CN103196658B

CN103196658B - Method and device for measuring phase delay spectral characteristic of wave plate

Info

Publication number: CN103196658B
Application number: CN201310138881.9A
Authority: CN
Inventors: 张璐
Original assignee: Shandong University
Current assignee: Shandong University
Priority date: 2013-04-19
Filing date: 2013-04-19
Publication date: 2015-02-18
Anticipated expiration: 2033-04-19
Also published as: CN103196658A

Abstract

The invention discloses a method and a device for measuring a phase delay spectral characteristic of a wave plate, comprising a broadband light source; and continuously emergent light is received after passing through a multi-wavelength photoelectric detector through a collimator, a polarizer, two wave plates to be detected, a polarization analyzer and an optical splitter respectively, wherein the two wave plates to be detected are connected with a motor, data received by the multi-wavelength photoelectric detector are uploaded to a data acquisition card which transmits the data to a computer which is connected with the motor. The method disclosed by the invention can automatically measure the phase delay spectral characteristics of the two wave plates to be detected within a wide spectral range, not only can be used for measuring the phase delay spectral characteristics of two rotary wave plates in a rotating double-compensator type broad-spectrum ellipsometer so as to eliminate system errors caused by inaccurate calibration, but also can be used for directly calibrating the phase delay spectral characteristics of two unknown wave plates in practical production and research work, and besides, the measurement result is not influenced by the light source and the spectral characteristic of a detector.

Description

Method and device for measuring phase delay spectral characteristics of wave plate

技术领域technical field

本发明属于偏振光学检测领域，特别是一种波片相位延迟光谱特性的测量方法及装置。The invention belongs to the field of polarization optical detection, in particular to a method and device for measuring the phase delay spectrum characteristic of a wave plate.

背景技术Background technique

波片常用作椭偏测量或光学测量中光信号偏振态的变换器件。波片的相位延迟误差会对测量结果产生很大的影响。因此，在制作和使用波片的过程中，经常需要精确测量波片的相位延迟光谱特性。例如在旋转双补偿器式广谱椭偏仪（PCSCA型椭偏仪）中，两个补偿器C1、C2延迟量的精确定标是实现高精度测量的前提，两个旋转补偿器的工作波长范围对整机特性有重要影响。Waveplates are often used as devices for transforming the polarization state of optical signals in ellipsometry or optical measurements. The phase delay error of the wave plate will have a great impact on the measurement results. Therefore, in the process of making and using the wave plate, it is often necessary to accurately measure the phase retardation spectral characteristics of the wave plate. For example, in the rotating double compensator type broad-spectrum ellipsometer (PCSCA type ellipsometer), the precise calibration of the delays of the two compensators C1 and C2 is the premise of high-precision measurement. The working wavelength of the two rotating compensators Range has a significant impact on overall machine characteristics.

众所周知，虽然PCSCA型椭偏仪中的旋转补偿器C1和C2设计为宽带1/4波片，但实际的宽带1/4波片在所考虑的带宽范围内，其相位延迟量并不总是严格的90°，而是有一定的误差范围；以氟化镁复合的零级波片为例，在光谱范围为200～1000nm时，该波片的相位延迟量就在60°～130°范围内起伏变化。As we all know, although the rotary compensators C1 and C2 in the PCSCA type ellipsometer are designed as broadband 1/4 wave plates, the phase delay of the actual broadband 1/4 wave plates is not always within the considered bandwidth range Strictly 90°, but there is a certain error range; taking the magnesium fluoride composite zero-order wave plate as an example, when the spectral range is 200-1000nm, the phase retardation of the wave plate is in the range of 60°-130° Internal ups and downs.

在PCSCA型椭偏仪的设计制造过程中，首先需要进行的步骤就是对其中的两个补偿器C1和C2进行定标和自校准，即准确测定两个补偿器在每个波长处的相位延迟，以消除光谱仪接收端定标不准确带来的系统误差。通常采用的定标方式如文献[R.W.Collins and J.Koh,J.Opt.Soc.Am.A,16,1997(1999)]所述，即首先测量CCD像元的输出光电流，然后对其做傅立叶分析，分别求解其中的各个傅立叶系数，然后套用一定的公式求得椭偏仪中各补偿器的相位延迟量。In the design and manufacture process of the PCSCA ellipsometer, the first step is to calibrate and self-calibrate the two compensators C1 and C2, that is, to accurately measure the phase delay of the two compensators at each wavelength , to eliminate the systematic error caused by inaccurate calibration at the receiving end of the spectrometer. The commonly used calibration method is as described in the literature [R.W.Collins and J.Koh, J.Opt.Soc.Am.A, 16, 1997 (1999)], that is, firstly measure the output photocurrent of the CCD pixel, and then Do Fourier analysis, solve each of the Fourier coefficients separately, and then apply a certain formula to obtain the phase delay of each compensator in the ellipsometer.

但是，该方案受所用傅立叶变换分析仪的测量波长范围限制（该仪器通常应用在红外波段），误差来源多且求解过程相对复杂。当然也可以采用其它的仪器（如其它商用椭偏仪）对旋转双补偿器式椭偏仪的两个补偿器分别进行测量，然后再进行装配，这种方案的最大问题是补偿器的相位延迟谱特性受所用椭偏仪的测量光谱范围制约，而且过程更为复杂。However, this solution is limited by the measurement wavelength range of the Fourier transform analyzer used (this instrument is usually used in the infrared band), there are many error sources and the solution process is relatively complicated. Of course, other instruments (such as other commercial ellipsometers) can also be used to measure the two compensators of the rotating double compensator ellipsometer separately, and then assemble them. The biggest problem with this solution is the phase delay of the compensators. The spectral properties are limited by the measuring spectral range of the ellipsometer used, and the process is more complicated.

测量波片相位延迟的方法有很多种，但往往只适用于测量某一特定单色波长下的波片相位延迟量，不能同时测量多波长情况下波片的相位延迟光谱特性。而有的测量方法，能够、但只能够测量单个波片的相位延迟光谱特性，不能同时测量两个待测波片的相位延迟光谱特性。There are many methods for measuring wave plate phase retardation, but they are often only suitable for measuring the wave plate phase retardation at a specific monochromatic wavelength, and cannot simultaneously measure the phase retardation spectral characteristics of wave plates in the case of multiple wavelengths. However, some measurement methods can, but can only measure the phase delay spectral characteristics of a single wave plate, and cannot simultaneously measure the phase delay spectral characteristics of two wave plates to be tested.

中国专利CN1743796和CN100340838C等虽然均能够一次同时读取多波长的测量数据，但无法同时测量两个波片的相位延迟光谱特性。Although the Chinese patents CN1743796 and CN100340838C can simultaneously read the measurement data of multiple wavelengths at one time, they cannot simultaneously measure the phase delay spectral characteristics of two wave plates.

中国专利CN1632501、CN201032473Y和CN102589850A等的方法还需要通过单色仪每次选择单个波长，进行单个待测波片的特性测量，在要求测量的易操作性、以及测量速度的场合更为受限。The methods of Chinese patents CN1632501, CN201032473Y, and CN102589850A also need to select a single wavelength each time through the monochromator to measure the characteristics of a single wave plate to be tested, which is more limited in the occasions requiring ease of measurement and measurement speed.

中国专利（申请号：201110344206，专利名称：宽带波片及实现相位延迟相等的方法和偏振控制器），该专利的内容是如何利用色散元件将宽频光谱在空间上分开并实现在宽频带范围内得到相等的相位延迟，以及如何利用这种宽波片组合成偏振控制器，丝毫不涉及宽带波片相位延迟光谱特性的测量问题。Chinese patent (Application No.: 201110344206, patent name: broadband wave plate and method for achieving equal phase delay and polarization controller), the content of this patent is how to use dispersion elements to spatially separate the broadband spectrum and realize it in the broadband range Obtaining the equal phase delay and how to use the wide wave plate to form a polarization controller does not involve the measurement of the spectral characteristics of the phase delay of the wide band wave plate.

