TWI548870B - Adjustable Sensitivity Phase Measurement System - Google Patents

Description

Adjustable sensitivity phase measurement system

The invention relates to a measurement system, in particular to a phase measurement system with adjustable sensitivity.

As shown in FIG. 5, the conventional resonant phase sensor measuring system 90 is of a reflective type, and the sensor 91 is generally selected from a surface plasma resonator or other sensor. The reflection type is that the optical analyzer 92 and the power detector 93 must track the reflected light beam R of the sensor 91, and thereby determine the physical phenomenon of the object to be tested from the reflected light beam R. However, the reflective optical analyzer 92 and the power detector 93 need to track the reflected light beam R, that is, the optical analyzer 92 and the power detector 93 follow the change of the angle of the sensor 91, so the reflective measuring system 90 usually requires two rotating stages 94, 95, and the two rotating stages 94, 95 are respectively controlled by the computer 96 to drive the sensor 91, the optical analyzer 92 and the power detector 93, respectively, so that not only the control is improved. Difficulty, it is also necessary to consider the vibration phenomenon during the rotation of the two rotating tables.

For example, Taiwan No. 201300763 discloses a surface sensitive plasma resonance detecting method with high sensitivity and a detection system thereof, which discloses that the incident light source is generated to have the best sensitivity by changing the angle of the optical analyzer. Plasma resonance effect. Wherein, since the disclosure is a reflective technique, as the rotating stage drives the optical coupler (ie, the combination of the germanium and the metal layer), the angle of the reflected beam generated by the optical coupler also changes. It means that the optical analyzer and the photodetector should also be rotated, so that the control system is more difficult to control and the overall operation is more complicated. In the case of optical couplers composed of tantalum and metal layers, the manufacturing cost is also high.

In addition, Taiwan Patent No. I405959 discloses a device and method for measuring the physical parameters of an anisotropic substance by using a penetrating heterodyne interferometry, wherein the orthogonal beam of the patent passes through the substance to be tested, and then passes. Check the polarizer, the orthogonal beam is interfering on the analyzer. Finally, the parameters of the substance to be tested, such as the torsion angle of the liquid crystal cell, are obtained. Thus, the technique disclosed in the patent uses the same heterodyne interference principle to measure the parameters of the substance, but the patent does not mention any sense of phase. The detector and the sensitivity are adjustable, and therefore the measurement system with the adjustable sensitivity of the phase sensor of the present invention is different technology.

In addition, SFLin et al. published the "A polarization control system for intensity-resolved guided mode resonance sensors" in the English international journals in 2014. Although the technique uses a transmissive phase sensor measurement system, its detection The measurement method uses the technique of ellipsometer to convert the phase signal into a light intensity signal. Although it can achieve high sensitivity, it has no adjustable characteristics. In many measurement applications of sensors, the sensitivity can be adjusted. The system has both high sensitivity and high dynamic measurement range.

In view of the above-mentioned deficiencies, the present invention provides a phase measurement system with adjustable sensitivity, which can improve the measurement sensitivity of the object to be tested. Moreover, the optical analyzer of the phase measuring system of the present invention does not need to track the reflected beam, so it is more controllable than the reflective measuring system described in the prior art.

To achieve the above object, the adjustable sensitivity phase measuring system of the present invention comprises a light source device, an electro-optic modulator, a guided mode resonator, a rotating table, an analyzer and a processing device. The light source device is used to generate a collimated beam. The direction in which the collimated beam is directed is defined as an optical path. The electro-optic modulator is positioned on the optical path and processes the collimated beam into a horizontally polarized component beam and a vertically polarized component beam of different frequencies. The guided mode resonator is positioned on the optical path and has a light incident surface and a light exit surface. There is a test object on the light surface. The rotating stage carries a guided mode resonator and drives the guided mode resonator to rotate. The optical analyzer is positioned on the optical path and has a polarization axis, the polarization axis forms an angle with a horizontal axis, and the horizontal axis is perpendicular to the optical path. The horizontally polarized component beam and the vertically polarized component beam pass through the light incident surface and the light exit surface of the guided mode resonator, and generate a beat signal after passing through the object to be tested and the optical analyzer. The processing device receives and processes the beat signal to obtain a measurement result.

