Long-slit spectra taken with the TAURUS Tunable Filter
and a CuAr source through four filters: (top L) 710nm,
(top R) 760nm, (bottom L) 815nm, (bottom R) 910nm.
The long-slit spectrum is achieved with a focal plane
slit, stepping the TTF through 80 frequencies synchronized
with moving the charge on the detector (charge shuffling).
The seven strips correspond to CS100 coarse settings of
(+6, +5, +4, +3, +2, +1, 0) spanning a physical gap range
of 12$\mu$m to 5$\mu$m (left to right). There are three
dominant emission lines in all filters, except the 910nm
filter with two lines. The latter is the easiest to see
the major effect, that the orders separate out easily at
small gap where the wavelength free spectral range 
increases. But note, in particular, that the intrinsic
spectral resolution is falling as well.

From fitting to the lines as a function of wavelength against
y (row number), we have established the gap and order of 
interference, m.  The line wavelengths are given at the end.
In Fig. 1, we plot the coarse setting against the gap spacing
for all four filters. The non-linear variations along a mean 
slope are real.




wave = 710 nm

coarse	dlam/dy		arb off		m	     FSRy	     gap

+6.      0.96143       6767.26       33.8985        217.851         12.034  
+5.      1.0511        6759.96       30.8956        218.634        10.9679  
+4.      1.16926       6757.82       27.7204        219.051        9.84076  
+3.      1.31122       6789.79       24.597         220.141        8.73192  
+2.      1.49165       6845.44       21.6182        220.177        7.67447  
+1.      1.66892       6543.77       19.5391        217.73         6.93637  
+0.      1.97023       6572.55       16.4259        219.388        5.83119  



wave = 760 nm

coarse	dlam/dy		arb off		m	     FSRy	     gap

+6.	1.08666        7435.67        29.6646        235.765        11.2726  
+5.	1.16711        7227.01        27.7071        235.023        10.5287  
+4.	1.30121        7286.02        24.7026        236.441        9.38698  
+3.	1.48602        7393.55        21.7336        235.319        8.25876  
+2.	1.63109        7169.92        19.7029        236.486        7.48712  
+1.	1.90186         7303.1        16.8624        236.982        6.40771  
+0.	2.17589        6986.33        14.7566        236.696        5.60749  



wave = 815nm

coarse	dlam/dy		arb off		m	     FSRy	     gap

+6.	1.98551        7524.78        18.4421        222.574        7.51516<<< 
+5.	1.8246         7770.64        26.6759        167.444        10.8704  
+4.     1.94205        7580.93        25.0366        167.619        10.2024  
+3.	2.23765         7725.8        21.6977        167.862         8.8418  
+2.	2.48988        7528.55        19.3984        168.738        7.90485  
+1.	2.77405        7278.23        17.4692        168.178        7.11871  
+0.	3.31378        7470.35        14.6436        167.953        5.96725  



wave = 910 nm

coarse	dlam/dy		arb off		m	     FSRy	     gap

+6.     1.86052        8895.33        25.3906        192.634        11.5527  
+5.     2.0148         8778.27          23.45        192.605        10.6697  
+4.     2.24962        8639.19        20.9128        193.428        9.51532  
+3.     2.43229         8536.4        19.3734        193.117        8.81489  
+2.     2.70789        8417.08          17.34        193.803        7.88972  
+1.     3.21227        8823.86        14.6227        193.733        6.65331  
+0.     3.95173        8673.08          11.86        194.164        5.39631