| Author(s): |
Patrick F. Egan; Jack A. Stone Jr; |
| Title: |
Temperature stabilization system with millikelvin gradients for refractometry |
| Published: |
July 25, 2010 |
| Abstract: |
Refractometry of air is a central problem for interferometer-based dimensional measurements. Refractometry at the 10^{-9} level is only valid if air temperature gradients are controlled at the millikelvin level. Very precise tests of second-generation NIST refractometers involve comparing two instruments (two optical cavities made from ultralow expansion glass) that are located in nominally the same environment; temperature gradients must be kept below a few millikelvin to achieve satisfactory precision of these tests. In this paper we describe a thermal stabilization scheme that maintains < 1 mK thermal gradients over 100 hours in a 0.5 m x 0.15 m x 0.15 m volume. Our approach uses passive (aluminum envelopes and foam insulation) and active (thermistors, foil heaters, and PID control) temperature stabilization. Thermal gradients are sensed with thermocouples and a nanovoltmeter and switch; the reference junctions of the thermocouples being in thermal contact with a thermistor temperature standard. Our < 1 mK gradient performance is limited by the accuracy of the nanovoltmeter and switch. |
| Conference: |
2010 NCSL International Workshop and Symposium: 21st Century Innovations in Metrology |
| Proceedings: |
2010 NCSL International Workshop and Symposium |
| Pages: |
10 pp. |
| Location: |
Providence, RI |
| Dates: |
July 25-29, 2010 |
| Keywords: |
Temperature stabilization; Refractometry; Thermometry |
| Research Areas: |
Thermometry, Instrumentation, Length |
| PDF version: |
 Click here to retrieve PDF version of paper (1MB) |
