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CAT / CES Long Camera / CCD LO #38

 
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TYPE Loral/Lesser 2688 Grade good
Thin, back-illuminated, UV flooded, AR coated, MPP mode
IMAGE SIZE [pixels] 2688 x 512 (16 prescan pixels)
PIXEL SIZE [microns] 15 x 15
DARK CURRENT [e- / pixel /hr] 0 at 160 °K
FULL WELL CAPACITY [e- / pixel] 110k
CONTROLLER ESO VME
Mode slow [16 kpixel / sec] fast [31 kpixel / sec]
R.O.N. [e- rms] 7.1 9
CONVERSION FACTOR [e-/ADU] 1.6 1.7
Full Frame READOUT TIME [sec] 110 53


This CCD is suited for applications requiring a resolution up to 75-80000.
CCD #34 is offered when higher resolution is required. See also additional information.
Some vignetting present bluewards of pixel 550 and redwards of pixel 2000.
To proper adjust the predisperser slit width check for Special setting and Function disabling options with the assistant.

Charge Transfer Efficiency
Serial CTE:0.999991
Parallel CTE:0.999996

Full Well Capacity

Upper limit of linearity: 110k e- /pixel
Saturation Value: 130k e- / pixel

Cosmic Ray Event

The cosmic ray event rate is 2.43 [events / min / cm ²]

Shutter Error

Instrument Resolving Power

The resolving power with the CES and CCD#38 at different nominal resolutions and wavelengths has been measured by E. Schmidt on October 95. The results are as follows: 

                       Instrument Resolving Power
Wavel.  60000        70000        80000        90000       100000
3900   62000(3.91) 67000(3.64)  72000(3.40) 77000(3.17)  81000(3.00)
4800   60000(4.08) 65000(3.75)  69000(3.54) 74000(3.30)  78000(3.12)
6708   60000(4.05) 67000(3.64)  72000(3.39) 77000(3.17)  83000(2.94)
8400   64000(3.81) 71000(3.43)  76000(3.21) 83000(2.94)  91000(2.68)
These numbers (pixels are within parenthesis) should represent a good approximation: a R=243927 per pixel (measured at 6708) was used for all calculations. The width of unblended lines in the spectra may vary up to +/- 0.15 pixels peak to peak. We can be safe saying that the CCD#38 can be offered up to R=75-80000.

There are no strong hot or cold column defects. The number of traps is usual or even a bit better, if compared with other LORAL CCDs.

Number of hot defects: 7
Hot Spots: 3 ; Hot Clusters: 4 ; Hot Columns: 0

Number of dark defects: 87
Dark Pixels: 7 ; Dark COlumns: 9 ; Traps: 71

Fringing

There are interference fringes in the CCD at very red wavelenghts (beyond 700 nm). The frequency of the resulting modulation is rather low (distance between consecutive peaks greater than 100 pixels) in the central part of the CCD, but becomes much higher 9only a few pixels between peaks) close to the CCD edges.
The peak-to-peak amplitude of fringing reaches approx. 20% of the continuum level at 840 nm.
It appears possible to take this effect out by means of flat fielding, even using the internal lamp (e.g. at 840 nm, a S/N ratio of 150 was achieved)




The CCd is linear to better than 1% up to more than 100k e-/pix. In reality, above 86k e-/pix the CTE degrades rapidly and strong blurring of the images in the Y direction (perpendicular to the dispersion) is recorded. Therefore 70k e-/pix is a safe limit.

[QE 38 curve] 

      lambda (nm)  QE (%)
         320       68.15
         340       77.38
         360       74.44
         380       76.23
         400        84.7
         450       78.82
         500       82.93
         550       86.55
         600       90.03
         650          91
         700       91.86
         750       84.58
         800       76.44
         850       60.58
         900       42.35
         950       25.85
        1000       10.85

History

Date of delivery at the telescope: March, 1995
Date of last set of tests: June 16, 1997

Comment on the last test: Gain of fast mode has been restored to 8. Except for the higher bias level, all parameters look the same as before the change of VME.

Previous test: May 9, 1997
DARK CURRENT [e- / pixel /hr] 1.9 at 160 °K
Mode slow [16 kpixel / sec] fast [31 kpixel / sec]
R.O.N. [e- rms] 7.0 8.7
CONVERSION FACTOR [e-/ADU] 1.6 1.3
Previous test: August, 1995
DARK CURRENT [e- / pixel /hr] 1.9 at 160 °K
Mode slow [16 kpixel / sec] fast [31 kpixel / sec]
R.O.N. [e- rms] 7.4 8.9
CONVERSION FACTOR [e-/ADU] 1.6 1.3
Previous test: August 25, 1995
DARK CURRENT [e- / pixel /hr] 1.9 at 160 °K
R.O.N. [e- rms] 7.0 8.9
CONVERSION FACTOR [e-/ADU] 1.6 1.7



 

Image Files
©   1999/Dec/16 by Cyril Cavadore

Send comments to   odt@eso.org
Last update: 2004/Mar/24

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