发明内容Contents of the invention

本发明的目的就是为了解决上述问题，提供一种波片相位延迟光谱特性的测量方法及装置，它属于非接触测量，能够在宽光谱范围内同时自动测量两个未知波片相位延迟谱;使用方便高效，既可用于测量旋转双补偿器式广谱椭偏仪中两个旋转波片的相位延迟光谱特性，消除其定标不准确带来的系统误差；又可用于实际生产及研究工作中同时进行两个未知波片的相位延迟量光谱特性的直接定标，并且测量结果不受光源和探测器光谱特性的影响。The object of the present invention is to solve the above-mentioned problems, and to provide a method and device for measuring the phase delay spectral characteristics of a wave plate, which belongs to non-contact measurement, and can automatically measure the phase delay spectra of two unknown wave plates in a wide spectral range; Convenient and efficient, it can be used to measure the phase delay spectral characteristics of two rotating wave plates in the rotating double compensator broad-spectrum ellipsometer, eliminating the systematic error caused by inaccurate calibration; it can also be used in actual production and research work Simultaneously, the direct calibration of the spectral characteristics of the phase retardation of two unknown wave plates is performed, and the measurement results are not affected by the spectral characteristics of the light source and the detector.

为了实现上述目的，本发明采用如下技术方案：In order to achieve the above object, the present invention adopts the following technical solutions:

一种波片相位延迟光谱特性的测量装置，包括一个宽带光源，其出射的多波长连续光依次通过准直器、起偏器、第一待测波片、第二待测波片、检偏器和分光器后，经多波长光电探测器接收，接收后将数据传输给数据采集卡，数据采集卡的数据传输给计算机，所述第一待测波片和第二待测波片安装在手动控制的精密转台上。A device for measuring the phase delay spectral characteristics of a wave plate, comprising a broadband light source, the multi-wavelength continuous light emitted by it sequentially passes through a collimator, a polarizer, a first wave plate to be measured, a second wave plate to be measured, and a polarization detector After receiving the multi-wavelength photoelectric detector, the data is transmitted to the data acquisition card after receiving, and the data of the data acquisition card is transmitted to the computer. The first wave plate to be measured and the second wave plate to be measured are installed on On a manually controlled precision turntable.

一种波片相位延迟光谱特性的测量装置，包括一个宽带光源，其出射的多波长连续光依次通过准直器、起偏器、第一待测波片、第二待测波片、检偏器和分光器后，经多波长光电探测器接收；所述第一待测波片和第二待测波片均与同一电机连接、或与两个电机分别连接；所述多波长光电探测器接收的数据上传到数据采集卡中，数据采集卡将数据传输给计算机，计算机连接电机。A device for measuring the phase delay spectral characteristics of a wave plate, comprising a broadband light source, the multi-wavelength continuous light emitted by it sequentially passes through a collimator, a polarizer, a first wave plate to be measured, a second wave plate to be measured, and a polarization detector After the detector and the beam splitter, it is received by a multi-wavelength photodetector; the first wave plate to be measured and the second wave plate to be measured are connected to the same motor or connected to two motors respectively; the multi-wavelength photodetector The received data is uploaded to the data acquisition card, and the data acquisition card transmits the data to the computer, and the computer is connected to the motor.

所述光源为输出特性稳定的连续谱光源，该光源的光谱范围能覆盖待测波片的相位延迟光谱特性范围。The light source is a continuum light source with stable output characteristics, and the spectral range of the light source can cover the phase delay spectral characteristic range of the wave plate to be tested.

所述准直器采用由尾纤与自聚焦透镜精确定位而成的光纤准直器，用于将宽带光源发出的光转变成准直光。The collimator adopts a fiber optic collimator precisely positioned by a pigtail and a self-focusing lens, and is used to convert the light emitted by the broadband light source into collimated light.

所述起偏器和检偏器均采用二向色性起偏器或双折射起偏器中的一种。Both the polarizer and the analyzer use one of a dichroic polarizer or a birefringent polarizer.

所述的两个待测波片为延迟范围为0°～180°的零级波片，尤其是宽带零级波片，为由晶体材料或聚合物材料制作的真零级波片或复合零级波片。The two wave plates to be tested are zero-order wave plates with a delay range of 0° to 180°, especially broadband zero-order wave plates, which are true zero-order wave plates or composite zero-order wave plates made of crystal materials or polymer materials. wave plate.

所述分光器可采用分光棱镜或光栅等符合要求的色散型分光器，用于将多波长复合光束的波长展开，并将展开的各波长信号送入多波长光电探测器来检测。The beam splitter can adopt a dispersion type beam splitter that meets the requirements such as a beam splitting prism or a grating, which is used to expand the wavelengths of the multi-wavelength composite beam, and send the expanded wavelength signals to a multi-wavelength photodetector for detection.

所述的多波长光电探测器为多波长光电二极管阵列、光电倍增管阵列或CCD（Charge-coupled Device）线阵或面阵传感器，优选为CCD线阵或面阵传感器，用于将探测到的多波长光电流信号经数据采集卡传至计算机进行数据处理。The multi-wavelength photodetector is a multi-wavelength photodiode array, a photomultiplier tube array or a CCD (Charge-coupled Device) line array or an area sensor, preferably a CCD line array or an area array sensor, for detecting the The multi-wavelength photocurrent signal is transmitted to the computer through the data acquisition card for data processing.

所述电机及电机驱动器选用伺服电机、永磁式步进电机或反应式步进电机及其相应的驱动器。The motor and the motor driver are selected from servo motors, permanent magnet stepping motors or reactive stepping motors and their corresponding drivers.

所述第一待测波片和第二待测波片通过手动旋转或由电机带动旋转。The first wave plate to be tested and the second wave plate to be tested are rotated manually or driven by a motor.

所述计算机通过数据采集卡发出脉冲信号经电机驱动器调整电机的旋转状态。The computer sends pulse signals through the data acquisition card to adjust the rotation state of the motor through the motor driver.

一种波片相位延迟光谱特性的测量装置所采用的测量方法，主要包括如下步骤：A measuring method adopted by a measuring device of a wave plate phase delay spectral characteristic mainly comprises the following steps:

步骤一：调节第一待测波片的快轴方向与起偏器和检偏器平行，第二待测波片的快轴方向与第一待测波片垂直；Step 1: Adjust the fast axis direction of the first wave plate to be tested to be parallel to the polarizer and the polarizer, and the fast axis direction of the second wave plate to be tested to be perpendicular to the first wave plate to be tested;

步骤二：开启宽带光源，出射的连续波长的平行光束依次通过准直器、起偏器、第一和第二待测波片、检偏器和分光器后，经多波长光电探测器接收；计算机通过分析数据采集卡采集的数据控制电机带动两个待测波片以相同角速度w同向旋转；Step 2: Turn on the broadband light source, and the outgoing parallel beams of continuous wavelengths pass through the collimator, polarizer, first and second wave plates to be tested, polarizer and beam splitter in sequence, and then are received by multi-wavelength photodetectors; The computer controls the motor to drive the two wave plates to be tested to rotate in the same direction at the same angular velocity w by analyzing the data collected by the data acquisition card;

步骤三：将待测波片相对于起始位置的若干个绝对旋转角度下的光电流值采集过来，通过由相位延迟量公式和测量系统整体性能公式求出任意波长λ处第一待测波片的相位延迟量δ₁、第二待测波片的相位延迟量δ₂，以及表征该波长处测量系统整体性能的参数η，进而得到两个待测波片的相位延迟光谱特性；Step 3: Collect the photocurrent values at several absolute rotation angles of the wave plate to be measured relative to the initial position, and obtain the first wave to be measured at any wavelength λ by the phase delay formula and the overall performance formula of the measurement system The phase delay δ ₁ of the wave plate, the phase delay δ ₂ of the second wave plate to be measured, and the parameter η characterizing the overall performance of the measurement system at this wavelength, and then obtain the phase delay spectral characteristics of the two wave plates to be measured;

步骤四：根据所述测量装置的测量波长范围内的所有δ₁、δ₂和η数据，画出相应的δ₁(λ)、δ₂(λ)和η(λ)曲线，最后对所获得的曲线进行去“毛刺”的平滑处理，进一步减小误差。Step 4: Draw the corresponding δ ₁ (λ), δ ₂ (λ) and η (λ) curves according to all δ ₁ , δ ₂ and η data in the measuring wavelength range of the measuring device, and finally analyze the obtained The curve is smoothed to remove "burrs" to further reduce the error.

