Optical field space alignment detection and correction system and method based on optical interferometer

Abstract

The invention discloses a light field space alignment detection and correction system and method based on an optical interferometer, the inclination angles of a second beam splitter, a third beam splitter, a first plane mirror and a second plane mirror are the same, two light beams to be aligned and detected are emitted to the second beam splitter and are equally divided into two identical light beams by the second beam splitter, and the two identical light beams are emitted to the first plane mirror. One beam is reflected by the first plane mirror and then enters a third beam splitter, the other beam passes through the second plane mirror and a Dove prism which is horizontally arranged and then enters the third beam splitter, the two beams of light entering the third beam splitter are combined to obtain two different beams of light, one beam is in a symmetrical mode, and the intensity of the beam is detected through a photoelectric detector; the other beam is in an antisymmetric mode, and the intensity of the other beam is detected through a photoelectric detector. The device is simple in structure, the detection and correction process is greatly simplified, and targeted correction can be carried out according to the detection result.

Description

Technical Field

[0001] The invention relates to a light field space alignment detection and correction system and method based on an optical interferometer. Background Art

[0002] The problem of two-beam alignment has wide applications in many optical fields: for two coherent beams, this problem helps to improve the efficiency of interferometry such as heterodyne detection, homodyne detection and HOM interferometry. For two incoherent beams, this problem helps to improve the light source resolution and achieve super-resolution passive imaging, which is of great value for scenes such as fluorescence microscopy and astronomical observation. Therefore, the detection and correction of two-beam alignment is an important topic in the field of information optics.

[0003] There are two main types of traditional two-beam alignment detection methods: the first type is to observe the interference fringes formed by the two beams after passing through the beam splitter. This method is only applicable to coherent light, and lacks effective information about the spatial position of the misaligned beam, which makes correction difficult; the second method is to use a detector to detect the intensity of the two beams after passing through the beam splitter. This method needs to consider the phase difference between the two beams and the optical loss of the beam splitter, which brings certain difficulties to the alignment detection of unknown beams. Summary of the invention

[0004] The present invention provides a light field spatial alignment detection and correction system and method based on an optical interferometer in order to solve the problems existing in the above-mentioned prior art.

[0005] The technical solutions adopted in the present invention are:

[0006] An optical interferometer-based light field spatial alignment detection and correction system comprises a second beam splitter, a third beam splitter, a first plane reflector, a second plane reflector, a Dove prism, a first photodetector and a second photodetector, wherein the second beam splitter, the third beam splitter, the first plane reflector and the second plane reflector have the same inclination angle, two light beams to be aligned and detected are directed to the second beam splitter and are equally divided by the second beam splitter into two identical light beams, one of which is reflected by the first plane reflector and then directed into the third beam splitter, and the other is directed into the third beam splitter after passing through the second plane reflector and a horizontally placed Dove prism, and the two light beams directed into the third beam splitter are combined to obtain two different light beams, one of which is in a symmetrical mode and its intensity is detected by a photodetector; and the other is in an antisymmetric mode and its intensity is detected by a photodetector.

[0007] Furthermore, the ratio of light transmission to light reflection of the second beam splitter and the third beam splitter is 50:50.

[0008] Furthermore, the two light beams to be aligned and detected are emitted toward the second beam splitter in the same direction.

[0009] Furthermore, a first beam splitter is arranged on one side of the second beam splitter, and two beams to be aligned and detected are incident on the first beam splitter at 90 degrees to each other. After being equally split by the first beam splitter, the beam incident on the second beam splitter in the same direction is taken for detection and correction.

[0010] The present invention also discloses a correction method.

[0011] 1) Two beams of light with arbitrary intensity ratio and coherence to be detected, with amplitudes E1(x,y) and E2(x+Δx,y+Δy), where Δx and Δy represent the horizontal and vertical offsets of the two beams, respectively;

[0012] 2) The two light beams to be detected at the incident end become two identical light beams after passing through the second beam splitter, and the amplitudes are expressed as:

[0013] M(x,y)=E1(x,y)+E2(x+Δx,y+Δy);

[0014] One of the beams passes through the first plane reflector (4-1), causing its direction to change, and the amplitude remains M(x, y); the other beam passes through the second plane reflector and the horizontally placed Dove prism, causing its direction to change and produce a horizontal mirror flip, and the amplitude becomes M(-x, y);

[0015] 3) After the two beams of light pass through the first plane reflector and the Dove prism, they pass through the third beam splitter to obtain two different beams of light, where:

[0016] One beam is a symmetric mode, its amplitude is M(x,y)+M(-x,y), and its intensity can be calculated by the following formula:

[0017]

[0018] The other beam is an antisymmetric mode with an amplitude of M(x,y)-M(-x,y). Its intensity can be calculated by the following formula:

[0019]

[0020] If the two beams are not aligned in the horizontal direction, that is, Δx≠0, the asymmetric mode can detect the signal, that is,

[0021]

[0022] At this time, you only need to adjust the horizontal position of one of the beams of light at the incident end to gradually weaken the detection signal. When the corresponding photodetector no longer detects the signal, the two beams of light are aligned in the horizontal direction.

