focusing lenses, and the rear focal plane of the front lens in a specific band coincides with the front focal plane of the rear lens in the specific band. In this way, for lasers of a specific band, the spectrum at the front focal plane of the front lens in the specific band is the same as the spectrum at the rear focal plane of the rear lens in the specific band. That is, it can be considered that for lasers of a specific band, the 4f lens group can transfer the spectrum at the front focal plane of the front lens in the specific band to the rear focal plane of the rear lens in the specific band.

[0050] Let the focal length of the front lens in a specific band be f1, and the focal length of the rear lens in a specific band be f2, so the distance from the front focal plane of the front lens in a specific band to the back focal plane of the rear lens in a specific band is 2*(f1+f2). Therefore, after introducing the 4f lens group between the grating and the image sensor, under the premise of ensuring that "the grating is not located behind the front focal plane of the front lens in the target band" and "the image sensor is not located in front of the back focal plane of the rear lens in the target band", for the distance between the grating and the image sensor, it is only necessary to control the distance between the grating and the image sensor to be L+2*(f1+f2), so that the image sensor can collect a high-quality interference image, and thus it is no longer necessary to set the grating to a position close enough to the image sensor.

[0051] In the related art, for this type of wavefront detection system that introduces a 4f lens group, the grating is usually set at the position of the front focal plane of the front lens in the corresponding band; in this way, when building the system optical path, the related art needs to set the image sensor behind the rear focal plane of the rear lens in the corresponding band, and control the distance between the image sensor and the rear focal plane of the rear lens in the corresponding band to be L.

[0052] In order to control the distance between the image sensor and the rear focal plane of the rear lens in the corresponding band to L, the related technology needs to be able to accurately sense the position of the image sensor. However, since the image sensor is usually located in the camera, the position of the image sensor is not easy to accurately sense. Even if the position of the image sensor is accurately sensed, the related technology must use a device that can accurately measure the fixed distance between two points to control the distance between the image sensor and the rear focal plane of the rear lens in the corresponding band to L. It can be seen that the wavefront detection system provided by the related technology that introduces a 4f lens group is difficult to build a system optical path.

[0053] In order to overcome the above-mentioned defects of the related art, the present application provides a wavefront detection system. The wavefront detection system provided by the present application sets the image sensor at the rear focal plane of the rear lens in the target band, and sets the grating in front of the front focal plane of the front lens in the target band, so that when building the system optical path, it is not necessary to accurately perceive the position of the image sensor, nor to use a device that can accurately measure the fixed distance between two points, thereby reducing the difficulty of building the system optical path.

[0054] Figure 1 1 shows a system architecture diagram of the wavefront detection system provided by the present application. Figure 1 The wavefront detection system provided in the present application is provided with a target light source 1, which is used to emit a target laser of a target wavelength band. Along the propagation direction of the target laser, the wavefront detection system is also provided with a grating 3, a 4f lens group and a camera 6 in sequence.

[0055] Among them, the 4f lens group includes a front lens 4 and a rear lens 5 which are sequentially arranged along the propagation direction of the target laser. The front focal plane of the front lens 4 in the target band is 4A, the rear focal plane of the front lens 4 in the target band is 4B, the front focal plane of the rear lens 5 in the target band is 5A, and the rear focal plane of the rear lens 5 in the target band is 5B. In the embodiment of the present application, the rear focal plane 4B of the front lens 4 coincides with the front focal plane 5A of the rear lens 5.

[0056] In the embodiment of the present application, the camera 6 is disposed behind the 4f lens group. The image sensor 62 of the camera 6 is used to sense the target laser, that is, the image sensor 62 is mainly sensitive to light in the target band. In addition, the image sensor 62 is disposed at the rear focal plane 5B of the rear lens 5.

