Microbolometer Spectrometer MIBS...Kuala Lumpur,EOSS, November 2007 MIBS and Last Results 4 Structure of the presentation •Introduction Microbolometer spectrometer (MIBS): Optical

MIBS and Last Results

Mic

robolo

mete

r Spectr

om

ete

r M

IBS

Murat Durkut

Netherlands Organisation for

Applied Scientific Research

Kuala Lumpur,EOSS, November 2007


2

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3

from a

fundamental

problem to a

proven,

workingsolution

Ultra-precise

High reliability

Harsh environments

Attitude

Sensors

MEM

S/M

OEM

S

for Space

Working in the

front line

Extreme stability and

accuracy for Scie

nce

An extreme

challenge

Equipment for

JET and

ITER

An established

world class

position

Spectrometers for

Eart

h O

bserv

ation

Space

Optics

Precision Mechanics

Control

Science

Nuclear fusion

Space &

Scie

nce

Scie

nce &

Industr

y



4

Structure of the presentation

•Introduction

•Microbolometer spectrometer (M

IBS): Optical Diagram

•Alignment

•Intensity Variations

•Therm

al Stability

•NETD(NoiseEquivalent Temperature Difference)

•CTF (Contrast Transfer Function) Measurements

•Conclusions



5

Introduction

EarthCARE2012

MSI Phase A

MIBS Breadboard



6

Optical diagram

Prism Spectrometer:

•Uncooled 2D microbolometer

array detector: 384x288, Ulis

•NADIR view ±10 ˚

•Operated at Room temperature

Collimator

Correction mirrors



7

MIBS during alignment

Using:

•CO

2Laser

•Integrating Sphere



8

Detector alignment

Gco: Gmean corrected for offset (column effect), for 200 frames

50

100

150

200

250

300

350

130

135

140

145

150

155

01000

2000

3000

4000

5000

Alignment (m

ore or less within 1 pixel)



9

Average Intensity variation

Standard deviation on a

single pixel on intensity

reduced by 28.5 %

by

averaging 200 frames.



10

Very clean image on large part of the detector



11

Therm

al Stability

Influence of slit temperature clearly measurable 2 degrees slit

temperature increase

Equals

60 degrees scene

temperature increase

(In line with predictions)



12

Therm

al Stability

Influence of camera (germ

anium Lenses L1 and L2)

2 degrees temperature

increase

Equals

29.5 %

decrease signal

due to increased

absorbtion in lenses.



13

Therm

al Stability

Influence of detector + electronics of camera(2.5 W

)

•Distinct intensityvariation over

image (electronincs or detector?) 2

brands used

•Signal 500 on offset of 10000

•Background level determ

ined outside

illuminated area: average 200 points

After

substr

acting

•Curv

e fitting



14

NETD calculations perform

ed.

Expected NETD(40 mKbolometer and 230K bench temp)

0.93 K

Com

pensating for 150m

K b

olo

mete

r Expecte

d3.5

K

Measure

d

3.7

K

Com

pensation for lo

wer re

flecta

nce (16%

) 0.6

K

Obta

inable

NETD

3.1

K

(despite E

MC

issues s

till p

ert

ain

ing)



15

CTF (Contrast Transfer Function)m

easurements

Gdif: Gmean (Hot-Cold) or Gco(ADU), Tdif= 70-0C, 200 frames

130

135

140

145

150

155

160

165

170

175

120

125

130

135

140

145

150

155

160

165

-20

020

40

60

80

130

135

140

145

150

155

160

165

170

175

0

20

40

60

80

100

Gdif around peak rows, for 200 frames

145

146

147

148

149

150

115

120

125

130

135

140

145

150

155

160

165

0

20

40

60

80

100

Gdif (ADU) along vertical lines, Tdif= 70-0C,200 frames

145

146

147

148

149

150

151

152

153

154

155

156

157

158

159

Ebas, FOV(deg), target(*0.01 lp/mrad) = _3800_plus2_board1_013

•CTF for 7.7

mR

ad and larg

er

should

be 1

•Low

est m

easure

d is 5

mR

ad a

nd

CTF is s

till 1

•Measure

for lo

wer fr

equencys



16

Conclusions and way forth

•M

IBS w

ould

meet N

ETD

specific

ations if better dete

cto

r is

used.

•Slit images leaves plenty of reference pixels needed for signal

processing

•Final temperature calibration can most probably be done using slit (so

only one blackbody required).

•Signal processing and ADC resolution will be important.

•Next phase consists of:

•Improving on-board blackbody’s

•Processing of CTF data

•Measurement of radiometric accuracy

•Search for flight opportunity???

•Proposed improvements:

•Gold coating should be improved

•Holes in slit should be covered.

•Alignment in rotation should be improved for flight experiment

•Lightweighting; Optimisation



17

Thank you for your

attention.

Murat Durkut

+31 15 269 2451

Murat.Durkut@

tno.nl



18

Speckle and mode hopping

Two laser modes:

10.57 and 10.61 µm



19

Space

Optics

Precision Mechanics

Control

An established

world class

position

Spectrometers for

Eart

h O

bserv

ation

Working in the

front line

Extreme stability and

accuracy for Scie

nce

An extreme

challenge

Equipmentfor

JET and

ITER

A paradigm

shift?

MEM

S/M

OEM

S

for Space

Science

Nuclear fusion

Space &

Scie

nce

Scie

nce &

Industr

y

Documents

Microbolometer Spectrometer MIBS...Kuala Lumpur,EOSS, November 2007 MIBS and Last Results 4 Structure of the presentation •Introduction Microbolometer spectrometer (MIBS): Optical