CN103411689B - Based on optical maser wavelength direct measuring method and the device of the orthogonal line polarized light of single-frequency - Google Patents

Abstract

The present invention discloses a kind of optical maser wavelength direct measuring method based on the orthogonal line polarized light of single-frequency and device. Wavelength is ��_xTesting laser after polaroid, quarter-wave plate, form circularly polarized light, penetrate to two cover Michelson interferometers, formed respectively horizontal polarization and vertical polarization component two-way interfere signal; First come and go motion by PZT driving mechanism modulation reference prism of corner cube, record the phase differential that two-way interferes signal; Then static with reference to prism of corner cube, measure prism of corner cube and move certain displacement �� L, record number N complete cycle of horizontal polarisation component interference signal by two-way counting module; Modulation reference prism of corner cube records the phase differential of now two-way interference signal again; ByShow that horizontal polarisation component interferes the decimal variable quantity of signal; According to displacement L and the number N and small number epsilon complete cycle that records, calculate wavelength X to be measured by computer_x. The light channel structure of the present invention is simple, it is not necessary to reference laser diode, measuring accuracy height, it may be achieved to the large-range measuring of wavelength.

Description

Based on optical maser wavelength direct measuring method and the device of the orthogonal line polarized light of single-frequency

Technical field

The present invention relates to laser wavelength measurement method and device, especially relate to a kind of optical maser wavelength direct measuring method based on the orthogonal line polarized light of single-frequency and device.

Background technology

Optical maser wavelength is as measuring basis value, it is widely used in the measurement of length, speed, angle, planeness, linearity and verticality etc., it is the important measuring parameter of delicate metering, precision optical machinery and microelectronics industry, and accurately to measure wavelength size be the key ensureing geometry measurement accuracy and magnitude tracing. Laser wavelength measurement method is divided into substantially: 1, based on the measuring method of laser frequency (wavelength) of harmonic wave optical frequency chain, if this method excessive clearance (more than 10GHz) between optical frequency in chain in actual measuring process, it is very difficult for will erecting bridge between known optical frequency and arbitrary unknown optical frequency; 2, based on optical frequency (wavelength) measuring method of point (OFID) frequency chain in optical frequency interval, but one can cover the OFID chain still extremely complexity of microwave section to several hundred THz of optical frequency section; 3, based on optical frequency (wavelength) measuring method of optical frequency com, the accuracy of measurement utilizing the method to be reached very high is very difficult, and accuracy of measurement is more high, and the requirement of instrument is also more high, and measuring system is also more complicated; 4, based on the laser wavelength measurement method of Michelson interference principle, it is necessary to reference laser diode is as with reference to light source, measuring accuracy is subject to the impact of reference laser diode; 5, based on laser frequency (wavelength) measuring method of empty synthetic wavelength principle, the method relates to the phase compare between different frequency signals.

Based on the optical maser wavelength direct measuring method of the orthogonal line polarized light of single-frequency, it is not necessary to reference light source, there is not the phase compare between different frequency signals, the continuously measured on a large scale to wavelength can be realized, measuring accuracy height.

Summary of the invention

In order to meet the needs to high-precision laser wavelength measurement, it is an object of the invention to provide a kind of optical maser wavelength direct measuring method based on the orthogonal line polarized light of single-frequency and device, the measurement of unknown wavelength will be converted into interferometric fringe signal counting complete cycle and two-way interferes the measurement of signal phase difference, do not need reference light source, directly measuring continuously of optical maser wavelength can be realized on a large scale.

