CN1475780A - Measuring device for characteristics of polarizing beam splitting film with wide angle and wide spectrum - Google Patents

Abstract

A device for measuring the characteristics of a polarization beam splitter film with a wide angle and a wide spectrum is characterized in that it includes a light source, a monochromator, a polarizing prism, a beam splitter, an aperture, a conical prism, and an energy meter in sequence along the main light path, the polarizing prism is placed on a rotating platform 1, the conical prism and the sample to be tested are placed on a rotating platform 2, a contrast light energy meter is arranged on the reflected light path of the beam splitter, and a computer is provided. The computer controls the movement of the rotating platform 1 and the rotating platform 2 according to the measurement program on the one hand, and receives the test results of the energy meter and the contrast light energy meter and performs data processing on the other hand, and displays or prints out the spectrum and extinction ratio of the test sample. The device has the advantages of stable and reliable performance, convenient operation, and accurate test results.

Description

The measurement mechanism of the polarization beam splitting membrane property of wide angle and wide spectrum

Technical field

The present invention relates to the measurement mechanism of the polarization beam splitting membrane property of the spectral measurement of film, particularly a kind of wide angle and wide spectrum.

Background technology

The network technology of information age, the needs of the information of sharing and aggregate information are become increasingly conspicuous, this has brought up the greatest requirements that jumbotron is shown, traditional with CRT as the display technique of image forming source because its large volume, big weight and the restriction that is subjected to self brightness, become the bottleneck that limits its development gradually, generation and what come is with LCD (Liquid Crystal Display), DLP (Digital Light Processing), LCOS (Liquid Crystal on Silicon) is the large screen projection display system of mechanism, except DLP showed, projection display system all will be used and contain the spectroscopical optical element of wide angle and wide spectrum polarizing.Polarization spectroscope is a thin-film component important in the above-mentioned projection display system, and its performance directly has influence on the contrast of image, the consistance of color and the utilization factor of luminous energy.

In the development process of above-mentioned wide angle and wide spectrum thin-film component, a problem that always allows everyone puzzle is how accurately to measure the spectral characteristic and the extinction ratio thereof of its two polarized light on each angle and each wavelength.The most advanced Lambda series of tests of existing spectral measurement device if want to satisfy above measurement demand, needs to make the rack of a large amount of different angles, and it can't directly provide extinction ratio, therefore is very restricted in actual applications.In some document, also reported the device of this respect, but they can only measure extinction ratio roughly, perhaps can only measure the spectral characteristic of two kinds of polarized lights.Therefore in fact how study invent out one not only the measurement mechanism of energy measurement extinction ratio but also energy measurement spectrum also be blank always.

Summary of the invention

The technical problem to be solved in the present invention is to overcome the difficulty of above-mentioned prior art, a kind of measurement mechanism of polarization beam splitting membrane property of wide angle and wide spectrum is provided, it can survey the spectrum of Kuan Guang Spectrum polarizing beam splitting film, its extinction ratio of energy measurement again, most importantly it can carry out the spectral measurement of different incidence angles degree.

Technical solution of the present invention:

A kind of measurement mechanism of polarization beam splitting membrane property of wide angle and wide spectrum, be characterized in comprising light source successively along main optical path, monochromator, polarizing prism, beam splitter, diaphragm, the taper prism, energy meter, described polarizing prism places on the rotation platform 1, described taper prism and testing sample all place on the rotation platform 2, on the reflected light path of beam splitter, establish the contrast luminous energy, also has a computing machine, this computing machine is pressed the motion of process of measurement control rotation platform 1 and rotation platform 2 on the one hand, the test result of received energy meter and the contrast luminous energy line data of going forward side by side is handled on the other hand, shows or print the spectrum and the extinction ratio of specimen.

Described light source is wide spectrum halogen tungsten lamp, with the light source of Wide spectrum that visible waveband is provided.

Its precision of described grating monochromator is answered≤0.1nm.

Described polarizing prism is the polarizing prism combination, fundamental purpose is to guarantee that output light has the polarization characteristic of height, the emergent light of parallel incident light is that P polarization state light, vertical emergent light are the S polarization state light), this combination is placed on the rotation platform that can accurately control 1, thereby can select needed polarization state according to the needs of back process of measurement.

Rotatable platform 2 should be able to accurately be controlled the incident angle of incident light and measuring samples face, realizes the wide angle spectral measurement.

Beam splitter, by its accurate dichroism, the contrast light beam that can provide and measuring beam to compare for us, it can eliminate since the shake of light source and instability to the influence of measurement result.