[0023] After completing the horizontal correction, rotate the Dove prism 90 degrees clockwise and repeat the above steps. If the two light beams are not aligned in the vertical direction, the asymmetric mode can detect the signal. At this time, you only need to adjust the vertical position of one of the light beams at the incident end to gradually weaken the detection signal. When the corresponding photodetector no longer detects the signal, the two light beams are aligned in the vertical direction.

[0024] The present invention has the following beneficial effects:

[0025] The present invention has a simple structure, greatly simplifies the detection and correction process, and can perform targeted correction according to the detection results. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of two light beams to be aligned and detected being emitted in the same direction.

[0027] Figure 2 Schematic diagram of the light beam to be aligned and detected being emitted in different directions.

[0028] Figure 3 Schematic diagram of the spatial intensity distribution of the light field at different stages, where (a) is the light field to be detected; (b) is the horizontally symmetric mode; and (c) is the horizontally antisymmetric mode. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with the accompanying drawings.

[0030] like Figure 1 The present invention provides a light field spatial alignment detection and correction system based on an optical interferometer, comprising a second beam splitter 3-2, a third beam splitter 3-3, a first plane reflector 4-1, a second plane reflector 4-2, a Dove prism 5, a first photodetector 6-1 and a second photodetector 6-2. The second beam splitter 3-2, the third beam splitter 3-3, the first plane reflector 4-1 and the second plane reflector 4-2 have the same inclination angle. Two beams to be aligned and detected are emitted to the second beam splitter 3-2 and are reflected by the first and second beam splitters 3-3 and 3-4. The second beam splitter 3-2 is divided into two identical beams, one beam is reflected by the first plane reflector 4-1 and then enters the third beam splitter 3-3, and the other beam is passed through the second plane reflector 4-2 and the horizontally placed Dove prism 5 and then enters the third beam splitter 3-3. The two beams of light entering the third beam splitter 3-3 are combined to obtain two different beams of light, one of which is in a symmetrical mode, and its intensity is detected by the photodetector 6-1; the other beam is in an antisymmetric mode, and its intensity is detected by the photodetector 6-2.

[0031] The present invention can direct the two beams to be aligned and detected toward the second beam splitter 3-2 in the same direction. Figure 2, which are all incident on the second beam splitter 3-2 in the horizontal direction.

[0032] The present invention can also inject two beams of light to be aligned and detected from different directions, such as Figure 1 , which is to set the first beam splitter 3-1 on the side of the second beam splitter 3-2, and the first beam splitter 3-1 and the second beam splitter 3-2 are arranged symmetrically. The two beams to be aligned and detected are incident on the first beam splitter 3-1 at 90 degrees to each other, and after being equally split by the first beam splitter 3-1, the beam incident on the second beam splitter 3-2 in the same direction is taken for detection and correction, such as Figure 1 .

[0033] by Figure 2 As an example, the detection and correction method of the present invention is further described.

[0034] Two light beams with arbitrary intensity ratio and arbitrary coherence have amplitudes E1(x,y) and E2(x+Δx,y+Δy), where Δx and Δy represent the horizontal and vertical offsets of the two light beams, respectively.

[0035] The first light beam 1 and the second light beam 2 placed at the incident end are both obtained as two beams to be detected after passing through the first beam splitter 3-1. The two beams in the horizontal direction are taken as the beams to be detected. The beams to be detected become two identical beams after passing through the second beam splitter 3-2. The amplitudes can be expressed as

[0036] M(x,y)=E1(x,y)+E2(x+Δx,y+Δy)

[0037] One of the beams passes only through the first plane reflector 4-1, causing its direction to change, but the amplitude remains M(x, y);

[0038] The other beam passes through the second plane reflector and the horizontally placed Dove prism, causing its direction to change and produce a horizontal mirror flip, and the amplitude becomes M(-x, y).

[0039] The two beams of light after passing through the first plane reflector and the Dove prism are passed through the third beam splitter to obtain two different beams of light, where:

[0040] One beam is a symmetric mode, its amplitude is M(x,y)+M(-x,y), and its intensity can be calculated by the following formula:

[0041]

[0042] The other beam is an antisymmetric mode with an amplitude of M(x,y)-M(-x,y). Its intensity can be calculated by the following formula:

[0043]

[0044] If the two beams are not aligned in the horizontal direction, that is, Δx≠0, the asymmetric mode can detect the signal, that is,

[0045]

[0046] At this time, you only need to adjust the horizontal position of one of the beams of light at the incident end to gradually weaken the detection signal. When the corresponding photodetector no longer detects the signal, the two beams of light are aligned in the horizontal direction.

