CN1071896C - Magnetic CD performance test equipment - Google Patents

Abstract

The present invention relates to a magnetic CD performance test device which adopts a servo tracking mechanism. Signals of a differential amplifier drive a polarization spectroscope rotary table to rotate by the servo tracking mechanism; information of rotation angles is displayed and conveyed to an X-Y recorder by an angle indicator; output voltage of a photo-electric conversion circuit is displayed by a voltage indicator. The device adopts a series of measures to increase the stability of the servo tracking mechanism and eliminate transmission errors, and meanwhile, the device can measure the reflectivity and magnetooptical characteristics (Kerr angles, Kerr effect hysteresis loops, coercivity and rectangular degrees) of samples; thereby, the test operating process is greatly simplified; the tracking precision for the angles can be 0.001 DEG; the present invention can be used for the development, the production and the inspection of magnetooptical thin film materials and magnetic CD.

Description

Magnetic CD performance test equipment

The present invention utilizes light, electricity, magnetism method test magneto-optic disk and the magneto-optical property of magneto-optic memory technique sample and the device of reflectivity.

Magneto-optic disk is as the storer in computing machine and the audio and video equipment, is the recording medium of new generation of competitively developing in the world and producing at present, and it is big to have memory capacity, information be difficult for losing and can duplicate record etc. advantage.In the development and production run of magneto-optic disk, need carry out a series of test, wherein the test of magneto-optical property and reflectivity is the most important, and the magneto-optical property test comprises the drafting of Kerr magnetooptical effect magnetic hysteresis loop and the measurement of Ke Er angle, coercive force and rectangle degree.Measure polarization angle method commonly used " differential method " and " symmetric angle vibratory drilling method " arranged, differential method utilizes polarization spectroscope that the reflected light of magneto-optic disk is divided into two-way light, determine polarisation of light angle variable quantity by the difference and the rotatory polarization spectroscope that detect the two-way photosignal, thereby determine the Ke Er angle; The symmetric angle vibratory drilling method makes the incident light polarization surface vibration with modulator, identifies the component of signal of representing the Ke Er angle then from the catoptrical photoelectricity background signal of sample.The apparatus structure complexity of symmetric angle vibratory drilling method, to calibrate with standard polarization angle sample during test, " Measurement of Kerr Rotation of Magnetic Film research " literary composition that 1987 the 15th the 3rd phases of volume of Huazhong Institute of Technology journal deliver, a kind of differential method measurement mechanism is provided, its circuit and light path are simple than the symmetric angle vibratory drilling method, but operation is complicated when measuring, the rotatory polarization spectroscope is with the variable quantity of compensation sample reflected light polarization angle by hand, its compensation precision is relatively poor, be generally about 0.01 °, and measurement result is subjected to the influence of light source power fluctuation, and consequent relative error equals the relative undulating quantity of light source power.The device of these two kinds of methods all can only be measured the Ke Er angle of magneto-optic disk or magneto-optic memory technique film system in addition, and can not test reflectivity.

The objective of the invention is to overcome present differential method measurement mechanism and be awkward the problem relatively poor with precision, accomplish to simplify the operation course, be convenient to Installation and Debugging, eliminate the influence of light source power fluctuation to test result, reduce test error, improve the total degree of accuracy of instrument, increase measurement function simultaneously, not only energy measurement magneto-optical property but also energy measurement reflectivity.For achieving the above object, the present invention adopts servo tracking mechanism to replace artificial rotatory polarization spectroscope, get road photoelectric signal in the servo control mechanism simultaneously as the indication of sample reflected optical power,, can determine the reflectivity of sample by the standard reflection reference sample.

Device of the present invention comprises linear polarization light source, plane mirror, polarization spectroscope, photoelectric switching circuit, differential amplifier, magnetic field feedback circuit, field drives circuit and the X-Y recorder that shows the magneto-optic loop line; Described proving installation has adopted servo tracking mechanism, this mechanism comprises driving circuit, servomotor and speed reduction unit, driving circuit amplifies the signal power of differential amplifier, drive servomotor, the servomotor rotating speed promotes the rotation of polarization spectroscope turntable after speed reduction unit slows down, after the corner information of turntable is received by angular transducer, send the Y input end of X-Y recorder to, the corner information of angular transducer is shown that by angle display the photoelectric switching circuit output voltage is shown by voltage indicator.

