CN109521655B - Fringe locking type holographic interference lithography system and fringe locking method - Google Patents
Fringe locking type holographic interference lithography system and fringe locking method Download PDFInfo
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Abstract
The invention belongs to the technical field of information optics, and relates to a holographic interference lithography system, which is used for solving the problem of reduced contrast of interference fringe drift holographic gratings, and a first high-speed photoelectric detector is used for collecting moire fringe light intensity signals on the surface of a reference grating and simultaneously transmitting the light intensity signals to a single chip microcomputer and a PID controller; the second high-speed photoelectric detector monitors a light intensity signal of the laser through the light beam sampling grating, the light intensity signal is transmitted to the single chip microcomputer, and a signal output end of the PID controller is transmitted to a frequency modulation input end of the first ultrasonic generator; when the PID controller judges that the light intensity signal detected by the first high-speed photoelectric detector in real time changes, the PID controller outputs a feedback signal to the first ultrasonic generator, the frequency of the first ultrasonic generator correspondingly changes, and the phase of-1 order diffraction light of the first acousto-optic modulator changes, so that the phase of moire fringes is locked, and the locking of the phase of interference fringes is realized.
Description
Technical Field
The invention belongs to the technical field of information optics, and relates to a holographic interference lithography system.
Background
When a large-sized holographic grating is photographed, a long time of exposure is required because the photographing light intensity is weak. However, the relative phases of the object light and the reference light are changed by external vibration, air flow, temperature fluctuation and other factors, and interference fringes formed by the object light and the reference light are randomly shifted, so that the contrast of the recording fringes is reduced. The current holographic lithography system can not solve the problem of interference fringe drift in a long time, so for a long-time exposure situation, an active vibration isolation method is required to be adopted to control the drift of the interference fringe. The existing stripe locking method comprises the following steps: the invention patent with the patent number of 2006100399676 discloses a linear array CCD fitting fringe locking method, which adopts a linear array CCD to collect reference moire fringes, finds the wave troughs of the fringes through the fitting method, locks the phases of the fringes by controlling piezoelectric ceramics, and has the locking bandwidth of only 2-3 Hz; the invention patent with patent number 2013106933281 discloses a heterodyne fringe locking method, which utilizes a light splitting sheet to derive two sub-beams, respectively uses a phase receiver to receive signals, controls the frequency of a frequency conversion acousto-optic modulator through a man-machine interaction interface and software, and locks interference fringes in real time. Particularly, when the low-noise holographic grating is shot, the exposure recording plate needs to be moved at a low speed in the shooting process, and the vibration of the guide rail can cause the jitter of the interference fringes to change rapidly in the moving process.
Disclosure of Invention
In order to solve the technical problem that the contrast of the recorded fringes is reduced due to the random drift of the interference fringes during long-time moving exposure, the invention provides a fringe locking type holographic interference lithography system, which comprises a laser, a light beam sampling grating, a half-wave plate, a beam splitter prism, a first plane reflecting mirror, a second plane reflecting mirror, a third plane reflecting mirror, a first acousto-optic modulator, a first ultrasonic generator, a second acousto-optic modulator, a second ultrasonic generator, a first spatial filter, a second spatial filter, a first collimating lens, a second collimating lens, a grating substrate to be exposed, a reference grating, a first high-speed photoelectric detector, a second high-speed photoelectric detector, a PID controller and a single chip microcomputer; the reference grating is arranged on the grating substrate to be exposed, and the surface of the reference grating and the surface of the grating substrate to be exposed are in the same plane; light emitted by a laser passes through a beam sampling grating, 0-grade transmitted diffraction light enters a beam splitting prism and is divided into transmitted light beams and reflected light beams, wherein the transmitted light beams pass through a half-wave plate, then pass through a first plane reflector and a second plane reflector and enter a first acousto-optic modulator, the-1-grade diffracted light of the first acousto-optic modulator enters a first spatial filter, then passes through a first collimating lens and is expanded into parallel light, and finally the parallel light is projected onto a grating substrate to be exposed and a reference grating; the reflected light beam enters a second sound optical modulator through a third plane reflector, and-1 st-order diffracted light of the second sound optical modulator enters a second spatial filter, then passes through a second collimating lens, is expanded