![low-cut off wavelength low-cut off wavelength](https://www.rp-photonics.com/img/step_index_fiber_mode.png)
We recommend orienting the optic as illustrated in the diagram to the upper right. These optics feature a dichroic coating on one surface and an antireflection (AR) coating on the opposing surface. Please see below for transmission and reflection plots of each mirror. These mirrors are designed for use at a 45° angle of incidence and are available in five sizes: Ø1/2", Ø1", Ø2", 25 mm x 36 mm, and 35 mm x 52 mm. Our shortpass dichroic mirrors are offered in several different cutoff wavelengths ranging from 425 to 1800 nm, which are listed in the selection guide graphic to the right. It is highly transmissive below the cutoff wavelength and above the cut-on wavelength, while highly reflective between the cutoff and cut-on. This dichroic has two transmission bands and one reflection band that are separated by a cutoff and cut-on wavelength. We also offer a multi-band dichroic mirror that can be used as a shortpass mirror. This type of dichroic is highly transmissive below the cutoff wavelength and highly reflective above it. Shortpass dichroic mirrors have a transmission and reflection band that are divided by a cutoff wavelength. Thorlabs' Dichroic Mirrors/Beamsplitters spectrally separate light by transmitting and reflecting light as a function of wavelength.