[0057] It should be noted that since both the front lens 4 and the rear lens 5 are focusing lenses, if the rear lens 5 is set before the front lens 4 when building the system optical path, it can be considered that the target laser of parallel light will be focused first after being incident on the rear lens 5; when the target laser propagates to the rear focal plane 5B of the rear lens 5, the degree of concentration of the target laser is the highest; if it propagates further, the target laser will diverge.

[0058] It can be seen that if the rear lens 5 is set before the front lens 4 when constructing the system optical path, when adjusting the position of the camera 6, when the image sensor 62 is located at the rear focal plane 5B of the rear lens 5, the light spot sensed by the image sensor 62 will have the maximum brightness or the smallest area. It can be seen that in this case, it is only necessary to monitor the brightness of the light spot sensed by the image sensor 62 when adjusting the position of the camera 6, and then set the camera 6 at the position where the brightness of the light spot is the largest, so that the image sensor 62 can be set at the rear focal plane 5B of the rear lens 5; or, it is only necessary to monitor the size of the light spot sensed by the image sensor 62 when adjusting the position of the camera 6, and then set the camera 6 at the position where the area of ​​the light spot is the smallest, so that the image sensor 62 can be set at the rear focal plane 5B of the rear lens 5. In this process, it is not necessary to accurately perceive the position of the image sensor 62, nor is it necessary to use a device that can accurately measure the fixed distance between two points.

[0059] In the embodiment of the present application, the grating 3 is arranged in front of the front focal plane 4A of the front lens 4, and the sample 2 to be detected is arranged between the target light source 1 and the grating 3. The sample 2 can be a traditional lens, a diffractive optical element, or a super lens.

[0060] The distance between the grating 3 and the front focal plane 4A of the front lens 4 is L. It should be noted that if, when constructing the optical path of the system, before setting the grating 3, the image sensor 62 has been set at the rear focal plane 5B of the rear lens 5, and the rear focal plane 4B of the front lens 4 has also overlapped with the front focal plane 5A of the rear lens 5, then when adjusting the position of the grating 3, the edge of the grating 3 can be sensed according to the image collected by the image sensor 62; it can be understood that when the grating 3 overlaps with the front focal plane 4A of the front lens 4, the clarity of the edge of the grating 3 will reach the highest level; therefore, in this case, it is only necessary to monitor the clarity of the sensed edge of the grating 3 when adjusting the position of the grating 3, and then set the grating 3 at the position with the highest clarity, and the grating 3 can be set at the front focal plane 4A of the front lens 4. After the grating 3 is disposed at the front focal plane 4A of the front lens 4, the grating 3 is moved forward by a distance L by means of a motion mechanism capable of accurately moving the relative distance, so that the grating 3 is disposed at a distance L before the front focal plane 4A of the front lens 4. In this process, it is also not necessary to accurately sense the position of the image sensor 62, nor is it necessary to use a device capable of accurately measuring a fixed distance between two points.

[0061] It should also be noted that the two spatial positions recorded on the optical axis of the 4f lens group are the first spatial position P1 and the second spatial position P2, the first spatial position P1 is located behind the rear focal plane of the rear lens 5 in the preset band, and the second spatial position P2 is also located behind the rear focal plane of the rear lens 5 in the preset band. When the rear focal plane of the front lens 4 in the preset band coincides with the front focal plane of the rear lens 5 in the preset band, and the sample 2 is not set in the optical path, the light beam transmitted by the 4f lens group is parallel light, and the spot size of the light beam transmitted by the 4f lens group at the first spatial position P1 and the spot size at the second spatial position P2 will be consistent. Therefore, when adjusting the distance between the front lens 4 and the rear lens 5, it is only necessary to detect the light spots at the first spatial position P1 and the second spatial position P2, and then determine whether the light spot sizes at the two spatial positions are consistent within the allowable error range; the distance between the front lens 4 and the rear lens 5 is continuously adjusted until the light spot sizes at the two spatial positions are consistent within the allowable error range, so that the rear focal plane of the front lens 4 in the preset band can be controlled to coincide with the front focal plane of the rear lens 5 in the preset band.

