Dependence of ghost on the incident light angle into dichroic mirror.

Abstract

The dichroic mirror (DM) is a key component in microscope. We found ghost in the reflection channel of a dual-channel fluorescence microscope, and studied the relationship between the ghost and the incidence angle 𝜃 into the DM. The DM emission surface reflection generated ghost if the 𝜃 is not 45◦ . We analyzed the distance and intensity relationship between the ghost and the primary image, which is 𝜃-dependent and was demonstrated by imaging live cells and stage micrometer. The ghost can be eliminated by placing the DM between objective and tube lens, but not between tube lens and detector, ensuring that the incident light into the DM is approximately parallel. Furthermore, the transmitted light of the DM is shifted towards longer wavelength with increasing 𝜃. Collectively, microscopists must carefully optimize the 𝜃 when designing a microscope to avoid the ghost. This article is protected by copyright. All rights reserved.