Microthermal fluctuations are introduced by atmospheric turbulence very near the ground. In order to detect microthermal fluctuations at Fuxian Solar Observatory (FSO), a microthermal instrument has been developed. The microthermal instrument consists of a microthermal sensor, which is based on a Wheatstone bridge circuit and uses fine tungsten filaments as resistance temperature detectors, an associated signal processing unit, and a data collection, & communication subsystem. In this paper, after a brief introduction to surface layer seeing, we discuss the instrumentation behind the microthermal detector we have developed and then present the results obtained. The results of the evaluation indicate that the effect of the turbulent surface boundary layer to astronomical seeing would become sufficiently small when installing a telescope at a height of 16m or higher from the ground at FSO.

ABSTRACT
1. INTRODUCTION
2. PRINCIPLE OF SEEINGMEASUREMENT
3. DESCRIPTION OF THE INSTRUMENT
    3.1 Microthermal Sensor
    3.2 Signal Processing Unit
    3.3 Data Collection and Communication Subsystem
4. RESULTS AND DISCUSSIONS
5. CONCLUSIONS
REFERENCES

• XUE-BAO LI(Yunnan Astronomical Observatory, Chinese Academy of Sciences)
• YAN-FANG ZHENG(Yunnan Astronomical Observatory, Chinese Academy of Sciences) Corresponding Author
• LIN HUA DENG(Yunnan Astronomical Observatory, Chinese Academy of Sciences)
• GUANG XU(Yunnan Astronomical Observatory, Chinese Academy of Sciences)