Shortpass Filters

Shortpass filters are a specialized category of high transmission edge filters, meticulously engineered to allow the passage of shorter wavelengths while effectively blocking longer ones. At Avantier, we take pride in crafting high quality short wave pass edge filters tailored to a diverse range of applications, including the medical industry, research, and defense. Our filters, often made from durable materials like colored glass, are characterized by exceptional light transmission capabilities, making them suitable for ultraviolet, visible, and infrared applications. Engineered for robust performance across varying conditions, these high transmission filters exhibit remarkable durability, withstanding normal handling and cleaning processes.

Comprehending Shortpass Filters

Within the realm of edge filters, including both shortpass and longpass filters, the primary objective is to selectively transmit a specific range of light while suppressing or rejecting another. In the case of shortpass optical filters, the pivotal transition point between transmission and rejection is referred to as the “cut-off wavelength” – the wavelength at which transmission reaches 50%. The cut-off wavelength is the most critical specification and is typically expressed as a single numerical value, such as 600 nm.

A well-crafted shortpass filter boasts a sharp cut-off, effectively blocking light above the cut-off wavelength. Nearly 100% of light shorter than the cut-off wavelength passes through the filter without alteration. These two distinct regions are commonly referred to as the “rejection range” and the “transmission range”.

Proper Mounting of Your Shortpass Filter

While shortpass filters can effectively filter light in both directions with minimal differences in intensity or spectral characteristics, we recommend orienting the filter with the coated side facing the light source. This orientation eliminates the risk of thermal damage to your filter and minimizes potential thermal effects from intense out-of-band radiation.

Our standard filters are typically used with a normal angle of incidence, although adjustments in orientation can fine-tune the cut-off wavelength. As a general guideline, every 45-degree change in incidence angle will lead to a 10% alteration in the cut-off wavelength.

Applications

Shortpass edge filters play a significant role in various imaging and photometry devices, offering invaluable assistance in eliminating distortions by effectively blocking broad ranges of unwanted light. A common application is their use as “hot mirrors,” which effectively obstruct undesirable infrared radiation. These filters are also prominent in Raman spectroscopy and fluorescence microscopy. Furthermore, they can be combined with longpass filters to create bandpass filters. In this configuration, radiation passing through one filter proceeds into the other, resulting in the elimination of both high and low wavelength ranges, allowing only the desired passband to transmit.

Custom Shortpass Filters

Avantier maintains an extensive inventory of standard and hard-coated optical filters, available individually or in comprehensive kits. Our seasoned engineering and design team is also at your service, ready to assist in devising the optimal filter arrangement tailored to your specific application requirements. Please contact us to access a catalog of in-stock or custom shortpass filters designed to meet your unique needs.