into parallel light and finally is projected onto a grating substrate to be exposed and a reference grating; the transmission light beam and the reflection light beam interfere on the surface of the grating substrate to be exposed, and meanwhile, an interference light field of the transmission light beam and the reflection light beam forms a virtual grating on the reference grating, and the virtual grating and the reference grating have a slight difference in grid line direction to form Moire fringes; the single chip microcomputer is provided with a first input end, a second input end, a reference input end and an output end; the PID controller is provided with a correction signal input end, an input end and a PID signal output end; the first ultrasonic generator is provided with a frequency modulation input end and a frequency modulation output end; the second ultrasonic generator is provided with an output end; the first acousto-optic modulator and the second acousto-optic modulator are provided with input ends; the moire fringes are projected onto a first high-speed photoelectric detector, and light intensity signals of the moire fringes are simultaneously transmitted to a first input end of a single chip microcomputer and a sensor signal input end of a PID controller; the light emitted by the laser passes through the light beam sampling grating, the 1 st-order reflected diffraction light enters the second high-speed photoelectric detector, the light intensity signal of the second high-speed photoelectric detector is transmitted to the second input end of the singlechip, and the signal output end of the PID controller is transmitted to the frequency modulation input end of the first ultrasonic generator; the output end of the first ultrasonic generator is connected with the input end of the first acousto-optic modulator, the output end of the second ultrasonic generator is connected with the input end of the second acousto-optic modulator, when a light intensity signal transmitted to the PID controller and detected by the first high-speed photoelectric detector changes, the PID controller outputs a feedback signal to the first ultrasonic generator, the frequency of the first ultrasonic generator correspondingly changes, and the phase of-1-level diffraction light of the first acousto-optic modulator changes, so that the phase of moire fringes is locked. The reference input end on the singlechip inputs the acquired target light intensity of the moire fringes, and the output end of the singlechip is connected with the correction signal input end of the PID controller; when the light intensity signal transmitted to the first high-speed photoelectric detector in the PID controller is changed, the PID controller outputs a feedback signal to the first ultrasonic generator, so that the frequency of the first ultrasonic generator is changed, the moire fringes move in the opposite direction, and the phase of the moire fringes is locked, namely the phase of the holographic interference fringes is locked unchanged.
The working principle of the fringe locking type holographic interference lithography system is as follows: in the same optical field, the phase information of the moire fringes reflects the real-time phase information of the interference fringes, and the phase of the moire fringes, that is, the phase of the interference fringes can be locked. The frequency of the second ultrasonic generator in the device is set to be f2, namely the input frequency of the second acousto-optic modulator is set to be a fixed value f2, the frequency f1 of the first ultrasonic generator is adjustable and is in an external signal frequency modulation working state, namely the input frequency f1 of the first acousto-optic modulator changes along with the change of an external signal, and by changing the frequency of the first ultrasonic generator, moire fringes can be moved, namely the phase of interference fringes changes continuously. The moire fringes are projected on the first high-speed photoelectric detector, the light intensity signals of the moire fringes are simultaneously transmitted to the first input end of the single chip microcomputer and the sensor signal input end of the PID controller, the moire fringes move by finely adjusting the frequency f1 of the first ultrasonic generator, and the single chip microcomputer obtains the variation range V of the light intensity signals of the first high-speed photoelectric detectorRmin~VRmaxTaking the median value of the light intensity signal 1/2 (V)Rmin+VRmax) And as a reference signal of the PID controller, the PID controller compares the reference signal with a light intensity signal detected by the first high-speed photoelectric detector in real time at a high speed, if the reference signal and the light intensity signal are different, the PID controller outputs a feedback signal to the first ultrasonic generator to change the output frequency, so that the phase of moire fringes is changed, the position of the moire fringes detected by the first high-speed photoelectric detector is changed, namely the detected light intensity signal is changed, the light intensity signal is input into the PID controller, the reference signal compared by the PID controller at a high speed with the light intensity signal detected by the first high-speed photoelectric detector in real time is repeatedly compared, and the PID outputs a feedback quantity until the reference signal is consistent with the light intensity signal detected by the first high-speed photoelectric detector in real time, and the moire fringes are locked at the moment.
