| 摘要 |
A method of studying a sample using an optical microscope, comprising the following steps:
- Providing the sample in a sample holder comprising means to maintain the sample at a temperature T below 273 K;
- Providing a microscope objective lens having an extremal lens element proximal the sample holder;
- Bringing the lens into a focus position proximal the sample, the extremal lens element and sample being separated by an intervening space,
which method comprises the following steps:
- Providing the objective lens in a thermally insulating jacket;
- Providing a transparent window in said intervening space, with a gap between the window and the extremal lens element;
- Providing a flow of substantially dry gas in said gap;
- Tailoring the geometry and velocity of said flow so that, at least in said gap, the flow:
- Is non-laminar;
- Does not excite substantial acoustic vibration in a structure proximal the gap.
Said structure may, for example, be at least one of:
- The window;
- The sample;
- The sample holder. |