所述步骤三的具体步骤为：将待测波片相对于起始位置的绝对旋转角度记作α且有α=wt，t＝0的起始时刻对应于α=0，每旋转角度步长Δθ，其中0＜Δθ≤π/4；数据采集卡采集一次光电流并传给计算机，这样当电机带动待测波片旋转一周时，在每个波长处均得到至少八组光电流数据；由于在系统性能稳定的情况下，光电流I（α）关于自变量α是周期为π的周期函数；所以在任一波长处，均着重考虑α取几个特殊角度，所述特殊角度是α＝kπ，kπ＋π/4，kπ＋π/2，kπ＋3π/4处光电流I的值，k为整数且k≥0，然后由相位延迟量公式和测量系统整体性能公式求出任意波长处第一待测波片的相位延迟量δ₁、第二待测波片的相位延迟量δ₂，以及表征该波长处测量系统整体性能的参数η，进而得到两个待测波片的相位延迟光谱特性。The specific steps of said step three are: record the absolute rotation angle of the wave plate to be measured relative to the initial position as α and have α=wt, the initial moment of t=0 corresponds to α=0, and each rotation angle step Δθ, where 0<Δθ≤π/4; the data acquisition card collects a photocurrent and transmits it to the computer, so that when the motor drives the wave plate to be tested to rotate for one revolution, at least eight sets of photocurrent data are obtained at each wavelength; because In the case of stable system performance, the photocurrent I(α) is a periodic function with a period of π with respect to the independent variable α; so at any wavelength, it is important to consider that α takes several special angles, and the special angle is α=kπ , kπ+π/4, kπ+π/2, kπ+3π/4 photocurrent I value, k is an integer and k≥0, and then the first wave plate to be measured at any wavelength is obtained by the phase delay formula and the overall performance formula of the measurement system The phase delay δ ₁ of the second wave plate to be tested, the phase delay δ ₂ of the second wave plate to be tested, and the parameter η that characterizes the overall performance of the measurement system at this wavelength, and then the phase delay spectral characteristics of the two wave plates to be tested are obtained.

所述步骤三中的第一待测波片的相位延迟量δ₁、第二待测波片的相位延迟量δ₂，以及表征该波长处测量系统整体性能的参数η，如下列公式所示；The phase delay δ ₁ of the first wave plate to be measured in the step 3, the phase delay δ ₂ of the second wave plate to be measured, and the parameter η characterizing the overall performance of the measurement system at this wavelength, as shown in the following formula ;

$η η = = \frac{11}{88} \cdot &Center Dot; \{\begin{matrix} I I ((kπ kπ)) + + I I ((kπ kπ + + \frac{π π}{44})) + + I I ((kπ kπ + + \frac{π π}{22})) + + I I ((kπ kπ + + \frac{33 π π}{44})) + + \\ \sqrt{{[[I I ((kπ kπ)) + + I I ((kπ kπ + + \frac{π π}{44})) + + I I ((kπ kπ + + \frac{π π}{22})) + + I I ((kπ kπ + + \frac{33 π π}{44}))]]}^{22} - - 1616 \cdot &Center Dot; I I ((kπ kπ)) \cdot &Center Dot; I I ((kπ kπ + + \frac{π π}{22}))} \end{matrix}\}$

${δ δ}_{11} = = {cos cos}^{- - 11} [[I I ((kπ kπ + + \frac{π π}{22})) / / η η - - 11]]$

δ₂＝cos^-1[I(kπ)/η-1]。δ ₂ =cos ⁻¹ [I(kπ)/η−1].

本发明的有益效果：Beneficial effects of the present invention:

1）本发明的测量方法属于非接触测量，可同时测量两个未知宽带波片的相位延迟光谱特性，使用方便高效，既可用于测量PCSCA型椭偏仪中两个旋转波片的相位延迟谱，消除其定标不准确带来的系统误差；又可用于实际生产及研究工作中同时进行两个未知零级波片的相位延迟量的直接定标，并且测量结果不受光源和检偏器光谱特性的影响。1) The measurement method of the present invention belongs to non-contact measurement, and can measure the phase delay spectrum characteristics of two unknown broadband wave plates at the same time, which is convenient and efficient to use, and can be used to measure the phase delay spectrum of two rotating wave plates in a PCSCA type ellipsometer , to eliminate the system error caused by inaccurate calibration; it can also be used for direct calibration of the phase delay of two unknown zero-order waveplates simultaneously in actual production and research work, and the measurement results are not affected by the light source and analyzer Influence of spectral properties.

2）在多波长光电探测器中各探测单元的特性以及入射光强未知的情况下，不需要复杂的傅立叶分析及求解即能快速准确地同时标定两个待测零级波片在待考察波段的相位延迟谱；同时，还可得到测量系统在待考察波段工作性能的参数η，对该参数的分析有助于排查本发明所述测量系统的故障，以及分析、标定测量系统中各组成部件的工作性能；例如，在宽带光源的光谱特性以及各器件损耗特性已知、而多波长光电探测器光谱特性未知的情况下，可利用η（λ）特性来标定、分析多波长光电探测器的光谱特性。2) When the characteristics of each detection unit in the multi-wavelength photodetector and the incident light intensity are unknown, it can quickly and accurately calibrate the two zero-order waveplates to be tested in the wavelength band to be investigated without complicated Fourier analysis and solution. At the same time, the parameter η of the measurement system’s performance in the band to be investigated can also be obtained, and the analysis of this parameter helps to check the faults of the measurement system of the present invention, and analyze and calibrate each component in the measurement system For example, when the spectral characteristics of the broadband light source and the loss characteristics of each device are known, but the spectral characteristics of the multi-wavelength photodetector are unknown, the η (λ) characteristic can be used to calibrate and analyze the multi-wavelength photodetector. spectral properties.

3）可利用电机的正反向旋转及相应测量消除元件方位角偏差引起的测量误差，并进一步利用误差校正措施实现了任意零级波片的快速高精度测量。3) The forward and reverse rotation of the motor and the corresponding measurement can be used to eliminate the measurement error caused by the azimuth angle deviation of the component, and the error correction measures can be used to realize the fast and high-precision measurement of any zero-order wave plate.

4）本发明可同时测量两个零级波片的相位延迟光谱特性，相对于其它测量方法，所测量的零级波片相位延迟范围更广，既可以是1/4波片，也可以不是1/4波片。4) The present invention can measure the phase delay spectral characteristics of two zero-order wave plates at the same time. Compared with other measurement methods, the phase delay range of the measured zero-order wave plate is wider, which can be either a 1/4 wave plate or not 1/4 wave plate.

附图说明Description of drawings

图1为本发明所涉及的波片相位延迟光谱特性测量装置在采用电机控制待测波片旋转时的装置示意图；Fig. 1 is the schematic diagram of the device when the wave plate phase delay spectral characteristic measuring device involved in the present invention is controlled by a motor to rotate;

图2为本发明所涉及的波片相位延迟光谱特性的测量装置的通用结构示意图。FIG. 2 is a schematic diagram of the general structure of the measuring device for the phase delay spectral characteristics of the wave plate involved in the present invention.

其中，1、宽带光源，2、准直器，3、起偏器，4、第一待测波片，5、第二待测波片，6、检偏器，7、分光器，8、多波长光电探测器，9、数据采集卡，10、计算机，11、电机。Among them, 1. broadband light source, 2. collimator, 3. polarizer, 4. the first wave plate to be tested, 5. the second wave plate to be tested, 6. polarizer, 7. beam splitter, 8. Multi-wavelength photoelectric detector, 9, data acquisition card, 10, computer, 11, motor.

