一支腔长小于100mm的He-Ne激光器不能正常工作,因为在出光带宽内有时可能没有纵模存在,输出光功率会不时地大幅度变化.提出和研究解决这一问题的方法.用一片经过适当设计的石英晶体作为纵模间隔大于出光带宽的一支He-Ne激光器的一个腔镜,导致等间隔纵模分裂,即纵模的数目加倍,实际纵模间隔减半,因此可以造成出光带宽内总有一个以上纵模存在.用此方法制成的腔长85mm的He-Ne激光器,输出功率达到0.24mW. A He-Ne laser with a cavity length of less than 100 mm does not work properly because sometimes there may be no longitudinal mode within the bandwidth of the light output, and the output optical power can vary greatly from time to time. A properly designed quartz crystal, as a cavity mirror of a He-Ne laser with a longitudinal mode spacing greater than the light output bandwidth, results in an equally spaced longitudinal mode split, doubling the number of longitudinal modes and halving the actual longitudinal mode spacing, There is always more than one longitudinal mode exists.The He-Ne laser with a cavity length of 85mm made by this method achieves an output power of 0.24mW.