| 摘要 |
PURPOSE:To obtain a prism of which the sepn. angle hardly changes with a temp. change by pasting two sheets of transparent materials of which the ratio of the respective refractive indices is approximately equal to the ratio of the respective temp. coeffts., and using the boundary face thereof as a prism face. CONSTITUTION:A prism plate 18 is formed by pasting two transparent materials 18a and 18b having a prescribed angle alpha of inclination and the boundary face thereof is constituted as a prism face. A sepn. angle theta is determined by n2/n1 from the equation where the refractive index of the material 18a is designated as n1, the coefft. of temp. as DELTAn1, the refractive index of the material 18b as n2, the coefft. of temp. as DELTAn2, a solid line A as a prism face, an incident angle as alpha and the sepn. angle as theta. If the respective refractive indices upon changing of the temp. by DELTAt, as designated as n1(t), n2(t), are so selected as to make n2/n1 and DELTAn2/DELTAn1 approximately equal, the prism of which the sepn. angle theta hardly changes with the temp. change is obtd. as shown by the equation. |