[0062] When the rear focal plane of the front lens 4 in the preset band is controlled to coincide with the front focal plane of the rear lens 5 in the preset band, the selected preset band can be a target band or a non-target band. When the preset band is the target band, f1' is equal to f1, and f2' is equal to f2; in this case, it is obvious that the rear focal plane 4B of the front lens 4 in the target band can be controlled to coincide with the front focal plane 5A of the rear lens 5 in the target band. When the preset band is a non-target band, f1' is not equal to f1, and f2' is not equal to f2; in this case, the distance between the front lens 4 and the rear lens 5 can be controlled to be (f1'+f2') first (that is, the rear focal plane of the front lens 4 in the preset band is controlled to coincide with the front focal plane of the rear lens 5 in the preset band), and then with the help of a motion mechanism that can accurately move the relative distance, according to the distance difference between (f1'+f2') and (f1+f2), the distance between the front lens 4 and the rear lens 5 can be further adjusted to (f1+f2), thereby controlling the rear focal plane 4B of the front lens 4 in the target band to coincide with the front focal plane 5A of the rear lens 5 in the target band. In this process, it is also not necessary to accurately perceive the position of the image sensor 62, nor is it necessary to use a device that can accurately measure the fixed distance between two points.

[0063] In summary, it can be seen that the wavefront detection system provided in the present application arranges the image sensor 62 at the rear focal plane 5B of the rear lens 5 in the target band, and arranges the grating 3 in front of the front focal plane 4A of the front lens 4 in the target band. As a result, when building the system optical path, there is no need to accurately perceive the position of the image sensor 62, nor is there a need to use a device that can accurately measure the fixed distance between two points, thereby reducing the difficulty of building the system optical path.

[0064] In one embodiment, the target wavelength is the visible light wavelength. That is, in this embodiment, the target light source 1 emits a target laser in the visible light wavelength; the grating 3, the front lens 4 and the rear lens 5 all have high transmittance for visible light; the rear focal plane of the front lens 4 in the visible light wavelength coincides with the front focal plane of the rear lens 5 in the visible light wavelength; the image sensor 62 is mainly used to sense visible light; the image sensor 62 is arranged at the rear focal plane of the rear lens 5 in the visible light wavelength; the grating 3 is arranged in front of the front focal plane of the front lens 4 in the visible light wavelength; the sample 2 works in the visible light wavelength.

[0065] In one embodiment, the target wavelength is outside the visible wavelength, that is, in this embodiment, the target light source 1 emits a target laser in a non-visible wavelength, which includes but is not limited to ultraviolet wavelength, near infrared wavelength, and far infrared wavelength.

[0066] Specifically, when the target band is the far infrared band, the grating 3, the front lens 4 and the rear lens 5 all have high transmittance for the far infrared band; the rear focal plane of the front lens 4 in the far infrared band coincides with the front focal plane of the rear lens 5 in the far infrared band; the image sensor 62 is mainly used to sense the light beam in the far infrared band; the image sensor 62 is arranged at the rear focal plane of the rear lens 5 in the far infrared band; the grating 3 is arranged in front of the front focal plane of the front lens 4 in the far infrared band; the sample 2 works in the far infrared band. Similarly, the specific performance of the adaptation of each component in other non-visible light bands will not be repeated.

[0067] In one embodiment, the target laser is incident vertically on the grating 3 .

[0068] In one embodiment, the target laser is incident on the grating 3 at a preset angle.

[0069] In one embodiment, the target laser is at least perpendicular to the front lens 4 and the rear lens 5, and the target laser passes through at least the center of the front lens 4 and the center of the rear lens 5. Thus, the 4f lens group can correctly transfer the spectrum at the front focal plane 4A of the front lens 4 to the rear focal plane 5B of the rear lens 5.

