NIRSPEC

UCLA Astrophysics Program	U.C. Berkeley	W.M. Keck Observatory

Don Figer	February 25, 1999

NIRSPEC Optics Design Note 19.7a

Addendum to NIRSPEC Optics Design Note 19.00

Blocking, Narrow-band, and Broad-band Filters

This addendum gives a list of the final filters, their characteristics, i.e. size, transmission properties, location in the filter wheels, etc.

Table 1

Filter Characteristics

Filter	HPP1	HPP2	Peak T	Ave T	thickness1 (mm)
NIRSPEC-1	0.950	1.1182	94	86	7.06
NIRSPEC-2	1.0918	1.2853	94	90	7.04
NIRSPEC-3 (J)	1.1410	1.36473	91	80	7.04
NIRSPEC-4	1.250	1.59091	91	77	7.04
NIRSPEC-5 (H)	1.418	1.80473	88	83	3.86
NIRSPEC-6	1.56	2.30286	89	85	3.86
NIRSPEC-7	1.854	2.619	89	75	2.54
K	1.99	2.38	74	71	3.12
K'	1.945	2.296	95	92	3.28
KL	2.16	4.19	97	90	2.54
L'	3.42	4.12	97	94	3.12
M'	4.57	4.80	93	90	3.12
Mw	4.40	5.60	90	89	2.72
Br-gamma	2.15505	2.17475	77	75	3.16
Pa-beta	1.2757	1.2888	68	66	5.5
HeI (1.083 um)	1.0805	1.0900	85	85	5.5
FeII (1.644 um)	1.638	1.654	77	75	3.16
CO	2.27955	2.30165	77	75	3.16
H2 (2.121 um)	2.10965	2.12955	70	68	3.16
PK50 -2.5 mm	N/A	N/A	N/A	N/A	2.5
PK50 -3.5 mm	N/A	N/A	N/A	N/A	3.5
1This is the thickness of the filter, not the mount which surrounds it.

Out-of-band blocking is generally 105 or better for the NIRSPEC filters, except in the case of NIRSPEC-
7, where there is a red leak near 4.7 m. The PK50 -2.5 mm has a transmission between 10−4 to 10−6 between 3 and 6 m. The PK50 -3.5 mm has a transmission which is roughly a factor of 10 less.

Table 2 gives a list of the filters distributed in the two filter wheels. The precise positions of the filters is not important. It is only important that all the filters listed in one wheel end up completely in one filter wheel. This is because the filters in one wheel might be teamed with blockers / Lyot stops in the other wheel.

Table 2

Filter Positions in the Filter Wheels

FW1	FW2
Open + NLS	Open + ILS
L'	NIRSPEC-1
M'	NIRSPEC-2
KL	NIRSPEC-3
HeI (1.083 um)	NIRSPEC-4
Br-gamma	NIRSPEC-5
Mw	NIRSPEC-6
CO	NIRSPEC-7
Pa-beta	H2 (2.121 um)
PK50 -2.5 mm + NLS	FeII (1.644 um)
PK50 -3.5 mm + NLS	K
B	K'
ILS=inscribed Lyot stop

NLS =nominal Lyot stop

I assume that the pupil image is on the Lyot stops in FW1 .

The following plots give the transmission curves for the filters.