锁相放大器(Lock-in-Amplifier)的原理与应用

lock-in

D y T nV¡C a A i H µq C Lock-in-Amplifier D n u I ”¯e ”¡A q S v P A L o i q o C Lock-in-Amplifier ]PSD(phase sensitive detector)¡A q S v B A L o L q H C

Lock-in q n v A A O i A v f 1G

)2sin(1111φπ+=f E e P )2sin(2222φπ+=f E e

q L V (mixer)²V o µG G

)2sin()2sin(221121213φπφπ++=×=f f E E e e e )]()(2cos[2

)]()(2cos[2212121212121φφπφφπ+++−−+−=

f f E

E f f E E (difference frequency component) (sum frequency component)

PSD AC A p q L C q o i A AC

o C p G f 1µ¥f 2®ÉA difference frequency component DC

A o p U PSD )cos(2

212

13φφ−=

E E e )1)(cos(21≈−φφ

Lock-in

lock-in i1V q A q I+P I-

S C H q eµn u C B p U G

1.q e A i q q q A A P q q y

p A o B n A P A q y a C

2.q(q u p)A i q(1M[B

10M[B100M[B1G[)M q y K q10K[(]q 10K[)

3. lock-in

(1) ¥lock-in sensitivity A A lock-inµu(p G)

µu C

(2) °10-7A A i q10M[A q A

A lock-in sensitivity A(1mV)A qµ

10V(q O lock-in q10µG)C

(3) ¿(OSC LvL)]1V A v(OSC F)P60

(p G23)A K P A(REF PH)Aµ(90o)µ0-V Bµê(270 o)µ0+V A(0 o B180 o)10V C p U

G

Lock-in

A lock-inµq C

1.lock-in sensitivity A o i BP A time constant]1s A

A lock-in I qµu(p)µu C

2. °10-7A A i q10M[A q A A

lock-in sensitivity A(1mV)A qµ10V C

3. ·lock-in i q o q P v A q q o V xx MµV xy/µB i(n)M E v(µ)C

4. °lock-in t lock-in A Aµ

µq A q(p)C

µG

1. ½sensitivity n A q n110V d A]p

G p A M A e L C

2. °Vxy Y A A sensitivity C

3. ¶sensitivity A]v q

C

4. ¶

5. ´(time constant)A]LµLªk t A n]

1s C

6.

G q u(V S lock-in q)

G lock-in I qµu

G q