A fringe locking method for a fringe locking type holographic interference lithography system comprises the following steps,
step one, manufacturing a reference grating: after an exposure light path of the holographic interference lithography system is adjusted, placing a reference grating substrate to be prepared at the position of a reference grating, setting the frequency of a first ultrasonic generator to be f1 (105 MHz-115 MHz), setting the frequency of a second ultrasonic generator to be f2 (105 MHz-115 MHz), ensuring that f1= f2, exposing and developing the reference grating substrate to be prepared in a short time, placing the developed reference grating in situ, adjusting moire fringes, wherein the interval between every two fringes is 1 cm-2 cm, projecting the moire fringes into a first high-speed photoelectric detector, and adjusting the position of the first high-speed photoelectric detector to enable a photosensitive surface of the first high-speed photoelectric detector to be located at the middle position of the dark fringe and the bright fringe of the moire fringes;
step two, setting an initial reference signal: setting the frequency of a first ultrasonic generator to be f1 (105 MHz-115 MHz), setting the frequency of a second ultrasonic generator to be f2 (105 MHz-115 MHz), ensuring that f1-f2= +/-10 Hz, enabling Moire fringes to translate at the frequency of 10Hz, transmitting a light intensity signal of a first high-speed photoelectric detector to a first input end of a single chip microcomputer, and recording a corresponding signal variation range V by the single chip microcomputerRmin~VRmaxMeanwhile, the signal of the second high-speed photoelectric detector is transmitted to the second input end of the singlechip, and the singlechip records the corresponding signal VS0The second high-speed photoelectric detector monitors the output optical power of the laser by monitoring the 1 st-order reflected diffraction light energy of the light beam sampling grating; because the ratio of the energy of the part of light to the energy of the 0-order transmitted diffracted light is determined by the diffraction efficiency of the 1-order reflected diffracted light of the beam sampling grating, the signal of the second high-speed photodetector can reflect the output optical power of the laser in real time as long as the beam sampling grating is unchanged, and the initial reference signal at the correction signal input end of the PID controller is set to be VR0=(VRmin+VRmax)/2，VS0The optical power variation of the laser is monitored in real time, within 1s, the optical power variation of the laser is negligible, and then VR0/ VS0Is a constant;
step three, the PID controller controls the interference fringe locking: setting the center frequency of the first ultrasonic generator to be f1 (105 MHz-115 MHz), and setting the frequency of the second ultrasonic generator to be f2 (105 MHz-115 MHz); setting the working mode of the first ultrasonic generator to be externalThe signal frequency modulation mode is that the modulation frequency is 5KHz, the input range of external signals is-5V, and the frequency of corresponding ultrasonic signals is changed into f1-5 KHz-f 1+5 KHz; the light intensity signal V of the first high-speed photoelectric detector is converted into a light intensity signal VSTransmitting the signal to the sensor signal end of the PID controller, maintaining the signal of the second high-speed photoelectric detector to be transmitted to the second input end of the singlechip, and setting the initial reference input end of the singlechip to be VR0(ii) a The singlechip executes division and multiplication to calculate a corrected reference signal value VR：VR=（VR0/VS0）*VSWill VRThe signal is transmitted to a reference signal input end of the PID controller; PID controller real-time comparison VSAnd the output signal of the PID controller and the value of the VR are transmitted to the frequency modulation input end of the first ultrasonic generator, the ultrasonic frequency is changed, the corresponding frequency of the first acousto-optic modulator is changed, and the phase of the holographic interference fringe is controlled in real time.
If the reference signal of the PID controller is not corrected in time, the PID controller can mistakenly send a signal to drive the acousto-optic modulator, so that the stability of stripe locking can be influenced. Due to the use of the technical scheme, the reference signal of the PID controller is corrected in real time, so that the interference fringe locking is realized, the harsh requirements on the ring damping condition and the device structure damping condition are reduced, and the fringe quality is improved.
