import re
lst = [u'Name1_Cap23_o2_A_20160830_20170831_test.tif',
u'Name0_Cap44_o6_B_20150907_20170707.tif',
u'Name99_Vlog_o88_A_20180101_20180305_exten.tif']
pattern = re.compile(r'^\w+_\d{8}_\d{8}')
pattern_list=map(lambda x: pattern.search(x).group(), lst)
print(pattern_list)
aW1wb3J0IHJlCgpsc3QgPSBbdSdOYW1lMV9DYXAyM19vMl9BXzIwMTYwODMwXzIwMTcwODMxX3Rlc3QudGlmJywKICAgICAgIHUnTmFtZTBfQ2FwNDRfbzZfQl8yMDE1MDkwN18yMDE3MDcwNy50aWYnLAogICAgICAgdSdOYW1lOTlfVmxvZ19vODhfQV8yMDE4MDEwMV8yMDE4MDMwNV9leHRlbi50aWYnXQoKCnBhdHRlcm4gPSByZS5jb21waWxlKHInXlx3K19cZHs4fV9cZHs4fScpCnBhdHRlcm5fbGlzdD1tYXAobGFtYmRhIHg6IHBhdHRlcm4uc2VhcmNoKHgpLmdyb3VwKCksIGxzdCkKcHJpbnQocGF0dGVybl9saXN0KQ==