具体实施方式detailed description

下面结合附图与实施例对本发明作进一步说明。The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

本发明的创新点在于采用自校准方法同时实现了两个未知波片的相位延迟光谱特性的实时测量。其具体实施方式如下：The innovation of the present invention is that the self-calibration method is adopted to simultaneously realize the real-time measurement of the phase delay spectral characteristics of two unknown wave plates. Its specific implementation is as follows:

首先，本发明需要搭建波片相位延迟光谱特性的测量装置，然后通过自校准方法和正反向测量法等技术方案实现本发明的目的。First of all, the present invention needs to build a measuring device for the phase delay spectral characteristics of the wave plate, and then achieve the purpose of the present invention through technical solutions such as self-calibration method and forward and reverse measurement method.

如图1所示，一种波片相位延迟光谱特性的测量装置，包括一个宽带光源1，其出射的多波长连续光依次通过准直器2、起偏器3、第一待测波片4、第二待测波片5、检偏器6和分光器7后，经多波长光电探测器8接收；所述第一待测波片4和第二待测波片5与电机11连接，所述多波长光电探测器8接收的数据上传到数据采集卡9中，数据采集卡9将数据传输给计算机10，计算机10控制电机11。As shown in Figure 1, a device for measuring the phase delay spectral characteristics of a wave plate includes a broadband light source 1, and the multi-wavelength continuous light emitted by it passes through a collimator 2, a polarizer 3, and a first wave plate to be measured 4 in sequence , after the second wave plate 5 to be measured, the polarizer 6 and the beam splitter 7, it is received by a multi-wavelength photodetector 8; the first wave plate 4 to be measured and the second wave plate 5 to be measured are connected to the motor 11, The data received by the multi-wavelength photodetector 8 is uploaded to the data acquisition card 9, and the data acquisition card 9 transmits the data to the computer 10, and the computer 10 controls the motor 11.

如图2所示，一种波片相位延迟光谱特性的测量装置，包括一个宽带光源1，其出射的多波长连续光依次通过准直器2、起偏器3、第一待测波片4、第二待测波片5、检偏器6和分光器7后，经多波长光电探测器8接收，所述第一待测波片4和第二待测波片5安装在手动控制的精密转台上。所述多波长光电探测器8接收的数据上传到数据采集卡9中，数据采集卡9将数据传输给计算机10。As shown in Figure 2, a device for measuring the phase delay spectral characteristics of a wave plate includes a broadband light source 1, and the multi-wavelength continuous light emitted by it passes through a collimator 2, a polarizer 3, and a first wave plate to be measured 4 in sequence , the second wave plate to be measured 5, the polarizer 6 and the beam splitter 7, after receiving by the multi-wavelength photodetector 8, the first wave plate to be measured 4 and the second wave plate to be measured 5 are installed in a manually controlled on a precision turntable. The data received by the multi-wavelength photodetector 8 is uploaded to the data acquisition card 9 , and the data acquisition card 9 transmits the data to the computer 10 .

所述的准直器2可采用由尾纤与自聚焦透镜精确定位而成的光纤准直器等一切可以将宽带光源1发出的光转变成准直光(平行光)功能的光器件。The collimator 2 can be any optical device capable of converting the light emitted by the broadband light source 1 into collimated light (parallel light), such as a fiber optic collimator precisely positioned by a pigtail and a self-focusing lens.

所述宽带光源1为输出特性稳定的连续谱光源，该光源的光谱范围能覆盖待测波片的相位延迟光谱范围。The broadband light source 1 is a continuum light source with stable output characteristics, and the spectral range of the light source can cover the phase delay spectral range of the wave plate to be tested.

所述的起偏器3和检偏器6均采用二向色性起偏器或双折射起偏器中的一种。Both the polarizer 3 and the analyzer 6 use one of a dichroic polarizer or a birefringent polarizer.

所述的多波长光电探测器8为多波长光电二极管阵列、光电倍增管阵列或CCD线阵或面阵传感器，优选为CCD线阵或面阵传感器。The multi-wavelength photodetector 8 is a multi-wavelength photodiode array, a photomultiplier tube array or a CCD line or area array sensor, preferably a CCD line or area array sensor.

所述电机11选用伺服电机、永磁式步进电机或反应式步进电机及其相应的驱动器。The motor 11 is a servo motor, a permanent magnet stepping motor or a reactive stepping motor and its corresponding driver.

所述分光器7可采用分光棱镜或光栅等符合要求的色散型分光器，用于将多波长复合光束的波长展开，并将展开的各波长信号送入探测器阵列来检测。The beam splitter 7 can be a dispersion type beam splitter that meets requirements such as a beam splitting prism or a grating, and is used to expand the wavelengths of the multi-wavelength composite light beam, and send the expanded wavelength signals to the detector array for detection.

所述的两个待测波片的旋转，除采用电机11控制外，亦可通过手动或其它方式实现。The rotation of the two wave plates to be tested can be realized manually or in other ways besides being controlled by the motor 11 .

所述计算机10及数据采集卡9采用的类型及型号不限，相互匹配即可。The types and models of the computer 10 and the data acquisition card 9 are not limited, as long as they match each other.

所述的计算机10通过数据采集卡9采集、计算数据，并发送脉冲信号到两个电机11的驱动器以控制电机11以固定步长旋转波片。The computer 10 collects and calculates data through the data acquisition card 9, and sends pulse signals to the drivers of the two motors 11 to control the motors 11 to rotate the wave plate with a fixed step.

本发明的工作原理及工作过程具体如下：Operating principle and working process of the present invention are specifically as follows:

步骤一：将第一待测波片4和第二待测波片5依次置于透振方向平行放置的起偏器3和检偏器6的光路之中，调节第一待测波片4的快轴方向与起偏器3和检偏器6平行，第二待测波片5的快轴方向与第一待测波片4垂直；Step 1: Place the first wave plate to be tested 4 and the second wave plate to be tested 5 in sequence in the optical path of the polarizer 3 and the analyzer 6 placed parallel to the vibration transmission direction, and adjust the first wave plate to be tested 4 The fast axis direction of the polarizer 3 and the polarizer 6 are parallel, and the fast axis direction of the second wave plate 5 to be measured is perpendicular to the first wave plate 4 to be measured;

步骤二：开启宽带光源1，出射的连续波长的平行光束依次通过准直器2、起偏器3、第一待测波片4和第二待测波片5、检偏器6和分光镜后，经多波长光电探测器8接收；计算机10通过数据采集卡9控制电机11带动两个待测波片以相同角速度w同向旋转，将波片相对于起始位置的绝对旋转角度记作α且有α=wt（t＝0的起始时刻对应于α=0），每旋转角度步长Δθ，数据采集卡9采集一次光电流并传给计算机10，其中0＜Δθ≤π/4；这样当电机11带动待测波片旋转一周时，在每个波长处均可得到至少八组光电流数据。根据偏振光学的相关理论，图1或图2所示装置中的输入与输出光信号的Stokes表示，即S_in和S_out之间满足以下关系：Step 2: Turn on the broadband light source 1, and the outgoing parallel beams of continuous wavelength pass through the collimator 2, the polarizer 3, the first wave plate 4 to be tested, the second wave plate 5 to be tested, the analyzer 6 and the beam splitter Finally, it is received by the multi-wavelength photodetector 8; the computer 10 controls the motor 11 through the data acquisition card 9 to drive the two wave plates to be tested to rotate in the same direction at the same angular velocity w, and the absolute rotation angle of the wave plate relative to the initial position is recorded as α and α=wt (the initial moment of t=0 corresponds to α=0), every rotation angle step Δθ, the data acquisition card 9 collects a photocurrent and transmits it to the computer 10, where 0<Δθ≤π/4 ; In this way, when the motor 11 drives the wave plate to be tested to rotate for one revolution, at least eight groups of photocurrent data can be obtained at each wavelength. According to the relevant theory of polarization optics, the Stokes representation of the input and output optical signals in the device shown in Figure 1 or Figure 2, that is, the relationship between S _in and S _out satisfies the following relationship:

