1. Status of the Chroma-Matic “Trials and Tribulations With the Black Art of RF” 27 October, 2006 Alan Stummer

2. Embedded software (Rabbit) mostly ready. Panel software ready. ADWin software ready. Monitor software ready. Hardware tested but problems with electrical beat frequency. Still no full system test. Present Status

3. Lock-in Amp 87 Rb Reference Laser Tuneable Laser ÷16 PLL DDS 983MHz Ftune Current Piezo Current Rosa Fig.1 Laser Tuning Configuration λ1 To Experiment λ2 To Experiment AD9858 Eval Module LIA

4. Issues With Present Configuration 1. Improper output from dividers. The Hittite HMC363 et al require higher input power at “low” frequencies such as <100MHz. The particular ROSA (Receiver Optical Sub-Assembly) used is at the low end of the output spec. 2. Relatively high minimum beat frequency. With the rule of thumb that the frequency into the filters should be at least 10 times the bandwidth required for the laser current, and with the fixed prescaler modulus of 16 built into the DDS evaluation board, the minimum beat frequency is 0.5MHz * 10 *16 = 80MHz. Fig. 2 HMC363 at 29MHz and ~300mV p-p input

5. Possible Receiver Configurations ÷8 ÷2 LIA Rosa Existing: Divider is tri-state at f < 100MHz, needs higher power from LIA (Limiting Amp, AKA Post Amp). CON: f min is 0.5MHz * 10 * 16 = 80MHz DDS PCB LIA Rosa New LIA: Possible to get one with higher output? CON: f min is 0.5MHz * 10 * 16 = 80MHz DDS PCB LIA Rosa New Ext. Dividers 1: Possible to find ones that accept lower input levels? PRO: good, short RF connections. CON: f min is 0.5MHz * 10 * 16 = 80MHz DDS PCB ÷8 ÷2 ÷8 ÷2 0) 1) 2) LIA Rosa New Ext. Dividers 2: Possible to find ones that accept lower input levels? Programmable or switch selectable? PRO: good, short RF connections. CON: f min is 0.5MHz * 10 = 5MHz DDS PCB ÷2 n 3)