[0070] In one embodiment, the target laser is incident perpendicularly to the image sensor 62. Specifically, since the various lens elements arranged in the area in front of the image sensor 62 are generally parallel to the image sensor 62, the posture of the image sensor 62 can be indirectly determined by observing the posture of the lens element 61 arranged at the front of the camera 6 (for example, the protective lens arranged at the front of the camera 6), thereby making the target laser incident perpendicularly to the image sensor 62.

[0071] In one embodiment, the distance L between the grating 3 and the front focal plane 4A of the front lens 4 in the target wavelength band is positively correlated with the period of the grating 3 and is negatively correlated with the numerical aperture of the sample 2 .

[0072] Specifically, as mentioned above, when the 4f lens group is not introduced, in order to ensure that the image sensor 62 captures a high-quality interference image, it is necessary to control the distance L between the grating 3 and the image sensor 62; after the 4f lens group is introduced, when the image sensor 62 is controlled to be located at the rear focal plane 5B of the rear lens 5, it is necessary to control the grating 3 to be located in front of the front focal plane 4A of the front lens 4, and control the distance L between the grating 3 and the front focal plane 4A of the front lens 4.

[0073] It should be noted that the distance L is positively correlated with the Talbot distance of the grating 3. Wherein, d is the period of the grating 3, and λ is the central wavelength of the working band. It can be seen that the Talbot distance of the grating 3 is positively correlated with the period of the grating 3; therefore, the distance L that should be maintained between the grating 3 and the front focal plane 4A is positively correlated with the period of the grating 3.

[0074] Moreover, as the period of the grating 3 increases, the distance from the center of the first-order spectrum of the grating 3 to the center of its zero-order spectrum will become smaller and smaller, which will lead to a smaller and smaller spectrum filtering range of the grating 3. Since the upper limit of the numerical aperture of the sample 2 to be tested mainly depends on the spectrum filtering range of the grating 3, the smaller the spectrum filtering range of the grating 3, the smaller the upper limit of the numerical aperture of the sample 2 that can be tested by the grating 3; therefore, the distance L that should be maintained between the grating 3 and the front focal plane 4A is also inversely correlated with the numerical aperture of the sample 2.

[0075] In one embodiment, the period of the grating 3 is 72 μm±3 μm.

[0076] In this embodiment, when the numerical aperture of the sample 2 is 0.04, the distance L between the grating 3 and the front focal plane 4A of the front lens 4 in the target wavelength band is 0.4 mm to 0.8 mm (including 0.4 mm and 0.8 mm).

[0077] When the numerical aperture of the sample 2 is 0.1, the distance L between the grating 3 and the front focal plane 4A of the front lens 4 in the target band is 0.3 mm to 0.45 mm (including 0.3 mm and 0.45 mm);

[0078] When the numerical aperture of the sample 2 is 0.15, the distance L between the grating 3 and the front focal plane 4A of the front lens 4 in the target wavelength band is 0.15 mm to 0.25 mm (including 0.15 mm and 0.25 mm).

[0079] In one embodiment, the period of the grating 3 is 144 μm±3 μm.

[0080] In this embodiment, when the numerical aperture of the sample 2 is 0.04, the distance L between the grating 3 and the front focal plane 4A of the front lens 4 in the target wavelength band is 0.3 mm to 1.8 mm (including 0.3 mm and 1.8 mm).

[0081] When the numerical aperture of the sample 2 is 0.1, the distance L between the grating 3 and the front focal plane 4A of the front lens 4 in the target wavelength band is 0.2 mm to 0.75 mm (including 0.2 mm and 0.75 mm).

[0082] When the numerical aperture of the sample 2 is 0.15, the distance L between the grating 3 and the front focal plane 4A of the front lens 4 in the target wavelength band is 0.2 mm to 0.45 mm (including 0.2 mm and 0.45 mm).

