What is meant by cutoff wavelength, transition width, and optical density in shortpass filters?

The cutoff wavelength (or edge wavelength) is defined at a specific transmission level (commonly 50%) and marks the boundary between the transmitting and blocking regions. Transition width describes how steeply the filter transitions from high transmission to high blocking, often specified between T=80% and OD>3 or OD>4 points on the spectrum. Optical density (OD) quantifies blocking performance on a logarithmic scale, where OD 3, 4, and 6 correspond to 0.1%, 0.01%, and 0.0001% transmission, respectively.

What are the main types of shortpass filters and how do they differ in performance?

Common types include interference (dichroic) shortpass filters, absorptive glass shortpass filters, and graded or tunable variants. Interference shortpass filters use multilayer dielectric stacks, offering high peak transmission, steep edges, and high OD in the stopband, but can be angle-sensitive. Absorptive types use doped glass for broadband blocking with lower angle sensitivity, but typically exhibit gentler transitions, lower peak transmission, and higher in-band absorption.

Which key specifications should I focus on when selecting a shortpass filter for my application?

Critical parameters include the cutoff wavelength and its tolerance, in-band transmission level, stopband optical density, and transition width between passband and stopband. You should also consider substrate material, surface quality, and flatness if the filter is in an imaging path, as well as size, thickness, and mechanical mounting constraints. For high-power or pulsed lasers, damage threshold, coating type, and thermal characteristics are also important.

How do angle of incidence and polarization affect the performance of shortpass filters?

Interference shortpass filters exhibit wavelength shift with angle of incidence (AOI): the effective cutoff wavelength moves to shorter values as AOI increases from the nominal (typically 0° or 45°) design angle. This shift can differ for s- and p-polarizations, causing polarization-dependent transmission and blocking characteristics, particularly near the edge. When comparing products, check the specified AOI, polarization conditions, and whether the spectral curves are for unpolarized, s-, or p-polarized light.

What typical lead times, customization options, and pricing drivers exist for shortpass filters?

Standard catalog shortpass filters in common diameters (e.g., 12.5 mm, 25 mm) and cutoffs often ship from stock or within 1–2 weeks, while custom sizes, edges, or substrates can range from 4–10 weeks depending on coating complexity. Customization can include non-standard cutoff wavelengths, tighter tolerances, higher OD in the stopband, specialized substrates (e.g., fused silica, UV-grade, IR materials), and AR coatings. Pricing is driven by coating design complexity, yield for high-OD/steep-edge filters, substrate size and material, and batch volume.

How can I find, compare, and request quotes for shortpass filters on FindLight without registering?

On FindLight, you can navigate to Optics > Filters > Shortpass Filters and then use filters for cutoff wavelength, size, substrate, optical density, and vendor to narrow down options. Product pages show key specifications, spectral plots, mechanical formats, and datasheets so you can directly compare multiple items in separate tabs. To request pricing or a technical quote without registration, use the “Request Quote” or “Contact Supplier” form on each product page, providing your quantity, target specs, and required delivery timeframe; the inquiry is sent directly to the supplier.

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Shortpass Filters for Precise Wavelength Control