阅读说明：本技术 光学延迟结构 (Optical delay structure ) 是由 胡晗 齐静波 于 2021-04-07 设计创作，主要内容包括：本申请公开了一种光学延迟结构,该光学延迟结构包括：转盘,所述转盘沿所述转盘的中心轴线旋转；光学部件,位于所述转盘的下表面,与所述转盘相连,所述光学部件呈环形；反射镜,位于所述光学部件的下方,所述反射镜的反射面与从所述光学部件射出的光线垂直；其中,所述光学部件的厚度随所述转盘的圆周方向进行变化,入射光线从所述转盘的上表面射向所述转盘,经过所述光学部件后从所述光学部件的出射面射向所述反射镜,同一入射位置的所述入射光线的光程随着所述光学部件厚度的变化而变化。通过采用沿圆周薄厚变化的光学部件,使转盘的旋转即可实现所需的延迟,进而实现超短光脉冲对待测脉冲波形的扫描和探测。(The application discloses optical delay structure, this optical delay structure includes: a turntable that rotates along a central axis of the turntable; the optical component is positioned on the lower surface of the turntable and connected with the turntable, and the optical component is annular; a reflector positioned below the optical component, a reflection surface of the reflector being perpendicular to the light emitted from the optical component; the thickness of the optical component changes along with the circumferential direction of the turntable, incident light rays are emitted to the turntable from the upper surface of the turntable and emitted to the reflector from the emergent surface of the optical component after passing through the optical component, and the optical path of the incident light rays at the same incident position changes along with the change of the thickness of the optical component. The optical component which changes along the thickness of the circumference is adopted, so that the rotation of the turntable can realize the required delay, and further, the scanning and the detection of the ultrashort optical pulse to the pulse waveform to be detected are realized.)

1. An optical delay structure, comprising:

a turntable that rotates along a central axis of the turntable;

the optical component is positioned on the lower surface of the turntable and connected with the turntable, and the optical component is annular;

a reflector positioned below the optical component, a reflection surface of the reflector being perpendicular to the light emitted from the optical component;

the thickness of the optical component changes along with the circumferential direction of the turntable, incident light rays are emitted to the turntable from the upper surface of the turntable and emitted to the reflector from the emergent surface of the optical component after passing through the optical component, and the optical path of the incident light rays at the same incident position changes along with the change of the thickness of the optical component.

2. An optical delay structure as recited in claim 1, wherein the rotating disk and the optical component are both made of a uniform transparent medium, and the refractive indices of the rotating disk and the optical component are the same or different.

3. An optical delay structure as recited in claim 1, wherein the exit surfaces of the incident light rays passing through the optical components of different thicknesses are parallel to each other.

4. An optical delay structure as recited in claim 1, wherein the optical member has a longitudinal cross-section of at least one of a trapezoid, a triangle, and a quadrilateral.

5. The optical delay structure of claim 1 wherein the mirror is one of inverted cone or flat.

6. The optical delay structure of claim 1 wherein the optical component comprises a plurality of optical submodules, the plurality of optical submodules providing a periodic variation in the thickness of the optical component in the circumferential direction.

7. An optical delay structure as claimed in claim 6, wherein the optical component comprises a plurality of submodules, the cross-sectional thickness of each submodule increasing in a clockwise direction, such that the thickness of the optical component comprises a plurality of identical periodic variations of the increasing in a circumferential direction.

8. An optical delay structure as recited in claim 6, wherein the thickness of the optical component varies cyclically over at least 2 cycles during one revolution of the turntable.

9. An optical delay structure as claimed in claim 1, wherein the turntable is coupled to a motor to rotate the turntable at a constant speed, and the center of gravity of the optical element is located on the axis of the turntable to reduce the moment of inertia during rotation.

Technical Field

The invention relates to the technical field of optics, in particular to an optical delay structure.

Background

At present, in the field of optical detection, optical delay lines have wide application fields, such as terahertz time-domain spectroscopy, ultrafast time resolution spectroscopy, optical coherence tomography, optical pump detection, and the like.

In a terahertz time-domain spectroscopy system and an electro-optical sampling system, a variable optical delay means is required to change the relative delay between two paths of light, so that the scanning and detection of the pulse waveform to be detected by the ultrashort light pulse are realized. The optical delay means commonly used at present mainly include a linear electric displacement table, a circular involute, an optical fiber expansion device, asynchronous optical sampling and the like, wherein the linear electric displacement table is the most commonly used method at present due to simplicity and easiness in use, unlimited scanning length and relatively low cost. In the method, two right-angle reflecting mirrors are usually fixed on a displacement table, and light beams are reflected twice to reciprocate once, so that the optical path is changed along with the movement of the displacement table, and the change of relative time delay is realized. In order to ensure higher displacement precision and stability, the speed of the displacement table is often lower, so that the single scanning time is longer, and usually reaches more than several minutes. Particularly, when large-scale scanning is required, the size of the required displacement table is very large, the scanning time is as long as several hours, the measuring efficiency is very low, the size of the whole system is very large, a large amount of space is occupied, the assembly, disassembly and debugging are also abnormal, complex and time-consuming, and the current requirements cannot be met gradually.