In this way, the adjustable sensitivity phase measurement system of the present invention can achieve the purpose of adjusting the measurement sensitivity by changing the polarization direction of the optical analyzer, that is, the angle between the polarization axis and the horizontal axis. Moreover, the present invention uses a transmissive guided mode in comparison with the prior art. The vibrator, and the optical analyzer does not have to follow the rotation of the guided mode resonator. Therefore, the present invention requires only one rotating stage, and the control is also relatively simple.

The detailed construction, features, assembly or use of the phase measurement system with respect to the adjustable sensitivity provided by the present invention will be described in the detailed description of the subsequent embodiments. However, it should be understood by those of ordinary skill in the art that the present invention is not limited by the scope of the invention.

10‧‧‧Adjustable sensitivity phase measurement system

11‧‧‧Light source device

111‧‧‧Laser light source

112‧‧‧ polarizer

12‧‧‧ Modulation device

121‧‧‧Signal Generator

122‧‧‧High voltage amplifier

123‧‧‧Electro-optic modulator

13‧‧‧ guided mode resonator

131‧‧‧Into the glossy surface

132‧‧‧Glossy

14‧‧‧Rotating table

15‧‧‧Light analyzer

16‧‧‧Processor device

161‧‧‧Power Detector

162‧‧‧Lock-in amplifier

163‧‧‧ computer

17‧‧‧ drive

20‧‧‧Test object

L‧‧‧Light Road

P‧‧‧polarization axis

H‧‧‧ horizontal axis

‧‧‧‧ angle

Figure 1 is a schematic diagram showing the composition of an embodiment of the adjustable sensitivity phase measuring system of the present invention.

Fig. 2 is an enlarged schematic view showing the optical path, the optical analyzer, and the driving device in Fig. 1.

Figure 3 is a measurement phase diagram of the measurement when the angle between the optical analyzer and the optical path is -50 degrees.

Figure 4 is a measurement phase diagram of the measurement when the angle between the optical analyzer and the optical path is -60 degrees.

Figure 5 is a schematic diagram of the composition of a conventional reflective measurement system.

Hereinafter, the components of the phase-measurement system of the adjustable sensitivity of the present invention and the achievement of the efficacy will be described with reference to the preferred embodiments of the drawings. However, the components, dimensions, and appearance of the phase-measurement system of the tunable sensitivity in the various figures are only used to illustrate the technical features of the present invention, and are not intended to limit the present invention.

As shown in FIG. 1 , the adjustable sensitivity phase measuring system 10 of the present invention comprises a light source device 11 , a modulation device 12 , a guided-mode resonance sensor 13 , a rotating table 14 , and a The optical analyzer 15 and a processor device 16.

The light source device 11 includes a laser light source 111 and a polarizer 112. The laser source 111 is used to generate a collimated beam, such as a 685 nm laser beam, wherein the direction of the collimated beam is defined as an optical path L, the thicker dashed line in the figure, and the direction of the thick dashed arrow is the collimated beam. Direction. Collimated beam through the polarizer 112.

The modulating device 12 is positioned on the optical path L and processes the collimated beam into a horizontally polarized component beam and a vertically polarized component beam at different frequencies. The modulation device 12 includes a function generator 121, a high voltage amplifier 122, and an electro optic modulator 123. In this embodiment, the signal generator 121 is connected to the high voltage amplifier 122, and the high voltage amplifier 122 is connected to the electro-optic modulator 123. The electro-optic modulator 123 is driven by the 100Hz sawtooth signal provided by the signal generator 121 to the high voltage amplifier 122. A horizontally polarized component beam having a frequency difference and a vertically polarized component beam are generated.

The guided mode resonator 13 is located on the optical path L and has a light incident surface 131 and a light exit surface 132. The light-emitting surface 132 has a sample to be tested 20, wherein the object to be tested 20 may be in a liquid, solid or gaseous form.

Among them, the guided mode resonator 13 can confirm its resonance point by an optical power measuring system (not shown), but this is a disclosed technique. When the guided mode resonator 13 is operated at the resonance point, the guided mode resonator 13 undergoes a guided mode resonance phenomenon, and the guided mode resonance phenomenon causes the light beam to have a transmittance close to 100%. There have been many published studies on the guided mode resonator 13 and the present invention mainly uses the resonance point characteristics of the guided mode resonator 13, and thus its structure will not be described herein.

