699-416

APPENDIX A - TEST RESULTS SUMMARY

TEST DESCRIPTION
TEST REQUIREMENTS AND RESULTS
LEVEL
PARAMETER
CAMERA
REQUIREMENT
TEST PERFORMANCE
REQUIREMENT MET ?
COMMENTS

COMPONENT

OPTICS THROUGHPUT
NAC

Throughput allocation varies over spectral range of the camera ; see Section 4.1.2.

Exceeded allocated throughput, with the exception of the 200-400 nm region (falls as much as 1.64 % below allocated throughput in this region).
MOSTLY
 

COMPONENT

OPTICS THROUGHPUT
WAC

Throughput allocation varies over spectral range of the camera ; see Section 4.1.2.

Falls below allocated throughput except for the region between 442.5 nm and 490 nm.
NO

The WAC optics was inherited from Voyager with the policy being "use as is".

COMPONENT

FOCAL LENGTH
NAC
2000 mm
2000 mm
+/- 4 mm
Estimated measurement uncertainty of 4mm is outside the +/- 0.5 mm accuracy requirement.

From E. Motts.

COMPONENT

FOCAL LENGTH
WAC
200 mm
200.22 mm
+/- 0.251 mm
YES

From E. Motts memo.

COMPONENT

APERTURE AREA
NAC
 
218.04 sq cm
 

From B. Wallis/K. Manatt Optics Report.

COMPONENT

APERTURE AREA
WAC
 
4.127 sq in
 

From B. Wallis/K. Manatt Optics Report.

COMPONENT
SHUTTER OFFSET
NAC

Average exposure +/- 1 msec

Greatest offset = 1.65 msec at -10C for 25 msec measurement. Five measurements in all exceeded the +/- 1 msec rqmt : all 3 temp measurements for 25 msec and -10C measurements for 5 msec and 100 msec. No shutter bounce observed.
NO

Although component level offsets do not meet the requirement, subsystem level tests showed the offset requirement was met.

COMPONENT
SHUTTER OFFSET
WAC

Average exposure +/- 1 msec

Greatest offset < 0.5 msec at -10C for 25 msec measurement. No shutter bounce detected.
YES
 

COMPONENT

STRAY LIGHT
NAC

RQMT : Off- axis point-source attenuation factor <= 10-4 at 6 ° off-axis , and <= 10-10 at 40 ° off-axis

GOAL : Off- axis point-source attenuation factor <= 1.03x10-12 @ 6 ° off-axis , and <= 3.68x10-15 @ 40 ° off-axis

VISIBLE : Off- axis point-source attenuation factor = 1.7x10-8 at 6 ° off-axis , and = 2.8x10-12 at 40 ° off-axis

UV : Off- axis point-source attenuation factor = 5.8x10-9 at 6 ° off-axis , and = 5.2x10-10 at 40 ° off-axis

RQMT : YES

GOAL : IN PART

 
SUBSYSTEM
BLEMISHES
NAC

Identify pixels whose response as a function of exposure cannot be reliably calibrated.

Blemishes mostly confined to image borders.

Image interior pixels flagged as blemishes limited to 3 in Gain 2 and 1 in Gain 1 (all within 3 pixels of any border).

High exposure behavior generally caused pixels to be flagged as blemishes.

Gain 0 exhibited spatial relationship w/ respect to the degree of response shortfall at high exposures.

Anti-blooming pixel pairs for long exposures observed.

 
 
SUBSYSTEM
BLEMISHES
WAC

Identify pixels whose response as a function of exposure cannot be reliably calibrated.

Blemishes mostly confined to image borders.

Blemishes found in 1st 100 pixels of line 2 (200 pixels in 4x4 mode).

Only one image interior pixel flagged as blemishes for 2x2 summation mode.

Low exposure behavior generally caused pixels to be flagged as blemishes.

Gain 2 exhibited spatial relationship w/ respect to the degree of response shortfall.