Disclosure of Invention

In view of the above problems, an object of the present invention is to provide an optical delay structure, which employs an optical component with thickness varying along the circumference, can implement the required delay through the rotation of a turntable, and implement the scanning and detection of the pulse waveform to be detected by the ultrashort optical pulse, and has the advantages of small volume, small occupied space, high speed sampling, short time consumption for single scanning, high efficiency, and strong practicability.

The present invention provides an optical delay structure, comprising:

a turntable that rotates along a central axis of the turntable;

the optical component is positioned on the lower surface of the turntable and connected with the turntable, and the optical component is annular;

a reflector positioned below the optical component, a reflection surface of the reflector being perpendicular to the light emitted from the optical component;

the thickness of the optical component changes along with the circumferential direction of the turntable, incident light rays are emitted to the turntable from the upper surface of the turntable and emitted to the reflector from the emergent surface of the optical component after passing through the optical component, and the optical path of the incident light rays at the same incident position changes along with the change of the thickness of the optical component.

Preferably, the turntable and the optical component are both made of a uniform transparent medium, and the refractive indices of the turntable and the optical component are the same or different.

Preferably, the exit surfaces of the incident light after passing through the optical components with different thicknesses are parallel to each other.

Preferably, the longitudinal section of the optical member is at least one of a trapezoid, a triangle, and a quadrangle.

Preferably, the mirror is one of inverted cone or flat.

Preferably, the optical component includes a plurality of optical submodules, and the plurality of optical submodules cause the thickness of the optical component to vary periodically in the circumferential direction.

Preferably, the optical component comprises a plurality of submodules, the cross-sectional thickness of each submodule increases gradually along the clockwise direction, and the thickness of the optical component comprises a plurality of same periodic changes of increasing gradually along the circumferential direction.

Preferably, the thickness of the optical member varies cyclically over at least 2 cycles during one revolution of the turntable.

Preferably, the turntable is connected with a motor to enable the turntable to rotate at a constant speed, and the center of gravity of the optical component is located on the axis of the turntable to reduce the rotational inertia during rotation.

The embodiment of the invention has the following advantages or beneficial effects: the optical delay structure provided by the invention adopts the optical component with thickness change along the circumference, the required delay can be realized through the rotation of the turntable, and the scanning and the detection of ultrashort optical pulses to the pulse waveform to be detected are realized. The optical delay structure provided by the invention has the advantages of high precision, small volume, small occupied space, capability of realizing high-speed sampling, short time consumption of single scanning and high efficiency, and further, compared with a linear displacement platform, the optical delay structure is simpler and easier to use, can be laid and debugged conveniently, and has strong practicability.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

FIG. 1 shows a schematic diagram of an optical delay structure of an embodiment of the present invention;

FIG. 2 shows a schematic cross-sectional view of an optical delay structure of an embodiment of the present invention;

FIG. 3 shows a schematic view of a turret and optical components of an optical delay structure of an embodiment of the invention;

fig. 4 shows a schematic diagram of signal delay of an embodiment of the present invention.

Detailed Description

Various embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Like elements in the various figures are denoted by the same or similar reference numerals. For purposes of clarity, the various features in the drawings are not necessarily drawn to scale.

The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples.

FIG. 1 shows a schematic diagram of an optical delay structure of an embodiment of the present invention; as shown in fig. 1, the optical retardation structure includes: a turntable 110, an optical component 120, and a reflector 130, wherein the turntable 110 is, for example, a uniform transparent medium disk with a refractive index n, the turntable 110 can rotate along an axis O, the incident point position of the incident light is unchanged, the optical component 120 is disposed on the lower surface of the turntable 110, and in order to explain the principle of the optical retardation structure, a solid line is used in fig. 1 to depict a first cross section 121 corresponding to the incident light of the optical component 120 at a first moment, a broken line is used in fig. 1 to depict a second cross section 122 corresponding to the incident light at a second moment after the turntable 110 rotates by a certain angle, accordingly, a light path corresponding to the first cross section 121 is depicted as a solid line, and a light path corresponding to the second cross section 122 is depicted as a broken line; for the convenience of calculation and explanation, dotted lines are shown as auxiliary lines in the figure.

As can be seen from fig. 1, after the turntable 110 rotates a certain angle, the thickness of the optical component 120 increases by Δ X, the optical path of the light in the optical component 120 changes, and the light travels a distance Δ X more in the optical component 120, but travels a distance Δ X' less after exiting from the optical component 120. The second emitting surface 1221 of the second cross section 122 of the optical component 120 is parallel to the first emitting surface 1211 of the first cross section 121, so that the emitting angle θ 2 of the light passing through the optical component 120 is not changed, and the light can still vertically emit to the reflector 130 and then be emitted from the reflector 130 according to the original light path.

