s o SANH VONG CHUAN DAU DQ DAI
NGUON LASER HENE ON DINH TAN SO BANG lOT CHUAN DAU DQ DAI
Bin Quoc Thu, Cao Xudn Qudn, Le Hint Thdng Vi?n Do ludng Vii?t Nam
Tom tdt:
Cudi ndm 2007 phdng Do ddi-Viin Do ludng Vigt Nam(VMI) mang ngudn Uiser He-Ne 6n dinh tdn sd bdng idt budc sdng 633iim sang Viin nghiin cuu khoa hge chudn Hdn Quoc (KRISS) tham gia chuong trinh so sdnh vdng mang ma so APMP.L- Kll.l(http://ksdb.bipm.org ). Ngi dung bdi viit trinh bdy kit qud so sdnh vong dugc phong thi nghiem thugc viin nghien ciru khoa hge vi chuan (KRISS) ( Phdng thi nghi?m chu tri-Host laboratory [2[) bdo cdo tgi cugc hgp thuong niin cua to chuc do ludmg chau A -Thai binh duong (APMP) ndm 2008 tgi INDONESIA.
I. Md dau.
Ndm 2005 Phong do ludng Dd ddi VMI dugc trang bj ngudn Laser He-Ne budc sdng 633 nm dn djnh tdn so bdng Idt (Iodine stabilized He-Ne laser at 633nm) do dn djnh tan sd 2x10"
.Do Id mdt trong cdc ngudn laser dn djnh tdn sd - chudn dau do ludmg dg dai do Vien can do Qudc td (BIPM) khuydn cao[l] thudc dy an phdng thf nghiem trgng didm Qudc Gia giai doan I. Theo gidy chimg nhdn hieu chuan sd 821/271357-05 cua Vien tieu chudn va cong nghe Hoa ky (NIST) tdn sd cua ngudn Laser tai dinh i(ai3) la
fi=473 612 214 714,1 kHz
Vdi do khdng ddm bdo do U = 6,2 kHz; k=2
Dd ddm bdo tfnh ddn xudt chudn ciing nhu cdc bdng chiing ky thuat dd tham gia thoa thuan todn cau vd do ludng (MRA) ITnh vyc Dg ddi, Vien Do ludng Viet Nam da de nghi phdng thf nghiem do ludng Do ddi thudc KRISS tham gia chuang tnnh so sdnh vdng ve ngudn Laser He-Ne budc sdng 633 nm dn djnh tdn sd bang idt. Ngudn Laser dn djnh tan sd
I f f '
bdng idt ddng thdi ciing la chudn Do ludng Qudc gia cua Han Qudc da dugc so sdnh h^c tiep vdi ngudn Laser dn djnh tdn sd cua BIPM theo chuang trinh so sanh vdng BIPM. L-KU nam 2006 (http://ksdb.bipm.org).
II. Cac dac trung ky thuat cua nguon laser He-Ne bu'dc sdng 633nm on dinh tan so bang l6t tham gia so sanh vong.
Ten ggi
n ^
Chuan dau do dai ciia Hdn qudc Kriss-R061
Chudn ddu do dai Viet Nam
VMI-206
yoi.TBi.oi
Hang San xudt ^- Sd hieu
Chidu dai phan tir Idt/ cm Ky hidu Phdn tu Idt
Do lech chudn tuang ddi Allan tai 1000s
Chieu dai budng cgng hudng/cm Kieu guang cua phdn tir idt Ty le phan tram tia Laser di qua
guong phdn tii idt
Kieu guong cua dng phdng Laser
Ty Id phdn tram(%) tia Laser di qua guong dng phdng Laser Cdng sudt laser trong budng cdng
hudng mW
Winters # 100 S/N 218
10 BIPM #385
3x10-"
26,5 Phdng
20
Cdu 1dm, bdn kfnh: - 3 0 cm
70
10
Winters # 100 S/N 206
10 BIPM # 459 S
3x10-'-^
26,5 Phdng
20
Cdu 1dm, bdn kinh:- 30 cm
70
10
III. Thu tuc do (protocol)
Thu tyc do tidn hanh dya tren hudng dan thii tyc do (Protocol) CCL-kl 1 [2] bao gom cac budc sau:
mO: Tien hdnh do khdo sat cdc dac trung ky thudt ciia ngudn laser He-Ne dn djnh tan sd budc sdng 633nm cua VMI bao gdm dnh hudmg cua nhiet do phdn tu idt, cdng suat phdt ra cua laser, he sd dieu bien (Modulation). Tir dd xdc djnh cdc he sd dnh hudmg ciia nhiet do phdn tu idt (Temperature Shift), cdng sudt phdt ra ciia Laser (Power Shift), he so dieu bidn(Modulation Shift) ddn dg chfnh xac tan sd cua nguon Laser, [2]