Drawings
FIG. 1 is a schematic diagram of a fringe-locked holographic interference lithography system;
FIG. 2 is a flow chart of a PID controller controlling fringe locking;
FIG. 3 is an open loop closed loop error voltage;
FIG. 4 is a power spectral density of an open-loop closed-loop error voltage
Wherein: 1-laser, 2-beam sampling grating, 3-half-wave plate, 4-beam splitting prism, 5-first plane reflector, 6-second plane reflector, 7-third plane reflector, 8-first acousto-optic modulator, 9-second acousto-optic modulator, 10-first spatial filter, 11-second spatial filter, 12-first collimating lens, 13-second collimating lens, 14-grating substrate to be exposed, 15-reference grating, 16-Moire fringe, 17-first high-speed photoelectric detector, 18-second high-speed photoelectric detector, 19-single chip microcomputer, 20-PID controller, 21-first ultrasonic generator and 22-second ultrasonic generator.
Detailed Description
The invention is further described below with reference to the accompanying drawings:
the first embodiment is as follows:
a fringe locking type holographic interference lithography system is shown in figure 1 and comprises a laser 1, a light beam sampling grating 2, a half-wave plate 3, a beam splitter prism 4, a first plane reflector 5, a second plane reflector 6, a third plane reflector 7, a first acousto-optic modulator 8, a first ultrasonic generator 21, a second acousto-optic modulator 9, a second ultrasonic generator 22, a first spatial filter 10, a second spatial filter 11, a first collimating lens 12, a second collimating lens 13, a grating substrate 14 to be exposed, a reference grating 15, a first high-speed photoelectric detector 17, a second high-speed photoelectric detector 18, a PID controller 20 and a single chip microcomputer 19; the reference grating is arranged on the grating substrate to be exposed, and the surface of the reference grating and the surface of the grating substrate to be exposed are in the same plane; light emitted by a laser passes through a beam sampling grating, 0-grade transmitted diffraction light enters a beam splitting prism and is divided into transmitted light beams and reflected light beams, wherein the transmitted light beams pass through a half-wave plate, then pass through a first plane reflector and a second plane reflector and enter a first acousto-optic modulator, the-1-grade diffracted light of the first acousto-optic modulator enters a first spatial filter, then passes through a first collimating lens and is expanded into parallel light, and finally the parallel light is projected onto a grating substrate to be exposed and a reference grating; the reflected light beam enters a second sound optical modulator through a third plane reflector, and-1 st-order diffracted light of the second sound optical modulator enters a second spatial filter, then passes through a second collimating lens, is expanded into parallel light and finally is projected onto a grating substrate to be exposed and a reference grating; the transmitted light beam and the reflected light beam interfere on the surface of the grating substrate to be exposed, and meanwhile, an interference light field of the transmitted light beam and the reflected light beam forms a virtual grating on the reference grating, and the virtual grating and the reference grating form Moire fringes 16; the moire fringes are projected onto a first high-speed photoelectric detector, and light intensity signals of the moire fringes are simultaneously transmitted to a first input end of a single chip microcomputer and a sensor signal input end of a PID controller; the light emitted by the laser passes through the light beam sampling grating, the 1 st-order reflected diffraction light enters the second high-speed photoelectric detector, the light intensity signal of the second high-speed photoelectric detector is transmitted to the second input end of the singlechip, and the signal output end of the PID controller is transmitted to the frequency modulation input end of the first ultrasonic generator; the output end of the first ultrasonic generator is connected with the input end of the first acousto-optic modulator, the output end of the second ultrasonic generator is connected with the input end of the second acousto-optic modulator, when a light intensity signal transmitted to the PID controller and detected by the first high-speed photoelectric detector changes, the PID controller outputs a feedback signal to the first ultrasonic generator, the frequency of the first ultrasonic generator changes correspondingly, and the phase of-1-level diffraction light of the first acousto-optic modulator changes, so that the phase of a locking fringe, namely the phase of a locking holographic interference fringe, is unchanged.
Example two:
a fringe locking method for a fringe locking type holographic interference lithography system comprises the following steps,
step one, manufacturing a reference grating: after the optical path of the holographic interference lithography system is adjusted, a reference grating substrate to be prepared is placed at the position of a reference grating, the frequency of a first ultrasonic generator is set to be f1 (105 MHz-115 MHz), the frequency of a second ultrasonic generator is set to be f2 (105 MHz-115 MHz), f1= f2 is guaranteed, the reference grating substrate to be prepared is exposed and developed, the developed reference grating is placed in the original position, moire fringes are adjusted, the interval between every two fringes is 1 cm-2 cm, the moire fringes are projected into a first high-speed photoelectric detector, and the position of the first high-speed photoelectric detector is adjusted, so that the photosensitive surface of the first high-speed photoelectric detector is located in the middle position of the moire dark fringes and the bright fringes.
