A pulsed Tuneable LAser system for the

characterisation of Spectrometers (ATLAS).

WP3510: Ground based instrument calibration

ESA/Ideas+ Task 3 phase 1 2015/03 – 2016/06

Julian Gröbner, Natalia Kouremeti, Stelios Kazadzis

Physikalisch Meteorologisches Observatorium Davos, World Radiation Center, PMOD/WRC

Project Deliverables

Project Duration : March 2015 – June 2016

• WP1: Commissioning of tuneable laser system.

• WP2: Radiometric characterisation of 2 array spectroradiometers

using tuneable laser sources

• WP3: Development of correction methodologies for stray light and

linearity

The optical laboratory of PMOD/WRC

Global Spectral

irradiance calibration

Direct Spectral

irradiance calibration ATLAS Tuneable

Laser

Spectral

responsivity

ATLAS Tuneable laser facility

Entrance optic

Microlens

array

Filterwheel

Tuneable laser

Monitor

detector

Wavemeter

Tuneable laser setup at PMOD/WRC

OPO Laser

Filterwheel Wedge filter

Monitor Detector Wavemeter

Radiometer

Tuning range 210 -2600 nm

Pulse 5 ns

repetition rate 1000 Hz

Pulse power at 450 nm ~300 mW 200 400 600 800 10000

0.2

0.4

0.6

0.8

1

Wavelength /nm

A.U

.

ATLAS Tuneable Laser output

Microlens array

379.5 380 380.50

0.05

0.1

0.15

0.2

0.25

0.3

Wavelength /nm

A.U

.

NT242 Laser

WL=379.932 nm

FWHM = 5.7 pm

Instrument characterisations performed on

the ATLAS setup

Completed :

Phaeton/Avantes – DOAS/ mini MAXDOAS System

PSR 006/ PMOD/WRC- spectral aerosol optical depth

PFR N02 / GAWPFR – 4 channel Moonphotometer

To be done : (in ESA/Ideas+ Task 3 phase 2)

Pandora #120 /PANDONIA

(deployed at PMOD/WRC since April 2016)

Spectroradiometer characterisations

• Phaeton Avantes 1509101U1 (cooled CCD version)

• PSR 006 Precision solar Spectroradiometer

1) Linearity Characterisation at different wavelengths

a) Intensity fixed, varying integration time (electronic nonlinearity)

b) Varying intensity (photons/sec nonlinearity)

2) Line-Spread Function measurement

a) Slit function

b) Stray-light matrix

Linearity characterisation : photons/second

1760 1780 1800 1820 1840 1860 188010

-4

10-3

10-2

10-1

100

Pixel

No

rma

lis

ed

Phaeton_440nm

101.9 Cpms

162.5 Cpms

257.0 Cpms

425.3 Cpms

641.5 Cpms

1013.4 Cpms

1629.1 Cpms

2621.9 Cpms

4025.0 Cpms

Each line-spread function contains a large range of intensities

&

Several line-spread functions are measured for different intensity levels

-0.0

6-0

.04

-0.0

20

0.0

20.0

40.0

60

10

20

30

40

50

60

Resid

uals

Phaeto

n n

onlin

earity

U95=

2.1

%200 220 240 260 280 300 320

10-4

10-3

10-2

10-1

100

Pixel

No

rma

lis

ed

Phaeton_320nm

5.4 Cpms

8.7 Cpms

14.3 Cpms

24.4 Cpms

38.1 Cpms

61.5 Cpms

100.5 Cpms

167.0 Cpms

258.1 Cpms

415.8 Cpms

679.9 Cpms

1095.7 Cpms

1876.4 Cpms

3028.8 Cpms

4681.6 Cpms

2933.9 Cpms

4557.7 Cpms

440 460 480 500 520 540 56010

-4

10-3

10-2

10-1

100

Pixel

No

rma

lis

ed

Phaeton_340nm

4.0 Cpms

6.4 Cpms

10.3 Cpms

17.3 Cpms

26.4 Cpms

43.5 Cpms

70.2 Cpms

116.0 Cpms

177.0 Cpms

280.3 Cpms

468.3 Cpms

744.7 Cpms

1238.4 Cpms

1989.6 Cpms

3067.1 Cpms

4897.8 Cpms

U95=2.1%

>4 orders of magnitude

Sampled range 0.1 to 4898 cpms

Nonlinearity < ±2.1% (95%)

