CN107102436B - A Waveplate Design Method for Compensating Arbitrary Optical Phase Delay - Google Patents

Abstract

The invention discloses a wave plate group design method for compensating any optical phase delay, which comprises the following steps: 1) the wave plate set is arranged at the front end or the rear end of an optical path of the optical system with the optical phase delay to be compensated; 2) establishing a Cartesian coordinate system by taking an optical system to be compensated for optical phase delay as a reference and taking the fast axis direction of the optical system as an abscissa; 3) sequentially left-multiplying the corresponding Jones matrix to obtain the Jones matrix of the optical system modulated by the wave plate set; 4) sequentially left-multiplying the corresponding Jones vectors to obtain the Jones vectors of the emergent light waves; 5) comparing the modulated Jones vector of the emergent light wave with the Jones vector corresponding to the polarization state of the emergent light wave, and calculating the included angle between each wave plate in the wave plate group to be adjusted and the abscissa of the reference coordinate system; 6) and rotating each wave plate in the wave plate group according to the calculated included angle between each wave plate in the wave plate group and the abscissa of the reference coordinate system to complete the compensation of the optical phase delay generated by the optical phase delay optical system to be compensated.

Description

A Waveplate Design Method for Compensating Arbitrary Optical Phase Delay

technical field

The invention relates to the technical field of crystal wavefront phase compensation and polarization modulation technology, in particular to a wave plate group design method for compensating any optical phase delay.

Background technique

With the development of optical fiber communication technology, super-resolution microscopy technology, optical fiber sensing technology and other technologies, the precise control of optical phase has brought higher requirements. Due to the existence of various polarization devices in the optical system, the optical phase retardation will be induced, which will then change the polarization state of the light, which ultimately directly affects the energy utilization rate or imaging effect of the optical system. Therefore, the optical phase delay caused by non-design factors in the optical system must be compensated to eliminate or reduce the influence of the optical phase delay caused by the non-design factors in the system, thereby improving the work efficiency and work quality of the optical system.

In the patent document "Dual-wavelength Optical Phase Retardator" by Wu Wendi et al., the publication number is CN105700059A, a wave plate combination for optical phase retardation compensation is provided. The patent document adopts a monolithic birefringent crystal plate combination. Calculate the thickness of the birefringent crystal plate to be compensated for the optical phase, and change the thickness of the birefringent crystal plate to obtain the required optical phase difference. However, the present invention has limitations, and can only compensate for a fixed optical phase delay. The optical phase retardation compensation has great limitations, and the patented technology needs to adjust the thickness of the birefringent crystal plate to change the optical phase difference, which is complicated to operate and difficult to implement. In the patent document "Optical Phase Retarder" by Zhao Shuqing et al., the publication number is CN1387071A, a birefringent crystal is used to split the beam, one beam is ordinary light, the other beam is extraordinary light, and then parallel beam splitting is used. The required optical phase retardation can be obtained by controlling the angle of the optical axes of the two beam splitters, but there are still some defects: First, the use of birefringent crystal beam splitting method will lead to optical The precision of the phase retardation is not high; secondly, when the required optical phase retardation is generated, it must be realized by changing the thickness of the parallel beam splitter, which is complicated in operation, high in cost and poor in universality.

SUMMARY OF THE INVENTION

Aiming at the poor universality, versatility and flexibility of the existing optical phase delay compensator, the optical phase delay compensation in the optical system is too complicated, and the compensation accuracy is not high, and the invention proposes a compensation for any optical phase delay. wave plate set design method. The optical phase retardation caused by non-design factors in the optical system to be compensated for optical phase retardation is compensated by using the optical phase difference generated by the wave plate group consisting of half-wave plate and quarter-wave plate. The angle between the wave plate and the quarter wave plate and the abscissa of the reference coordinate system can realize the compensation of any optical phase delay generated in the optical system.