The rotary table 14 carries the guided mode resonator 13 and drives the guided mode resonator 13 to rotate. Wherein, when the guided mode resonator 13 is in a perpendicular relationship with the optical path L, the defined angle is equal to zero degrees, and thus the rotational range of the guided mode resonator 13 compared to the optical path L is between minus 90 degrees and plus 90 degrees.

An optical analyzer 15 is positioned on the optical path L and has a polarization axis P. An angle α is formed between the polarization axis P and a horizontal axis H (as shown in FIG. 2), that is, the polarization direction of the optical analyzer 15. The horizontal axis H is perpendicular to the optical path L and is a virtual direction axis.

The horizontally polarized component beam and the vertically polarized component beam pass through the light incident surface 131 and the light exiting surface 132 of the guided mode resonator 13 and pass through the object to be tested 20 and the optical analyzer 15 to generate a beat signal. Due to the folding of the substance, composition and composition of the surface of the object 20 itself The radiation rate affects the phase of the beat signal. Therefore, the phase measurement system of the present invention can measure the change in the refractive index of the object 20 on the light exit surface 132 of the guided mode resonator 13.

The processing device 16 receives the beat signal passed through the optical analyzer 15 and processes the beat signal to obtain a measurement result. The processing device 16 includes a power detector 161, a lock in amplifier 162, and a computer 163. The power detector 161 receives the beat signal and converts the beat signal into an electrical signal. Then, the lock-in amplifier 162 receives and processes the electrical signal to obtain a measurement result of the electrical signal. The measurement result is also the phase value of the beat signal. The computer 163 is connected to the lock-in amplifier 162 and receives the measurement result and records the measurement result.

Wherein, the electrical signal can be represented by the formula 1, T _P and T _S respectively represent the transmission coefficients of the horizontal component and the vertical component of the guided mode resonant component, and α represents the angle between the polarization axis of the optical analyzer and the horizontal axis. In this case, the phase difference between the horizontal light and the vertical light is ignored, and the equation 1 is expanded into the second and third equations. The t _P and t _S in the second and third equations are respectively the horizontally polarized component beam and the vertical polarization. The transmission coefficient of the component beam, the phase value of the beat signal can be obtained from Equation 3 (ie measurement results).

A _{formula: E PD = T P cos α} + T S sin α

The phase value △ can also be seen from the third formula. It is affected by the transmission coefficients t _P and t _S and the angle α , that is, changing the angle α between the polarization axis of the optical analyzer 15 and the horizontal axis can cause a change in the measurement result.

Thus, the phase measurement system 10 of the adjustable sensitivity of the present invention can be used to obtain different measurement sensitivities by changing the angle α between the polarization axis of the optical analyzer 15 and the horizontal axis.

Referring to FIGS. 1 and 2 simultaneously, the measurement sensitivity can be changed by changing the angle α between the polarization axis of the optical analyzer 15 and the horizontal axis. Therefore, the adjustable sensitivity phase measurement system 10 of the present invention further includes A drive unit 17. The driving device 17 is connected to the optical analyzer 15 and drives the optical analyzer 15 to rotate along the optical path L. Thus, the adjustable sensitivity phase measuring system 10 of the present invention can accurately control the optical analyzer by the driving device 17. The angle α between the polarization axis of 15 and the horizontal axis is convenient for adjustment. However, the polarization axis and the horizontal axis of the optical analyzer 15 can also be manually adjusted, and thus are not limited to the driving of the driving device 17.

Subsequently, the inventor of the present invention dripped 3% of the glucose solution into the ionic water as the test object, and successively added 0.1 ml of the glucose solution to the test object for measurement to demonstrate the adjustable sensitivity of the present invention. The actual measurement results of the phase measurement system.

The concentration of the analyte in this experiment changes as shown in Table 1. It can be understood from Table 1 that the concentration of the analyte in the experiment changes due to the addition of the glucose solution, and the refractive index of the concentration of the different analytes will also be different.

In each experiment, the glucose solution was sequentially added in the order of Table 1, and each time the concentration of the analyte was changed, the measurement was performed for 200 seconds to record the measurement result of the analyte, that is, the phase change. The present invention discloses two measurement results. The measurement results are verified by taking the angle between the polarization axis of the fixed optical analyzer and the horizontal axis as -50 degrees and -60 degrees, respectively.