Step two, setting an initial reference signal: setting the frequency f1 of the first ultrasonic generator to be 105 MHz-115 MHz, setting the frequency f2 of the second ultrasonic generator to be 105 MHz-115 MHz, setting the frequency f1-f2= +/-10 Hz, enabling the moire fringes to translate at the frequency of 10Hz, and transmitting the light intensity signal of the first high-speed photoelectric detector to the first high-speed photoelectric detector of the single chip microcomputerThe input end and the singlechip record the corresponding signal change range VRmin~VRmaxMeanwhile, the signal of the second high-speed photoelectric detector is transmitted to the second input end of the singlechip, and the singlechip records the corresponding signal VS0The initial reference signal of the PID controller is set to VR0= (VRmin+VRmax)/2. The second high-speed photoelectric detector monitors the output optical power of the laser by monitoring the 1 st-order reflected diffraction light energy of the light beam sampling grating; since the ratio of the energy of the part of light to the energy of the 0 < th > order transmitted diffracted light is determined by the diffraction efficiency of the 1 < st > order reflected diffracted light of the beam sampling grating, the signal of the second high-speed photodetector can reflect the output optical power, V, of the laser in real time as long as the beam sampling grating is unchangedS0The optical power variation of the laser is monitored in real time, within 1s, the optical power variation of the laser is negligible, and then VR0/ VS0Is a constant.
Step three, the PID controller controls the interference fringe locking: the working process is shown in fig. 2, the central frequency f1 of the first ultrasonic generator is set to be 105 MHz-115 MHz, and the frequency f2 of the second ultrasonic generator is set to be 105 MHz-115 MHz; setting the working mode of the first ultrasonic generator into an external signal frequency modulation mode, wherein the modulation frequency is 5KHz, the input range of the external signal is-5V, and the frequency of the corresponding ultrasonic signal is changed into f1-5 KHz-f 1+5 KHz; the light intensity signal V of the first high-speed photoelectric detector is converted into a light intensity signal VSTransmitting the signal to the sensor signal end of the PID controller, maintaining the signal of the second high-speed photoelectric detector to be transmitted to the second input end of the singlechip, and setting the initial reference signal end of the singlechip to be VR0(ii) a The singlechip executes division and multiplication to calculate a corrected reference signal value VR：VR=（VR0/VS0）*VSWill VRThe signal is transmitted to a reference signal input end of the PID controller; PID controller real-time comparison VSAnd the output signal of the PID controller and the value of the VR are transmitted to the frequency modulation input end of the first ultrasonic generator, the ultrasonic frequency is changed, the corresponding frequency of the first acousto-optic modulator is changed, and the phase of the holographic interference fringe is controlled in real time. When the first high-speed photodetector detectsWhen the light intensity signal is changed, the PID controller judges the moving direction of the moire fringes by comparing the real-time light intensity signal with the reference light intensity signal, at the moment, a feedback signal is output to the first ultrasonic generator, the frequency of the first ultrasonic generator is changed, the moire fringes move towards the opposite direction, the feedback signal is continuously compared and output, the light intensity signal detected by the first high-speed photoelectric detector is kept unchanged, and closed-loop control is achieved.
The time domain and the frequency domain of the error voltage condition of the output voltage of the first high-speed photodetector and the reference signal when the open loop and the closed loop are locked are shown in the attached fig. 3 and 4. During moving exposure, interference fringes are subjected to random drift and serious vibration during open loop, the vibration of the interference fringes at each frequency is large under the moving exposure environment, and the interference fringes are stably locked during closed loop locking.
The invention provides a PID-based frequency signal control acousto-optic modulator, and a self-adaptive real-time stripe locking method. The high-speed photoelectric detector is adopted to detect the light intensity signal of the middle point of the reference moire fringe, the other high-speed photoelectric detector detects the fluctuation of light emitted by the laser in real time, the reference signal of the PID is corrected in real time, software is not needed, the whole locking system is guaranteed by hardware, the response speed is high, and the locking precision is high.