The technical solution adopted for the present invention to solve the technical problems is:

One, a kind of optical maser wavelength direct measuring method based on the orthogonal line polarized light of single-frequency:

(1) testing laser device output wavelength is ��_xLaser form line polarized light through polaroid, penetrate and form circularly polarized light after the quarter-wave plate at angle at 45 ��, the polarization direction of e axle and line polarized light, this circularly polarized light is made up of the orthogonal line polarized light of single-frequency, penetrate after two cover Michelson interferometers, form the interference signal of horizontal polarisation component and vertical polarization component, respectively by respective photoelectric detector;

(2) first measure prism of corner cube not move, in 5 ��m of strokes, come and go motion by PZT driving mechanism modulation reference prism of corner cube, measure module by phase differential and record ��_xThe interference signal of vertical polarization component and ��_xThe phase differential of the interference signal of horizontal polarisation componentPZT driving mechanism stops modulation;

(3) then measure prism of corner cube and move �� L=100mm, record �� by two-way counting module_xHorizontal polarisation component interferes number N complete cycle of signal intensity;

(4) modulation reference prism of corner cube comes and goes motion in 5 ��m of strokes again, measures module by phase differential and records ��_xThe interference signal of vertical polarization component and ��_xThe phase differential of the interference signal of horizontal polarisation component isThen ��_xThe decimal variable quantity �� of horizontal polarisation component interference signal is:

(5) according to measuring the displacement L that prism of corner cube moves and the �� recorded_xHorizontal polarisation component interferes the number N and decimal variable quantity �� complete cycle of signal intensity, and obtaining testing laser wavelength is:

${\mathrm{\λ}}_x=\frac{2\·\mathrm{\ΔL}}{(N+\mathrm{\ϵ})}$

So far the wavelength of testing laser device is obtained.

Two, a kind of direct measuring apparatus of optical maser wavelength based on the orthogonal line polarized light of single-frequency:

The present invention comprises testing laser device, polaroid, quarter-wave plate, first spectroscope, PZT driving mechanism, with reference to prism of corner cube, first polarization spectroscope, measures prism of corner cube, the 2nd polarization spectroscope, 2nd spectroscope, first photodetector, the 2nd photodetector, the 3rd photodetector, phase differential measures module, two-way counting module and computer; Testing laser device output wavelength is ��_xLaser form line polarized light through polaroid, penetrate to e axle with form the circularly polarized light being made up of the orthogonal line polarized light of single-frequency after the quarter-wave plate at angle at 45 ��, the polarization direction of line polarized light, wherein ��_xVertical polarization component is penetrated to the first cover Michelson interferometer being made up of the first spectroscope, the reference prism of corner cube being arranged on PZT driving mechanism and the first polarization spectroscope, forms the interference signal of vertical polarization component, ��_xHorizontal polarisation component is penetrated to the 2nd cover Michelson interferometer being made up of the first spectroscope, reference prism of corner cube and measurement prism of corner cube, forms the interference signal of horizontal polarisation component; Vertical polarization component interferes signal after the 2nd polarization spectroscope reflects by the first photoelectric detector, horizontal polarisation component interferes signal after the 2nd polarization spectroscope transmission, the 2nd spectroscope light splitting, respectively by the 2nd photodetector and the 3rd photoelectric detector; The described two-way that first photodetector and the 2nd photoelectric detector arrive interferes signal to send into phase differential measurement module, 2nd photodetector and the 3rd photoelectric detector to described two-way interfere signal to send into two-way counting module, phase differential measures module and two-way counting module connects computer.

The useful effect that the present invention has is:

The measurement of unknown wavelength will be converted into interferometric fringe signal counting complete cycle and two-way interferes the measurement of signal phase difference by the present invention, the high precision to optical maser wavelength can be realized measure, the light channel structure of the present invention is simple, do not need reference laser diode, easy to use, measuring accuracy height, it may be achieved to the large-range measuring of wavelength, can be widely used in technical field of optical precision measurement.

Accompanying drawing explanation

Fig. 1 is the direct measuring principle figure of optical maser wavelength based on the orthogonal line polarized light of single-frequency.

Fig. 2 measures prism of corner cube to move front and back ��_xVertical polarization component and ��_xThe phase differential change schematic diagram of the interference signal of horizontal polarisation component.

