Filter Naming Conventions
Reading Typical Part Numbers
Understanding Chroma filter part numbers allows you to quickly identify key specifications such as center wavelength, bandwidth, filter type, and coating family.
Excitation filter (e.g., ET480/40x) – For this example, the center wavelength is at 480 nm; full bandwidth is 40 nm (±20 nm). In some cases where the bandwidth is not specified, the letter “x” is used to define the filter as an excitation filter. This is generally used for narrow band UV excitation filters (e.g., ET340x).
Dichroic beamsplitter (e.g., T495LPXR) – The cut-on wavelength where transmission is approximately 50% is 495 nm for this dichroic longpass mirror.
Emission filter (e.g., ET535/50m) – The center wavelength is at 535 nm; full bandwidth is 50 nm (±25 nm).
Prefixes and Coating Families
Code | Description |
|---|---|
AT | Magnetron-sputtered exciter, emitter, or dichroic, typically 45° AOI; recommended for only basic, visual applications (such as cell culture) (basic performance) |
D | Obsolete parts; early-generation bandpass filter (thermal/“soft” coating) |
ET | Magnetron-sputtered exciter or emitter, typically normal incidence (0° AOI) for maximum performance |
HQ | Obsolete parts; improved soft-coated bandpass filter |
T | Magnetron-sputtered dichroic/polychroic, typically 45° AOI |
ZET | Magnetron sputtered exciter or emitter specifically designed for laser use |
ZT | Magnetron-sputtered dichroic/polychroic designed for laser use, typically 11–45° AOI |
Suffixes and Spectral Function Codes
Code | Description |
|---|---|
BS | Beamsplitter or dichroic mirror |
DC | Shorthand for “dichroic”, typically 45° AOI |
LP | Indicates a longpass filter or dichroic mirror which transmits wavelengths longer than the cut-on and blocks or reflects shorter wavelengths respectively |
M | Emission filter |
PC | Polychroic beamsplitter. Reflects and transmits more than two bands of light, typically 45° AOI |
SP | Indicates a shortpass filter or dichroic mirror which transmits wavelengths shorter than the cut-on and blocks or reflects longer wavelengths respectively |
X | Excitation filter |
XR | Extended reflection, typically 45° AOI |
XRU | Extended reflection including the UV, typically 45° AOI |
Glass Type Abbreviations
Code | Description |
|---|---|
GG | Green Glass. Longpass absorption glass from Schott Glassworks with cut-on wavelengths in the violet and blue-green regions |
OG | Orange Glass. Longpass absorption glass from Schott Glassworks with cut-on wavelengths in the green, yellow, and orange regions |
RG | Red Glass. Longpass absorption glass from Schott Glassworks with cut-on wavelengths in the red and far red regions |
