SOFIE Spectral ResponseMark Hervig, GATS Inc.•Drivers:

Filter Response

Preceding Optics

Detector Response

Solar Source

•Out-of-band performance is critical

Requirement: Out of band exoatmospheric solar energy < 1% of total signal

•Spectral performance is analyzed using total response based on predicted and measured characteristics of the optical elements and detectors.

•The optical layout is shown on the following page.

•For example, the total response (TR) for band 14 is

TR14 = R17 T19 R13 T14 DR14

where R is reflection, T is transmission, DR is detector response, and subscript indicates optical element number.

•Below “actual” means that the filter transmissions are measurements from real filters. In the case of “actual” total response a number of other optical elements could be based on predictions.

Detector Optics

and Detector

OpticalElement #

CollimatedInput Beam

2.577 -2.632

2.427 -2.475

2.907-2.967

2.740 -2.793

3.472 -3.546

3.333 -3.401

3.160 -3.226

3.030 -3.091

4.255 -4.444

4.951 -5.051

4.630 -4.740

5.263 -5.376

0.286 -0.294

0.323 -0.333

0.848 -0.877

1.010 -1.053

Dichroic B S: Reflect UV, NIR;Transmit IR

Dichroic B S: Reflect <2.967Transmit > 3.030

Dichroic B S: Reflect .286-.333;Reflect .848-1.053 & 4.255-5.376: Transmit 2.427-3.546

Metal Mirror

Channel SeparationModule Filter Layoutas ordered April 2004

6 5

8 7

17

18B12

10

9

13

1514

16

11

19

4

2

3

1

Detector at 208K

Detector at 233K

Detector at 260K

SOFIE CSM layout

Notes and Definitions

•Half-power points (HPP) are the wavelengths where the filter bandpass transmission is 50% of the peak transmission value.

•The HPP on the short wavelength side of the bandpass is known as the cuton wavelength, or lower HPP (LHPP). The HPP on the long wavelength side is known as the cutoff wavelength, or upper HPP (UHPP).

•The bandpass is generally defined as the wavelength region between cuton and cutoff.

•Bandpass center is defined as the average of cuton and cutoff wavelengths

•Bandpass (filter) width is given in percent as:

200*(cutoff-cuton)/(cutoff+cuton).

•For the out-of-band (OOB) analysis, the in-band region was defined as the wavelength region 3 filter widths wide centered on the band center wavelength

Filter Part and Data list, bands 1-4

Band Part # Bandpass Data

Angle / temperature

Out-of-band Data

Angle / temperature / wavelength (m)

Comment

1 14?

15°/ 260K15°/ 260K

15°/ 260K No part #2 2

3?

15°/ 260K15°/ 260K

15°/ 260K No part #3 2

4?

15°/ 260K15°/ 260K

15°/ 260K No part #4 1

4?

15°/ 260K15°/ 260K

15°/ 260K / 0.7-2.0 No part #

Underlined bandpass data were used the in following OOB analysisAmb = ambient temperature (? K)*part received by SDL

Filter Part and Data list, bands 5 - 8

Band Part # Bandpass Data

Angle / temperature

Out-of-band Data

Angle / temperature / wavelength (m)

Comment

5 13

15°/ 260K15°/ 260K 15°/ 260K

6 12

15°/ 260K15°/ 260K

15°/ 260K

7 12

15°/ 260K15°/ 260K

15°/ 260K

8 12

15°/ 260K15°/ 260K

15°/ 260K

Underlined bandpass data were used the in following OOB analysisAmb = ambient temperature (? K)*part received by SDL

Filter Part and Data list, bands 9-12

Band Part # Bandpass Data

Angle / temperature

Out-of-band Data

Angle / temperature / wavelength (m)

Comment

9 12

15°/ 260K15°/ 260K

15°/ 260K

10

11 1(wit)2*3*456?