From the sign of the auxiliary line, the incident angle between the incident light and the first emission surface 1211 is θ 1, and similarly, the incident angle between the incident light and the second emission surface 1221 is also θ 1, the triangle of the second cross section 122 and the triangle of the first cross section 121 are similar triangles, the angle between the second emission surface 1221 and the lower surface of the turntable 110 is θ 1, and the length difference between the triangle of the second cross section 122 and the base of the triangle of the first cross section 121 is Δ L, which is known from the relationship:

ΔX＝ΔL·tanθ1，n·sinθ1＝1·sinθ2，ΔX'＝ΔX·cos(θ2-θ1)

when the speed of light is c, the time t1 taken for the incident light to pass through the optical path Δ X 'is Δ X'/c

The time t2 for the incident ray to traverse the optical path Δ X is Δ X/(c/n)

The second time is compared with the first time, the incident light beam passes through the turntable 110, passes through the optical component 120 and irradiates the reflector 130 with a time delay Δ t of t2-t1

Given the partial parameters in the following example, if Δ L ≈ 1mm, θ 1 ≈ 10 °, and n ≈ 1.5, θ 2 ≈ 15 °, Δ X ≈ 0.176mm, Δ X' ≈ 0.175mm can be calculated

t1＝ΔX'/c＝0.58ps，t2＝ΔX/(c/n)＝0.88ps，Δt＝t2-t1＝0.3ps。

Since the mirror 130 can return the light along the original path (the rotation speed of the turntable is much less than the speed of light, so the light reflected by the mirror 130 is considered to still return along the original path), the delay Δ T of the time consumed by the light from the incident to the return at the second time is 2 Δ T compared to the first time.

With the turntable 110 rotating at a high speed, two light pulses are perpendicularly incident on the incident point of the turntable 110 at a first time and a second time, and the optical component 120 at the second time is increased by Δ X in thickness from the optical component 120 at the first time, so that a time delay is generated between the light pulse at the first time and the light pulse at the second time, and the delay can be continuously and repeatedly generated by the optical component 120 having undulations (continuously changing thickness) arranged along the circumference, and further, a function of high-speed optical modulation can be realized by using the time delay.

FIGS. 2 and 3 show a cross-sectional view and a perspective view, respectively, of an optical delay structure of an embodiment of the present invention; as can be seen from the figure, the optical member 120 is connected to the lower surface of the turntable 110, the optical member 120 is ring-shaped, and the thickness of the optical member 120 varies periodically in the circumferential direction, including a plurality of identical stepwise increasing cycles, for example, having a trapezoidal cross section. The reflector 130 is a sheet and is in an inverted cone shape, the upper surface of the reflector 130 has a reflective surface capable of reflecting light, an included angle between the reflective surface and the vertical direction is α, the included angle α enables the light to be incident into the turntable 110 and to be emitted through the optical component 120, the light is perpendicular to the reflective surface of the reflector 130, and the reflector 130 can reflect the light back along the original path. Further, referring to fig. 3, the optical component 120 is composed of a plurality of sub-modules 1201, wherein the sub-modules 1201 gradually increase in cross-sectional thickness in a clockwise direction, and further, adjacent sub-modules 1201 are connected end to form the optical component 120 in a ring shape along the entire circumference. Of course, the above is only an example, the circumference may be divided into more sector areas to set corresponding sub-modules, so that the rotating disc 110 rotates a circle with more variation cycles, thereby improving the precision, and further, a counterweight may be further disposed on the rotating disc 110, so that the weight distribution of the combination of the rotating disc 110 and the optical component 120 on the circumference is balanced, and the rotating stability is ensured when the rotating disc 110 rotates at a high speed.

Fig. 4 shows a schematic diagram of signal delay according to an embodiment of the present invention, when consecutive laser pulses are incident as incident light, the turntable 110 rotates, the thickness of the optical component 120 continuously changes, if a trigger signal with a fixed time delay is given, the thickness of the optical component 120 through which two adjacent laser pulses pass is different, the laser pulses may be from thin to thick, a set of data is measured, when the laser pulses rotate to the thickest place, next cycle is followed, a plurality of sampling points (as shown in the figure, 5 sampling points are used) are taken in each cycle, and different points of a sampling waveform can be obtained by the trigger signal with the fixed delay, and finally the whole waveform is obtained.

Compared with the existing linear displacement platform, the optical delay structure of the embodiment of the invention not only occupies less space and has smaller volume, but also can realize high-speed sampling, has short single scanning time and higher efficiency, and obviously improves the portability and the usability.

The embodiment of the invention has the following advantages or beneficial effects: the optical delay structure provided by the invention adopts the optical component with thickness change along the circumference, the required delay can be realized through the rotation of the turntable, and the scanning and the detection of ultrashort optical pulses to the pulse waveform to be detected are realized. The optical delay structure provided by the invention has the advantages of high precision, small volume, small occupied space, capability of realizing high-speed sampling, short time consumption of single scanning and high efficiency, and further, compared with a linear displacement platform, the optical delay structure is simpler and easier to use, can be laid and debugged conveniently, and has strong practicability.

While embodiments in accordance with the present invention have been illustrated and described above with particularity, the drawings are not necessarily to scale, the proportions and dimensions shown therein are not intended to limit the spirit and scope of the invention, and the embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. The invention is limited only by the claims and their full scope and equivalents.