ml: So sdnh tryc tidp tdn sd nguon Laser tai dinh f [2] vdi ddng hd nguyen tii Cs (chudn dau thdi gian) thdng qua he thdng Optical comb, khao sdt dg dn djnh tdn sd theo phuang sai Allan (Allan Variation)
m2: Do tdn sd phach (heterodyne measurement) [3] theo so do hinhl (khdng sii dyng bg bien ddi quang am AOM) sii dyng phuang phdp ma tran xac djnh do lech tan sd giiia hai ngudn laser
m3: So sanh tryc tiep tan sd phach giira hai ngudn laser tai dinh f bang each do tan sd phach [3] cd su dung bg bien ddi quang am AOM ( acCisto-optical - modulation) ciia VMI cd gia trj tan sd fAOM = 80 MHz xac djnh do lech tan sd tai dinh f theo cdng thiic :
fl-fl = ^ ±fAOM
(1)
+ So sanh do dn dinh tdn so ciia ngudn laser theo phuong sai Allan (Allan Variation) khdng sii' dung bd bidn ddi quang am AOM.
Khi lidn hanh cac birdc do mO, ml va m3 chimg tdi da ldp dat thidt bj do theo so dd do BIPM khuydn cao [2j.
fl
,\0M C
TB
f2
> *
Hinh 1. Sff do do so sanh tan so giira hai nguon laser / / : Ngudn laser cua VM ; /? Ngudn laser ciia KRISS
AOM: Bd bidn ddi quang dm; Counter : Bd ddm tdn sd PD: Phd td di dt; BS: Bd tdch tia (Beam spliter)
Theo so dd hinh 1 thdng qua phd td di 6t (PD) bd ddm tdn sd se do dugc tdn sd phdch 4/"
4/"=/y-/2 ±fAOM (2)
Trong trudng hgp khdng sir dung AOM
Af=M2 (3)
IV. Kdt qua so sanh vdng dat dugc.
4.1. Ket qua do mO [4]
Bang 2. Ket qua do xac dinh cac thong so dde trung ky thuat cua laser
Power shift Modulation shift Tempareture shift
' VMI -96,5 Hz/pW -8,3 kHz/MHz -13,2 kHz/°C
KRISS -95,7 Hz/ pW -7,9 kHz/MHz
-13.2 kHz/ °C
4.2 Kdt qua do ml[4]
Tan sd tai dinh f ciia ngudn laser He-Ne budc sdng 633 dn dinh tan sd bdng idt ciia VMI dugc so sanh trirc tidp vdi chudn ddu thdi gian tdn sd ciia KRISS (Giay chung nhan hidu chuan sd 0800-01567) kdt qua nhu sau:
fivMi = 473 612 353 609,6 kHz ; U = 2,7 kHz (k=2)
Ket qud do so sanh do dn djnh tan sd (Allan Variation) cua ngudn laser VMI vd KRISS sir dung he thdng do Optical Comb
K R I S S VMI
i
a
KRISS-071127 - • - c ? t i ; 7 - 0 4 - » - 0 " n 2 7 - o ;
• 0 7 n 2 ' - 0 f - T - o T i i j r - o ?
0 r i l 2 7 J l
••<- 071127.0}
. 2 * 1 0 TTTr <,-}
< = ^
Averiging Time (i,
.S S t a
V V I I - 0 7 1 1 2 7
^L
\
- • - 0 7 1 127-01 - . - 0 7 1 1 2 7 - 0 2
' 0 7 1 1 1 7 - 0 ;
2 * 1 0 " ' T ' ' ' 2
^:C
Avtraging "^mt (si
Hinh 2. Do thi k£t qua do theo phirong sai Allan sun dung he thong do optical comb Kdt qua do m2 [4]
f^Mi= 473 612 353 609,6 kHz (u=l,4 kHz k=l) ffVMi= 473 612 353 609,2 kHz (u=0,2 kHz k=l)
f(0 VMI := +5,6 kHz + F(f) CIPM ; f(f) KRISS= + 5,2 kHz-H F(f) CIPM f(0 KRISS F(f) VMI = - 0 , 4 2 kHz
10000 9000
^ 6000
2 iooo a,
O 4000
— 3000 2000 1000
•7CT
- I T H - V - -^r-w-v-
"•aL
- T ± 2 kHz
* KRISS. I. coflKIKl t. KRISS. I, uneorracttd
• VMI. I, corraclod V VMI. I, uncorraclad
• KRISS, I, coiraclod
•1 KRISS, i, uncorricled I I • I • I ' I ' I • I • I ' I ' I • I • I • I ' I • I ' I • I ' I • I '
i i i i i i i i i i i i i i E s i i i i i i i i i i i
Measurement
Hinh 3. Do thi so sanh do Idn tdn s6 giua hai nguon Laser ciia VMI va KRISS tai dinh f
K6l qua do ,so ,sanh do dn dinh lan .so ihco phuong sai Allan giira hai ngudn Ia.ser VMI va q
KRISS
Q j.
