diode pulsed lidar-rangefinder: eye-safe measurements with ... · diode pulsed lidar-rangefinder:...

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Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev 1) , V.S. Makarov 2) , A.V. Turin 2) 1) Wave Research Center, Prokhorov General Physics Institute, Moscow, 119991, Vavilov, 38. 2) Space Research Institute Russian Academy of Sciences, 82/34 Profsouznaya Street, Moscow 117133, Russia [email protected]

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Page 1: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm

accuracy by 15 ns pulse

Sergey Pershin, V.N. Lednev1), V.S. Makarov2), A.V. Turin2)

1)Wave Research Center,Prokhorov General Physics Institute, Moscow, 119991,

Vavilov, 38.2)Space Research Institute Russian Academy of Sciences,

82/34 Profsouznaya Street, Moscow 117133, [email protected]

Page 2: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

• S.Pershin, V.Linkin, V.Makarov, I.Prochazka, K.Hamal,

“Spaceborn laser altimeter based on the SPAD receiver and semiconductor laser transmitter”, Proc. CLEO, Advance Program p.120 (1991).

S.Pershin et al. Compact “eye-safe” lidar for environmental monitoring,

SPIE, v. 2107, 336 (1993)

S.PershinTrouble-free compactLidar for in/out door atmosphere

monitoring, SPIE v. 2506, 428 (1995)

Page 3: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Micro-Joule Lidar based on diode laser and single photon detector

• Covered by Patent of Russia -2007

Page 4: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Outline• Noval approach based on high repetition rate eye-

safe microJoules pulses and quantum counter• Advantages

• High efficiency diode pulsed lasers as transmitter• High efficiency Single Photon Avalanche Diode as

receiver• Results

• The first Lidar on Mars was the lidar of • Russian Academy of Sciences • which was delivered by NASA “Mars Polar

Lander” mission in 1999

Page 5: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Lidar LIMS for NASA project Mars Polar Lander –99

Weight – 940 gConsumption - 0.2 WТ = –100 +50 0СData volume2kB per set36 kB/12 sets per solRange 750 metersresolution 10 m

Page 6: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),
Page 7: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

1999 - The first Lidar onMars surface (South Pole )

Congratulations with 10th anniversary !!

Page 8: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

LIMS

Page 9: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Lidar principle with Single Photon Avalanche Diode as receiver

laser pulse

gates

hysto noisesignal

Page 10: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Motivation• Can we measured the distance

with centimeter accuracyby τ =15 ns (~4.5m) pulsed rangefinder based on eye-safe diode laser and SPAD as receiver?

• distance is L = c ∆t /2,where ∆t is time of flight;

accuracy is ∆L = сτ/2,where τ is pulse duration (about 4.5 m)

Page 11: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

N E W L A S E R S A F E T Y C O N C E P T SD . S L I N E Y . L A S E R F O C U S W O R L D . 1 9 9 4 . P . 1 8 5

L A S E R T Y P E W A V E -L E N G T H

M a x i m u m p e r m i s s i b l ee x p o s u r e ( M P E )

A r g o n F l u o r i d e 1 9 3 n m 3 , 0 m J / c m 2 o v e r 8 h

X e n o n C l o r i d e 3 0 8 n m 4 0 m J / c m 2 o v e r 8 hN i t r o g e n 3 3 4 n m 1 . 0 J / c m 2 o v e r 8 hA g r o n I o nH e l i u m - N e o nK r i p t o n I o n

4 8 8 , 5 1 4 . 5 n m6 3 2 . 8 n m5 6 8 , 6 4 7 n m

3 . 2 m W / c m 2 f o r 0 . 1 s2 . 5 m W / c m 2 f o r 0 . 2 5 s1 . 8 m W / c m 2 f o r 1 . 0 s1 . 0 m W / c m 2 f o r 1 0 s

N d : Y A G / 2R u b y

5 3 2 n m6 9 4 . 3 n m

0 . 5 J / c m 2 f o r 1 n s t o 1 8 s

D i o d e s 8 5 0 n m( t y p i c a l )

1 . 0 J / c m 2 f o r 1 n s t o 1 8 s2 . 0 m W / c m 2 f o r 1 0 s

N d : Y A G 1 0 6 4 n m ,1 3 3 4 n m

N o M P E f o r t < 1 n s5 . 0 J / c m 2 f o r 1 n s t o 5 0 s5 . 0 m W / c m 2 a t 1 0 6 4 n m / 1 0 s4 0 m W / c m 2 a t 1 3 3 4 n m / 1 0 s