0°/ amb, 15°/ 260K, 15°/amb0°/ amb0°/ amb0°/ amb0°/ amb0°/ amb

15°/ 260K/ 2.0–3.32

15°/ 260K/ 1.0–2.0, 15°/ 260K/ 3.42–5.5 No part #12 7*

89

10*11(wit)

?

0°/ amb0°/ amb0°/ amb0°/ amb0°/ 260K, 15°/ 260K, 15°/amb

15°/ 260K/ 1.0–2.0, 15°/ 260K/ 2.0–3.44, 15°/ 260K/ 3.54–6.0 No part #

Underlined bandpass data were used the in the following analysisAmb = ambient temperature (? K)*part received by SDL

Filter Part and Data list, bands 13-16

Band Part # Bandpass Data

Angle / temperature

Out-of-band Data

Angle / temperature / wavelength range (m)

Comment

13 12*34*5

wit?

0°/ amb, 15°/ 260K, 15°/200K0°/ amb0°/ amb0°/ amb0°/ amb15°/ 260K, 15°/ 200K

15°/ 260K/ 1.0–2.0, 15°/ 260K/ 2.0–4.2, 15°/ 260K/ 4.6–6.0No part #No part #

14 2*3*5

15°/ 260K, 15°/ amb15°/ 260K, 15°/ amb

15°/ 260K/ 2.0–3.26, 15°/ 260K/ 4.79–6.0 no OOB 3.3-cuton15 2

3*5*?

15°/ 260K, 15°/ amb0°/ amb0°/ amb

15°/ amb/ 1.0–2.0, 15°/ 260K/ 2.0-4.85, 15°/ 260K/ 5.24-6.0 No part #16 2*

3*5

Wit

0°/ amb0°/ amb15°/ 260K0°/ amb, 15°/ amb, 15°/ 260K 15°/ 260K/ 1.0-3.0, 15°/ 260K/ 3.0-6.0 No part #

Underlined bandpass data were used the in following analysisAmb = ambient temperature (? K)*part received by SDL

SOFIE Bandpass PerformanceBand Measurement Center (m)

spec /

actual filter

Width (%)

spec /

actual filter

Cuton – Cutoff (m)

spec / actual filter

Cuton – Cutoff (cm-1)

spec / actual filter

1 O3 strong 0.290 / 0.292 2.9 / 4.1 0.2857-0.2941 / 0.285- 0.298 34000-35000 / 33605 – 35033

2 O3 weak 0.328 / 0.327 3.3 / 4.2 0.3226-0.3333 / 0.320– 0.333

30000-31000 / 29988 - 31274

3 particle strong 0.862 / 0.864 3.4 / 3.7 0.8475-0.8772 / 0.848- 0.880 11400-11800 / 11363 - 11786

4 particle weak 1.03 / 1.03 4.4 / 4.3 1.0101-1.0526 / 1.009-1.054 9500-9900 / 9487-9908

5 H2O weak 2.45 / 2.46 2.0 / 2.2 2.427-2.475 / 2.432 - 2.486 4040-4120 / 4022- 4111

6 H2O strong 2.60 / 2.61 2.1 / 2.0 2.577-2.632 / 2.587 - 2.640 3800-3880 / 3787 - 3865

7 CO2 strong 2.77 / 2.78 2.0 / 2.1 2.740-2.749 / 2.750 - 2.809 3580-3650 / 3560 - 3636

8 CO2 weak 2.94 / 2.94 2.1 / 2.0 2.907-2.967 / 2.910 - 2.970 3370-3440 / 3366 - 3435

9 particle strong 3.06 / 3.07 2.0 / 2.0 3.030-3.091 / 3.037 - 3.098 3235-3300 / 3228 - 3292

10 particle weak 3.19 / 3.19 2.1 / 2.2 3.160-3.226 / 3.150 - 3.220 3100-3165 / 3106 - 3174