The taper prism is to eliminate because the skew that the variation that takes measurement of an angle brings the outgoing hot spot.

The test philosophy of apparatus of the present invention is as follows:

If beam splitter is α (T/R+T) (this is a known conditions) to the splitting ratio of P light, the energy of establishing the preceding light of beam splitter is I, and the reading of two energy meters is respectively I ₁, I ₂, testing sample the transmitance of P light be T _p, then concerning a certain single wavelength and specific incident angle, have:

I·α·T _p＝I ₁

I (1-α)=I ₂Get by following formula: $\frac{\mathrm{\&alpha;}}{1-\mathrm{\&alpha;}}{T}_p=\frac{I_1}{{\mathrm{<figure-callout\; id="2"\; label="I"\; filenames="A0312934400081.png"\; state="\{\{state\}\}">I</figure-callout>}}_2}$ So: $T_p=\frac{I_1}{{\mathrm{<figure-callout\; id="2"\; label="I"\; filenames="A0312934400081.png"\; state="\{\{state\}\}">I</figure-callout>}}_2}\&CenterDot;\frac{\mathrm{\&alpha;}}{1-\mathrm{\&alpha;}}$ As a same reason, when rotating prism combination 90 degree, because the variation of the plane of incidence, the polarization state of light of transmission this moment is S light, and we also can be in the hope of T according to the method described above.So extinction ratio $\mathrm{\&rho;}=\frac{T_p}{T_s}$ Also can obtain.

Therefore we measure its T to each incident angle to a specific wavelength _p, T _s, ρ, we repeat above test mode and test needing each wavelength in the test spectral scope then, measure T separately respectively _p, T _s, ρ, we through Computer Processing, just can obtain needed test result with all test datas at last.

How to eliminate because angle changes moving of the hot spot bring?

Because the variation of incident angle causes moving of testing sample exit facet outgoing beam focal spot, this has brought certain difficulty to energy meter to locating tab assembly, how to realize dynamic tracking to emergent light, we adopt is that the total reflection principle of trapezoidal taper prism is realized, as Fig. 2: the 8-1 condenser lens, 8-2 optical fiber, the outgoing beam of different incidence angles is through the total reflection effect of prism, converge to a bit, scioptics is coupled into optical fiber then, wherein be with the test sample product, the taper prism, the tail end of coupled lens and optical fiber all is fixed together, place simultaneously on the rotatable platform 2, so just can overcome all because the problem that the variation of angle brings measurement.

Suppose the taper prism refractive index be n, its total reflection angle θ then _c=Sin ^-1(1/n), the cut-open view of establishing this prism as shown in Figure 3, its drift angle is ω because ω＞0, so light on the inwall primary event takes place after, emission angle just reduces ω/2, from reflection for the second time, after reflecting later on, reflection angle just reduces ω at every turn,

So in order to satisfy total reflection condition Prism is realized the condition of " funnel ": $\sin ({\mathrm{\&theta;}}_0+\mathrm{\&omega;}/2)<\frac{a_1}{a_2}{[1-{\left(\frac{1}{n}\right)}^2]}^{1/2}$ If ω is very little, then: $\sin (\mathrm{\&omega;}/2)<\frac{\frac{a_1}{a_2}{[1-{\left(\frac{1}{n}\right)}^2]}^{1/2}-{\sin \mathrm{\&theta;}}_0}{\cos {\mathrm{\&theta;}}_0}$ And: $\sin (\mathrm{\&omega;}/2)=\frac{a_2-a_1}{l}$ So $l>\frac{(a_2-a_1)\cos {\mathrm{\&theta;}}_0}{\frac{a_1}{a_2}{[1-{\left(\frac{1}{n}\right)}^2]}^{1/2}-\sin {\mathrm{\&theta;}}_0}$

Therefore just can realize its " funnel " effect as long as when selecting taper prism big or small, satisfy this condition, reach our purpose.

Advantage of the present invention:

1, the spectrum to each incident angle that apparatus of the present invention can the tests polarization beam splitter also can provide its extinction ratio simultaneously.

2, the introducing of taper prism has solved the variation owing to incident angle, and the hot spot of emergent light produces the mobile difficulty of bringing to the measurement of energy meter, and the present invention can realize dynamic tracking, measures thereby reach multi-angle.

3, adopt prism make up partially, in the very high extinction ratio of maintenance than general Glan Taylor prism cheaply, be easy to make, be not subjected to the restriction of size and be easy to installation.

