CN102297823B - Method and apparatus for measuring dynamic light scattering nano-particles based on bandpass filtering - Google Patents
Method and apparatus for measuring dynamic light scattering nano-particles based on bandpass filtering Download PDFInfo
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- CN102297823B CN102297823B CN 201110127051 CN201110127051A CN102297823B CN 102297823 B CN102297823 B CN 102297823B CN 201110127051 CN201110127051 CN 201110127051 CN 201110127051 A CN201110127051 A CN 201110127051A CN 102297823 B CN102297823 B CN 102297823B
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Abstract
The invention discloses a method and an apparatus for measuring dynamic light scattering nano-particles based on bandpass filtering. According to the invention, lasers are radiated on nano-particles performing Brownian motions in a solution. The scattered lights of the particles are directly detected; or the scattered lights of the particles are interfered with part of the original lights, and are detected; or the scattered lights are fed-back into a laser-tube cavity, self mixing is occurred, and self mixing signals are detected. Signals output by a photoelectric detector are pre-amplified, and are simultaneously delivered into a circuit formed by components of an M route buffer, bandpass filters with different central frequencies, and an RMS root-mean-square processor, which are connected in series, such that signal root-mean-square values at different frequencies with a number of M are obtained. The values are sampled by an A/D collecting card, such that power spectrum density functions at different frequencies with a number of M are obtained. With the method and the apparatus provided by the invention, a problem in prior arts of poor robustness of inverse calculations caused by seriously ill-conditioned coefficient matrix is solved. With the method and the apparatus provided by the invention, requirements on data collecting speed, data collecting amount, storage amount and processing amount are reduced; data processing time is reduced; and rapid measuring of nano-particle sizes can be realized.
Description
Technical field
The present invention relates to a kind of method and device of measuring nano particle, particularly a kind of dynamic light scattering nano particle measuring method and device based on bandpass filtering belong to field of measuring technique.Can be used for a plurality of fields that scientific research, biological medicine, the chemical industry energy, environmental protection etc. relate to nano particle production and process control.
Background technology
In dynamic light scattering nano particle measuring technique, general adopt digital correlator to obtain the autocorrelation function of scattered light signal or utilize the Power Spectrum Estimation Method to obtain the power spectral density function of scattered light signal, obtain thus the particle diameter distribution parameter of nano particle by inverse matrix.
The laser that laser instrument sends is formed on the nano particle that shines after the converging light in the solution by single or multiple lens combinations scattering occurs, and has comprised the particle diameter information of particle in the scattered light signal.
The detection of scattered light signal generally has three kinds of modes: one. after assembling, direct detection scattered light signal or process lens survey; Two. survey behind the part laser interference that scattered light signal and light source are sent; Three. scattered light is fed back in the laser cavity with the output of endovenous laser generation self-mixing modulated laser and by the photodetector detection that is arranged on the laser instrument rear end.
The scattered light signal of particle to be measured is processed through correlator and is obtained autocorrelation function:
(1)
Corresponding power spectral density function is:
(2)
Wherein,
jIt is grain diameter stepping number
, corresponding different particle diameter steppings,
It is particle diameter stepping sum;
x j jShelves grain diameter mean value;
jThe stepping width of shelves particle diameter; For power spectral density function,
iIt is frequency channel number
, corresponding different frequencies,
It is total number of channels; For autocorrelation function,
iIt is stepping sequence number correlation time
, corresponding different correlation time,
It is sum correlation time; Adopt detection mode for the moment, have
Adopt detection mode two or at 3 o'clock, have
qIt is Scattering of Vector;
D j jThe particle diffusivity of shelves particle diameter has comprised nano particle diameter
x j Information;
ω i Be and
iThe angular frequency relevant with Brownian movement on the passage;
jThe distribution of particles function of shelves particle diameter.Matrix form can be write respectively as in formula (1) and (2):
(4)
Wherein
RAutocorrelation function Distribution of A Sequence vector,
SPower spectrum density Distribution of A Sequence vector,
TThe matrix of coefficients that autocorrelation function distributes,
KThe matrix of coefficients that power spectrum density distributes,
HIt is the particle size distribution column vector.
