Device for measuring torsional pendulum micro impulse through linear frequency modulation multi-beam laser heterodyne and torsional pendulum micro impulse measurement method based on the same

1. Linear frequency modulated multi-beam laser heterodyne measuring torsional pendulum micro impulse device, characterized in that it comprises a linear frequency modulation laser (5), 1st plane mirror (6), 2nd plane mirror (4), plane standard mirror (7), the standard beam (3), the vacuum chamber (11), pulse laser (1), working substance target (2), the convergent lens (8), the photoelectric detector (9) and a signal processing system (10),

The linear frequency modulation laser (5), 1st plane mirror (6), 2nd plane mirror (4), plane standard mirror (7), the standard beam (3), pulse laser (1), working substance target (2) and a convergent lens (8) are placed in a vacuum chamber (11) the inner,

The standard beam (3) is fixed with the center of the rotating shaft,

The stated working substance target (2) adhesive in the standard beam (3) on the upper surface of the, 2nd plane mirror (4) adhesive in the standard beam (3) the lower surface of, and working substance target (2) and the 2nd plane reflector (4) are located on the standard beam (3) one end of the same,

Pulse laser emitted from the laser for working substance target role (2) produce the plasma spraying, the standard beam back (3) rotate, in the standard beam (3) rotate at the same time, linear frequency modulation laser (5) continuously emit the linear frequency modulation laser, linear frequency modulation laser through the 1st plane mirror (6) and 2nd plane mirror (4) reflected incident to plane standard mirror (7), plane standard mirror (7) of the front surface and a rear surface of the laser to the linear frequency modulation of the convergent lens and is reflected (8) convergence to the photoelectric detector (9) on the photosensitive surface of the, photoelectric detector (9) with the electric signal output terminal of the signal processing system (10) is connected with the input end of the electrical signal.

2. Linear frequency modulated multi-beam laser heterodyne measuring device impulse torsional pendulum micro according to Claim 1, characterized in that the signal processing system (10) comprises a filter (10-1), the pre-amplifier (10-2), A/D converter (10-3) and DSP (10-4), filter (10-1) as the electrical signal input end of the signal processing system (10) electrical input terminal of the photoelectric detector (9) is connected with the output end of the electrical signal, filter (10-1) filtering of the signal output end of the pre-amplifier (10-2) is connected with the input end of the filter signal, pre-amplifier (10-2) with an amplified signal output end of the converter A/D (10-3) is connected to the analog signal input end of the, converter A/D (10-3) with the digital signal output of DSP (10-4) is connected with the input end of the digital signal.

3. Linear frequency modulated multi-beam laser heterodyne measuring device impulse torsional pendulum micro according to Claim 1, characterized in that the vacuum chamber (11) is provided with a vacuum window, the vacuum window used for making the vacuum chamber (11) to the light convergence in the vacuum chamber (11) the external photoelectric detector (9) on the photosensitive surface.

4. Based on claim 1 or 2 wherein the linear frequency modulated multi-beam laser heterodyne measuring torsional pendulum microtorsional pendulum micro impulse of the impulse of the method for measuring of the device, characterized in that it is realized by the following process:

The pulse laser (1), linear frequency modulation laser (5), the photoelectric detector (9) and a signal processing system (10) switching to working state, the photoelectric detector (9) divides the received optical signals into electrical signals sent to the signal processing system (10), a signal processing system (10) according to the received continuous electrical signal by the standard beam (3) angle of θ ',

According to:

I′=2JωD[!CenterDot!][!theta!]′=4πJDT′[!CenterDot!][!theta!]′(Formula a),

Obtain pulse laser (1) with working medium the laser emitted by the target (2) I micro impulse generated from the action of ', wherein J of inertia of the pendulum system, to damping frequency ω, T' to damping cycle, D as the standard beam (3) length, make k=4 π J/DT ', is:

'=k·θ' I (formula II).

5. Based on a linear frequency modulated multi-beam laser heterodyne measuring torsional pendulum micro of the device of the impulse of the method for measuring the impulse torsional pendulum micro according to Claim 4, characterized in that signal processing system (10) according to the received continuous electrical signal by the standard beam (3) angle of θ ' is realized by the following process:

When the linear frequency modulation laser (5) of linear frequency modulation continuous emission laser at an incident angle θ₀ oblique incidence to plane standard mirror (7), the, plane standard mirror (7) of the incident light field E (t) is:

E (t) = E₀ exp {i (ω₀ t+k't²)} (formula III),

Wherein The rate of change of the frequency modulation bandwidth, frequency modulation cycle is T, delta F into frequency modulation bandwidth, E₀ the incident optical field amplitude, for time t, ω₀ the incident light field angular frequency, expressed i imaginarg,