In figure: 1, testing laser device, 2, polaroid, 3, quarter-wave plate, 4, the first spectroscope, 5, PZT driving mechanism, 6, with reference to prism of corner cube, 7, the first polarization spectroscope, 8, measure prism of corner cube, the 9, the 2nd polarization spectroscope, 10, the 2nd spectroscope, the 11, first photodetector, the 12, the 2nd photodetector, 13, the 3rd photodetector, 14, phase differential measures module, and 15, two-way counting module, 16, computer.

Embodiment

Below in conjunction with drawings and Examples, the present invention is further illustrated.

As shown in Figure 1, the present invention comprises testing laser device 1, polaroid 2, quarter-wave plate 3, the first spectroscope 4, PZT driving mechanism 5, with reference to prism of corner cube 6, first polarization spectroscope 7, measure prism of corner cube 8,2nd polarization spectroscope the 9, two spectroscope 10, first photodetector 11,2nd photodetector 12,3rd photodetector 13, phase differential measures module 14, two-way counting module 15 and computer 16. Testing laser device 1 output wavelength is ��_xLaser form line polarized light through polaroid 2, penetrate and form circularly polarized light after the quarter-wave plate at angle at 45 ��, the polarization direction of e axle and line polarized light, this circularly polarized light is made up of the orthogonal line polarized light of single-frequency, wherein ��_xVertical polarization component is penetrated to the first cover Michelson interferometer being made up of the first spectroscope 4, the reference prism of corner cube 6 being arranged on PZT driving mechanism 5 and the first polarization spectroscope 7, forms the interference signal of vertical polarization component; Meanwhile, ��_xHorizontal polarisation component is penetrated to the 2nd cover Michelson interferometer being made up of the first spectroscope 4, reference prism of corner cube 6 and measurement prism of corner cube 8, forms the interference signal of horizontal polarisation component; The interference signal of vertical polarization component is received by the first photodetector 11 after the 2nd polarization spectroscope 9 reflects, the interference signal of horizontal polarisation component is after the 2nd polarization spectroscope 9 transmission, reflect through the 2nd spectroscope 10 again and after transmission, receive by the 2nd photodetector 12 and the 3rd photodetector 13; Two-way that first photodetector 11 and the 2nd photodetector 12 receive interferes signal to send into phase differential to measure module the 14, two photodetector 12 and theThreeThe two-way that photodetector 13 receives interferes signal to send into two-way counting module 15, and the measuring result that phase differential measures module 14 and two-way counting module 15 sends into computer 16.

Note L₀It is initial light path difference, the L of the reference path of the first cover Michelson interferometer and optical path₁It is the reference path of the 2nd cover Michelson interferometer and the initial light path difference of optical path.

Before measurement starts, the first detector 11 detects that the phase place of vertical polarization component interference signal is:

The phase place of the horizontal polarisation component interference signal that the 2nd detector 12 detects is:

Initial phase difference between two-way interference signal is:

Measuring prism of corner cube 8 moving displacement �� L, horizontal polarisation component interferes the phase place of signal to turn into:

The phase difference variable of now two-way interference signal is:

Two-way interferes this kind of phase differential change of signal, as shown in Figure 2, and V (��_{x����}) represent wavelength X_xThe interference signal waveform of vertical polarization component, V (��_X||) represent that measuring prism of corner cube moves front ��_xThe interference signal waveform of horizontal polarisation component, V (�� '_X||) represent that measuring prism of corner cube moves rear ��_xThe interference signal waveform of horizontal polarisation component.

Subtract formula (3) formula by formula (5) formula to obtain:

In formula: N is ��_xHorizontal polarisation component interferes number complete cycle of signal intensity, and �� is ��_xHorizontal polarisation component interferes the decimal variable quantity of signal.

