Two-photon microscopy (TPM) has shown its great impact in studying neuronal activity of live animals. Commercial TPM systems require the animals under study to be restrained under the microscope and the 3D images are obtained typically by using bulky galvo scanning mirrors, which limits the flexibility of animal brain imaging to a large extent. To study freely moving animals, miniaturization of the optical scanning system is the key. In this work, a miniature TPM probe has been developed based on an electrothermal MEMS mirror that can be driven under low voltage. The MEMS mirror has an initial tilt angle after fabrication, and its footprint is 3 mm x 4 mm and reflective mirror plate is aluminumcoated with an equivalent diameter of 2.5 mm. This MEMS probe can be directly adapted to a commercial TPM system. In addition to the MEMS mirror for laser beam scanning, inside the MEMS probe head there are a fixed mirror to fold the laser beam and a high NA polymer lens for focusing. This miniature probe can realize an FOV of 3.5°, or a scanning range of 150 μm. This MEMS probe head is compact with a size of 8 mm x 16 mm, which can be further scaled down.
Nature reserves are facing a very challenging conflict between conservation and development today. The protection
effect of Jiuzhaigou Nature Reserve has received considerable attention, especially in view of its stimulating tourism
after the 1990s. Remote sensing data from 1974, 1994 and 2002 were chosen for the analysis of this reserve, since they
closely represented the vegetation situation before and after felling, as well as the disturbance from the flush of tourism.
We find that the quality and quantity of the forest in Jiuzhaigou Nature Reserve continues to decline, owing to the
conifer area and whole forest area constantly shrinking, as well as the landscape fragmentation increasing. The rate of
loss of forest in the second period (1994-2002) had showed down much than that in the first period (1974-1994), due to
nature protection. Shrubland area continued to increase throughout the two periods, with an increased speed in the
second period which was about 3.5 times that in the first period. The treeline was consistently retreating, contributing a
total of 467.96 ha of conifer forest lost. However, the causes involved in tree mortality and the resulting regression of the
treeline are not clear. In any case, under the general background of global warming, human impact undoubtedly should
have direct or indirect cause dramatic consequences for the forest in this very sensitive zone, while there are many
uncertainties in the behaviour of high mountain ecosystems.
Keywords: Jiuzhaigou Nature Reserve, Vegetation, Habitats fragment,