In the conventional method, the obtaining of particle size distribution, or derive from the inverting of autocorrelation signal, or derive from the power spectrum signal retrieve.During inverting, matrix
TOr
Calculated vector by theory according to definition in formula (1) or (2)
ROr
Be measuring amount, select suitable inversion method, obtain vector
Concrete numerical value.Yet the inverting that no matter is based on autocorrelation signal also is based on the inverting of power spectrum signal, and matrix of coefficients all is Very Ill-conditioned, and as shown in Figure 5, small measuring-signal error will cause huge particle diameter distribution bias, even obtains wrong particle diameter distribution.This has limited the confidence level of grain diameter.Secondly, the estimation of the digital correlator of the processing requirements costliness of autocorrelation signal, the power spectrum of dynamic scattering light needs higher data collecting card (A/D card) sampling rate, larger computer stored resource and certain CPU processing time, to cost control and measure in real time unfavorable.
Summary of the invention
The present invention seeks on conventional dynamic light scattering nano particle measuring principle basis, by the analog bandpass filtering technology, original theory and signal processing mode to be improved.Solve the difficulty of original theory model coefficient matrix Very Ill-conditioned, improved the robustness of Inversion Calculation.Avoid the use of digital correlator, reduced requirement, saving signal processing time to the data capture card, realized economy, Quick Measurement to grain graininess.
Technical scheme of the present invention is: a kind of dynamic light scattering nano particle measuring method based on band-pass filtering is characterized in that method step is:
1. on the nano particle of the Ear Mucosa Treated by He Ne Laser Irradiation that is sent by laser instrument in the solution, the scattered light of particle is directly surveyed by photodetector, or with the part interference of light of original laser after surveyed by photodetector, or be fed back in the laser cavity and survey with the output of endovenous laser generation self-mixing modulated laser and by the photodetector that is arranged on the laser instrument rear end;
2. the signal that is detected by photodetector walks abreast successively after prime amplifier amplifies and sends into the bandpass filter at M routing cache device, different frequency center and the circuit that RMS r.m.s. processor is in series, obtain the signal root-mean-square valve at M different frequency place, sampled by the A/D capture card, the final power spectral density function that obtains M different frequency place can be expressed as with theoretical formula:
Wherein,
iIt is frequency channel number
, corresponding different band passband rates,
It is total number of channels;
jIt is grain diameter stepping number
,
It is particle diameter stepping sum;
x j jShelves grain diameter mean value;
jThe stepping width of shelves particle diameter; Scattered light at particle directly arrives in the situation of photodetector, has
, in the situation that arrives photodetector after the part interference of light of the scattered light of particle and original laser or the scattered light of particle be fed back in the situation of laser cavity internal modulation Laser output and have
qIt is the value of Scattering of Vector;
D j jThe particle diffusivity of shelves particle diameter has comprised nano particle diameter
x j Information;
ωThe angular frequency relevant with Brownian movement;
iThe frequency response function of channel bandpass filter is applicable to the passive and active filter in each rank;
jThe particle size distribution function of shelves particle diameter;
3. formula (5) is transformed into the form of matrix, is expressed as
, wherein, power spectrum density Distribution of A Sequence vector
SBe one group of measuring amount, obtain the matrix of coefficients that power spectrum density distributes by the mimic channel actual measurement
KIn formula (5)
The definition theory calculates the solution matrix equation
, obtain tested particle size distribution column vector
H
A kind of device of realizing based on the dynamic light scattering nano particle measuring method of bandpass filtering, characteristics are, this device comprises laser instrument, measurement zone, photodetector and mimic channel, described mimic channel comprises a prime amplifier and the corresponding M routing cache of frequency channel sum M device, the circuit that the bandpass filter at different frequency center and RMS r.m.s. processor are in series, the light beam irradiates of being launched by laser instrument is to measurement zone, measurement zone endoparticle scattered light is received by photodetector, the signal of photodetector output is after prime amplifier amplifies, walk abreast and send into described M routing cache device, the circuit that the bandpass filter at different frequency center and RMS r.m.s. processor are in series, obtain the signal root-mean-square valve at a plurality of different frequencies place, sampled by the A/D capture card, finally obtain a plurality of power spectrum densities.
Beneficial effect of the present invention: solved the problem that matrix of coefficients Very Ill-conditioned in original model causes the Inversion Calculation poor robustness.Adopt mimic channel directly to obtain power spectrum density, reduced the requirement to aspects such as data picking rate, data acquisition amount, amount of data storage and data processing amounts, greatly shortened data processing time, can realize Quick Measurement.Can be used for a plurality of fields that scientific research, biological medicine, the chemical industry energy, environmental protection etc. relate to production and the process control of nano particle.