S_out＝M_AR(-C₂)M_C2(δ₂)R(C₂)R(-C₁)M_C1(δ₁)R(C₁)M_pS_in S _out ＝M _A R(-C ₂ )M _C2 (δ ₂ )R(C ₂ )R(-C ₁ )M _C1 (δ ₁ )R(C ₁ )M _p S _in

$= = (\begin{matrix} 11 & 11 & 00 & 00 \\ 11 & 11 & 00 & 00 \\ 00 & 00 & 00 & 00 \\ 00 & 00 & 00 & 00 \end{matrix}) \cdot &Center Dot; (\begin{matrix} 11 & 00 & 00 & 00 \\ 00 & cos cos {C C}_{22} & - - sin sin {C C}_{22} & 00 \\ 00 & sin sin {C C}_{22} & cos cos {C C}_{22} & 00 \\ 00 & 00 & 00 & 11 \end{matrix}) \cdot \cdot (\begin{matrix} 11 & 00 & 00 & 00 \\ 00 & 11 & 00 & 00 \\ 00 & 00 & cos cos {δ δ}_{22} & sin sin {δ δ}_{22} \\ 00 & 00 & - - sin sin {δ δ}_{22} & cos cos {δ δ}_{22} \end{matrix}) \cdot \cdot (\begin{matrix} 11 & 00 & 00 & 00 \\ 00 & cos cos {C C}_{22} & sin sin {C C}_{22} & 00 \\ 00 & - - sin sin {C C}_{22} & cos cos {C C}_{22} & 00 \\ 00 & 00 & 00 & 11 \end{matrix}) \cdot \cdot - - - - - - ((11))$

$\cdot &Center Dot; (\begin{matrix} 11 & 00 & 00 & 00 \\ 00 & cos cos {C C}_{11} & - - sin sin {C C}_{11} & 00 \\ 00 & sin sin {C C}_{11} & cos cos {C C}_{11} & 00 \\ 00 & 00 & 00 & 11 \end{matrix}) \cdot &Center Dot; (\begin{matrix} 11 & 00 & 00 & 00 \\ 00 & 11 & 00 & 00 \\ 00 & 00 & cos cos {δ δ}_{11} & sin sin {δ δ}_{11} \\ 00 & 00 & - - sin sin {δ δ}_{11} & cos cos {δ δ}_{11} \end{matrix}) \cdot &Center Dot; \begin{matrix} (\begin{matrix} 11 & 00 & 00 & 00 \\ 00 & cos cos {C C}_{11} & sin sin {C C}_{11} & 00 \\ 00 & - - sin sin {C C}_{11} & cos cos {C C}_{11} & 00 \\ 00 & 00 & 00 & 11 \end{matrix}) \cdot \cdot (\begin{matrix} 11 & 11 & 00 & 00 \\ 11 & 11 & 00 & 00 \\ 00 & 00 & 00 & 00 \\ 00 & 00 & 00 & 00 \end{matrix}) \cdot &Center Dot; (\begin{matrix} {S S}_{00} \\ {S S}_{11} \\ {S S}_{22} \\ {S S}_{33} \end{matrix}) \end{matrix}$

公式（1）中，M_P、M_A、M_C1、M_C2分别为起偏器3、检偏器6、第一待测波片4和第二待测波片5的穆勒矩阵；R(C₁)、R(C₂)、R(-C₁)和R(-C₂)为第一待测波片4、第二待测波片5旋转时所对应的坐标变换矩阵，δ₁为第一待测波片4的相位延迟量，δ₂为第二待测波片5的相位延迟量。由于第一待测波片4的快轴方向与起偏器3、检偏器6的透振方向相互平行（均为0）,第二待测波片5的快轴方向与第一待测波片4垂直，且两者以相同角速度w同向旋转，第一待测波片4的旋转角度C₁=wt=α,第二待测波片5的旋转角度C₂=π/2＋α,（w为波片旋转的角速度，t表示测量时间，测量起始时刻t＝0对应于α＝0），则输出光信号的Stokes表达式可进一步化为：In formula (1), M _P , M _A , M _C1 , and M _C2 are the Mueller matrices of the polarizer 3, the analyzer 6, the first wave plate 4 to be tested, and the second wave plate 5 to be tested, respectively; R (C ₁ ), R(C ₂ ), R(-C ₁ ) and R(-C ₂ ) are the corresponding coordinate transformation matrices when the first wave plate 4 to be measured and the second wave plate 5 to be measured rotate, δ ₁ is the phase delay of the first wave plate 4 to be tested, and δ ₂ is the phase delay of the second wave plate 5 to be tested. Since the fast axis direction of the first wave plate 4 to be tested is parallel to the vibration transmission directions of the polarizer 3 and the analyzer 6 (both are 0), the fast axis direction of the second wave plate 5 to be tested is parallel to the direction of the first wave plate to be tested. The wave plate 4 is vertical, and both rotate at the same angular velocity w in the same direction, the rotation angle C ₁ =wt=α of the first wave plate 4 to be measured, and the rotation angle C ₂ =π/2+α of the second wave plate 5 to be measured, (w is the angular velocity of the wave plate rotation, t is the measurement time, and the measurement start time t=0 corresponds to α=0), then the Stokes expression of the output optical signal can be further transformed into:

${S S}_{out out} = = (\begin{matrix} A A & A A & 00 & 00 \\ A A & A A & 00 & 00 \\ 00 & 00 & 00 & 00 \\ 00 & 00 & 00 & 00 \end{matrix}) \cdot \cdot (\begin{matrix} {S S}_{00} \\ {S S}_{11} \\ {S S}_{22} \\ {S S}_{33} \end{matrix}) = = B B \cdot &Center Dot; (\begin{matrix} {S S}_{00} + + {S S}_{11} \\ {S S}_{00} + + {S S}_{11} \\ 00 \\ 00 \end{matrix}) - - - - - - ((22))$

其中B是α和δ₁、δ₂的函数，其具体表达式如下：Where B is a function of α and δ ₁ , δ ₂ , and its specific expression is as follows:

$B B ((α α,, {δ δ}_{11},, {δ δ}_{22})) = = 11 + + (({sin sin}^{22} α α + + {cos cos}^{22} α α \cdot &Center Dot; cos cos {δ δ}_{22})) \cdot &Center Dot; (({cos cos}^{22} α α + + {sin sin}^{22} α α \cdot &Center Dot; cos cos {δ δ}_{11}))$

$+ + [[\frac{11}{44} \cdot &Center Dot; {sin sin}^{22} 22 α α \cdot \cdot ((11 - - cos cos {δ δ}_{11})) \cdot \cdot ((11 - - cos cos {δ δ}_{22}))]] - - \frac{11}{22} sin sin 22 α α \cdot &Center Dot; sin sin {δ δ}_{11} \cdot \cdot sin sin {δ δ}_{22} - - - - - - ((33))$

由于在任意波长处，本发明所述测量装置的接收端光电探测器单元的输出光电流正比于该波长处输出光信号S₀分量的光强，即Because at any wavelength, the output photocurrent of the photodetector unit at the receiving end of the measuring device of the present invention is proportional to the light intensity of the output optical signal _S0 component at this wavelength, i.e.