[0083] In one embodiment, the period of the grating is 180 μm±3 μm.

[0084] In this embodiment, when the numerical aperture of the sample 2 is 0.04, the distance L between the grating 3 and the front focal plane 4A of the front lens 4 in the target wavelength band is 0.2 mm to 2.3 mm (including 0.2 mm and 2.3 mm).

[0085] When the numerical aperture of the sample 2 is 0.1, the distance L between the grating 3 and the front focal plane 4A of the front lens 4 in the target wavelength band is 0.2 mm to 0.9 mm (including 0.2 mm and 0.9 mm).

[0086] When the numerical aperture of the sample 2 is 0.15, the distance L between the grating 3 and the front focal plane 4A of the front lens 4 in the target wavelength band is 0.5 mm to 0.6 mm (including 0.5 mm and 0.6 mm).

[0087] In one embodiment, the value of f1 / f2 is positively correlated with the size of the sample 2; wherein f1 is the focal length of the front lens 4 in the target band, and f2 is the focal length of the rear lens 5 in the target band.

[0088] Specifically, if the beam diameter of the target laser before modulation by the 4f lens group remains unchanged, the larger the value of f1 / f2, the smaller the beam diameter of the target laser after modulation by the 4f lens group. That is, without changing the target laser, increasing the value of f1 / f2 can shrink the target laser after modulation by the 4f lens group. Similarly, if the beam diameter of the target laser before modulation by the 4f lens group remains unchanged, the smaller the value of f1 / f2, the larger the beam diameter of the target laser after modulation by the 4f lens group. That is, without changing the target laser, reducing the value of f1 / f2 can expand the target laser after modulation by the 4f lens group.

[0089] In this embodiment, when the size of sample 2 is relatively small, the value of f1 / f2 can be reduced, thereby expanding the target laser modulated by the 4f lens group, thereby amplifying the imaging image to increase the number of samples, and thus more accurately performing wavefront detection.

[0090] When the size of sample 2 is too large, the value of f1 / f2 can be increased, thereby narrowing the target laser modulated by the 4f lens group, thereby reducing the imaging image, and further expanding the detection range of sample 2.

[0091] In one embodiment, the period of the grating 3 is positively correlated with the value of f1 / f2, wherein f1 is the focal length of the front lens 4 in the target band, and f2 is the focal length of the rear lens 5 in the target band.

[0092] Specifically, the adjustment of the value of f1 / f2 due to the need for beam contraction or beam expansion will cause the accuracy of the phase distribution restored from the interference image to change. If the accuracy of the restoration of the phase distribution needs to be kept basically unchanged, the period of the grating 3 can be adjusted synchronously.

[0093] Therefore, in this embodiment, after adjusting the value of f1 / f2, the period of the grating 3 is also adjusted accordingly. Specifically, if the value of f1 / f2 is increased, the period of the grating 3 is also increased; if the value of f1 / f2 is reduced, the period of the grating 3 is also reduced, thereby maintaining the restoration accuracy of the phase distribution basically unchanged.

[0094] In one embodiment, the grating 3 is a two-dimensional grating in the shape of a chessboard, and the phase difference provided by the alternating phases of the cells thereon is π. Therefore, the target laser passing through the sample 2 will generate four-wave shear interference when passing through the grating 3.

[0095] It should be noted that since four-wave shearing interference can occur for both coherent light and incoherent light, this embodiment reduces the requirement for the coherence of the target laser by performing wavefront detection based on four-wave shearing interference.

[0096] In one embodiment, the wavefront detection system is further provided with a reflector group for adjusting the propagation direction of the target laser between the target light source 1 and the grating 3, and the reflector group includes at least one reflector.