11 CH4 strong 3.37 / 3.38 2.2 / 2.3 3.333-3.401 / 3.341 - 3.418 2940-3000 / 2926 - 2993

12 CH4 weak 3.51 / 3.49 2.1 / 2.0 3.472-3.546 / 3.454 - 3.523 2820-2880 / 2838 - 2894

13 CO2 strong 4.35 / 4.36 4.3 / 4.8 4.255-4.444 / 4.257 - 4.465 2250-2350 / 2239 - 2348

14 CO2 weak 4.68 / 4.66 2.3 / 2.8 4.630-4.740 / 4.592 - 4.721 2110-2160 / 2118 - 2177

15 NO weak 4.98 / 5.02 2.0 / 1.9 4.951-5.051 / 4.976 - 5.069 1980-2020 / 1972 - 2009

16 NO strong 5.32 / 5.34 2.1 / 3.1 5.263-5.376 / 5.259 - 5.422 1860-1900 / 1844 - 1901

•All values based on total response curves, not just filter transmission curves.•Filter width is defined from the half-power points (cuton to cutoff).•Band center is the average of the cuton and cutoff wavelengths.

SOFIE Bandpass PerformanceBand Measurement Filter Transmission (%)

Average in-band

spec / predicted / actual

Detector Response (%)

Average in-band

actual (part #)

Total Response (%)

Average in-band

predicted / actual filter

Out of Band Solar Energy (%)

(Spec is < 1%)

predicted / actual filter1 O3 strong >80 / 95.2 / 43.9 87.6 (G07) 17.6 / 14.9 0.020 / 2.837

2 O3 weak >80 / 93.4 / 64.4 52.1 (G07) 9.0 / 14.9 0.326 / 0.024

3 particle strong >80 / 97.7 / 83.9 23.8 (J540) 5.1 / 4.4 0.029 / 0.123

4 particle weak >80 / 98.4 / 80.8 38.6 (J550) 20.1 / 16.8 0.449 / 0.0085 H2O weak >80 / 92.9 / 78.0 51.2 (J562) 34.8 / 26.6 0.118 / 0.019

6 H2O strong >80 / 93.0 / 72.4 48.9 (J541) 32.2 / 25.8 0.152 / 0.047

7 CO2 strong >80 / 93.0 / 73.4 60.0 (J554) 41.6 / 29.3 0.010 / 0.102

8 CO2 weak >80 / 93.0 / 68.3 59.8 (J553) 41.3 / 31.4 0.028 / 0.388

9 particle strong >80 / 92.9 / 67.0 62.3 (J559) 44.4 / 28.0 0.002 / 0.053

10 particle weak >80 / 93.0 / 66.4 66.3 (J561) 42.9 / 30.4 0.013 / 0.107

11 CH4 strong >80 / 93.0 / 77.3 70.3 (J560) 46.3 / 40.4 0.009 / 0.025

12 CH4 weak >80 / 93.0 / 75.1 78.7 (J552) 53.1 / 45.1 0.078 / 0.092

13 CO2 strong >75 / 94.0 / 77.0 90.8 (J546) 60.9 / 48.0 0.178 / 0.021

14 CO2 weak >75 / 92.7 / 69.9 96.8 (J544) 66.0 / 51.6 0.118 / 0.008

15 NO weak >75 / 92.3 / 68.9 98.5 (J542) 66.6 / 51.2 0.173 / 0.310

16 NO strong >75 / 92.6 / 70.8 78.5 (J547) 54.3 / 40.1 0.250 / 1.178

Total response includes all preceding optical elements & detector response

Band 1 analysis

Band 2 analysis

Band 3 analysis

Band 4 analysis

Band 5 Analysis

Notes:

Band 6 Analysis

Band 7 Analysis

Band 8 Analysis

Band 9 Analysis

Band 10 Analysis

Band 11: part to part consistency

Shown are the filter transmissions for individual parts, all measured at 0 deg angle of incidence and ambient temperature.

Band 11 Analysis

Notes:

•Filter location shift

Band 12: part to part consistency

Shown are the filter transmissions for individual parts, all measured at 0 deg angle of incidence and ambient temperature.

