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Custom Longpass Filters

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Knight Optical is known for its range of high-quality longpass filters. These filters, also known as edge filters, are crucial in applications that require the elimination of unwanted wavelengths.

For instance, a long pass optical filter with an 850nm cutoff will effectively block most wavelengths from UV and NIR up to 850nm. Beyond this point, the transmission of these longpass filters increases sharply, often exceeding 80%. This feature makes longpass filters ideal for applications where isolating specific wavelengths or reducing stray light is necessary, such as in photometry or longpass filter fluorescence studies.

Knight Optical provides bespoke custom long pass optical filters tailored to a range of requirements, from UV at 350nm to NIR at 1.55µm.

These filters, which include infrared longpass filters and dichroic longpass filters, are designed to meet specific edge cutoffs, transition steepness, and transmission or blocking needs. The dichroic longpass filter, for example, reflects unwanted wavelengths, enhancing system efficiency, and can also be supplied on white float glass or borosilicate or equivalent.

In addition to these, Knight Optical offers custom colour glass longpass filters. These filters are great at selectively transmitting long wavelengths while absorbing shorter ones, resulting in the achievement of high out-of-band blocking. They are particularly cost-effective and stable, making them an excellent choice for a wide range of applications, including scientific instruments where precise spectral selection is crucial. Our custom longpass filters can be supplied in a range of mounting options. For example custom longpass filters can be supplied to screw directly onto tamron lenses.

For those requiring flexible options, Knight Optical also supplies custom polyester and Wratten longpass filters. These filters cover a broad spectrum from visible to NIR, ideal for minimising atmospheric light in displays or enhancing theatre lighting. The versatility of Wratten longpass colour filters and their ease of customisation to specific dimensions make them suitable for a wide array of applications.

Moreover, Knight Optical’s custom dichroic longpass filters are a foundation in advanced optical applications. These filters are instrumental in devices like LCD projectors and sensor systems, where they enhance performance by selectively transmitting light.

Speak to our experts about your Custom Longpass Filter needs today

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Dive into the forefront of optical solutions. Got questions about an optical product? Reach out now and let our expertise guide you.

    Metrology Testing and Quality Assurance

    Knight Optical’s commitment to quality is evident in every filter provided, tested rigorously in our state-of-the-art metrology lab using sophisticated equipment like the Agilent Cary 5000 spectrometers. We ensure that each long pass ir filter or uv longpass filters meets the highest standards of quality and performance.

    For more information on our range of long pass vs bandpass filters and other specialised optical solutions, or to discuss your specific requirements with our multilingual technical sales team, get in touch. Discover how Knight Optical’s superior longpass filters and expert services can enhance your instrumentation and streamline your supply chain.

    Frequently Asked Questions

    A long pass filter is a type of optical filter that allows light with wavelengths longer than a certain threshold to pass through while blocking shorter wavelengths. This makes it ideal for applications that require the isolation of longer wavelengths from a broad spectrum of light.

    Long pass filters differ from bandpass filters in their functionality. While a long pass filter blocks light below a certain wavelength, a bandpass filter allows light within a specific range of wavelengths to pass through, blocking light outside this range on both the higher and lower sides of the spectrum.

    Long pass optical filters are essential in fluorescence applications for separating the longer-wavelength emission light from the shorter-wavelength excitation light. This separation is crucial for enhancing the clarity and contrast of fluorescence imaging and spectroscopy.

    Yes, infrared long pass filters are specifically designed to pass infrared light while blocking visible light. These filters are commonly used in thermal imaging, night vision technology, and various scientific applications that require infrared light.

    Dichroic long pass filters offer high precision and efficiency in reflecting unwanted wavelengths while allowing desired longer wavelengths to pass. This makes them particularly effective in applications requiring high spectral purity and minimal optical loss.

    Yes, UV longpass filters are available that allow ultraviolet light to pass while blocking visible and shorter ultraviolet wavelengths. These filters are useful in scientific research, forensic analysis, and UV photography to isolate specific UV wavelengths.

    Is your question not here?

    We are ready and waiting to answer any queries you may have about longpass filters.

    Typical Applications

    Aspherical Lenses for Microscopy

    Fluorescence Studies


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    With our in-house state-of-the-art metrology laboratory you can be confident that your optical components will meet your requirements. You can find out more about our testing facilities here.

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