Anti-blooming pixel pairs for long exposures observed.

 
 
SUBSYSTEM
DARK CURRENT
NAC

<= 0.3 e-/pixel/sec @ operating temperature
(-90 °C)

Dark Current mean DN ranges from -0.001 DN @ 5 msec (overcompensated from bias) to 28.744 DN @ 1200 sec.

Gain 3 sensitive to Sensor Head temp.

Antiblooming has no significant effect.

With Lightflood "Off", the mean DN does not rise above noise except for 1000 and1200 sec exposures.

With Lightflood "On", rhe mean DN does not rise above 0.5 DN until after an exposure of 1.5 sec.

Line number profile observed with Lightflodd "On".

Simultaneous imaging will change profile if NAC readout second.

 
Dark current has many dependent variables; in-flight calibration recommended.

NAC dark frame data has coherent noise patterns from unknown source (presumably environmental).

SUBSYSTEM
DARK CURRENT
WAC

<= 0.3 e-/pixel/sec @ operating temperature
(-90 °C)

Dark Current mean DN ranges from -0.15 DN @ 5 msec (overcompensated from bias) to 30.73 DN @ 1200 sec.

Gain 3 sensitive to Sensor Head temp.

Antiblooming has no significant effect.

With Lightflood "Off", the mean DN does not rise above noise except for 1000 and1200 sec exposures.

With Lightflood "On", rhe mean DN does not rise above 0.5 DN until after an exposure of 1.2 sec.

Line number profile observed with Lightflood "On".

Simultaneous imaging changes the line profile (WAC imaged readout 2nd by default).

 
Dark current has many dependent variables; in-flight calibration recommended.
SUBSYSTEM
DISTORTION
NAC
-
-
-
-

SUBSYSTEM

DISTORTION
WAC
 

Mean coefficient value for all images at nominal target position is 9.51x10-9 +/-
0.21x10-9 (including contributions from the collimator and chamber window). This corresponds to 3.61 +/- 0.08 pixels of distortion at the corner pixels.

 
 
SUBSYSTEM
ELECTRICAL NOISE
NAC
and
WAC

< 60 e- rms
(goal of 20 e- rms)

Bias frames (0 sec exposure) have low amplitude noise spectrum.

Significant vertical fixed pattern noise consistent w/ CCD "step-and repeat" pattern of mfg process (@ frequency of 0.0233 and its harmonics).

Horizontal fixed pattern noise from 0 to 0.1 cycles per second (1x1 mode) for exposed frames. Shows up at lower resolution @ other summation modes. Most likely due to "step-and-repeat" pattern of CCD.

No vertical electrical noise apparent.

Anti-blooming "on" increases the amplitude for well-exposed frames.

No difference observed due to change in temperature or lossless compression.

 
 
SUBSYSTEM
GAIN
NAC

Gain 0,1 and 2 : provide encoding with the maximum DN value occurring between 90 and 100% average CCD fullwell capacity for specified summation mode

Gain 3 : 12 e-/DN

@ +25C
Gain 0 : 219.8 e-/DN
Gain 1 : 99.32 e-/DN
Gain 2 : 29.15 e-/DN
Gain 3 : 13.93 e-/DN

@ +5C
Gain 0 : 233.04 e-/DN
Gain 1 : 98.88 e-/DN
Gain 2 : 30.27 e-/DN
Gain 3 : 12.85 e-/DN

 
Gain 0 : 4x4 summation
Gain 1 : 2x2 summation
Gain 2 : 1x1 summation
Gain 3 : 1x1 summation
SUBSYSTEM
GAIN
WAC

Gain 0,1 and 2 : provide encoding with the maximum DN value occurring between 90 and 100% average CCD fullwell capacity for specified summation mode
Gain 3 : 12 e-/DN

@ +25C
Gain 0 : 194.30 e-/DN
Gain 1 : 90.13 e-/DN
Gain 2 : 27.66 e-/DN
Gain 3 : 11.74 e-/DN