Claims (2)
1. A fringe-locking holographic interference lithography system, comprising: the device comprises a laser (1), a light beam sampling grating (2), a half-wave plate (3), a beam splitting prism (4), a first plane reflector (5), a second plane reflector (6), a third plane reflector (7), a first acousto-optic modulator (8), a first ultrasonic generator (21), a second acousto-optic modulator (9), a second ultrasonic generator (22), a first spatial filter (10), a second spatial filter (11), a first collimating lens (12), a second collimating lens (13), a grating substrate (14) to be exposed, a reference grating (15), a first high-speed photoelectric detector (17), a second high-speed photoelectric detector (18), a PID controller (20) and a single chip microcomputer (19);
the reference grating is arranged on the grating substrate to be exposed, and the surface of the reference grating and the surface of the grating substrate to be exposed are in the same plane; light emitted by a laser passes through a beam sampling grating, 0-grade transmitted diffraction light enters a beam splitting prism and is divided into transmitted light beams and reflected light beams, wherein the transmitted light beams pass through a half-wave plate, then pass through a first plane reflector and a second plane reflector and enter a first acousto-optic modulator, the-1-grade diffracted light of the first acousto-optic modulator enters a first spatial filter, then passes through a first collimating lens and is expanded into parallel light, and finally the parallel light is projected onto a grating substrate to be exposed and a reference grating;
the reflected light beam enters a second sound optical modulator through a third plane reflector, and-1 st-order diffracted light of the second sound optical modulator enters a second spatial filter, then passes through a second collimating lens, is expanded into parallel light and finally is projected onto a grating substrate to be exposed and a reference grating; the transmission light beam and the reflection light beam interfere on the surface of the grating substrate to be exposed, and meanwhile, the interference light field of the transmission light beam and the reflection light beam forms a virtual grating on the reference grating, and the virtual grating and the reference grating form Moire fringes (16);
the single chip microcomputer is provided with a first input end, a second input end, a reference input end and an output end; the PID controller is provided with a correction signal input end, an input end and a PID signal output end; the first ultrasonic generator is provided with a frequency modulation input end and a frequency modulation output end; the second ultrasonic generator is provided with an output end; the first acousto-optic modulator and the second acousto-optic modulator are provided with input ends;
the first high-speed photoelectric detector is aligned with the moire fringes, and the acquired light intensity signal is simultaneously transmitted to a first input end of the single chip microcomputer and an input end of the PID controller; the light emitted by the laser passes through the light beam sampling grating, the 1 st-order reflected diffraction light enters the second high-speed photoelectric detector, the light intensity signal is transmitted to the second input end of the singlechip, and the signal output end of the PID controller is connected with the frequency modulation input end of the first ultrasonic generator; the output end of the first ultrasonic generator is connected with the input end of the first acousto-optic modulator, and the output end of the second ultrasonic generator is connected with the input end of the second acousto-optic modulator; the reference input end on the singlechip inputs the acquired target light intensity of the moire fringes, and the output end of the singlechip is connected with the correction signal input end of the PID controller;
when the light intensity signal transmitted to the first high-speed photoelectric detector in the PID controller is changed, the PID controller outputs a feedback signal to the first ultrasonic generator, so that the frequency of the first ultrasonic generator is changed, the moire fringes move in the opposite direction, and the phase of the moire fringes is locked, namely the phase of the holographic interference fringes is locked unchanged.
