METIS WCU calibration mode

[astronomyk]

We have been asked to add a wcu mode to the METIS package.

Rationale

During AIT many tests will require the Warm Calibration Unit (WCU) to be set to a very specific flux level. To prepare the functional- and performance test "instruction manual", the AIT team would like to be able to use the simulator to determine realistic estimates for the instrument settings before actually turning on METIS.

Requirements

This requires a couple of minor additions to the METIS package, and/or a new mode-yaml section.
For his new mode we should:

• remove (or turn off, or block) any upstream effects from Armazones and ELT
• Add an emitting surface that is the WCU integrating sphere. For now the flux distribution is flat (TLR ~1% variation, so basically flat)
• The emission spectrum associated with the surface should be either the blackbody spectrum for a (variable) temp, OR a laser spectrum with an option for setting the wavelength of the tunable laser in the range [4.6, 4.75]µm
• Include the various masks in the aperture wheel (pin-hole, single source, open, closed
• Add an option to decrease the WCU emission by a certain percentage, as per the plan of including a further mask wheel in the WCU with the following apertures. See WCU design doc, table 3.10

Aperture Diameter | % Area
[mm] | [0..1]

25.40   1.00000
24.03   0.89504
22.22   0.76528
20.41   0.64568
18.60   0.53624
16.79   0.43695
14.98   0.34782
13.17   0.26885
11.36   0.20003
9.55    0.14136
7.74    0.09286
5.93    0.05451
4.12    0.02631
2.31    0.00827
5.0     0.00039
0.0     0.00000