| 摘要 |
PURPOSE:To maintain initial characteristics of an etalon without adsorbing moisture or particles by housing the etalon in an airtight holder in which an adsorber is provided and drying the inside of the airtight holder and providing a clean inert atmosphere therein. CONSTITUTION:When an inert gas, e.g. a highly pure gas such as N2, is introduced into a airtight holder 10 through a gas introducing pipe 13 via a filter 17, the atmosphere around the etalon 4 is extremely dried and clean state without particles or active gas can be realized. Further, the moisture permeating and entering through a seal part, etc., from the outside of the airtight holder 10, or the active gas generated from constituent parts inside the airtight holder 10 is adsorbed and removed by an adsorber 12 so that the inside of the airtight holder 10 can be always kept clean. Thus, the initial characteristics can be maintained for a long time without adhesion or adsorption of particles, water, vapor of oil, or active gas, etc. |
