Learn why custom optical filters offer superior value over off-the-shelf alternatives
Custom vs. Catalogue Optical Filters: Benefits for Instrument Makers
Introduction
Optical filters play a crucial role in the performance of scientific and industrial instruments such as fluorescence microscopes, spectrophotometers, and colorimeters. The quality and precision of these filters can significantly affect both the functionality and cost-efficiency of a product. While catalogue filters offer a variety of standard options, they often fail to meet the specific needs of specialized applications. This is where custom optical filters become invaluable, providing tailored solutions that enhance the overall performance of your instruments.
Custom optical filters, typically composed of multiple thin dielectric layers of alternating high and low refractive indices coated onto a transparent substrate, are engineered to meet precise specifications. Unlike catalogue filters, custom options can be optimized for critical factors like wavelength range, edge steepness, out-of-band blocking, illumination, and physical dimensions.
By using custom optical filters, manufacturers can ensure their instruments perform to the highest standards, offering improved accuracy and functionality. This tailored approach not only boosts instrument performance but also provides a competitive advantage, allowing manufacturers to deliver products that meet the exact needs of their market. In a field where precision is key, custom optical filters offer superior value over off-the-shelf alternatives.
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Understanding Custom Optical Filters
Custom optical filters are specialized components tailored to meet specific requirements, especially when standard catalogue filters fail to provide optimal solutions. These customizations can cover various aspects, such as optical, mechanical, and surface finish requirements. For example, optical characteristics like center wavelength, bandwidth, and transmission levels can be precisely defined to meet the specific needs of an application. Mechanical customizations may involve adjusting the filter’s dimensions, thickness, or mounting features to ensure seamless integration with the instrument. Additionally, surface finish requirements, including surface roughness and defect count, can be optimized to improve durability and performance in challenging environments. See Table 1 for a list of examples of parameters that are commonly customized for optical filters.
By working closely with a supplier, OEM manufacturers can achieve cost-effective filter solutions by ensuring the filters meet—but do not exceed—the exact requirements of their instruments. This collaboration enables the fine-tuning of parameters to meet precise performance criteria, which in turn enhances the overall accuracy and reliability of the instrument.
Why Opt for Custom Optical Filters?
During the initial proof-of-concept phase of a new instrument, off-the-shelf filters are typically used to build a prototype on an optical table. At this stage, factors such as size, cost, and complexity are generally less critical. However, when the instrument moves towards becoming a manufacturable product, off-the-shelf filters often prove to be sub-optimal.
Custom optical filters, in contrast, can be more cost-efficient by meeting the exact requirements of the instrument. For example, if your design only requires an optical density (OD) of 5, there’s no need to pay for a more expensive OD-8 filter. Similarly, if steep spectral edges are not necessary, you can avoid paying for those features as well.
Custom designs also offer the advantage of reducing system complexity. In some cases, multiple off-the-shelf filters can be combined into a single custom filter, simplifying the instrument and enhancing performance. Additionally, custom filters can be optimized for specific usage conditions. For instance, the angle of incidence (AOI) and the opening angle of illumination for your filter might differ from the standard angles offered by catalogue filters, ensuring better performance in your system.
Custom filters not only improve accuracy, sensitivity, and reliability but also integrate more efficiently with your system, providing superior results over generic options.
Key Considerations When Choosing a Supplier
Selecting the right supplier for custom optical components is critical to ensuring high-quality and reliable products. A key factor in this process is the supplier’s ability to provide expert consultation services. This means they should be able to help you clearly define your optical, mechanical, and performance requirements, and guide you toward finding the right balance between performance, cost, and manufacturability. Their expertise is helping you navigate the complexities of custom filter design, ensuring that your specifications are met without over-engineering the product.
Additionally, a reputable supplier should have rigorous quality assurance processes in place. This includes comprehensive testing and verification procedures to ensure that each custom optical filter meets the desired specifications. A proven track record of successfully turning custom designs into consistently high-quality manufactured products is another crucial factor to look for.
It is also essential to confirm that the supplier has the capability to scale production to meet your specific needs, whether it is for prototyping, small batch production, or full-scale manufacturing. By ensuring that your supplier can maintain strict quality standards while offering flexibility, you set the foundation for a successful partnership that delivers reliable, high-performance custom optical filters tailored to your instruments.
Advanced Manufacturing Technologies for OEM Needs
To meet the demands of OEM manufacturing, advanced production technologies are critical. Delta Optical Thin Film has invested in state-of-the-art equipment specifically designed for the cost-effective production of optical filters. This investment ensures that custom filters are manufactured with high precision and consistency, meeting the strict performance and cost requirements of OEM applications. Furthermore, our machines are modified for large batch sizes, reducing the manufacturing cost of the individual pieces.
At Delta Optical Thin Film, we recognized early on that the key to high-performance filter manufacturing lies in the in-house development of our own filter design tools. By creating these tools internally, we can ensure that our filter designs are not only optimized for performance but also for manufacturability from the very beginning of the design phase. This approach minimizes the risk of design revisions later in the process, allowing for a smoother and faster transition from concept to production.