Phaeton

-0.0

6-0

.04

-0.0

20

0.0

20.0

40.0

60

50

100

150

200

250

300

350

Resid

uals

Phaeto

n n

onlin

earity

U95=

1.5

%

100

101

102

103

104

0.9

0.92

0.94

0.96

0.98

1

1.02

1.04

1.06

1.08

1.1

Counts per ms

No

n-L

ineari

ty (

based

o

n lin

e sh

ap

e)

PSR_006

Linearity characterisation : photons/second

1760 1780 1800 1820 1840 1860 188010

-4

10-3

10-2

10-1

100

Pixel

No

rma

lis

ed

Phaeton_440nm

101.9 Cpms

162.5 Cpms

257.0 Cpms

425.3 Cpms

641.5 Cpms

1013.4 Cpms

1629.1 Cpms

2621.9 Cpms

4025.0 Cpms

Each line-spread function contains a large range of intensities

&

Several line-spread functions are measured for different intensity levels

200 220 240 260 280 300 32010

-4

10-3

10-2

10-1

100

Pixel

No

rma

lis

ed

Phaeton_320nm

5.4 Cpms

8.7 Cpms

14.3 Cpms

24.4 Cpms

38.1 Cpms

61.5 Cpms

100.5 Cpms

167.0 Cpms

258.1 Cpms

415.8 Cpms

679.9 Cpms

1095.7 Cpms

1876.4 Cpms

3028.8 Cpms

4681.6 Cpms

2933.9 Cpms

4557.7 Cpms

440 460 480 500 520 540 56010

-4

10-3

10-2

10-1

100

Pixel

No

rma

lis

ed

Phaeton_340nm

4.0 Cpms

6.4 Cpms

10.3 Cpms

17.3 Cpms

26.4 Cpms

43.5 Cpms

70.2 Cpms

116.0 Cpms

177.0 Cpms

280.3 Cpms

468.3 Cpms

744.7 Cpms

1238.4 Cpms

1989.6 Cpms

3067.1 Cpms

4897.8 Cpms

U95=1.5%

>5 orders of magnitude

Sampled range 0.1 to 16000 cpms

Nonlinearity < ±1,5% (95%)

PSR 006

Linearity characterisation : count space

Constant Intensity, only variation of integration times

245 250 255 260 265 2700

0.5

1

1.5

2

2.5

3

3.5x 10

4

Pixel

Co

un

ts

Phaeton 320 nm

40

50

60

70

80

90

100

200

300

400

500

600

700

800

900

1000

1500

2000

2500

3000

3500

4000

4500

5000

5500

6000

Significant nonlinearities of up to 15% at low counts

102

103

104

105

0.9

0.95

1

1.05

1.1

1.15

1.2

1.25

Counts

De

pa

rtu

re f

rom

lin

ea

rity

Phaeton nonlinearity WL=320

U95=1.4% - 10.5%

102

103

104

105

0.9

0.95

1

1.05

1.1

1.15

1.2

1.25

Counts

Rati

o o

f C

pm

s IT

i/IT

max

PSR_006

U95=+-2.0%

Line-Spread function measurement

500 1000 1500 200010

-6

10-4

10-2

100

Pixel

No

rma

lis

ed

Phaeton Line Spread Function 297.7 nm

142

344

1214

2032

10558

Slope

IT

To achieve sufficient dynamic range measurements at different saturation levels

are combined into one line spread function

2 orders of

magnitude

improvement

Line-Spread function measurement To achieve sufficient dynamic range measurements at different saturation levels

are combined into one line spread function

0 100 200 300 400 500 600 700 800 900 100010

-7

10-6

10-5

10-4

10-3

10-2

10-1

100

Pixel

No

rmli

se

d

PSR 006 410 nm

6 orders of

magnitude

In-band Stray-light correction

300 350 400 45010

-6

10-5

10-4

10-3

10-2

10-1

100

wavelength(nm)

Sli

t F

un

cti

on

The stray-light corrected in-band signal YIB can be retrieved from the measurement by applying a stray-light correction matrix A-1 to the measured signal, following the method of Zong, 2006.