H o l m i u m /T h u l i u m

1 . 9 – 2 . 2 m 1 0 0 m W / c m 2 f o r 1 0 s t o 8 h ,l i m i t e d a r e a1 0 m W / c m 2 f o r > 1 0 s f o rm o s t o f b o d y

C a r b o nm o n o x i d eC a r b o n d i o x i d e

m

1 0 . 6 m

1 0 0 m W / c m 2 f o r 1 0 s t o 8 h ,l i m i t e d a r e a1 0 m W / c m 2 f o r > 1 0 s f o rm o s t o f b o d y

S o u r c e e s : A N S I s t a n d a r d Z – 1 3 6 . 1 - 1 9 9 3

Page 12: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Micro-Lidar advantages• Eye-safe and full trouble-free• High efficiency – diode laser & photon counting• Digital circuit– high stability to environment• Reliability• No interference• High repetition rate-short acquisition time• Photon counting – discrete statistics• Multilayer clouds, plume detection and smoke

mass measured for forest fires, bio-mass restoration after forest fires

Page 13: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Hand-held aerosol Lidar

Page 14: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),
Page 15: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Urban aerosol monitoring• 50 meters over the surface

Page 16: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Clouds-layer monitoring in strong snowing

0 200 400 600 800 1000 120010000

15000

20000

25000

30000

Lida

r cou

nts

Height, m

boundary layer

cloudslow boundary

strongsnowing

850 elevation

Moscow, 09.11.06

Page 17: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Clouds-layer monitoring in strong snowing

0 200 400 600 800 1000 120010000

15000

20000

25000

30000

35000

Lida

r cou

nts

Height, m

600 elevation

shift with elevation

height layers

strongsnowing

Moscow, 09.11.06

Page 18: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

0 200 400 600 800 1000 1200 1400 1600 1800 20000

5000

100000 200 400 600 800 1000 1200 1400 1600 1800 2000

0

5000

100000 200 400 600 800 1000 1200 1400 1600 1800 2000

0

5000

100000 200 400 600 800 1000 1200 1400 1600 1800 2000

0

5000

10000

15000 0 200 400 600 800 1000 1200 1400 1600 1800 20000

500010000

elevation 100 21:30

cloud's low boundary, m

elevation 200 21:33

elevation 450 21:38

elevation 75-800 21:43

Moscow, Vargy street, 21:30 -21:55, 11/09/07ph

otoc

ount

s32 000 pulses

elevation 450

21:55

aperture 25 mmno saturation

Page 19: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Eye-safe pulsed rangefinder

• Improvements of space resolution

Page 20: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Lidar principle with Single Photon Avalanche Diode as receiver

laser pulse

gates

hysto noisesignal

Page 21: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Target ranging through canopy, 5 m step

0 10 20 30 40 50 60 70 80 90 1000

500

1000

1500

2000

2500

SPA

D p

hoto

coun

ts

Distance, m

building wall

tree canopyglass of window

Page 22: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Target ranging through canopy, 5 m step

40 50 60 70 80 90 1000

500

1000

1500

2000

2500

SPA

D p

hoto

coun

ts

Distance, m

building wall

tree canopy5 m step

Page 23: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Target ranging through canopy, 5 cm step

5000 6000 7000 8000 9000 100000

20

40

60

80

Pho

toco

unts

Distance, cm

tree’s canopy

target:building wall

Page 24: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Range measurement scheme

Lidar target

Lidar shift = i * 1 cm

Ranges = ~ 0.3 and 500 m

Page 25: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Distance measurements

0 2 4 6 8 10

3804

3806

3808

3810

3812

3814

3816

Dis

tanc

e to

targ

et, c

m

Lidar shift, cm

Y = A + B * XWeight given by Datadistcompa_C error bars.

Parameter Value ErrorA 3804.84489 0.48122B 1.00675 0.10646

R SD N P0.99668

Page 26: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Distance measurements(curve fitting analysis)

3500 3600 3700 3800 3900 4000 4100 42000

300

600

900

1200

1500

1800

2100

Sign

al, a

.u.

Distance, cm

3700 3720 3740

800

900

1000

1100

1200

Comparison by fittingTwo curves are different

3750 3800 3850 3900

1400

1600

1800

2000

Nonlinear fitting by Voight profile

confidence bands(shift 0 cm)

confidence bands(shift 1 cm)

FWHM = 2.25 m

Page 27: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Distance measurements(curve fitting analysis)

3500 3600 3700 3800 3900 4000 4100 42000

300

600

900

1200

1500

1800

2100

Sign

al, a

.u.