[0097] Specifically, sometimes the volume and weight of the target light source 1 are both relatively large. In this case, it is inconvenient to directly adjust the posture of the target light source 1. Therefore, in order to adjust the propagation direction of the target laser without adjusting the posture of the target light source 1, in this embodiment, a reflector group is provided between the target light source 1 and the grating 3, and the reflector group includes at least one reflector. Therefore, when it is necessary to adjust the propagation direction of the target laser, it is only necessary to adjust the posture of at least one reflector in the reflector group.

[0098] Figure 2 FIG. 1 is a schematic diagram showing the system architecture of a wavefront detection system provided by an embodiment of the present application. Figure 2 In one embodiment, a first reflector 7 and a second reflector 8 are provided between the target light source 1 and the grating 3. The first reflector 7 and the second reflector 8 together form a reflector group.

[0099] In this embodiment, the target light source 1 can be placed horizontally. When constructing the system optical path, by adjusting the angle of at least one of the first reflector 7 and the second reflector 8, the target laser can continue to propagate horizontally at different heights.

[0100] See also Figure 2In one embodiment, the wavefront detection system is further provided with a laser attenuator 9 between the target light source 1 and the light source 3. The laser attenuator 9 is provided because if the optical power of the target laser is large, the target laser with large optical power is incident on the image sensor 62, which is likely to cause damage to the image sensor 62. Therefore, in this embodiment, the laser attenuator 9 is provided between the target light source 1 and the light source 3, thereby reducing the optical power of the target laser, thereby preventing the target laser from damaging the image sensor 62.

[0101] The present application also provides a phase detection system. Figure 3 Schematic diagram of the phase detection system provided by the present application is shown. Figure 3 The phase detection system provided in the present application includes: a wavefront detection system as provided in the above embodiment; a sample 2; and a processor 10.

[0102] The sample 2 is disposed between the target light source 1 and the grating 3, and the target laser is incident vertically on the sample 2 and passes through the center of the sample 2. Therefore, the target laser passing through the sample 2 will interfere when passing through the grating 3, and under the effect of the 4f lens group on the spectrum transfer, the image sensor 62 senses the target laser and collects a high-quality interference image.

[0103] The processor 10 is electrically connected to the camera 6. Thus, the processor 10 can receive the interference image collected by the image sensor 62 from the camera 6. Furthermore, the processor 10 can restore the phase distribution of the sample 2 from the interference image, thereby realizing phase detection.

[0104] Figure 4 A schematic diagram of an interference image captured by an image sensor when no sample is added to the optical path of a wavefront detection system provided in an embodiment of the present application is shown. Figure 5 Shown in Figure 4 Based on the embodiment, a schematic diagram of the interference image obtained by the image sensor after the sample is further added into the light path. Figure 6 Shows Figure 5 Schematic diagram of the theoretical phase distribution of the sample in the embodiment.

[0105] Figure 7 Shown according to Figure 5 The schematic diagram of the phase distribution obtained after the phase distribution of the sample is restored by the interference image shown in the embodiment.

[0106] See also Figures 4 to 7In one embodiment, the target light source emits a far-infrared laser with a central wavelength of 10.6 μm; the grating is a chessboard-shaped two-dimensional grating with a period of 72 μm; the front lens and the rear lens are both zinc selenide lenses with a focal length of 25.4 mm in the far-infrared band; the grating is arranged in front of the front focal plane of the front lens in the far-infrared band, and the distance between the grating and the front focal plane of the front lens in the far-infrared band is 0.6 mm; the working band of the camera is 8 to 12 μm; the diameter of the light spot sensed by the camera is about 6 mm, and since the focal lengths of the front lens and the rear lens are the same, it can be shown that the diameter of the light spot projected on the sample is about 6 mm; the sample is a zinc selenide lens with a focal length of 75 mm in the far-infrared band, and combined with the diameter of the light spot on the sample of 6 mm, it can be determined that the actual numerical aperture of the sample is 0.04.

[0107] In this embodiment, after the optical path of the wavefront detection system is established, before the sample is added to the optical path, the image sensor of the camera will collect Figure 4 After the sample is added to the light path, the image sensor will capture the interference image. Figure 5 The interference image is shown.