4, the introducing of contrast light beam has been eliminated because the shake of light source and the influence that instability is brought to measurement result.

5, the part light path adopts Optical Fiber Transmission, has reduced the loss of luminous energy, has improved coupling precision and measuring accuracy.

6, this device is all accurately controlled with computing machine, and test result can directly show.That installs is stable and reliable for performance, and test result is accurate.

Description of drawings

Fig. 1 is the structured flowchart of measurement mechanism most preferred embodiment of the polarization beam splitting membrane property of wide angle and wide spectrum of the present invention

Fig. 2 is the constitutional diagram of the tail end of band test sample product, taper prism, coupled lens and optical fiber

Fig. 3 is a taper prism cut-open view

Embodiment

See also Fig. 1 earlier, Fig. 1 is the structured flowchart of measurement mechanism most preferred embodiment of the polarization beam splitting membrane property of wide angle and wide spectrum of the present invention, as seen from the figure, the formation of the measurement mechanism of the polarization beam splitting membrane property of wide angle and wide spectrum of the present invention is to comprise wide spectrum halogen tungsten lamp light source 1 successively along main optical path, monochromator 2, a pair of polarizing prism combination 3, beam splitter 5, diaphragm 6, taper prism 8, energy meter 10, described polarizing prism 3 places on the rotation platform 4, described taper prism 8 backs also have coupled lens 81 and optical fiber 82, and with testing sample 7, taper prism 8, the tail end of coupled lens 81 and optical fiber 82 all is fixed together, and places simultaneously on the rotatable platform 9.On the reflected light path of beam splitter 5, establish contrast luminous energy 11, also has a computing machine 12, this computing machine 12 press the motion of process of measurement control rotation platform 4 and rotation platform 9 on the one hand, the test result of received energy meter 10 and the contrast luminous energy 11 line data processing of going forward side by side on the other hand.

Described grating monochromator 2 its precision are answered≤0.1nm.

The flow process of whole optical path is: the light that is sent by wide spectrum halogen tungsten lamp light source 1, through becoming a quasi-monochromatic light after the grating monochromator 2, deflection device 3 through prism combination, the light of transmission is P light, through after the beam splitter 5, be divided into two parts, the a branch of light as a comparison that wherein is reflected, transmission be measuring beam, measuring beam is coupled to optical fiber 82 the insides by the back of taper prism 8 by coupled lens 81 through being directly incident on after collimating on the band test sample product 7, and energy meter 10 detects transmission potential, compare with it with by the contrast beam energy that records of contrast luminous energy 11, just can calculate spectrum and extinction ratio by computing machine 12.Concrete test process does not repeat them here as mentioned above.

Claims (5)

1, a kind of measuring device of the polarization beam-splitting film characteristic of wide-angle wide-spectrum, it is characterized in that comprising light source (1), monochromator (2), polarizing prism (3), beam-splitter mirror (5) successively along main optical path ), diaphragm (6), conical prism (8), energy meter (10), described polarizing prism (3) is placed on the rotating platform 1 (4), described conical prism (8) and The samples to be measured (7) are all placed on the rotary platform 2 (9), and a contrast light energy meter (11) is set on the reflected light path of the beam splitter (5), and a computer (12) is also arranged. On the one hand, the movement of the rotary platform 1 (4) and the rotary platform 2 (9) is controlled according to the measurement program; on the other hand, the test results of the energy meter (10) and the contrast light energy meter (11) are received and data processing is performed. 2. The device for measuring the characteristics of a wide-angle and wide-spectrum polarization beam-splitting film according to claim 1, characterized in that the light source (1) is a wide-spectrum tungsten halogen lamp. 3. The device for measuring the properties of a wide-angle and wide-spectrum polarization beam-splitting film according to claim 1, characterized in that the accuracy of the grating monochromator (2) should be ≤0.1 nm. 4. The device for measuring the characteristics of a wide-angle and wide-spectrum polarization beam-splitting film according to claim 1, characterized in that the polarizing prism (3) is a combination of polarizing prisms. 5. The measuring device for the characteristics of the polarization beam splitting film with wide angle and wide spectrum according to claim 1, characterized in that there are coupling lenses (81) and optical fibers (82) behind the pyramid prism (8), and Fix the end of the sample to be tested (7), the pyramidal prism (8), the coupling lens (81) and the optical fiber (82) connected to the energy meter (10) together, and place it on the rotatable platform 2 (9 )superior.

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