[0047] After completing the horizontal correction, rotate the Dove prism 90 degrees clockwise and repeat the above steps. If the two light beams are not aligned in the vertical direction, the asymmetric mode can detect the signal. At this time, you only need to adjust the vertical position of one of the light beams at the incident end to gradually weaken the detection signal. When the corresponding photodetector no longer detects the signal, the two light beams are aligned in the vertical direction.

[0048] Figure 3 Schematic diagram of the spatial intensity distribution of the light field at different stages, where (a) is the light field to be detected; (b) is the horizontally symmetric mode; and (c) is the horizontally antisymmetric mode.

[0049] All beam splitters involved in this application are non-polarization beam splitters suitable for the wavelength to be detected, and the ratio of transmittance to reflection is 50:50.

[0050] The above description is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements without departing from the principle of the present invention, and these improvements should also be regarded as within the protection scope of the present invention.

Claims

1. A light field spatial alignment detection and correction system based on optical interferometer, characterized in that: The invention comprises a second beam splitter (3-2), a third beam splitter (3-3), a first plane reflector (4-1), a second plane reflector (4-2), a Dove prism (5), a first photodetector (6-1) and a second photodetector (6-2); the second beam splitter (3-2), the third beam splitter (3-3), the first plane reflector (4-1) and the second plane reflector (4-2) have the same inclination angle; two beams to be aligned and detected are emitted to the second beam splitter (3-2) and are evenly aligned by the second beam splitter (3-2). The light beams are divided into two identical beams, one of which is reflected by a first plane reflector (4-1) and then incident on a third beam splitter (3-3), and the other is incident on a third beam splitter (3-3) after passing through a second plane reflector (4-2) and a horizontally placed Dove prism (5). The two beams of light incident on the third beam splitter (3-3) are combined to obtain two different beams of light, one of which is in a symmetrical mode, and its intensity is detected by a photodetector (6-1); and the other is in an anti-symmetrical mode, and its intensity is detected by a photodetector (6-2).

2. The optical interferometer-based light field spatial alignment detection and correction system as claimed in claim 1, characterized in that: The ratio of light transmission to light reflection of the second beam splitter (3-2) and the third beam splitter (3-3) is 50:

50.

3. The optical interferometer-based light field spatial alignment detection and correction system as claimed in claim 1, characterized in that: The two light beams to be aligned and detected are directed toward the second beam splitter (3-2) in the same direction.

4. The optical interferometer-based light field spatial alignment detection and correction system as claimed in claim 1, characterized in that: A first beam splitter (3-1) is arranged on one side of the second beam splitter (3-2), and two light beams to be aligned and detected are incident on the first beam splitter (3-1) at 90 degrees to each other. After being equally split by the first beam splitter (3-1), the light beam incident on the second beam splitter (3-2) in the same direction is taken for detection and correction.

5. A method for calibrating a system as claimed in any one of claims 1 to 2, characterized in that: 1) Two beams of light with arbitrary intensity ratio and coherence to be detected, with amplitudes E1(x,y) and E2(x+Δx,y+Δy), where Δx and Δy represent the horizontal and vertical offsets of the two beams, respectively; 2) The two light beams to be detected placed at the incident end become two identical light beams after passing through the second beam splitter (3-2), and the amplitudes are expressed as: M(x,y)=E1(x,y)+E2(x+Δx,y+Δy); One of the beams passes through the first plane reflector (4-1), causing its direction to change, and the amplitude remains M(x, y); the other beam passes through the second plane reflector (4-2) and the horizontally placed Dove prism (5), causing its direction to change and produce a horizontal mirror flip, and the amplitude becomes M(-x, y); 3) After the two beams of light pass through the first plane reflector (4-1) and the Dove prism (5), they pass through the third beam splitter (3-3) to obtain two different beams of light, wherein: One beam is a symmetric mode, its amplitude is M(x,y)+M(-x,y), and its intensity can be calculated by the following formula: The other beam is an antisymmetric mode with an amplitude of M(x,y)-M(-x,y). Its intensity can be calculated by the following formula: If the two beams are not aligned in the horizontal direction, that is, Δx≠0, the asymmetric mode can detect the signal, that is, At this time, you only need to adjust the horizontal position of one of the beams of light at the incident end to gradually weaken the detection signal. When the corresponding photodetector no longer detects the signal, the two beams of light are aligned in the horizontal direction. After completing the horizontal calibration, rotate the Dove prism (5) 90 degrees clockwise and repeat the above steps. If the two light beams are not aligned in the vertical direction, the asymmetric mode can detect the signal. At this time, it is only necessary to adjust the vertical position of one of the light beams at the incident end to gradually weaken the detection signal. When the corresponding photodetector no longer detects the signal, the two light beams are aligned in the vertical direction.

Images