$I I ((α α)) = = \frac{11}{44} \cdot &Center Dot; K K \cdot \cdot (({S S}_{00} + + {S S}_{11})) \cdot \cdot B B ((α α,, {δ δ}_{11},, {δ δ}_{22}))$

$= = \frac{11}{22} \cdot \cdot K K \cdot &Center Dot; {| | {E E.}_{p p} | |}^{22} \cdot &Center Dot; B B ((α α,, {δ δ}_{11},, {δ δ}_{22})) - - - - - - ((44))$

$\begin{matrix} = = η η \cdot &Center Dot; B B ((α α,, {δ δ}_{11},, {δ δ}_{22})) & η η = = \frac{11}{22} \cdot &Center Dot; K K \cdot &Center Dot; {| | {E E.}_{p p} | |}^{22} \end{matrix}$

其中K为考虑探测器量子效率等因素影响而引入的小于1的比例系数，E_p为检偏器6透振方向的光振幅。此处光电流I实际上是α，δ₁，δ₂以及波长λ的函数，为后续公式（6.a～6.d）以及（7.a～7.c）表示的方便，此处简写为I(α)。由此可见，探测器的输出光电流与测量装置接收端光信号的光强度（该光强由测量装置各器件的损耗以及光源的光谱特性等因素决定）、以及探测器本身的量子效率等特性直接相关。由于本发明涉及的实际测量装置中各组成器件均存在一定的插入损耗，而且该损耗以及实际宽带光源1的光谱特性可能并不平坦，所以很难通过简单的理论计算直接得到各波长处的E_p值（但这些影响因素几乎不随时间推移发生变化）。而对于实际的探测器件而言，其输出光电流的光谱响应曲线也并不平坦，即K值随波长变化而变。以当前国际主流的Hamamatsu公司紫外面阵CCD的光谱响应曲线（无玻璃视窗，25℃）为例，在200nm-400nm的波长范围内，量子效率在35-65％范围内变化。据此由公式（4）中的可知，很难通过各器件的指标直接获得一个准确的η值。所以在测量两个待测波片相位延迟光谱特性的过程中，如果能避开η的影响，直接测得δ₁、δ₂最为理想；当然，如果能同时测得η，并用它来进一步分析测量装置的工作状态及排查故障，更是一举多得。为此进一步研究公式（4）和（5），可得以下规律性公式：Wherein K is a proportionality coefficient less than 1 introduced considering the influence of factors such as the quantum efficiency of the detector, and E _p is the light amplitude in the transmission direction of the polarizer 6 . Here, the photocurrent I is actually a function of α, δ ₁ , δ ₂ and wavelength λ, which is convenient for the following formulas (6.a～6.d) and (7.a～7.c), here abbreviated as is I(α). It can be seen that the output photocurrent of the detector and the light intensity of the optical signal at the receiving end of the measuring device (the light intensity is determined by factors such as the loss of each device of the measuring device and the spectral characteristics of the light source), and the quantum efficiency of the detector itself D. Since there is a certain insertion loss in each component device in the actual measurement device involved in the present invention, and the loss and the spectral characteristics of the actual broadband light source 1 may not be flat, it is difficult to directly obtain the E at each wavelength through simple theoretical calculations. _p -values (but these influences hardly change over time). As for the actual detection device, the spectral response curve of the output photocurrent is not flat, that is, the K value changes with the wavelength. Taking the spectral response curve (without glass window, 25°C) of the current international mainstream Hamamatsu UV CCD as an example, in the wavelength range of 200nm-400nm, the quantum efficiency varies in the range of 35-65%. According to the formula (4) in It can be seen that it is difficult to directly obtain an accurate η value through the indicators of each device. Therefore, in the process of measuring the phase delay spectral characteristics of the two wave plates to be tested, if the influence of η can be avoided, it is ideal to measure δ ₁ and δ ₂ directly; of course, if η can be measured at the same time, and use it for further analysis Measuring the working status of the device and troubleshooting can serve multiple purposes. For this reason, formulas (4) and (5) are further studied, and the following regularity formulas can be obtained:

B(α,δ₁,δ₂)＝B(kπ+α,δ₁,δ₂)＝I(α)/η＝I(kπ+α)/η （5）B(α,δ ₁ ,δ ₂ )=B(kπ+α,δ ₁ ,δ ₂ )=I(α)/η=I(kπ+α)/η (5)

这表明在系统性能稳定的情况下，在任意一个确定的波长处，光电流I（α）和B（α，δ₁，δ₂）关于自变量α均是周期为π的函数（k为整数且k≥0），而且在几个特殊角度有如下关系出现：This shows that in the case of stable system performance, at any certain wavelength, the photocurrents I(α) and B(α, δ ₁ , δ ₂ ) are functions of period π with respect to the independent variable α (k is an integer and k≥0), and in several special angles, the following relationship appears:

B(0,δ₁,δ₂)＝B(kπ,δ₁,δ₂)＝I(0)/η＝1+cosδ₂ （6.a）B(0,δ ₁ ,δ ₂ )=B(kπ,δ ₁ ,δ ₂ )=I(0)/η=1+cosδ ₂ (6.a)

$B B ((\frac{π π}{22},, {δ δ}_{11},, {δ δ}_{22})) = = B B ((kπ kπ + + \frac{π π}{22},, {δ δ}_{11},, {δ δ}_{22})) = = I I ((\frac{π π}{22})) / / η η = = 11 + + cos cos {δ δ}_{11} - - - - - - ((66 . . b b))$

$B B ((\frac{π π}{44},, {δ δ}_{11},, {δ δ}_{22})) = = B B ((kπ kπ + + \frac{π π}{44},, {δ δ}_{11},, {δ δ}_{22})) = = I I ((\frac{π π}{44})) / / η η = = \frac{33}{22} + + \frac{11}{22} cos cos (({δ δ}_{11} + + {δ δ}_{22})) - - - - - - ((66 . . c c))$

$B B ((\frac{33 π π}{44},, {δ δ}_{11},, {δ δ}_{22})) = = B B ((kπ kπ + + \frac{33 π π}{44},, {δ δ}_{11},, {δ δ}_{22})) = = I I ((\frac{33 π π}{44})) / / η η = = \frac{33}{22} + + \frac{11}{22} cos cos (({δ δ}_{11} - - {δ δ}_{22})) - - - - - - ((66 . . d d))$

所以本发明所述测量方法的出发点就是测量在任一波长处α为几个特殊角度（如α＝kπ，kπ＋π/4，kπ＋π/2，kπ＋3π/4时）的光电流数值（k为整数且k≥0），然后由公式（6.a～6.d）求出该波长处第一待测波片4的相位延迟量δ₁、第二待测波片5的相位延迟量δ₂，以及表征该波长处测量系统整体性能的参数η，如公式（7.a～7.c）所示。Therefore, the starting point of the measurement method of the present invention is to measure the photocurrent value (k is an integer and k is an integer and k ≥0), and then calculate the phase delay δ 1 of the first wave plate to be tested 4 and the phase delay δ ₂ of the _second wave plate to be tested 5 at the wavelength by the formula (6.a~6.d), and The parameter η that characterizes the overall performance of the measurement system at this wavelength is shown in formulas (7.a~7.c).

$η η = = \frac{11}{88} \cdot \cdot \{\begin{matrix} I I ((kπ kπ)) + + I I ((kπ kπ + + \frac{π π}{44})) + + I I ((kπ kπ + + \frac{π π}{22})) + + I I ((kπ kπ + + \frac{33 π π}{44})) + + \\ \sqrt{{[[I I ((kπ kπ)) + + I I ((kπ kπ + + \frac{π π}{44})) + + I I ((kπ kπ + + \frac{π π}{22})) + + I I ((kπ kπ + + \frac{33 π π}{44}))]]}^{22} - - 1616 \cdot &Center Dot; I I ((kπ kπ)) \cdot &Center Dot; I I ((kπ kπ + + \frac{π π}{22}))} \end{matrix}\} - - - - - - ((77 . . a a))$

${δ δ}_{11} = = {cos cos}^{- - 11} [[I I ((kπ kπ + + \frac{π π}{22})) / / η η - - 11]] - - - - - - ((77 . . b b))$

δ₂＝cos^-1[I(kπ)/η-1] （7.c）δ ₂ =cos ^-1 [I(kπ)/η-1] (7.c)

步骤三：考虑到测量误差的影响，在同一波长处可多计算几组δ₁、δ₂和η数据，并分别取其均值。最后，可根据本发明所述测量装置的测量波长范围内的所有δ₁、δ₂和η数据，画出相应的δ₁(λ)、δ₂(λ)和η(λ)曲线，最后设置一定的算法规则，对所获得的曲线进行去“毛刺”的平滑处理，进一步减小误差。Step 3: Considering the influence of measurement error, several sets of δ ₁ , δ ₂ and η data can be calculated at the same wavelength, and their average values can be taken respectively. Finally, according to all δ ₁ , δ ₂ and η data in the measurement wavelength range of the measuring device of the present invention, draw the corresponding δ ₁ (λ), δ ₂ (λ) and η (λ) curves, and finally set Certain algorithm rules are used to smooth the obtained curve to further reduce the error.