Description of drawings
Fig. 1 analog signal processing system;
Fig. 2 measurement mechanism embodiment 1 synoptic diagram of the present invention;
Fig. 3 measurement mechanism embodiment 2 synoptic diagram of the present invention;
Fig. 4 measurement mechanism embodiment 3 synoptic diagram of the present invention;
The original dynamic light scattering method of Fig. 5 matrix of coefficients
KDistribution plan;
Fig. 6 has dynamic light scattering method matrix of coefficients now
KDistribution plan.
Embodiment
The present invention adopts the analog bandpass filtering technology to realize record and the processing of the power spectrum density that the dynamic light scattering nano particle is measured, and implementation is described in detail by reference to the accompanying drawings.Its method implementation step is:
1, the nano particle of the Ear Mucosa Treated by He Ne Laser Irradiation that is sent by laser instrument 6 in measurement zone 7 solution, the scattered light of particle is directly surveyed by photodetector 8, see Fig. 2, or with the part interference of light that obtains original laser through beam splitting behind the beam splitter 9 after surveyed by photodetector 8, see Fig. 3, or the scattered light of particle is fed back in laser instrument 6 chambeies and endovenous laser generation self-mixing modulated laser is exported and by photodetector 8 detections that are arranged on the laser instrument rear end, see Fig. 4;
2, the signal that is detected by photodetector 8 walks abreast successively after prime amplifier 2 amplifies and sends into the bandpass filter 4 at M routing cache device 3, different frequency center and the circuit that RMS r.m.s. processor 5 is in series, obtain the signal root-mean-square valve at M different frequency place, sampled by the A/D capture card, the final power spectral density function that obtains M different frequency place can be expressed as with theoretical formula:
Wherein,
iIt is frequency channel number
, corresponding different band passband rates,
It is total number of channels;
jIt is particle diameter stepping number
,
It is particle diameter stepping sum;
x j jShelves grain diameter mean value;
jThe stepping width of shelves particle diameter; Scattered light at particle directly arrives in the situation of photodetector, has
, in the situation that arrives photodetector after the part interference of light of the scattered light of particle and original laser or the scattered light of particle be fed back in the situation of laser cavity internal modulation Laser output and have
qIt is the value of Scattering of Vector;
D j jThe particle diffusivity of shelves particle diameter has comprised nano particle diameter
x j Information;
ωThe angular frequency relevant with Brownian movement;
iThe frequency response function of channel bandpass filter is applicable to the passive and active filter in each rank;
jThe particle size distribution function of shelves particle diameter;
3, formula (5) is transformed into the form of matrix, is expressed as
, wherein, power spectrum density Distribution of A Sequence vector
SBe one group of measuring amount, obtain the matrix of coefficients that power spectrum density distributes by mimic channel 1 actual measurement
KIn formula (5)
The definition theory calculates, as shown in Figure 6, and the solution matrix equation
, obtain tested particle size distribution column vector
H
A kind of device of realizing based on the dynamic light scattering nano particle measuring method of bandpass filtering, by Fig. 1-shown in Figure 4, characteristics are, this device comprises laser instrument 6, measurement zone 7, photodetector 8 and mimic channel 1, described mimic channel 1 comprises a prime amplifier 2 and the corresponding M routing cache of frequency channel sum M device 3, the circuit that the bandpass filter 4 at different frequency center and RMS r.m.s. processor 5 are in series, the light beam irradiates of being launched by laser instrument 6 is to measurement zone 7, measurement zone 7 endoparticle scattered lights are received by photodetector 8, the signal of photodetector 8 outputs is after prime amplifier 2 amplifies, walk abreast and send into described M routing cache device 3, the circuit that the bandpass filter 4 at different frequency center and RMS r.m.s. processor 5 are in series, obtain the signal root-mean-square valve at a plurality of different frequencies place, sampled by the A/D capture card, finally obtain power spectral density function.
The scattered light of embodiment 1(particle is directly surveyed by photodetector):
By shown in Figure 2, it comprises semiconductor laser 6, measurement zone 7, photodetector 8 and mimic channel 1.The light beam irradiates of being launched by laser instrument 6 is to measurement zone 7.Measurement zone 7 endoparticle scattered lights are received by photodetector 8, obtain power spectral density function by mimic channel 1 at last.
Surveyed by photodetector after the scattered light of embodiment 2(particle and the part interference of light of original laser):
By shown in Figure 3, it comprises semiconductor laser 6, beam splitter 9, measurement zone 7, photodetector 8 and mimic channel 1.Beam splitter 9 places between laser instrument 6 and the measurement zone 7, and the light beam by laser instrument 6 is launched is divided into two bundles by beam splitter 9.A branch of beam splitter that sees through shines measurement zone 7; A branch of rear as intrinsic light by the beam splitter reflection.Measurement zone 7 endoparticle scattered lights and the intrinsic interference of light are surveyed by photodetector 8, obtain power spectral density function by mimic channel 1 at last.