fl • •
<
K Riss vs. vr, 0711:
Q-W-^y-Wl
• ' , ; ; • ; so
1 w ; ; ; ;o
! • , ! • < ! ; ; :
1 1 1 ' , ! ; ; ;
!IS'.;-.:) 4
|ri»r"iin|ii'
IFS
"±•23^
— I — ' — I '—I—•—I
Hinh 4. Do tbi ket qua so .sanh dy 6n dinh tan so thco phuong sai Allan giua hai ngudn laser
4.3. Kdt qua do so sanh giua hai nguon Laser bdng phuomg phap ma tran (Matrix Measurement) [4].
Do lech tdn sd giira hai ngudn laser khi do bang phuang phap ma trdn tai cac dinh d,e,f,g Ma tran 4x4 (d,e,f,g)
KRISS-VMI
r
Kdt qua do 1 +0,826 kHz
»
Ket qua do 2 -0,575 kHz
r
Ket qud do Trung binh +0,126 kHz
Do lech tan sd giira hai ngudn laser khi do bdng phuang phap ma trdn tai cdc dinh h,i,j Ma tran 3x3 (h,i,j)
KRISS-VMI
7
Ket qua do I +0,761 kHz
F
Kdt qua do 2 -1,591 kHz
Kdt qud do Trung binh -0,415 kHz
Do lech tan sd tdng hgp tai cac che do phat d,e,f,g,h,i,j: KRISS-VMI = -0,145 kHz IV. Kdt luan:
Qua kdt qua so sanh vdng giQ-a hai ngudn laser He-Ne (633nm) dn djnh tdn sd cua Viet nam (VMI) va cua Han Qudc (KRISS) thudc chuang trinh so sdnh vdng APMP LK iM cho thdy do chfnh xac, do dn djnh tdn sd ciia ngudn laser VMI 206 VOl.TBI.01 ddng thdi chuan do ludng Qudc gia cua Viet Nam ITnh vyc Do ddi ddm bdo cdc yeu cdu ky thuat ciia chuan dau ITnh vuc dd dai.
- Kdt qua so sanh vong nay phan anh trinh do chudn do ludng do dai ciia Viet Nam tuang duang vdi trinh do chudn ciia cac nudc trong khu vuc ddng thdi dd cung la bdng chirng quan trgng khi chung ta tham gia thda thuan loan cau (MRA) ve do Iirdng do dai.
Qua qua trinh tham gia so sanh vdng dugc su hd trg ciia KRISS ve kidn thu'c cung nhu thiet bj, chiing tdi da bgc hdi dugc rdt nhieu kinh nghiem ky thuat do phuang phap danh gid do dn djnh ciia ngudn Laser. Chiing tdi xin chan thanh cam on Dr Hosuhng Suh va cac cdng sy ciia nhom nghien cuu ve laser cua KRISS da giiip dd chung tdi hoan thdnh nhiem vu.
Tai lieu tham khao
[1] BIPM Proc.-verb. Com.Int. Poids et Measures, 1983,51,25-28, Recommendation 1 (CI- 1983); Documents concering the New Difinition of metre Metrologia, 1985 19 163-177.
[2] Technical protocol for the CCL-Kll key comparison of optical frequency/wavelength standards TP CCL-KI! ver. 1.01
[3] Bayer-Hems F.,Chartier J-M., Helmck J., Wallard A.J., Evaluation of the Intercomparison Measurement (March 1976) with '^
structure, 1977 PTB-ME 17 139-146
Measurement (March 1976) with '^^l2 Stabilized He-Ne laser : Spacing of the Hyperfine
[4] Hosuhng Suh : Presentation " KRISS-VMI Intercomparison of Iodine stabilized He-Ne Laser @ 633 nm 2007"