Verify operation of controller

 To verify the operation of the etalon, we will now power up the controller. First, check that the X, Y, and Z settings of the dials on the left side of the controller are appropriate for the etalon being used (see Figure 10, Table 3). In all likelihood, unless you are using a special etalon, the dials will not need to be adjusted.

  

Figure 10: A blow-up of the etalon balance adjustment dials on the left side of the CS-100 Fabry-Perot controller. These dials need only be adjusted if you are using an etalon different from that previously used with the controller. You should verify the settings with those in Table 3.

 

 

Table 3: CS-100 Fabry-Perot controller settings for etalons commonly used at Palomar. Note that these values may only be appropriate for the Palomar CS-100 controller.

		ET-50	ET-50	ET-70
		#ET50-889FS	#ET50-889FS	#ET70-200FS
			(03/2001)
X	fine	5.10	5.10	1.55
	coarse	-2	-2	-3
	quad	4.06	4.06	4.18
Y	fine	7.70	7.70	0.40
	coarse	-2	-2	0
	quad	3.78	3.78	3.85
Z	fine	2.00	5.84	9.74
	coarse	-4	-5	-1
	quad	3.40	3.40	3.85

Next, make sure the operate/balance switch is on balance. For both power on and power off, the controller must be in balance mode. Then switch on the power to the unit. A green light on the power switch will illuminate, as well as a yellow ``balance'' indicator. If the meters appear normal, then switch the operate/balance switch to operate. The yellow balance light should switch to a green operate light, indicating that the parallelism of the etalon plates is now being maintained by the controller. With the offset/quadrature meter-selection switch on offset, the three meters should read within the range ±5 volts. If not, there is a problem. With the meter switch set to quadrature error, the reading should be close to 0 on all three meters. Please do not turn any knobs, except the power, operate/balance, and offset/quadrature switches, unless you are sure that you know what you are doing. Figure 11 illustrates a properly functioning CS-100 controller.

Note: The meters on the Palomar CS-100 are currently not working properly in ``balance'' mode. In particular, they appear to show a coupling between X and Z, which in fact is not occuring. Simply set the coarse and fine settings of the dials to the values in the table. If for some reason you think these values are incorrect, put the etalon on a fluorescent light table and confirm that the etalon is parallel (i.e., as you move your head side to side, the ring radius does not increase monotonically from one side to the other). It might in fact be a good idea to do this prior to installing the etalon in the instrument in order to confirm proper operation of the etalon and CS-100.

  

Figure 11: A properly functioning CS-100 Fabry-Perot etalon controller. Note that the green ``operate'' light is illuminated, as well as the red ``disabled'' light, indicating that the computer has control of the CS-100 interface. Note also that the meters read approximately 0, with the meter switch set to quadrature error.

If the red out of balance light illuminates instead of the green operate indicator, here are the recommended courses of action, in increasing order of complexity:

1.

Turn the etalon operate/balance switch back to balance, and then back to operate.

2.

Turn the etalon operate/balance switch back to balance, and then shut off the controller power. Repeat the power up sequence. Please always switch to the balance mode before turning the power off or on.

3.

Repeat the power cycling step, but reseat all cables while the unit is powered off. Double check that everything is connected properly, paying particular attention to match the small X, Y, and Z cables to the corresponding connectors on both the controller and the etalon.

4.

Repeat the power cycling step, but check again that the X, Y, and Z settings of the dials on the left side of the controller are appropriate for the etalon being used (see Table 3).

5.

Contact one of the Fabry-Perot instrument support people listed in Appendix D.

If there does appear to be a problem with the hardware, possible solutions include calling Queensgate Instruments in New York, or borrowing a controller from someone, such as John Trauger (JPL).