Band 12 Analysis

Notes:

•Filter location shift

CH4 channel (bands 11 & 12), filters & gas spectra

Band 13: part to part consistency

Shown are the filter transmissions for individual parts, all measured at 0 deg angle of incidence and ambient temperature.

Band 13 Analysis

Band 14 Analysis

Notes:

•Missing OOB data from 3.3 microns to cuton.

•Filter location shift

CO2 channel (bands 13 & 14), filters & gas spectra

Band 15 Analysis

Notes:

•Filter location shift

Band 16 Analysis

Notes:

•Filter location shift, broader

NO channel (bands 15 & 16), filters & gas spectra

Extra slides follow

Silicon Carbide Detectors, Bands 1 & 2

Ozone measurements originally used UV-enhanced silicon detectors

The spectral response of UV-Si detectors is less than ideal:

•UV-Si response combined with solar spectrum = amplified out-of-band energy

•Can be addressed with stacked filters, difficult to verify, questionable stability

A new option: Silicon Carbide (SiC) detectors

Ideal spectral response

twice as rad-hard as Si

Space flight heritage

Eliminates 2nd filter

Bands 1 & 2 now use SiC

solar source detector response

Band 1 Spectral Response with SiC detector

Predictions indicate excellent performance using silicon carbide detector

Solar out-of-band = 0.02%

Backup slides follow

SOFIE Out of Band PerformanceAs hardware arrives at SDL, the measured characteristics are used to predict performance and ensure that all parts meet our requirements.

Requirement: Out of band exoatmospheric solar energy < 1% of total signal

Band Measurement Center (m)

Out of Band Solar Energy (%), Predicted

Out of Band Solar Energy (%), Actual Filter

& Detector1 O3 strong 0.290 0.0202 O3 weak 0.328 0.3263 particle strong 0.862 0.4494 particle weak 1.03 0.0165 H2O weak 2.45 0.125 0.0156 H2O strong 2.60 0.167 0.0467 CO2 strong 2.77 0.260 0.0888 CO2 weak 2.94 0.236 0.3369 particle strong 3.06 0.003 0.042

10 particle weak 3.19 0.01511 CH4 strong 3.37 0.012 0.02012 CH4 weak 3.51 0.116 0.09313 CO2 strong 4.25 0.177 0.01414 CO2 weak 4.63 0.123 0.00815 NO weak 4.98 0.179 0.19916 NO strong 5.32 0.256 0.693

Here, in-band is defined as a region 3 filter widths wide centered on the band center wavelength

SOFIE Bandpass Performance, Continued

Band Measurement Filter Transmission (%)

Average in-band

spec / predicted or actual

Detector Response (%)

Average in-band

predicted or actual (part #)

Total Response (%)

Average in-band

predicted or actual filter

1 O3 strong >80 / 95.2 87.6 39.3

2 O3 weak >80 / 93.4 29.4 17.8

3 particle strong >80 / 97.7 23.8 (J540) 21.0

4 particle weak >80 / 98.4 38.6 (J550) 33.25 H2O weak >80 / 86.8 51.2 (J562) 37.2

6 H2O strong >80 / 93.0 48.9 (J541) 43.2

7 CO2 strong >80 / 93.0 60.0 (J554) 46.8

8 CO2 weak >80 / 93.0 59.8 (J553) 48.5

9 particle strong >80 / 92.9 62.3 (J559) 71.2

10 particle weak >80 / 93.0 66.3 (J561) 66.7

11 CH4 strong >80 / 86.8 70.3 (J560) 46.4

12 CH4 weak >80 / 84.2 78.7 (J552) 49.0

13 CO2 strong >75 / 84.6 90.8 (J546) 64.0

14 CO2 weak >75 / 78.6 96.8 (J544) 64.6

15 NO weak >75 / 79.1 98.5 (J542) 63.1

16 NO strong >75 / 80.6 78.5 (J547) 50.4

•In-band is wavelengths between the half-power points

•Total response includes all preceding optical elements & detector response