Distance, cm

Model: VoigtEquation:Weighting: y Statistical

Chi^2/DoF R^23.81067 0.99291

Parameter Value Errory0 -17.62557 1.94836xc 3805.49068 0.28506A 417099.75023 2739.20227wG 163.74087 1.99847wL 48.21054 2.43773

Model: VoigtEquation:Weighting: y Statistical

Chi^2/DoF R^24.781 0.99088

Parameter Value Errory0 -16.59373 2.19xc 3807.21457 0.3239A 404785.78912 3049.22477wG 165.89906 2.26771wL 46.28024 2.79002

3720 3750

800

1000

1200

sig

nal

distance

Comparison by fittingTwo curves are different according to fitting

3800

1400

2100

sig

nal

distance

Page 28: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Signal fragment: the target shift ~1 cm

3700 3710 3720 3730 3740800

900

1000

1100

1200

Cou

nter

num

ber

distance, cm

∆~ 1 cm

Page 29: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Лазерный измеритель нижней границы облаков

ООО «Центр исследований и разработок концерна АГАТ»ОАО « Лыткаринский завод оптического стекла»ЗАО НПАО «Эполар»

105275, г. Москва, шоссе Энтузиастов, д.29 E-mail: [email protected]Тел./факс +7(499)5038787, 5038778 Август 2013 г.

Skolkovo Center

Laser celeometer: cloud height

Page 30: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

ЛДВО - 01• НАЗНАЧЕНИЕ И

ОБЛАСТЬ ПРИМЕНЕНИЯ

• ЛДВО-01 предназначен для оперативного дистанционного измерения высоты нижней границы облаков и вертикальной видимости.

• ЛДВО-01 обеспечивает:

ЛДВО – 01Общий вид опытного

образцаблочного исполнения

Блок оптический

Блок питания и связи

Page 31: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Conclusion

Micro-Joule eye-safe Lidar can be widely used for environment

monitoring Without eyes protection

and with cm accuracy ranging

Page 32: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Thank for attention

Page 33: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

MicroJoule man-handle Lidara

b

Page 34: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Oil slick monitoring by lidar (Volga, 1994).

novel approach: double pass

L idar

S horeI IIIII

Page 35: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

500

400

300

200

100

0 50 100 150 200 250 300Range, m

Lidar backscattering, count

A1

A2

A3

aerosolwater

surface

double pass

S.M. Pershin, Phys. of Vibr. V.9(3) 192 (2001)

Page 36: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

10-FOLD increasing due to oil slickBackscattering photon, count20000

15000

10000

5000

010 20 30 40 50

Range, m

Clean water surface

Oilspot surface32000 pulsesaverage

22 l 2 .LA I R

Page 37: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Clouds and layers monitoring

Page 38: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Clouds height measurements

5 0 1 0 0 1 5 0 2 0 0 2 5 0 3 0 0 3 5 00

1 0 0

2 0 0

3 0 0

4 0 0

5 0 0

6 0 0

7 0 0

8 0 0

Phot

ount

s

H e i g h t , m

aerosolCloud’s low boundary

Page 39: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Multi-layers clouds

Three layers

Page 40: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Forest fires monitoring

USA, Montana-Idaho St.

Sept. 1999

Page 41: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),
Page 42: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),
Page 43: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Trees height monitoring

For biomass restoration after forest fires

Page 44: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Tree’s height monitoring via air-platform

Page 45: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Tree’s biomass estimation by Lidar profiling of forest canopy

Page 46: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Micro -Lidarin Moscow State

University,

Physics Department,

for student education courses

Page 47: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Compact microLidar

Page 48: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),
Page 49: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),
Page 50: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Acknowledgements

• Makarov V.• Patsaev D.• Bukharin A.• Nekhaenko V.• Lyash A.

Page 51: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Thanks for attention

Page 52: Diode pulsed lidar-rangefinder: eye-safe measurements with ... · Diode pulsed lidar-rangefinder: eye-safe measurements with ~1cm accuracy by 15 ns pulse Sergey Pershin, V.N. Lednev1),

Distance measurements(curve quality difference)

3600 3800 40000

700

1400

Sign

al, a

.u.

Distance, cm

0 cm 1 cm 10 cm

FWHM = 160 cm

target shift

3600 3610 3620 3630 3640 3650 3660 3670 3680

200

400

600

800

1000

1200

1400

Sign

al, a

.u.

Distance, cm

0 cm 1 cm 10 cm

target shift

3690 3700 3710 3720 3730 3740 3750 3760 3770 3780

600

800

1000

1200

1400

1600

Sign

al, a

.u.

Distance, cm

0 cm 1 cm 10 cm

target shift

3750 3760 3770 3780 3790 3800 3810 3820 3830 3840 3850

1600

Sign

al, a

.u.

Distance, cm

0 cm 1 cm 10 cm

target shift

Nonlinear fitting by Voight profile