A linear frequency modulation laser reaches the plane standard mirror (7) of the front surface of the optical path to l, moment t-l/c linear frequency modulation of the laser to reach the plane standard mirror (7) of the front surface of the reflected light field E₁ (t) to:

E1(t)=α1E0exp{i[ω0(t-lc)+k′(t-lc)2]}(Formula IV),

Plane standard mirror (7) the front surface of the transmitted light is at all times in a plane different standard mirror (7) of the front surface and a rear surface of the reflection and refraction by a plurality of times, each time of the reflected light of the optical reflection obtained for:

E2(t)=α2E0exp{iω0(t-l+2ndcosc)+k′(t-l+2ndcosc)2+2ω0ndcos[!theta!]c]}E3(t)=α3E0exp{i[ω0(t-l+4ndcos[!theta!]c)+k′(t-l+4ndcos[!theta!]c)2+4ω0ndcos[!theta!]c]}[!CenterDot!][!CenterDot!][!CenterDot!]Em(t)=αmE0exp{i[ω0(t-l+2(m-1)ndcos[!theta!]c)+k′(t-l+2(m-1)ndcos[!theta!]c)2+2(m-1)ω0ndcos[!theta!]c]}[!CenterDot!][!CenterDot!][!CenterDot!]

(Formula V),

Wherein m is a non-negative integer, α₁ =r, α_m =ββ 'r'^(2m-3) (m≥ 2), r the light from the ambient medium-injection plane standard mirror (7) the reflectivity of the, β is a light from the surrounding medium-injection plane standard mirror (7) of the transmissivity, r 'is a plane standard mirror (7) the reflectance of the surface of the, β' from the plane of the light standard mirror (7) internal into the surrounding medium the transmissivity of the, standard mirror is a plane d (7) thickness, the θ angle, n is a plane standard mirror (7) refractive index, c for lightspeed,

Photoelectric detector (9) of the received total optical field E ' (t) is:

E ' (t) = E₁ (t) +E₂ (t) +...+E_m (t) +... (Formula VI),

The photo-detector (9) output photocurrent I is:

I=ηehν1Z[!Integral!][!Integral!]D12[E1(t)+E2(t)+...+Em(t)+...][E1(t)+E2(t)+...+Em(t)+...]*ds(Formula VII),

Wherein e is an electronic electric quantity, Z is a photo-detector (9) the surface of the intrinsic impedance of the medium, the quantum efficiency η, the photoelectric detector D (9) the area of the photosensitive surface, h the Planck constant, the laser frequency v, in said * complex conjugate,

According to the formula VII was intermediate frequency current I_IF to:

IIF=ηe2hν1Z[!Integral!][!Integral!]DΣp=0m-1Σj=0m-p(Ej(t)Ej+p*(t)+Ej*(t)Ej+p(t))ds(Formula VIII),

The formula of the five four and eight the formula in the formula, in:

IIF=ηehνπZE02Σp=0m-1Σj=0m-pαj+pαjcos(4pk′ndcos[!theta!]ct-4pk′ndcos[!theta!](l+ndcos[!theta!])c2)(Formula IX),

Nine the formula the intermediate frequency in the Fourier transform of a frequency difference, to obtain the frequency of the interference signal f_p to:

fp=2pk′ndcos[!theta!]πc=Kpd(Formula ten),

Ten can be known according to the formula the frequency of the interference signal f_p standard mirror and the plane (7) is proportional to the thickness of, wherein K_p as a proportional coefficient, and Kp=2pk′ncos[!theta!]πc,

Linear frequency modulation laser (5) of linear frequency modulation continuous emission laser at an incident angle θ₀ oblique incidence to plane standard mirror (7) and is the center frequency of the incident to plane standard mirror (7) is the ratio of the center frequency of the ζ, and ζ and refraction in relationship to the angle θ:

Ζ =cosθ (formula XI),

XI was according to the formula the value of the refraction angle θ,

According to the known law of refraction with the angle of arrival θ refraction angle θ₀ the relationship is:

θ₀ =arcsin {nsin[arccos (cosθ)]} (formula XII),

Incident light path according to the known geometric relations of incidence θ 0 with the standard beam (3) angle of θ ' is the relationship between:

[!theta!]′=[!theta!]02=arcsin{nsin[arccos(cos[!theta!])]}2(Formula XIII),

Thirteen the formula obtained in the standard beam (3) angle of θ 'in the value of the second formula, obtain pulse laser (1) with working medium the laser emitted by the target (2) I micro impulse generated from the action of'.