Modulated laser was exported and is surveyed by photodetector after embodiment 3(particle scattered light was fed back into self-mixing occurs in the laser cavity):
By shown in Figure 4, it comprises semiconductor laser 6, measurement zone 7, photodetector 8 and mimic channel 1.Photodetector 8 places laser instrument 6 back, by the light beam that laser instrument 6 is launched, shines measurement zone 7, and the particle rear orientation light is fed back in the laserresonator and original laser generation mixing.The backward output light of laser instrument is surveyed by photodetector 8, obtains power spectral density function by mimic channel 1 at last.
Claims (4)
1. dynamic light scattering nano particle measuring method based on bandpass filtering is characterized in that method step is:
The nano particle of the Ear Mucosa Treated by He Ne Laser Irradiation that is sent by laser instrument in the solution, the scattered light of particle is directly surveyed by photodetector, or with the part interference of light of original laser after surveyed by photodetector, or be fed back into and surveyed by photodetector after producing the self-mixing signal in the laser cavity;
The signal that is detected by the photodetector parallel bandpass filter at M routing cache device, different frequency center and circuit that RMS r.m.s. processor is in series sent into successively after prime amplifier amplifies, obtain the signal root-mean-square valve at M different frequency place, sampled by the A/D capture card, the final power spectral density function that obtains M different frequency place can be expressed as with theoretical formula:
Wherein,
iIt is frequency channel number
,
It is total number of channels;
jIt is grain diameter stepping number
,
It is grain diameter stepping sum;
x j jShelves grain diameter mean value;
jThe stepping width of shelves particle diameter; Directly arriving at the scattered light of particle in the situation of photodetector has
, after the part interference of light of the scattered light of particle and original laser, arrive in the situation of photodetector or the scattered light of particle is fed back in the situation that the output of self-mixing modulated laser occurs in the laser cavity and has
qIt is the value of Scattering of Vector;
D j jThe particle diffusivity of shelves particle diameter has comprised nano particle diameter
x j Information;
ωThe angular frequency relevant with Brownian movement;
iThe frequency response function of channel bandpass filter is applicable to the passive and active filter in each rank;
jThe distribution of particles function of shelves particle diameter;
Formula (5) is transformed into the form of matrix, obtains:
, wherein, power spectrum density Distribution of A Sequence vector
SBe one group of measuring amount, obtain the matrix of coefficients that power spectrum density distributes by the mimic channel actual measurement
KIn formula (5)
The definition theory calculates the solution matrix equation
, obtain tested particle size distribution column vector
H
2. a realization is based on the device of the dynamic light scattering nano particle measuring method of bandpass filtering, be characterised in that, this device comprises laser instrument, measurement zone, photodetector and mimic channel, described mimic channel comprise a prime amplifier and with the corresponding M routing cache of frequency channel sum M device, the circuit that the bandpass filter at different frequency center and RMS r.m.s. processor are in series, the light beam irradiates of being launched by laser instrument is to measurement zone, measurement zone endoparticle scattered light is received by photodetector, the signal of photodetector output is after prime amplifier amplifies, walk abreast and send into described M routing cache device, the circuit that the bandpass filter at different frequency center and RMS r.m.s. processor are in series, obtain the signal root-mean-square valve at a plurality of different frequencies place, sampled by the A/D capture card, finally obtain power spectral density function.
3. realization according to claim 2 is based on the device of the dynamic light scattering nano particle measuring method of bandpass filtering, be characterised in that, between laser instrument and measurement zone, be equipped with beam splitter, the light beam of being launched by laser instrument, be divided into two bundles by beam splitter, a branch of beam splitter that sees through shines measurement zone; A branch of rear as intrinsic light by the beam splitter reflection, measurement zone endoparticle scattered light and the intrinsic interference of light are surveyed by photodetector, obtain power spectral density function by mimic channel at last.
4. realization according to claim 2 is based on the device of the dynamic light scattering nano particle measuring method of bandpass filtering, be characterised in that, photodetector places the laser instrument back, the light beam of being launched by laser instrument, shine measurement zone, the particle rear orientation light is fed back in the laser cavity and original laser generation mixing, and the backward output light of laser instrument is surveyed by photodetector, obtains power spectral density function by mimic channel at last.
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| CN105092426B (en) * | 2015-07-24 | 2017-11-28 | 清华大学 | The measuring method of 90 degree of scattering spectrums of nano particle |
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