A method for designing a wave plate group for compensating any optical phase delay, characterized in that it comprises the following steps:

1) The wave plate group is placed at the front or rear end of the optical path of the optical system to be compensated for the optical phase delay, and the wave plate group is placed perpendicular to the light wave propagation direction in the optical path to compensate for the optical phase generated by the optical system to be compensated for the optical phase delay. Delay;

2) Taking the optical system to be compensated for the optical phase delay as a reference, the direction of the fast axis of the optical system is the abscissa, and the direction of the slow axis of the optical system is the ordinate, and a Cartesian coordinate system is established;

3) the Jones matrix of the optical system to be compensated for optical phase delay and the Jones matrix of the wave plate group in step 1) are left-multiplied successively according to the light wave incident order in the optical path, to obtain the Jones matrix of the optical system modulated by the wave plate group;

4) Multiply the Jones matrix of the optical system to be compensated for the optical phase delay modulated by the wave plate group in step 3) and the Jones vector of the incident light wave to the left in turn to obtain the optical system to be compensated for the optical phase delay, after the wave plate group modulation The Jones vector of the outgoing light wave;

5) Compare the Jones vector of the outgoing light wave modulated by the optical system to be compensated for the optical phase delay and the wave plate group in step 4) with the Jones vector corresponding to the polarization state of the required outgoing light wave, and calculate the wave plate group that needs to be adjusted. The angle between each wave plate and the abscissa of the reference coordinate system;

6) According to the angle between each wave plate in the wave plate group and the abscissa of the reference coordinate system calculated in step 5), rotate each wave plate in the wave plate group to complete the compensation of the optical phase delay generated by the optical system to be compensated for the optical phase delay. .

In step 1), preferably, the wave plate group is a combination of a linear polarizer, a half-wave plate and a quarter-wave plate;

The linear polarizer is used to control the incident light wave to be linearly polarized light;

The optical phase delay is the phase difference between the vertical component and the parallel component of the light wave after passing through the optical system to be compensated for the optical phase delay.

In step 2), the fast axis of the optical system to be compensated for the optical phase delay is the polarization direction of the fast-propagating light wave component, and the vertical direction thereof is the slow axis direction.

In step 3), the angle between the fast axis of the quarter-wave plate and the abscissa of the reference coordinate system in the wave plate group is θ, and the angle between the fast axis of the half-wave plate and the abscissa of the reference coordinate system is α. The optical phase retardation generated by the optical system for compensating the optical phase retardation is η;

The fast axes of the half-wave plate and the quarter-wave plate in the wave plate group correspond to the polarization directions of the fast-propagating light wave components in the half-wave plate and the quarter-wave plate, respectively, and the vertical directions thereof correspond to the half-wave plate and the four-wave plate respectively. The direction of one-half of the slow axis;

The Jones matrix is a two-dimensional square matrix representing the linear transformation effect of the polarizing device;

The Jones matrix in the wave plate group includes a Jones matrix of a half-wave plate and a Jones matrix of a quarter-wave plate;

The Jones matrix of the half-wave plate is:

The Jones matrix of the quarter-wave plate is:

The Jones matrix of the optical system to be compensated for the optical phase delay is:

The Jones matrix of the optical system modulated by the wave plate group is:

In step 4), after the incident light wave passes through the linear polarizer, it is modulated into linearly polarized light;

The Jones vector of the modulated outgoing light wave is:

Among them, A, B, C, D, K are:

In step 5), the polarization state of the required outgoing light wave is the polarization state of the light wave that wishes to enter the focal plane of the optical system to be compensated for the phase, which can be any polarization state polarization such as linearly polarized light, circularly polarized light or elliptically polarized light. light, its Jones vector is expressed as:

Among them, a, b, c, d take appropriate values to represent the polarized light of any corresponding polarization state, and the Jones vector E ₁ of the outgoing light wave modulated by the optical system to be compensated for the optical phase delay and the wave plate group is equal to the required outgoing light. Compare the Jones vector E _out corresponding to the polarization state of the light wave, and calculate the angle θ ₀ between the fast axis of the quarter-wave plate and the abscissa of the reference coordinate system and the angle α between the fast axis of the half-wave plate and the abscissa of the reference coordinate system ₀ .

The angle between the wave plate and the abscissa of the reference coordinate system in the wave plate group to be adjusted includes: the angle θ between the fast axis of the quarter-wave plate and the abscissa of the reference coordinate system and the fast axis of the half-wave plate and the reference coordinate system The angle α of the abscissa.

In step 6), the modulation method of each wave plate in the rotating wave plate group is as follows: the angle between the fast axis of the quarter wave plate and the abscissa of the reference coordinate system is θ ₀ , the fast axis of the half wave plate is The angle between the abscissas of the reference coordinate system is α ₀ .