[0108] The processor uses the principle of four-wave shearing interference to Figure 5 The interference image shown is processed to restore the Figure 7 The phase distribution is shown. Figure 6 and Figure 7 It can be seen that in this embodiment, the phase distribution obtained by sample restoration is very close to the theoretical phase distribution, which shows that the phase detection accuracy in this embodiment is very high, and further shows that the position and posture of each component in the wavefront detection system provided in this embodiment are accurate.

[0109] Figure 8 A schematic diagram of an interference image captured by an image sensor when no sample is added to the optical path of a wavefront detection system provided in an embodiment of the present application is shown. Fig. 9 Shown in Figure 8 Based on the embodiment, a schematic diagram of the interference image obtained by the image sensor after the sample is further added into the light path. Fig.10 Shows Fig. 9 Schematic diagram of the theoretical phase distribution of the sample in the embodiment.

[0110] Fig.11 Shown according to Fig. 9 The schematic diagram of the phase distribution obtained after the phase distribution of the sample is restored by the interference image shown in the embodiment.

[0111] See also Figures 8 to 11In one embodiment, the target light source emits a far-infrared laser with a central wavelength of 10.6 μm; the grating is a chessboard-shaped two-dimensional grating with a period of 72 μm; the front lens is a zinc selenide lens with a focal length of 25.4 mm in the far-infrared band, and the rear lens is a zinc selenide lens with a focal length of 50.8 mm in the far-infrared band; the grating is arranged before the front focal plane of the front lens in the far-infrared band, and the distance between the grating and the front focal plane of the front lens in the far-infrared band is 0.7 mm; the working band of the camera is 8 to 12 μm; the diameter of the light spot sensed by the camera is about 6 mm, and since the focal length of the front lens is half of the focal length of the rear lens, it is explained that the diameter of the light spot projected on the sample is about 3 mm; the sample is a zinc selenide lens with a focal length of 50.8 mm in the far-infrared band, combined with the diameter of the light spot on the sample of 3 mm, it can be determined that the actual numerical aperture of the sample is 0.03.

[0112] In this embodiment, after the optical path of the wavefront detection system is established, before the sample is added to the optical path, the image sensor of the camera will collect Figure 8 After the sample is added to the light path, the image sensor will capture the interference image. Fig. 9 The interference image is shown.

[0113] It should be noted that, in this embodiment, the focal length of the rear lens is twice that of the front lens, so the far-infrared laser adjusted by the 4f lens group can be expanded; the expansion can be reflected by reducing the spot density. Figure 4 and Figure 5 The spot density of the interference image shown, Figure 8 and Fig. 9 The interference pattern shown has a spot density reduced by nearly half.

[0114] In this embodiment, the processor uses the principle of four-wave shearing interference to Fig. 9 The interference image shown is processed to restore the Fig.11 The phase distribution is shown. Fig.10 and Fig.11 It can be seen that in this embodiment, the phase distribution obtained by sample restoration is relatively close to the theoretical phase distribution, which indicates that the phase detection accuracy in this embodiment is relatively high, and further indicates that the position and posture of each component in the wavefront detection system provided in this embodiment are accurate.

[0115] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the utility model disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the appended claims.

Claims

1. A wavefront detection system, characterized in that: The wavefront detection system is provided with a target light source, and the target light source is used to emit a target laser of a target wavelength band; along the propagation direction of the target laser, the wavefront detection system is also provided with a grating, a 4f lens group and a camera in sequence; The 4f lens group includes a front lens and a rear lens sequentially arranged along the propagation direction of the target laser; the rear focal plane of the front lens in the target band coincides with the front focal plane of the rear lens in the target band; The image sensor of the camera is used to sense the target laser, and the image sensor is arranged at the rear focal plane of the rear lens under the target wavelength band; The grating is arranged in front of the front focal plane of the front lens in the target band; and is used to arrange the sample to be detected between the target light source and the grating.

