To investigate the following problems reported at SSO
Current chip is science chip #9 and the bottom left amplifier is currently connected.
|
Item |
Configuration |
|
Controller |
Astromed 3200 |
|
CCD |
CCD2 |
|
Dewar |
TTT |
|
Focal Plane |
TTT |
|
Cicada |
V2.0.9 |
|
Amplifier Setup |
Left bottom |
|
Initial Operating Temperature |
255K |
|
Test Instrument |
Test Box |
|
Bias Name |
Voltage (V) |
|
Output Drain VOD |
+17.5 |
|
Reset Drain VRD |
+9.2 |
|
Output Transfer Gate VOG |
-3.5 |
|
Unused Serial |
Not used |
|
Unused Transfer Gate |
Not used |
|
VSSL,VSSH |
-4.5 |
|
Clock Name |
Voltage(V) |
|
Reset low |
-4.5 |
|
Reset high |
+4.0 |
|
VROL |
-8.5 |
|
VROH |
+4.0 |
|
VIML |
-12.5 |
|
VIMH |
1.0 |
|
VSTOH |
1.0 |
The bottom left amplifier is the one connected at present.
|
Feature |
Value |
|
CCDI |
190 |
|
PGain |
4 |
On first initial cool down, the CCD got down to 250Kdeg.
|
VOD |
VRD |
VOG |
VRSPL |
VRSPH |
VROL |
VROH |
VIML |
VIMH |
IDS mA |
Comment |
|
17.5 |
9.19 |
-3.5 |
-4.5 |
4.0 |
-8.5 |
1.5 |
-12.5 |
1.0 |
1.2 |
No image, stage 1 does not balance (330) image 50,000 above black level |
|
17.5 |
9.19 |
-3.5 |
-4.5 |
4.0 |
-8.5 |
1.5 |
-12.5 |
1.0 |
0.8 |
Image, but badly smeared in serial direction |
Adjusting all other voltages did not reduce smearing in serial direction.
No improvement by adjusting voltage could be made, therefore it was decided to warm the dewar up so that
Cool Down 8 DEC 99
New thermo-electric cooler installed and detector (science serial #9) wired to bottom right amplifier.
Temperature got down to 223K from 300K. The thermo-electric cooler consumed 3.0A.
The right amplifier was driven with serial clock H2H13 and parallel clocks driven 132.
At high temperature, the input stage did not zero (stage 1=300, stage 2=0) properly. When the temperature got lower (<250K), the input zeroed OK, but the black level did not set properly. (target was 1000, cicada set it to 5000) Bias and object were ~52000 count. No improvement was possible with reducing IDS, the output current sink.
Alas, it was decided to wire back left bottom amplifier and check how it operates at lower temperatures.
Cool Down 13 DEC 99
Temperature got down to 227K from 300K. The thermo-electric cooler consumed 3.0A
Bottom left amplifier is wired. At low temperatures the amplifier does not operate any better. It still has problems nulling input stages with IDS=1.2mA. IDS must be reduced to 0.9mA before input nulls properly. At IDS=0.9mA, images are smeared in the serial direction.
Both the old science grade and the engineering chip do not operate well enough to be used for tiptilt. The new science CCD, serial no. 9 , now has no good operational amplifiers.
CCD |
Amplifier |
Status |
|
Original Science |
Bottom left |
Bad smearing |
|
|
Bottom Right |
Not operating |
|
|
Top Left |
Not operating |
|
|
Top Right |
Not operating |
|
Engineering Grade |
Bottom left |
Column defects, parallel smearing in B section. |
|
|
Bottom Right |
Column defects, parallel smearing in B section |
|
|
Top Left |
Column defects, parallel smearing in B section |
|
|
Top Right |
Column defects, parallel smearing in B section |
|
Serial Number 9 |
Bottom left |
Bad smearing |
|
|
Bottom Right |
Not operating |
|
|
Top Left |
Not operating |
|
|
Top Right |
Not operating |