Automatically the magnetic field intensity signal of field sweep electromagnet is after the magnetic field detection circuit amplifies, flow to the X input end of X-Y recorder, flow to the magnetic field feedback circuit simultaneously, the triangle wave voltage that produces with triangle wave generating circuit compares, its difference is superimposed upon on the triangle wave voltage, produce linear fabulous triangular voltage sweep magnetic field through field drives circuit de-energisation magnet coil, under this action of a magnetic field, magnetic medium magnetization reversal on the sample, cause the reflected light change of polarized direction, half of the angle of this change of polarized direction promptly equals the Ke Er angle.The present invention is owing to the effect of described servo control mechanism, and the corner of polarization spectroscope changes follows the tracks of the variation of sample reflected light polarization angle all the time, so can record the Ke Er angle of sample from the reading of angular display unit.X-Y recorder provides sample under angle signal and the acting in conjunction of scanning magnetic field strength signal the utmost point is to the Kerr effect magnetic hysteresis loop, can determine the coercive force and the rectangle degree of sample from loop line, also can determine the Ke Er angle of sample.

During the reflectivity of measuring samples of the present invention, be reflectivity ρ at first, non magnetic reflection normative reference be placed in the electromagnet air gap, normative reference reflexes to polarization spectroscope with the incident beam of linear polarization light source, be divided into transmitted light and reflected light, produce two voltage V respectively at the photoelectric switching circuit output terminal _STAnd V _SR, because the effect of servo tracking mechanism, these two voltages must equate, rotate otherwise differential amplifier drives servo tracking mechanism urges polarization spectroscope with output error voltage, till error signal is zero, so obtain V ,=V _ST=V _SR, can read by voltage indicator.Then, remove the reflection normative reference, put tested magnetic sample, the reflected light of sample produces two voltage V at the photoelectric switching circuit output terminal equally _TAnd V _R, because the servo control mechanism effect, these two voltages should equate, read V=V at voltage indicator _T=V _R, can determine the reflectivity of sample: ρ according to twice measurement $=\frac{v}{v_R}\·{\mathrm{\ρ}}_{9.}$

The present invention has simplified the operating process of test greatly owing to adopted servo tracking mechanism, and the angle tracking accuracy is easy to reach 0.001 °, has improved an order of magnitude than the performance accuracy of hand-turning polarization spectroscope.Owing to adopt servo control mechanism, 80% pair of Ke Er angular measurement test result of light source power fluctuation does not have obvious influence, has eliminated the error that light source fluctuation brings fully.The present invention is the magneto-optical property (comprising Ke Er angle, Kerr effect magnetic hysteresis loop, coercive force and rectangle degree) and the reflectivity of measuring samples simultaneously.When the change of sensitivity that light source power fluctuation is 1%, the non-linear and local heterogeneity of opto-electronic conversion causes is 1%, when the reflectivity calibration value error of standard reflection reference sample is 2%, the reflectance test error is 4%, can be advantageously used in the measurement in development, production and the commodity inspection process of the research measurement of magneto-optic thin film material and magneto-optic disk.

Fig. 1 is a structured flowchart of the present invention;

Fig. 2 is a servo-operated mechanism front elevation of the present invention;

Fig. 3 is the attached view of servo-operated mechanism of the present invention;

Fig. 4 is a midplane catoptron mirror holder stereographic map of the present invention;

Fig. 5 is the sectional view that towel electromagnet of the present invention and lower shoe are fixedly connected.

Now tie platform description of drawings the invention process situation:

Low-power laser 1 emission line light beam is after plane mirror 2 reflections, incide on the sample 4 that is arranged in electromagnet 3 air gaps, after sample 4 reflections, impinge perpendicularly on the polarization spectroscope 5, be divided into folded light beam and transmitted light beam, be converted to two photocurrents by photoelectric cell 6 and 7 respectively, be converted to two voltages through electric current one voltage changer 8 and 9 again, the difference signal of this two voltage is an error signal, after differential amplifier 10 amplifies, send driving circuit 11 power amplifications, in order to drive servomotor 12, the servomotor rotating speed is after speed reduction unit 13 slows down, promote 14 rotations of polarization spectroscope turntable, turntable 14 drives polarization spectroscope 5 and rotates, make the analyzing axle of polarization spectroscope 5 and the reflected light plane of polarization angle of sample 4 remain a steady state value, like this, the corner of polarization spectroscope 5 changes follows the tracks of the variation of sample reflected light polarization angle all the time, the corner information of turntable 14 is received by angular transducer 15, and by angle display 16 demonstrations, angular transducer 15 sends angle signal to the Y input end of X-Y recorder 17 simultaneously.Meanwhile, the Hall plate 18 that is arranged in electromagnet 3 air gaps is searched magnetic field intensity signal, after amplifying, magnetic field detection circuit 19 flows to the X input end of X-Y recorder, flow to magnetic field feedback circuit 20 simultaneously, the triangle wave voltage that magnetic field intensity signal and triangle wave generating circuit 21 produce in magnetic field feedback circuit 20 relatively, its difference is superimposed upon on the triangle wave voltage, the coil of the field drives circuit de-energisation electromagnet of forming through prime amplifier 22 and solenoid driver circuit 23 3.Be connected in the voltage indicator of electric current one voltage changer 9 output terminals, can read the opto-electronic conversion voltage after the servo tracking effect, be used for the reflectivity of measuring samples.