Unknown wavelength X can be calculated according to formula (6)_xFor:

${\mathrm{\λ}}_x=\frac{2\·\mathrm{\ΔL}}{(N+\mathrm{\ϵ})}---\left(7\right)$

The concrete implementation step directly measured based on the optical maser wavelength of the orthogonal line polarized light of single-frequency is as follows:

(1) before measurement starts, measure prism of corner cube 8 and do not move, in 5 ��m of strokes, come and go motion, the �� now recorded by the first photodetector 11 by PZT driving mechanism 5 modulation reference prism of corner cube 6_xThe �� that the interference signal of vertical polarization component and the 2nd photodetector 12 record_xThe interference signal of horizontal polarisation component is sent into phase differential and is measured module 14(Agilent 53220A type universal frequency counter), recording phase differential is

(2) PZT driving mechanism 5 stops modulation, measures prism of corner cube 8 and moves certain displacement �� L=100mm, by the mode of machinery phase shift, makes the �� that the 2nd photodetector 12 and the 3rd photodetector 13 detect_xHorizontal polarisation component interferes signal phase difference to be that the two paths of signals of 90 �� is sent into two-way counting module 15(Hewlett-Packard HCTL-2020 type and debated to counting circuit chip), record ��_xHorizontal polarisation component interferes number N complete cycle of signal;

(3) modulation reference prism of corner cube 6 comes and goes motion in 5 ��m of strokes again, and the phase difference variable recording now two-way interference signal is

(4) phase differential of front and back two-way interference signal is moved according to measurement prism of corner cube 8WithDraw ��_xThe interference signal decimal variable quantity �� of horizontal polarisation component:

(5) computer 16(Lenovo Qitian M7300 type) according to the �� recorded_xHorizontal polarisation component is interfered number N complete cycle of signal, is interfered signal decimal variable quantity ��, and the displacement L that measurement prism of corner cube 8 moves, and calculating testing laser wavelength as follows is:

${\mathrm{\λ}}_x=\frac{2\·\mathrm{\ΔL}}{(N+\mathrm{\ϵ})}---\left(9\right)$

Substitute into typical case's value: testing laser wavelength X_xFor 633nm, measure the displacement L=100mm that prism of corner cube 8 moves, number N complete cycle interfering signal is 315955, signal decimal variable quantity �� is interfered to be 0.7662, when the positioning precision measuring prism of corner cube moving displacement is 0.1nm, when interference fringe segmentation coefficient is 1/4096, the measuring accuracy of testing laser wavelength is 1.23 �� 10^-9��

So far the present invention is completed.

Claims (1)

1. the optical maser wavelength direct measuring method based on the orthogonal line polarized light of single-frequency, it is characterised in that:

(1) testing laser device output wavelength is ��_xLaser form line polarized light through polaroid, penetrate and form circularly polarized light after the quarter-wave plate at angle at 45 ��, the polarization direction of e axle and line polarized light, this circularly polarized light is made up of the orthogonal line polarized light of single-frequency, penetrate after two cover Michelson interferometers, form the interference signal of horizontal polarisation component and vertical polarization component, respectively by respective photoelectric detector;

(2) first measure prism of corner cube not move, in 5 ��m of strokes, come and go motion by PZT driving mechanism modulation reference prism of corner cube, measure module by phase differential and record ��_xThe interference signal of vertical polarization component and ��_xThe phase differential of the interference signal of horizontal polarisation componentPZT driving mechanism stops modulation;

(3) then measure prism of corner cube and move �� L=100mm, record �� by two-way counting module_xHorizontal polarisation component interferes number N complete cycle of signal intensity;

(4) modulation reference prism of corner cube comes and goes motion in 5 ��m of strokes again, measures module by phase differential and records ��_xThe interference signal of vertical polarization component and ��_xThe phase differential of the interference signal of horizontal polarisation component isThen ��_xThe decimal variable quantity �� of horizontal polarisation component interference signal is:

(5) according to measuring the displacement L that prism of corner cube moves and the �� recorded_xHorizontal polarisation component interferes the number N and decimal variable quantity �� complete cycle of signal intensity, and obtaining testing laser wavelength is:

${\mathrm{\λ}}_x=\frac{2\·\mathrm{\Δ}L}{(N+\mathrm{\ϵ})}$

So far the wavelength of testing laser device is obtained.