Our comprehensive approach to both design and manufacturing enables us to quickly turn custom optical filter designs into high-quality products that meet the specific needs of various applications. This combination of advanced production technology and in-house design expertise allows us to provide reliable, tailored solutions that deliver consistent performance, supporting the demanding requirements of OEM manufacturers across a range of industries.
Real-World Applications of Custom Optical Filters
Custom optical filters are extensively used in various OEM instruments across different industries. Below, we present three examples of custom optical filters that illustrate specialized illumination, system simplification, and cost optimization through innovative optical filter design.
Example 1: Angle-tolerant dichroic beam splitter
In fluorescence microscopes, it is common to use a dichroic beamsplitter optimized for a 45-degree Angle of Incidence (AOI) to separate the excitation light from the emission light. However, in instruments that utilize LEDs and in compact point-of-care systems, the AOI of the illumination may deviate significantly from 45 degrees. In a traditional dichroic beamsplitter, such an AOI deviation would cause a large shift in the filter passbands, which is naturally undesirable.
To address this issue, we developed a custom AOI-tolerant dichroic beamsplitter as part of one of our projects. This special design ensures that the filter’s angle dependent shift of the filter edge wavelength and polarization splitting have been minimized. Hereby, it is ensured that the reflection and transmission remain high in the specified wavelength ranges when the AOI varies. Figure 1 illustrates the resulting filter transmission across an AOI range from 33 degrees to 58 degrees, demonstrating the enhanced tolerance to AOI deviations without compromising the filter’s effectiveness.
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Example 2: Simplifying multi-wavelength fluorescence detection with multi-bandpass filters
In fluorescence microscopy and flow cytometry, the simultaneous detection of multiple molecules using multiple fluorophores is known as multiplexed detection. This technology enables the analysis of several parameters or interactions within complex biological systems at the same time. Traditionally, multiplexed excitation and detection are achieved by using multiple dichroic beamsplitters arranged in tandem on both the excitation and emission sides, as shown in Figure 2a) for a four-wavelength system. However, this approach can become quite complex, especially when three or more fluorophores need to be measured simultaneously.
To simplify wavelength-multiplexed instruments, we developed a quad-band beam spitter, which combines four dichroics beam splitter into a single one as illustrated on Figure 2 b). The quad-band beam splitter is designed to work with multi-wavelength LEDs as excitation sources, with each LED turned on sequentially, one at a time. Furthermore, the many single band excitation and emission filters are combined into quad-band filters as well.
This solution streamlines the detection process, reducing system complexity while enabling the detection of multiple wavelengths simultaneously. The use of a quad-band filters significantly improves the overall efficiency of fluorescence instruments by allowing the analysis of multiple targets with fewer components.
Example 3: Cost-efficient tunable wavelength filter with deep out-of-band blocking
A tunable wavelength filter can be created using two Linear Variable Filters (LVFs) that are translated relative to each other. This design is simpler and more stable than other types of tunable filters, as it only requires linear translations along one axis. By using a set of Linear Variable Short-Wave Pass and Linear Variable Long-Wave Pass filters, a variable bandpass filter can be created, where both the center wavelength and bandwith can be adjusted independently.
For a specific application, we needed to design a widely tunable filter set that covered a wavelength range of 400 – 1000 nm with a passband adjustable down to 5 nm.
Additionally, the tunable filter needed to provide deep out-of-band blocking. While this deep out-of-band blocking could be achieved through the LVF design itself, it would require an excessive number of coating layers, significantly increasing the cost. To address this, we introduced simple, cost-effective wide bandpass filters that could be shifted in and out of the beam, as illustrated in Figure 3. This approach relaxed the out-of-band blocking requirements for the LVF, allowing us to offer a cost-efficient solution that provides combined OD5 out-of-band blocking.
Summary
Custom optical filters play an essential role in optimizing the performance, accuracy, and cost-efficiency of OEM instruments across various industries. Unlike off-the-shelf filters, custom solutions are engineered to meet precise specifications, allowing for significant enhancements in instrument functionality, simplified design, and cost optimization. The ability to customize filters ensures that they can be tailored for even the most demanding applications.
Working closely with a supplier, OEM manufacturers can achieve cost-effective solutions that meet but do not exceed the exact needs of their instruments. This collaboration enables fine-tuning of parameters to optimize performance without unnecessary over-engineering, providing both enhanced reliability and efficiency.
The real-world applications of custom optical filters, such as the development of angle-tolerant dichroic beamsplitters, multi-bandpass filters, and cost-efficient tunable filters, highlight their ability to solve complex optical challenges while delivering superior performance. Whether it is improving multi-wavelength detection in fluorescence instruments or optimizing out-of-band blocking for tunable filters, custom optical filters offer distinct advantages over catalogue options.
In conclusion, custom optical filters not only improve the performance of scientific and industrial instruments but also provide OEM manufacturers with a competitive edge in the market by offering tailored, high-performance solutions that integrate seamlessly into their systems.
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Delta Optical Thin Film has more than 50 years of experience in design and manufacture of advanced interference filters. We have pioneered many innovative solutions that are now commonly used in analytical instruments.
Browse through the many examples of products we have made on our product pages.
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