DL – IFU (Prieto/Taylor) Slicer: –25mas sampling … 0.9mm slices ~f/250 (assuming no...

DL – IFU(Prieto/Taylor)

• Slicer:– 25mas sampling … 0.9mm slices

• ~f/250 (assuming no anamorphism)

• Detector = 2k array of 18um pixels– Slit subtends 1-pixel (spectral dithering as for TiPi)

• Camera f-ratio = f/5 (double TMA a la JWST system)• Full window requires ~800 pixels

– 4 slits per spectrograph/detector– Slit height = ~1000 pixels or 30-by-30 slicer with FoV ~0.752 arcsec.– 4 slits gives FoV ~1.52 arcsec.

• Is this a sufficient field ? Or do we need 2 or 4 units ?– NB: SRD asks for ~42 arcsec– If only we could use a 42k, 9m pixel, array at f/2.5 !

• Assume fore-optics can switch in factor of 5 magnification to give:– 25mas ; 20mas; 15mas; 10mas; 5mas– 5mas option would feed spectrograph at f/12.5– What beam-size would be required ? 50mm OK ?

prieto

OK

prieto

I would propose to have a 60x60 slicer feeding the 4 slits

prieto

A f/2.5 camera diffraction limited is difficult in reflective optics. Not impossible, but...For the SRD, the answer is not in my hand. To have multiple units is just a matter of money. If we cut the entrance field of view, the rest is simple

prieto

F/12.5 in the case of 9µm pixelsThe beam size? you mean at the level of the grating? 50 to 60 mm grating size

Optical Components• Cool box:

– 45 deg. fold to vertical

– Pupil imager onto ~25mm DM• Field lens or Field mirror ? (not exactly at focus)

– DM as steering mirror• feeding mirror at field stop (as in TiPi)

• but also an imaging system (as in TiPi) to give ~10 arcsec D-L field

• DM can switch from IFU to direct imaging field by small tip/tilt– Object can be viewed directly and then selected into IFU field

– Surrounding objects can be imaged directly while doing IFU spectroscopy

prieto

ok

prieto

Ok, collimator paraboloid (designed)

prieto

do you intend to have both mode in parallel or to be able to switch from one to the other?If you want to have both in parallel as in TiPi, the system will be more complex to accomodate. In TiPi, the imaging mode is following the IFU. If I understand well, here you want to have a fix imaging FOV and to pick-up un object in this FOV. I think it couldn't be done by only one mechanism

Optical Components• Cryo box:

– Magnification optics and scale changer optics• Non-anamorphic (25mas ; 12.5mas ; 5mas)

• Cold stop (rotating ?)

– 2 contiguous 60-slice slicer units• square FoV

• 2 slits into 1 spectrograph

– Double TMA spectrograph (a la JWST/NIRSPEC)• Collimator somewhere between f/10 and f/20 (tbd)

• Camera f/5

• Beam size ~50mm (plus pupil diffraction)

prieto

Rotating cold stop: it imply to have accesibility with a mechanism at this level. I will have to change the way of imaging on the slicer

prieto

I shall propose to have an unique 60 slicer stack of 60 pixels each2 long slit of 2K pixels each

prieto

OK

Scope of Work

• Optical concept at same level as TiPi– Field lens/mirror– DM – steering & image/IFU selector– Imaging system (FoV ~10” D-L)– Fore-optics / scale changer– Slicer unit– Spectrograph

• Approx. wave-front error budget ?

• Challenges:– Larger FoV ~3 arcsec2 ?– Faster cameras ~f/2.5 ?

DL – IFU (Prieto/Taylor) Slicer: –25mas sampling … 0.9mm slices ~f/250 (assuming no...

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