For increasing the servo tracking mechanism stability, the speed reduction unit 13 of servo tracking mechanism is by spool gear 26, gear wheel 27, screw mandrel 28, nut 30, connecting rod 33 and permanent-magnet block 32 constitute, servomotor 12 drives spool gear 26 and rotates, after gear wheel 27 slows down, drive connects firmly in the screw mandrel on the gear wheel 28 precession in nut 30, screw mandrel top 29 promotes connecting rod 33 and drives 14 rotations of polarization spectroscope turntable, permanent-magnet block 32 is installed on the connecting rod and screw mandrel top 29 iron cartridge 31 outsides of synapsis setting-in mutually, can realize that screw mandrel 28 connects with activity between the iron cartridge 31 with magnetic force, in order to eliminate the thread pitch between screw mandrel 28 and the nut 30, permanent-magnet block can be installed in nut 30 outsides simultaneously, makes to keep pretension magnetic force between steel screw mandrel and the nut.

For getting rid of driving error, speed reduction unit 13, polarization spectroscope turntable 14 and angular transducer 15 are installed on the same base plate, adopt floating outstanding gearing to connect between polarization spectroscope turntable 14 and the angular transducer 15, should floatingly hang gearing by support 42, reed 39, carriage 38, spring 40 and fixed mount 41 constitute, support 42 is fixed in base plate, support 42 is fixed in two reed parallel to each other 39 bottoms, top and carriage 38 are fixedly connected, constituting only can be at the elastic guide perpendicular to the motion of reed direction, angular transducer 15 is fixed on the carriage 38, the axle of angular transducer 15 is gone up fixed installation power wheel 36, form driving coupling with tinsel travelling belt 35 between this power wheel and the polarization spectroscope turntable 14, spring 40 1 ends are fixed on the carriage 38, the other end is fixed on the fixed mount 41 of the relative side of polarization spectroscope turntable, with tinsel travelling belt 35 with the tension of fixing pulling force, the friction force that is necessary between assurance travelling belt and the power wheel 36 guarantees that simultaneously this friction force remains unchanged when the axle of turntable 14 or angular transducer 15 has small rocking.

For debugging plane mirror 2 easily, described plane mirror 2 is installed on mirror holder, this mirror holder is made of rotating disk 54, microscope base 49, bearing 55, set screw 53, there is light hole 56 at the center of turntable position, microscope base 49 and bearing 55 all are fixed on the rotating disk 54, the edge of a knife 48 of plane mirror 2 is placed in the right angle V-shaped groove 50 of microscope base 49, plane mirror 2 back sides are U-shaped arm-tie 51 fixedly, U-shaped arm-tie 51 is fixed on spring 52 tensions on the rotating disk, connects the angle of the set screw 53 scalable plane mirrors 2 of U-shaped arm-tie and bearing 55.Incide the light beam at middle part, plane mirror 2 edges of a knife 48 edges from the left front, be injected into after reflection in the light hole 56, the angle of rotating rotating disk 54 among a small circle can change luminous point and drop on lateral attitude in the light hole (inciding the perpendicular direction of the plane of incidence of catoptron 2 with light), and set screw 53 can change the lengthwise position (with horizontal vertical direction) of luminous point.When installing, device can easily the luminous point of plane mirror 2 reflections be adjusted to the middle of electromagnet 3 air gaps like this, and owing to utilize the edge of plane mirror to reflect, level crossing will reduce to minimum to the covering part of light hole 56, will become than being easier to light during test.

