If the CSIs still have no luck, they can try the most recent and advanced method—vacuum metal deposition, or VMD.

如果调查人员仍然没有成功，他们可以尝试最新和先进的方法——真空金属沉积。

Once a voltage is passed through, the oily regions deflect the colored substances surrounding bare regions, which gives rise to a negative ridge pattern, similar to the VMD method.

一旦电压通过，油性区域会使裸露区域周围的有色物质发生偏转，从而产生一个负脊纹图案，类似于 VMD 方法。