The extended surface forces apparatus. II. Precision temperature control

We describe the design and performance of a low-cost, bidirectional tempera ture control system with very high stability and low thermal gradients in a working range from -10 to 70 degreesC. System elements such as thermal ins ulation, thermal pumps, and feedback control as well as safety features are discussed. The performance of the entire system under realistic experiment al conditions is documented. Precise temperature control has led to signifi cantly improved instrumental stability. An extension of the instrumental wi ndow towards slower measurements has been made possible. This temperature-c ontrol system is presented in the framework of the extended surface forces apparatus but is also applicable to other scientific instruments that requi re subnanometer positioning stability over extended periods of time. (C) 20 01 American Institute of Physics.