@ +5C
Gain 0 : 210.56 e-/DN
Gain 1 : 85.09 e-/DN
Gain 2 : 27.68 e-/DN
Gain 3 : 11.85 e-/DN

 
Gain 0 : 4x4 summation
Gain 1 : 2x2 summation
Gain 2 : 1x1 summation
Gain 3 : 1x1 summation
SUBSYSTEM
LIGHT LEAK
NAC

Detect light leaks (shutters closed) w/ ave response >= 0.1 DN, or pixel response > 2 DN for on axis irradiance as great as 100x that expected at Saturn.

<= 0.6 DN @ equivalent of 1000 seconds of exposure to Saturn or 12000 X what would have given fullwell response.

No signal trend noted with exposure time.

 
 
SUBSYSTEM
LIGHT LEAK
WAC

Detect light leaks (shutters closed) w/ ave response >= 0.1 DN, or pixel response > 2 DN for on axis irradiance as great as 100x that expected at Saturn.

<= 1 DN @ equivalent of 100 seconds of exposure to Saturn or 10,000 X what would have given fullwell response.

Linear signal increase with exposure time.

 
 
SUBSYSTEM
LINEARITY
NAC

Linear response with standard deviation from that response <=1%.

Linear to within 1%, except for 4x4 mode. 4x4 linear to 1000 DN.
YES
with the exception of 4x4 mode

+25C data more well-behaved than +5C data. 4x4 linearity breakdown at 1000 DN.

SUBSYSTEM
LINEARITY
WAC

Linear response with standard deviation from that response <=1%.

Linear to within 1%, except for 4x4 mode. 4x4 linear to 1000 DN.
YES
with the exception of 4x4 mode

4x4 linearity breakdown at 1000 DN.

SUBSYSTEM
MTF
NAC

>= 0.15 @ 32 line pairs / mm

Tabulated values show MTF with contributions from window and collimator ranging from 0.10 to 0.24. 80% of the tested filter combinations have an MTF >= to 0.15 (with window and collimator contributions). If the contributions from the window and collimator were removed, all MTF values would be above 0.15.
YES
 

SUBSYSTEM

MTF
WAC

>= 0.15 @ 32 line pairs / mm

Tabulated values show MTF with contributions from window and collimator ranging from 0.030 to 0.393. 59% of the tested filter combinations have an MTF >= to 0.15 (with window and collimator contributions). If the contributions from the window and collimator were removed, all but perhaps 3 of the MTF values would be above 0.15.
MOSTLY

Wide variation in filter MTF quality was expected because of focus tradeoffs in the design.

SUBSYSTEM
ORIENTATION OF POLARIZERS
NAC

Best Effort

PO / CL2 : -0.5 ° P60 / CL2 : 61.8 ° P120 / CL2 : 120.8 ° IRP0 / CL2 : 2.25 °
YES
 

SUBSYSTEM

ORIENTATION OF POLARIZERS
WAC

Best Effort

CL1 / IRP0 : 0.00 ° CL1 / IRP90 : 90.85 °
YES
 

SUBSYSTEM

SHUTTER OFFSET
NAC

average exposure +/- 1 msec

Absolute greatest shutter offset value < 0.2 msec. Shutter offset value passes through 0 within the frame indicating right side of frame has a longer exposure time than commanded and vice versa.
YES

A horizontal band of increased shutter offset value observed in the mid-portion of the frame. Suspect dark current bias vs frame line profiles not properly accounted for.

SUBSYSTEM
SHUTTER OFFSET
WAC

average exposure +/- 1 msec

Absolute greatest shutter offset value < 0.7 msec. All shutter offset values negative indicating that the actual exposure time is longer than the commanded time.
YES

A horizontal band of increased shutter offset value observed in the mid-portion of the frame. Suspect dark current bias frame vs line profiles not properly accounted for.





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