YIB=A-1 Ymeas

In-band Stray light correction procedure for array

spectroradiometers

Slit Functions obtained from tuneable

laser setup

1IB meas meas

Y A Y C Y

from Zong et al, 2006

In-band straylight matrix

Calculated Straylight

Characterization of Moonphotometer (Lunar PFR)

• Linearity

• Determination of PFR internal gain

• Filter Function

• Direct Irradiance Calibration

Setup

• Response (V/W.m-2)

Characterization of Moonphotometer

Filter Functions

Scanning Spectral region 300-950 nm

-10 -5 0 5 100

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

wavelength offset (nm)

Filte

r F

un

ctio

n

861.3

501.2

412.4

675.6

Filter Central Wavelength (nm)

Characterization of Moonphotometer

Filter Functions – Out-of-band rejection

300 400 500 600 700 800 900 100010

-6

10-5

10-4

10-3

10-2

10-1

100

wavelength offset (nm)

Filte

r F

un

ctio

n

861.3

501.2

412.4

675.6

Filter Central Wavelength (nm)

Characterization of Moonphotometer

Direct Irradiance Setup – Responsivity V W-2m2

300 400 500 600 700 800 900 10000

20

40

60

80

100

120

Irra

dia

nc

e -

La

mp

F4

67

(W

.nm

-1.m

-2)

wavelength (nm)

F467

861.3

501.2

412.4

675.6

1000 1500 2000 2500 30000.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

Distance from Lamp (mm)

Da

rk C

orr

ec

ted

Sig

na

l -1

/2 (

mV

-1/2

)

861.3

501.2

412.4

675.6

Irradiance at reference distance

Distance

Reference Plane (detector) to Front window

Determination of reference plane

ATLAS Project schedule, phase 1 Kick-Off (KO) 22 June 2015

Deliverable

number Deliverable Description

Due Date

(KO+#month)

Work

Packages Progress

TD0

Brief Monthly Reports Monthly all

TD1.1 Tuneable laser system operational 12.2015 WP1 completed

TD1.2 SOP for LSF and Oor stray light 2.2016 WP1 completed

TD1.3 SOP nonlinearity 3.2016 WP1 completed

TD2.1 LSF, Oor stray light and linearity

determined for System 1. 6.2016 WP2 completed (Phaeton)

TD2.2 LSF, Oor stray light and linearity

determined for System 2. 9.2016 WP2

completed (PSR006)

TBD (Pandora, phase 2)

TD3.1 Report on nonlinearity correction

method 6.2016 WP3 In progress,7.2016

TD3.2 Report on In-range and out-of-range

stray light method 10.2016 WP3

In progress,7.2016

TD4 Final report, Presentation 10.2016 all

ATLAS Project schedule, phase 2 Kick-Off (KO) 5 July 2016

Deliverable

number

Deliverable Description Type Due Date

(KO+#month)

Progress

T1.1 Report on the Wavelength calibration

of ATLAS

report KO+3 started

T2.1 Report on the field homogeneity of the

beam conditioning unit

Report KO+6 started

T2.1 Certificate for Linearity correction

function

Calibration

certificate

KO+9

T2.2 Report on Bandpass and Line-Spread

function and determination of stray-

light matrix

Report KO+10

T2.3 Report on wavelength dispersion

function

Report KO+10

T2.4 Calibration certificate for spectral

irradiance

Calibration

Certificate

KO+11

T3.1 Dataset from one Pandora system

deployed at PMOD/WRC

Data set KO+15

T3.2 Report on the comparison of the TCO

with Dobson and Brewer

Report KO+18

T3.3 Report on the comparison of AOD to

the WORCC reference Triad

Report KO+18