SPHERE/ZIMPOL high resolution polarimetric imager - I. System overview, PSF parameters, coronagraphy, and polarimetry

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Table 6.

Pass-band filters, neutral density filters, and calibration components available in the filter wheels FW0, FW1 and FW2 of ZIMPOL.

Component	λ_c	Δλ	Wheel FWx			Dicr.	4QPM^b
	(nm)	(nm)	0	1	2	BS^a	1/2
Open			+	+	+	y
Broadband filters
VBB	735	290		+	+
R_PRIM	626	149		+	+
I_PRIM	790	153		+	+
V	554	81		+	+
N_R	646	57		+	+	y	1
N_I	817	81		+	+		2
Narrowband filters
V_S	532	37	+
V_L	582	41	+
NB730	733	55	+
I_L	871	56	+
TiO717	716.8	19.7		+
CH4_727	730.3	20.5		+
Cnt748	747.4	20.6			+
KI	770.2	21.1		+
Cnt820	817.3	19.8		+	+		2
Line filters
HeI	588.0	5.4	+
OI_630	629.5	5.4	+			y	1
CntHa	644.9	4.1		+	+	y	1
B_Ha	655.6	5.5		+	+	y	1
N_Ha	656.9	1.0	+			y	1
Ha_NB	656.9	1.0			+	y	1
Neutral density filters^c
ND1	500–900		+			y
ND2	500–900		+			y
ND4	500–900		+			y
Calibration components
Polarizer			+			+
Quarter wave plate			+			+
Circular polarizer			+			+
Pupil imaging lens					+	+

Notes.

^(a)

This column indicates components (y = yes), which can be used together with the dichroic beam splitter.

^(b)

This column marks the the recommended color filters to be used with 4QPM1 (indicated by 1) or 4QPM2 (indicated by 2).

^(c)

The neutral density (ND) filters attenuate the throughput by about a factor ≈10⁻¹ for ND1, ≈10⁻² for ND2, and ≈10⁻⁴ for ND4.

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