It was decided quite early on in the project that the addition
of a dichroic and (undispersed) camera, centred at the H
wavelength corresponding to the appropriate [O III] wavelength,
would have considerable scientific return. As well as yielding
additional information about the PNe (and possibly helping to discriminate
against HII and Ly- galaxies) the camera would obtain
very deep images of the field, in which serendipitous
discoveries could be made. We asked Damien Jones to design this
option into the system, and modified the mechanical drawings
(at some expense). Meanwhile, we started to look for money for the
option.
Following minor modifications to the position of the optics
to allow for the dichroic to be placed, the current version is now V_18
(produced September 1998). A ZEMAX file is on the
project page.
Removal of the dichroic causes a simple lateral shift of the
collimated beam. At our request Damien Jones has
placed the grating assembly mid-way between the shifted
and unshifted position.
Postscript and Autocad files are on the
project page (corresponding GIFs are in
image gallery).
- DICHROIC
- OPTICS
-
A first-pass design, based on the [O III] camera, was
produced as part of the PNS-3 project by Damien
Jones. Some optimisation and adjustment is required.
- New design (2004) - see the optics page
- MECHANICAL WORK
-
Fabrication, focussing mechanism, and interfacing
- CCD CAMERA
-
One idea is to purchase a peltier-cooled CCD. Below I have
used a quote from
Apogee for a
14-bit camera based on a cooled Thomson 7899
2048x2048 (14 um) chip,
best cosmetic grade, but this is front-illuminated (QE=35%).
They do have a back-illuminated chip (1024x1024 x 24um) with QE=85%.
-
Nitrogen-cooled units are available commercially from
Roper Scientific (formerly Princeton
Instruments) with agents in NL
-
Another is to use Observatory CCDS as before, possibly
with financial contribution from project
- BUDGET ($A)
|
| Dichroic: mechanical construction | 7,700 | (Estimate 6/12/2001)
|
| Dichroic: optics | 8,000 | (Estimate 6/12/2001 - see also dichroic page
|
| Dichroic: coating | 3,000 | (Estimate 6/12/2001)
|
| Camera: final design etc | 5,280 | (Estimate 10/1/2002 by Prime Optics)
new estimate
|
| Camera: optics | 18,434 | (Estimate 11/98, check 12,000 commercial quote)
|
| Camera: coating | 7,000 | (Estimate 6/12/2001 - see also here)
|
| Mechanical detailing and construction | 10,000 | (Estimate 6/12/2001)
new estimate
|
| Focus module construction | 6,000 | (Estimate 6/12/2001)
|
| Three H Filters, total | 98,000 | (BARR quote - see filters for latest)
|
| Continuum Filters, each | 12,000 | (wide, does not need to have high transmission)
|
| Filter wheel/flipper | 10,000 | (guess)
|
| CCD camera | 92,000 | (Apogee AP16E with 4kx4kx9um grade 1 Kodak chip, QE 65%, quote 8/1/2002)
|
| Extra shutter, if reqd | -- | not required with above-mentioned CCD
|
| Assembly and test | 4,000 |
|
|
| Total (approx) | 282,000 |
|
|
Document date: January 4, 2001