Compared with the prior art, the present invention has the following beneficial technical effects:

In the present invention, the wave plate group composed of the introduced linear polarizer, half-wave plate, quarter-wave plate and other wave plates is placed in an appropriate position in the optical system, and the non-design factors introduced by the optical elements in the optical system are generated. The optical phase retardation is measured, and after accurate calculation, the angle that needs to be adjusted for each wave plate in the wave plate group is obtained, and finally the wave plate composed of linear polarizer, half wave plate, quarter wave plate The group makes corresponding adjustments to realize the compensation of the optical phase delay caused by the non-design factors introduced by the optical elements in the optical system. The present invention can relatively simply adjust the wave plate group composed of the linear polarizer, half-wave plate, quarter-wave plate and other wave plates after a series of relatively easy-to-implement measurements and calculations, and does not introduce additional On the premise of phase difference, any optical phase delay caused by non-design factors introduced by optical elements in the optical system is compensated. The method for compensating any optical phase delay of the invention is flexible, simple and easy to operate, and the implementation method is low in price and wide in application range.

Description of drawings

Figure 1 is a schematic structural diagram of a wave plate group design method for compensating any optical phase delay applied to a laser scanning confocal microscope system;

FIG. 2 is an optical phase retardation diagram of light reflected by a dichroic mirror.

Detailed ways

The present invention will be described below with reference to the accompanying drawings, but the present invention is not limited thereto.

FIG. 1 is a schematic structural diagram of a wave plate group design method for compensating any optical phase delay applied to a laser scanning confocal microscope system according to an embodiment of the present invention. The system of this embodiment includes: 1. a laser; 2. Linear polarizer; 3. Total reflection mirror; 4. Half-wave plate; 5. Quarter-wave plate; 6. Dichroic mirror; 7. Objective lens; 8. Sample cell; 9. Photodetector. The light wave output by the laser 1 is modulated into linearly polarized light by the linear polarizer 2, and is incident on the half-wave plate 4 and the dichroic mirror 6 after the total reflection mirror 3, and then modulated by the quarter-wave plate 5 from the objective lens 7. Reaching the sample cell 8, the sample in the sample cell 8 is irradiated by the excitation light, and the emitted detection light passes through the objective lens 7 and the dichroic mirror 6 to reach the photodetector 9, and passes through the half-wave plate 4 and the fourth wave plate in the wave plate group. The half-wave plate 5 is adjusted to compensate the optical phase delay caused by the non-design factors introduced by the dichroic mirror 6, so as to adjust the excitation light incident on the objective lens 7 to obtain the output light wave whose polarization state is circularly polarized light , and finally achieve the purpose of improving the resolution of the microscope system.

The wave plate group consisting of the linear polarizer 2 , the half-wave plate 4 and the quarter-wave plate 6 is placed at the front or rear of the dichroic mirror 5 as shown in FIG. 1 .

A Cartesian coordinate system is established with the fast axis of the dichroic mirror 6 as the x-axis, the angle between the fast axis of the quarter-wave plate and the x-axis is θ, and the angle between the fast axis of the half-wave plate and the x-axis is α; laser 1 The wavelength of the output excitation light is 550 nanometers, which is adjusted to linearly polarized light through the linear polarizer 2 . After the total reflection mirror 3 is incident on the half-wave plate 4, the Jones vector E ₀ of the excitation light modulated by the half-wave plate 4 is:

E ₀ is emitted from the half-wave plate 4 and is incident on the dichroic mirror 6. As shown in FIG. 2, the excitation light with a wavelength of 550 nm is incident on the dichroic mirror 6. The optical phase retardation η= 0.0332. Multiplying the Jones matrix of the dichroic mirror 6 and the Jones matrix of the quarter-wave plate according to the incident order of light waves in the optical path, the Jones matrix of the optical system modulated by the wave plate group is obtained as:

The Jones matrix of the optical system modulated by the wave plate group is multiplied by the Jones vector of the incident light wave to the left, and the Jones vector E ₁ of the outgoing light wave modulated by the dichroic mirror 6 and the wave plate group is obtained as:

in:

The required Jones vector of circularly polarized light is:

in:

a=0, b=1, c=0, d=1;

Compare the Jones vector E ₁ of the outgoing excitation light after modulation by the linear polarizer 2, the half-wave plate 4, the dichroic mirror 6, and the quarter-wave plate 5 with the required circularly polarized light Jones vector E _out , Calculate the angle θ between the fast axis of the quarter-wave plate 6 and the x-axis and the angle α between the fast axis and the x-axis of the half-wave plate 4 to be adjusted as:

α=0°, θ=45° or α=90°, θ=−45°.