2. A fringe locking method of a fringe locking type holographic interference photoetching system is characterized by comprising the following steps:
firstly, using the fringe-locked holographic interference lithography system of claim 1 to fabricate a reference grating: placing a reference grating substrate to be prepared at the position of a reference grating, setting the frequency f1 of a first ultrasonic generator to be 105 MHz-115 MHz, setting the frequency f2 of a second ultrasonic generator to be 105 MHz-115 MHz, ensuring that f1 is f2, exposing and developing the reference grating substrate to be prepared, placing the developed reference grating in the original position, calling moire fringes which are spaced by 1 cm-2 cm in the period of the fringes, projecting the moire fringes into a first high-speed photoelectric detector, and adjusting the position of the first high-speed photoelectric detector to enable the photosensitive surface of the first high-speed photoelectric detector to be aligned with the middle positions of the moire dark fringes and the bright fringes;
step two, setting an initial reference signal: setting the frequency f1 of a first ultrasonic generator to be 105 MHz-115 MHz, setting the frequency f2 of a second ultrasonic generator to be 105 MHz-115 MHz, setting f1-f2 to +/-10 Hz, translating the Moire fringes at the frequency of 10Hz, transmitting the light intensity signal of a first high-speed photoelectric detector to the first input end of a single chip microcomputer, and recording the corresponding signal variation range V by the single chip microcomputerRmin～VRmaxMeanwhile, the signal of the second high-speed photoelectric detector is transmitted to the second input end of the singlechip, and the singlechip records the corresponding signal VS0The initial reference signal at the modified signal input of the PID controller is set to VR0＝(VRmin+VRmax) 2; the second high-speed photoelectric detector monitors the 1 st order reflected diffraction light energy of the light beam sampling grating to realize the output light power of the laserMonitoring;
step three, the PID controller controls the interference fringe locking: setting the central frequency f1 of the first ultrasonic generator to be 105 MHz-115 MHz, and setting the frequency f2 of the second ultrasonic generator to be 105 MHz-115 MHz; setting the working mode of the first ultrasonic generator into an external signal frequency modulation mode, wherein the modulation frequency is 5KHz, the input range of the external signal is-5V, and the frequency of the corresponding ultrasonic signal is changed into f1-5 KHz-f 1+5 KHz; the light intensity signal V of the first high-speed photoelectric detector is converted into a light intensity signal VSThe signal is transmitted to the input end of the PID controller, the signal of the second high-speed photoelectric detector is kept to be transmitted to the second input end of the singlechip, and the reference input end of the singlechip is set to be VR0(ii) a The singlechip executes division and multiplication to calculate a corrected reference signal value VR：VR＝(VR0/VS0)*VSWill VRThe signal is transmitted to a correction signal input end of the PID controller; PID controller real-time comparison VSAnd VRAnd the output signal of the PID controller is transmitted to the frequency modulation input end of the first ultrasonic generator, the ultrasonic frequency is changed, the corresponding frequency of the first acousto-optic modulator is changed, and the phase of the holographic interference fringe is controlled in real time.
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| WO2000079345A1 (en) * | 1999-06-22 | 2000-12-28 | Massachusetts Institute Of Technology | Acousto-optic light projector |
| CN1845017A (en) * | 2006-04-24 | 2006-10-11 | 苏州大学 | Method and apparatus for stabilizing holographic interference fringes by control apparatus |
| JP2009216454A (en) * | 2008-03-07 | 2009-09-24 | Canon Inc | Wavefront aberration measuring apparatus, wavefront aberration measuring method, exposure apparatus, and device manufacturing method |
| CN103092002A (en) * | 2013-01-17 | 2013-05-08 | 清华大学 | Laser interference lithography system with pattern locking function |
| CN207965204U (en) * | 2018-04-09 | 2018-10-12 | 苏州大学 | It is a kind of to prepare a meter scanning-exposure apparatus for magnitude grating |
-
2018
- 2018-12-24 CN CN201811581256.0A patent/CN109521655B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2000079345A1 (en) * | 1999-06-22 | 2000-12-28 | Massachusetts Institute Of Technology | Acousto-optic light projector |
| CN1845017A (en) * | 2006-04-24 | 2006-10-11 | 苏州大学 | Method and apparatus for stabilizing holographic interference fringes by control apparatus |
| JP2009216454A (en) * | 2008-03-07 | 2009-09-24 | Canon Inc | Wavefront aberration measuring apparatus, wavefront aberration measuring method, exposure apparatus, and device manufacturing method |
| CN103092002A (en) * | 2013-01-17 | 2013-05-08 | 清华大学 | Laser interference lithography system with pattern locking function |
| CN207965204U (en) * | 2018-04-09 | 2018-10-12 | 苏州大学 | It is a kind of to prepare a meter scanning-exposure apparatus for magnitude grating |
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| CN109521655A (en) | 2019-03-26 |
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