本发明所述测量方法的具体算法流程举例如下：The specific algorithm flow of the measurement method of the present invention is exemplified as follows:

首先，按照上述测量步骤配置好本发明所述的测量系统，并打开光源和系统其它各组成部件。然后，等系统各部件稳定后，即可开始进行测量。设定波片旋转角度步长为π/4；首先在测量起始时刻读取各波长处的I(0)；然后将两个待测波片均转动π/4，读取各波长处的I(π/4)；再将两个待测波片转动π/4，读取各波长处的I(π/2)；以此类推，在波片从起始时刻开始旋转一周的情况下，随后可依次得到各波长处的I(3π/4)、I(π)、I(5π/4)、I(3π/2)、I(7π/4)和I(2π)。为消除两待测波片旋转角度偏差等的影响，发送驱动信号让波片反转一周，分别依次得到各波长处的I′(7π/4)、I′(3π/2)、I′(5π/4)、I′(π)、I′(3π/4)、I′(π/2)、I′(π/4)和I′(0)。为进一步减小误差，可分别计算各波长处光电流的如下方均根值AvaI(π)、AvaI(π/4)、AvaI(3π/4)、AvaI(π/2)，然后由公式（7.a～7.c）求出相应的δ₁、δ₂和η数据并保存到计算机10。最后，画出本发明所述测量装置的测量波长范围内的δ1（λ）、δ2（λ）和η（λ）曲线，并进行曲线拟合，对所获得的曲线进行去“毛刺”的平滑处理，进一步减小误差，保存数据并结束操作。First, configure the measurement system of the present invention according to the above measurement steps, and turn on the light source and other components of the system. Then, once the system components have stabilized, measurements can begin. Set the wave plate rotation angle step to π/4; first read the I(0) at each wavelength at the beginning of the measurement; then turn the two wave plates to be measured by π/4, and read the I(0) at each wavelength I(π/4); then rotate the two waveplates to be tested by π/4, and read the I(π/2) at each wavelength; and so on, when the waveplate rotates a circle from the initial moment , and then I(3π/4), I(π), I(5π/4), I(3π/2), I(7π/4) and I(2π) at each wavelength can be obtained sequentially. In order to eliminate the influence of the rotation angle deviation of the two wave plates to be measured, etc., the driving signal is sent to make the wave plate reverse one cycle, and the I′(7π/4), I′(3π/2), I′( 5π/4), I'(π), I'(3π/4), I'(π/2), I'(π/4), and I'(0). In order to further reduce the error, the following root mean value AvaI(π), AvaI(π/4), AvaI(3π/4), AvaI(π/2) of the photocurrent at each wavelength can be calculated respectively, and then by the formula (7. a~7.c) Calculate the corresponding δ ₁ , δ ₂ and η data and save them in the computer 10 . Finally, draw the δ1 (λ), δ2 (λ) and η (λ) curves within the measurement wavelength range of the measuring device of the present invention, and perform curve fitting, and smooth the obtained curves by deburring Processing, to further reduce the error, save the data and end the operation.

$AvaI AvaI ((π π)) = = \sqrt{\frac{{[[I I ((00))]]}^{22} + + {[[I I ((π π))]]}^{22} + + {[[I I ((22 π π))]]}^{22} + + {[[{I I}^{' '} ((π π))]]}^{22} + + {[[{I I}^{' '} ((00))]]}^{22}}{55}}$

$AvaI AvaI ((\frac{π π}{44})) = = \sqrt{\frac{{[[I I ((\frac{π π}{44}))]]}^{22} + + {[[I I ((\frac{55 π π}{44}))]]}^{22} + + {[[{I I}^{' '} ((\frac{55 π π}{44}))]]}^{22} + + {[[{I I}^{' '} ((\frac{π π}{44}))]]}^{22}}{44}}$

$AvaI AvaI ((\frac{33 π π}{44})) = = \sqrt{\frac{{[[I I ((\frac{33 π π}{44}))]]}^{22} + + {[[I I ((\frac{77 π π}{44}))]]}^{22} + + {[[{I I}^{' '} ((\frac{77 π π}{44}))]]}^{22} + + {[[{I I}^{' '} ((\frac{33 π π}{44}))]]}^{22}}{44}}$

$AvaI AvaI ((\frac{π π}{22})) = = \sqrt{\frac{{[[I I ((\frac{π π}{22}))]]}^{22} + + {[[I I ((\frac{33 π π}{22}))]]}^{22} + + {[[{I I}^{' '} ((\frac{33 π π}{22}))]]}^{22} + + {[[{I I}^{' '} ((\frac{π π}{22}))]]}^{22}}{44}}$

实际上，此处究竟是否需要绘制及拟合η（λ）曲线可视具体需要而定。因为对该参数的分析主要是为了排查本发明所述测量系统的故障，以及分析、标定测量系统中各组成部件的工作性能。例如，在宽带光源1的光谱特性以及各器件损耗特性已知、而多波长光电探测器8光谱特性未知的情况下，可利用η（λ）曲线和公式（4）来标定、分析多波长光电探测器8的光谱特性。In fact, whether it is necessary to draw and fit the η(λ) curve here depends on the specific needs. Because the analysis of this parameter is mainly to troubleshoot the faults of the measurement system of the present invention, and to analyze and calibrate the working performance of each component in the measurement system. For example, when the spectral characteristics of the broadband light source 1 and the loss characteristics of each device are known, but the spectral characteristics of the multi-wavelength photodetector 8 are unknown, the η (λ) curve and formula (4) can be used to calibrate and analyze the multi-wavelength photoelectric Spectral properties of detector 8.

利用本发明所述的波片光谱特性的测量方法，还可直接在PCSCA型椭偏仪中实现两个宽带1/4波片相位延迟光谱特性的自测量。首先，将PCSCA型椭偏仪设置为直通模式，调节第一待测波片4的初始方位角α（快轴方向）与起偏器3和检偏器6平行（α＝0），第二待测波片5的初始方位角与第一待测波片4垂直，且两者同速、等步长同向旋转；在任一波长处，均着重考虑α取几个特殊角度，如α＝kπ，kπ＋π/4，kπ＋π/2，kπ＋3π/4时的光电流数值（k为整数且k≥0），然后由公式求出任意波长处第一待测波片4的相位延迟量δ₁、第二待测波片5的相位延迟量δ₂，以及表征该波长处测量系统整体性能的参数η，进而得到两个待测波片的相位延迟光谱特性。Using the method for measuring the spectral characteristics of the wave plate of the present invention, the self-measurement of the phase delay spectral characteristics of two broadband 1/4 wave plates can also be directly realized in the PCSCA type ellipsometer. Firstly, set the PCSCA ellipsometer to the straight-through mode, adjust the initial azimuth angle α (fast axis direction) of the first wave plate to be measured 4 to be parallel to the polarizer 3 and the analyzer 6 (α=0), the second The initial azimuth angle of the wave plate 5 to be measured is perpendicular to the first wave plate 4 to be measured, and the two rotate at the same speed and at the same step length; at any wavelength, several special angles for α are emphatically considered, such as α= kπ, kπ+π/4, kπ+π/2, kπ+3π/4 photocurrent value (k is an integer and k≥0), and then calculate the phase delay δ ₁ and The phase delay δ ₂ of the second wave plate to be measured 5 and the parameter η characterizing the overall performance of the measurement system at this wavelength are used to obtain the phase delay spectral characteristics of the two wave plates to be measured.