2. The wavefront detection system according to claim 1, characterized in that: The target light source is used to emit a target laser in the far-infrared band; the rear focal plane of the front lens in the far-infrared band coincides with the front focal plane of the rear lens in the far-infrared band; the image sensor is used to sense a light beam in the far-infrared band; the image sensor is arranged at the rear focal plane of the rear lens in the far-infrared band; the grating is arranged in front of the front focal plane of the front lens in the far-infrared band; and the sample works in the far-infrared band.

3. The wavefront detection system according to claim 1, characterized in that: The target laser is at least perpendicular to the front lens and the rear lens, and the target laser passes through at least the center of the front lens and the center of the rear lens.

4. The wavefront detection system according to claim 1, characterized in that: The distance between the grating and the front focal plane of the front lens in the target band is positively correlated with the period of the grating and is negatively correlated with the numerical aperture of the sample.

5. The wavefront detection system according to claim 1, characterized in that: The period of the grating is 72 μm ± 3 μm; When the numerical aperture of the sample is 0.04, the distance between the grating and the front focal plane of the front lens in the target band is 0.4 mm to 0.8 mm; When the numerical aperture of the sample is 0.1, the distance between the grating and the front focal plane of the front lens in the target band is 0.3 mm to 0.45 mm; When the numerical aperture of the sample is 0.15, the distance between the grating and the front focal plane of the front lens in the target band is 0.15 mm to 0.25 mm.

6. The wavefront detection system according to claim 1, characterized in that: The period of the grating is 144 μm ± 3 μm; When the numerical aperture of the sample is 0.04, the distance between the grating and the front focal plane of the front lens in the target band is 0.3 mm to 1.8 mm; When the numerical aperture of the sample is 0.1, the distance between the grating and the front focal plane of the front lens in the target band is 0.2 mm to 0.75 mm; When the numerical aperture of the sample is 0.15, the distance between the grating and the front focal plane of the front lens in the target band is 0.2 mm to 0.45 mm.

7. The wavefront detection system according to claim 1, characterized in that: The period of the grating is 180 μm ± 3 μm; When the numerical aperture of the sample is 0.04, the distance between the grating and the front focal plane of the front lens in the target band is 0.2 mm to 2.3 mm; When the numerical aperture of the sample is 0.1, the distance between the grating and the front focal plane of the front lens in the target band is 0.2 mm to 0.9 mm; When the numerical aperture of the sample is 0.15, the distance between the grating and the front focal plane of the front lens in the target band is 0.5 mm to 0.6 mm.

8. The wavefront detection system according to claim 1, characterized in that: The value of f1 / f2 is positively correlated with the size of the sample; wherein f1 is the focal length of the front lens in the target band, and f2 is the focal length of the rear lens in the target band.

9. The wavefront detection system according to claim 1, characterized in that: The period of the grating is positively correlated with the value of f1 / f2, wherein f1 is the focal length of the front lens in the target band, and f2 is the focal length of the rear lens in the target band.

10. The wavefront detection system according to claim 1, characterized in that: The grating is a two-dimensional grating in the shape of a chessboard, and the phase difference provided by the alternating phases of each unit cell of the grating is π.

11. The wavefront detection system according to claim 1, characterized in that: The wavefront detection system is further provided with a reflector group for adjusting the propagation direction of the target laser between the target light source and the grating, and the reflector group includes at least one reflector.

12. A phase detection system, characterized in that: The phase detection system comprises: the wavefront detection system according to any one of claims 1 to 11; the sample disposed between the target light source and the grating, the target laser vertically incident on the sample and passing through the center of the sample; a processor; The processor is electrically connected to the camera, and is used to receive an interference image generated by the image sensor sensing the target laser, so as to detect the phase distribution of the sample according to the interference image.

Images