The electromagnet that this device uses is shown in Fig. 5 with the mode of being fixedly connected of device base plate, tighten up with screw 46 between electromagnet 3 and the base plate, between base plate and electromagnet 3, be placed with pad 44, such structure alleviates deformation that electromagnet causes by the magnetic force influence to bottom deformation greatly in the field sweep process, increase the stability of device light path, thereby increased the stability of whole device reading.

Claims (5)

1. a magnetic CD performance test equipment comprises linear polarization light source, plane mirror, polarization spectroscope, photoelectric switching circuit, differential amplifier, electromagnet, magnetic field detection circuit, triangle wave generating circuit, magnetic field feedback circuit, field drives circuit and the X-Y recorder that shows the magneto-optic loop line; Described linear polarization light source emission line light beam, after described plane reflection mirror reflection, incide on the sample of placing in the described electromagnet air gap, after the sample reflection, impinge perpendicularly on the described polarization spectroscope, be divided into folded light beam and transmitted light beam, convert two voltage signals to by described photoelectric switching circuit respectively, import described differential amplifier; The magnetic field intensity signal of described electromagnet is after described magnetic field detection circuit amplifies, flow to the X input end of described X-Y recorder, flow to described magnetic field feedback circuit simultaneously, the triangle wave voltage that produces with triangle wave generating circuit compares, its difference is superimposed upon on the triangle wave voltage, produces triangular voltage sweep magnetic field through field drives circuit de-energisation magnet coil; It is characterized in that:

(1) described proving installation adopts servo tracking mechanism, this mechanism comprises driving circuit, servomotor and speed reduction unit, driving circuit amplifies the signal power of differential amplifier, drive servomotor, the servomotor rotating speed is after speed reduction unit slows down, promote the rotation of polarization spectroscope turntable, after the corner information of turntable is received by angular transducer, send the Y input end of X-Y recorder to;

(2) described angular transducer corner information is shown by angle display;

(3) described photoelectric switching circuit output voltage is shown by voltage indicator.

2. proving installation as claimed in claim 1, it is characterized in that described servo tracking mechanism speed reduction unit is made of spool gear, gear wheel, screw mandrel, nut, connecting rod and permanent-magnet block, servomotor drives spool gear and rotates, after gear wheel slows down, drive connects firmly in the precession in nut of the screw mandrel on the gear wheel, the top promotion connecting rod of screw mandrel drives the polarization spectroscope turntable and rotates, Yong Jiu Ci Half-grown-beans iron block is installed on the connecting rod iron cartridge outside with the top synapsis mutually of screw mandrel setting-in, and can be installed in the nut outside.

3. proving installation as claimed in claim 1 or 2, it is characterized by described speed reduction unit, polarization spectroscope turntable and angular transducer are installed on the same base plate, adopt floating outstanding gearing to connect between polarization spectroscope turntable and the angular transducer, should floatingly hang gearing by support, reed, carriage, spring and fixed mount constitute, support is fixed in base plate, support is fixed in two reed bottoms parallel to each other, top and carriage are fixedly connected, constituting only can be at the elastic guide perpendicular to the motion of reed direction, angular transducer is fixed on the carriage, the axle of angular transducer is gone up the fixed installation power wheel, form driving coupling with the tinsel travelling belt between this power wheel and the polarization spectroscope turntable, spring one end is fixed on the carriage, the other end is fixed on the fixed mount of the relative side of polarization spectroscope turntable, with the tinsel travelling belt with the tension of fixing pulling force.

4. proving installation as claimed in claim 1 or 2, it is characterized by described plane mirror installs on mirror holder, mirror holder is made of rotating disk, microscope base, bearing, set screw, there is light hole at the center of turntable position, microscope base and bearing all are fixed on the rotating disk, and the edge of a knife of plane mirror is placed in the right angle V-shaped groove of microscope base, and the plane mirror back side is the U-shaped arm-tie fixedly, the U-shaped arm-tie is fixed on the spring tension on the rotating disk, connects the angle of the set screw scalable plane mirror of U-shaped arm-tie and bearing.

5. proving installation as claimed in claim 3, it is characterized by described plane mirror installs on mirror holder, mirror holder is made of rotating disk, microscope base, bearing, set screw, there is light hole at the center of turntable position, microscope base and bearing all are fixed on the rotating disk, and the edge of a knife of plane mirror is placed in the right angle V-shaped groove of microscope base, and the plane mirror back side is the U-shaped arm-tie fixedly, the U-shaped arm-tie is fixed on the spring tension on the rotating disk, connects the angle of the set screw scalable plane mirror of U-shaped arm-tie and bearing.

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