本发明在具体实施时还要注意保证本发明所述测量系统中所有光学元器件（如宽带光源1、起偏器3、检偏器6、多波长光电探测器8等）的工作波长范围能够覆盖待测波片的工作波长范围。这在实际应用中比较容易实现。以椭偏仪中经常采用的波片为例，该类波片的工作波长基本都在200nm～1100nm范围之内，为此可采用工作波长在190nm～2500nm、配有高精度稳压电源的氙灯作为宽带光源1；采用工作波长为200～2300nm的石英渥拉斯顿棱镜作为起偏器3和检偏器6；采用工作波长为200～1100nm的背照式面阵CCD（例如滨松FFT-CCD探测器）作为多波长光电探测器8；等等。When the present invention is implemented, attention should also be paid to ensuring that the working wavelength range of all optical components (such as broadband light source 1, polarizer 3, polarizer 6, multi-wavelength photodetector 8, etc.) in the measurement system of the present invention can Covers the operating wavelength range of the waveplate to be tested. This is relatively easy to achieve in practical applications. Taking the wave plate often used in ellipsometer as an example, the operating wavelength of this type of wave plate is basically within the range of 200nm to 1100nm. For this purpose, a xenon lamp with a working wavelength of 190nm to 2500nm and a high-precision regulated power supply can be used. As a broadband light source 1; a quartz Wollaston prism with a working wavelength of 200-2300nm is used as a polarizer 3 and an analyzer 6; a back-illuminated area CCD with a working wavelength of 200-1100nm (such as Hamamatsu FFT- CCD detector) as a multi-wavelength photodetector 8; and so on.

上述虽然结合附图对本发明的具体实施方式进行了描述，但并非对本发明保护范围的限制，所属领域技术人员应该明白，在本发明的技术方案的基础上，本领域技术人员不需要付出创造性劳动即可做出的各种修改或变形仍在本发明的保护范围以内。Although the specific implementation of the present invention has been described above in conjunction with the accompanying drawings, it does not limit the protection scope of the present invention. Those skilled in the art should understand that on the basis of the technical solution of the present invention, those skilled in the art do not need to pay creative work Various modifications or variations that can be made are still within the protection scope of the present invention.

Claims

1. The measuring method of wave plate phase retardation spectral characteristic is characterized in that, mainly comprises the following steps:

Step 1: Adjust the fast axis direction of the first wave plate to be tested to be parallel to the polarizer and the polarizer, and the fast axis direction of the second wave plate to be tested to be perpendicular to the first wave plate to be tested;

Step 2: Turn on the broadband light source, and the outgoing parallel beams of continuous wavelengths pass through the collimator, polarizer, first and second wave plates to be tested, polarizer and beam splitter in sequence, and then are received by multi-wavelength photodetectors; The computer controls the motor to drive the two wave plates to be tested to rotate in the same direction at the same angular velocity w by analyzing the data collected by the data acquisition card;

Step 3: Collect the photocurrent values at several absolute rotation angles of the wave plate to be measured relative to the initial position, and obtain the first value to be measured at any wavelength λ by using the phase delay formula and the formula for measuring the overall performance of the system. The phase delay δ ₁ of the wave plate, the phase delay δ ₂ of the second wave plate to be measured, and the parameter η characterizing the overall performance of the measurement system at this wavelength, and then obtain the phase delay spectral characteristics of the two wave plates to be measured;

The phase delay δ ₁ of the first wave plate to be measured in the step 3, the phase delay δ ₂ of the second wave plate to be measured, and the parameter η characterizing the overall performance of the measurement system at this wavelength, as shown in the following formula ;

η η = = \frac{11}{88} \cdot &Center Dot; \{\begin{matrix} I I ((kπ kπ)) + + I I ((kπ kπ + + \frac{π π}{44})) + + I I ((kπ kπ + + \frac{π π}{22})) + + I I ((kπ kπ + + \frac{33 π π}{44})) + + \\ \sqrt{{[[I I ((kπ kπ)) + + I I ((kπ kπ + + \frac{π π}{44})) + + I I ((kπ kπ + + \frac{π π}{22})) + + I I ((kπ kπ + + \frac{33 π π}{44}))]]}^{22} - - 1616 \cdot \cdot I I ((kπ kπ)) \cdot &Center Dot; I I ((kπ kπ + + \frac{π π}{22}))} \end{matrix}\}

{δ δ}_{11} = = {cos cos}^{- - 11} [[I I ((kπ kπ + + \frac{π π}{22})) / / η η - - 11]]

δ ₂ =cos ^-1 [I(kπ)/η-1];

Step 4: Draw the corresponding δ ₁ (λ), δ ₂ (λ) and η (λ) curves according to all δ ₁ , δ ₂ and η data in the measuring wavelength range of the measuring device, and finally analyze the obtained The curve is smoothed to remove "burrs" to further reduce the error.

2. the measuring method of a kind of wave plate phase delay spectrum characteristic as claimed in claim 1, it is characterized in that, the specific step of described step 3 is: write the absolute rotation angle of wave plate to be measured with respect to starting position as α and α=wt, the initial moment of t=0 corresponds to α=0; every rotation angle step Δθ, where 0<Δθ≤π/4, the data acquisition card collects the photocurrent once and transmits it to the computer, so when When the motor drives the wave plate to be tested to rotate for one revolution, at least eight sets of photocurrent data are obtained at each wavelength; because in the case of stable system performance, the photocurrent I(α) is a periodic function with a period of π with respect to the independent variable α ; so at any wavelength place, all emphatically consider α to take the value of photoelectric current I of several special angles, and described special angle is α=kπ, kπ+π/4, kπ+π/2, kπ+3π/4, wherein k is an integer and k≥0, then calculate the phase delay δ ₁ of the first wave plate to be measured and the phase delay δ of the second wave plate to be measured at any wavelength by the phase delay formula and the formula for measuring the overall performance of the system ₂ , and the parameter η that characterizes the overall performance of the measurement system at this wavelength, and then obtain the phase delay spectral characteristics of the two waveplates to be measured.

3. The measuring device adopted by the method according to claim 1, characterized in that, comprising a broadband light source, the multi-wavelength continuous light of its emission passes through collimator, polarizer, the first wave plate to be measured, the first wave plate successively After the wave plate to be measured, the polarizer and the beam splitter, the multi-wavelength photodetector receives the data, and after receiving, the data is transmitted to the data acquisition card, and the data of the data acquisition card is transmitted to the computer. The first wave plate to be measured and The second wave plate to be tested is mounted on a manually controlled precision turntable.

4. The measuring device adopted by the method as claimed in claim 1, comprising a broadband light source, the multi-wavelength continuous light of its emission passes through collimator, polarizer, first wave plate to be measured, second wave plate to be measured successively after the multi-wavelength photodetector; the first wave plate to be measured and the second wave plate to be measured are all connected to the same motor, or connected to two motors respectively; The data received by the wavelength photodetector is uploaded to the data acquisition card, and the data acquisition card transmits the data to the computer, and the computer controls the motor.

5. The measuring device according to claim 3 or 4, characterized in that,

The two wave plates to be tested are zero-order wave plates with a delay range of 0° to 180°, and the zero-order wave plates are true zero-order wave plates or composite zero-order wave plates made of crystal materials or polymer materials. piece.

6. The measuring device according to claim 3 or 4, characterized in that,

The collimator adopts a fiber optic collimator precisely positioned by a pigtail and a self-focusing lens, which is used to convert the discrete light emitted by a broadband light source into collimated light; both the polarizer and the analyzer use two One of a chromatic polarizer or a birefringent polarizer; the beam splitter adopts a beam splitter or a grating dispersion type beam splitter, which is used to expand the wavelength of the multi-wavelength composite beam, and send the expanded wavelength signals to into a multi-wavelength photodetector for detection.

7. The measuring device according to claim 3 or 4, characterized in that,

The broadband light source is a continuum light source with stable output characteristics, and the spectral range of the light source can cover the range of the wave plate phase delay spectral characteristic to be measured.

8. The measuring device according to claim 3 or 4, characterized in that,

The multi-wavelength photodetector is a multi-wavelength photodiode array, a photomultiplier tube array or a CCD line array or an area sensor, preferably a CCD line array or an area array sensor, which is used to pass the detected wavelength photocurrent signals through data The acquisition card is transmitted to the computer for data processing.

9. The measuring device according to claim 4, characterized in that,

The motor is selected from a servo motor, a permanent magnet stepping motor or a reactive stepping motor and its corresponding driver; the computer sends a pulse signal through a data acquisition card to adjust the rotation state of the motor through the motor driver.