Figures 3 and 4 are drawn by computer. When the angle between the polarization axis of the optical analyzer and the horizontal axis is -50 degrees, it can be seen from Fig. 3 that the phase value of the object with a refractive index of 1.3330 is about -90 degrees, and then the refractive index is 1.3338. changing the phase value of the analyte to about 11 degrees (approximately -79 degrees), and finally a refractive index of 1.3345 to phase values was tested also significantly changed, by the operational available lock-in amplifier measuring sensitivity was 7.2 * 10 ^{- 7} RIU.

When the angle between the polarization axis of the optical analyzer and the horizontal axis is -60 degrees, it can be seen from Fig. 4 that the phase value of the object with a refractive index of 1.3330 is about -90 degrees, and then the refractive index is 1.3338. The phase value of the object to be tested changes by about 44 degrees (about -46 degrees), and the phase value of the object to be tested with a final refractive index of 1.3345 also changes significantly. The sensitivity of the measurement by the lock-in amplifier is 1.8*10 ^{- 7} RIU.

Comparing Figures 3 and 4, it can be seen that when the angle between the polarization axis of the optical analyzer and the horizontal axis is changed, the sensitivity of the measurement can be effectively improved. In detail, 0.1ml of glucose solution is a trace amount. At an angle of -60 degrees, this trace amount of glucose solution is sufficient for the phase measuring system of the present invention to obtain significant measurement results, and therefore, applied to biomedical or In the case of food safety and the like, only a small amount of the analyte is required to measure the result by the phase measuring system of the present invention, so that the time for collecting and cultivating the specimen (ie, the object to be tested) can be greatly shortened, and the detection is improved. The ability to measure the physical phenomena of the object itself.

In addition, since the present invention is not a conventional reflective measurement system, the power detector of the optical analyzer and the processor does not need to track the reflected beam, so the control system of the adjustable sensitivity phase measurement system of the present invention is more conventional. The reflective measurement system is simple and reduces costs.

Finally, it is emphasized that the constituent elements disclosed in the foregoing embodiments are merely illustrative and are not intended to limit the scope of the present invention, and alternatives or variations of other equivalent elements should also be the scope of the patent application of the present application. Covered.

10‧‧‧Adjustable sensitivity phase measurement system

11‧‧‧Light source device

111‧‧‧Laser light source

112‧‧‧ polarizer

12‧‧‧ Modulation device

121‧‧‧Signal Generator

122‧‧‧High voltage amplifier

123‧‧‧Electro-optic modulator

13‧‧‧ guided mode resonator

131‧‧‧Into the glossy surface

132‧‧‧Glossy

14‧‧‧Rotating table

15‧‧‧Light analyzer

16‧‧‧Processor device

161‧‧‧Power Detector

162‧‧‧Lock-in amplifier

163‧‧‧ computer

20‧‧‧Test object

L‧‧‧Light Road

P‧‧‧polarization axis

H‧‧‧ horizontal axis

Claims (3)

An adjustable sensitivity phase measuring system comprising: a light source device for generating a collimated beam, the collimated beam direction is defined as an optical path; and an electro-optic modulator is positioned on the optical path and The collimated beam is processed as a horizontally polarized component beam and a vertically polarized component beam at different frequencies; a guided mode resonator is positioned on the optical path, and has a light incident surface and a light exit surface, and the light exit surface has a to be tested a rotating table carrying the guided mode resonator and driving the guided mode resonator to rotate; an optical analyzer is positioned on the optical path and has a polarization axis, the polarization axis and a horizontal axis Forming an angle therebetween, the horizontal axis is perpendicular to the optical path, wherein the horizontally polarized component beam and the vertically polarized component beam pass through the light incident surface and the light exit surface of the guided mode resonator, and pass through the The measuring object and the optical analyzer generate a beat signal; and a processing device receives the beat signal passing through the optical analyzer, and processes the beat signal to obtain a measurement result. The adjustable sensitivity phase measuring system according to claim 1, further comprising a driving device connected to the optical analyzer and driving the optical analyzer to rotate the optical path as an axis to change the angle. The phase-measurement system of the adjustable sensitivity according to the first aspect of the invention, wherein the processing device comprises a detector, a lock-in amplifier and a computer, wherein the detector receives the beat signal, and The beat signal is converted into an electrical signal, and the lock-in amplifier receives the electrical signal and processes the phase value.