At the same time, the angle θ between the fast axis of the quarter-wave plate 6 and the x-axis is 45°, and the angle α between the fast axis of the half-wave plate 4 and the x-axis is 0°; The included angle θ between the fast axis of the plate 6 and the x-axis is -45°, and the included angle α between the fast axis of the half-wave plate 4 and the x-axis is 90°. At this time, the Jones vector E ₁ of the modulated outgoing light wave is:

in:

At this time, after the modulation of the linear polarizer 2, the half-wave plate 4 and the quarter-wave plate 5, the compensation for the optical phase delay caused by the non-design factor introduced by the dichroic mirror 6 is completed, so that E ₁ is obtained as Circularly polarized light required.

Claims (5)

1. a wave plate group design method for compensating any optical phase delay, is characterized in that, comprises the following steps: 1) Place the wave plate group at the front or rear end of the optical path of the optical system to be compensated for the optical phase delay. The wave plate group is placed perpendicular to the light wave propagation direction in the optical path to compensate for the optical phase generated by the optical system to be compensated for the optical phase delay. retardation; the wave plate group is a combination of half-wave plate and quarter-wave plate; 2) Taking the optical system to be compensated for the optical phase delay as a reference, the direction of the fast axis of the optical system is the abscissa, and the direction of the slow axis of the optical system is the ordinate, and a Cartesian coordinate system is established; 3) the Jones matrix of the optical system to be compensated for optical phase delay and the Jones matrix of the wave plate group in step 1) are left-multiplied successively according to the light wave incident order in the optical path, to obtain the Jones matrix of the optical system modulated by the wave plate group; 4) Multiply the Jones matrix of the optical system to be compensated for the optical phase delay modulated by the wave plate group in step 3) and the Jones vector of the incident light wave to the left in turn to obtain the optical system to be compensated for the optical phase delay, after the wave plate group modulation The Jones vector of the outgoing light wave; 5) Compare the Jones vector of the outgoing light wave modulated by the optical system to be compensated for the optical phase delay and the wave plate group in step 4) with the Jones vector corresponding to the polarization state of the required outgoing light wave, and calculate the wave plate group that needs to be adjusted. The angle between each wave plate and the abscissa of the reference coordinate system; 6) According to the angle between each wave plate in the wave plate group and the abscissa of the reference coordinate system calculated in step 5), rotate each wave plate in the wave plate group to complete the compensation of the optical phase delay generated by the optical system to be compensated for the optical phase delay. . 2. a kind of wave plate group design method for compensating any optical phase delay according to claim 1 is characterized in that: the fast axis of the optical system to be compensated for optical phase delay described in step 2) is the light wave component that propagates fast The polarization direction of , its vertical direction is the slow axis direction. 3. a kind of wave plate group design method for compensating any optical phase delay according to claim 1, is characterized in that: the Jones matrix in the wave plate group described in step 3) comprises the Jones matrix of half-wave plate and quartile A waveplate of the Jones matrix. 4. a kind of wave plate group design method for compensating any optical phase delay according to claim 1 is characterized in that: in the wave plate group that needs to be adjusted described in step 5), the angle between the wave plate and the abscissa of the reference coordinate system Including: the angle between the fast axis of the quarter-wave plate and the abscissa of the reference coordinate system and the angle between the fast axis of the half-wave plate and the abscissa of the reference coordinate system. 5. a kind of wave plate group design method for compensating any optical phase delay according to claim 1, it is characterized in that: the modulation method of each wave plate in the rotating wave plate group described in step 6) is: rotate four minutes simultaneously The angle between the fast axis of one wave plate and the abscissa of the reference coordinate system and the angle between the fast axis of the half-wave plate and the abscissa of the reference coordinate system.

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