Dichroic Filter Applications
A dichroic filter is a thin optical filter designed to transmit light within a specific, narrow wavelength range while reflecting all other wavelengths. These filters are also referred to as thin-film or interference filters.
Typically, dichroic filters are positioned at a 45-degree angle to the light source. In this setup, the blocked light is reflected at a 90-degree angle, while the desired wavelengths pass through the filter.
For example, when white light passes through, the light that makes it through appears highly saturated in color. A red filter will transmit red wavelengths and reflect cyan, while a green filter will transmit green and reflect magenta.
At Notch Optics, we produce high-quality dichroic filters in various forms, including longpass, shortpass, bandpass, bandblocking, and color correction types.
Each filter is meticulously crafted to meet precise specifications, and since the color is inherently part of the filter, it won’t fade over time. This results in a significantly longer lifespan compared to conventional filters. Additionally, our dichroic filters boast a high laser damage threshold.
Dichroic Filters Types
Longpass filters are designed to transmit all wavelengths above a specific cut-on point, while shortpass filters allow the passage of wavelengths below a defined cut-off.
Bandpass filters, by contrast, transmit light within a narrow, specified range of wavelengths.
These filters have a wide range of applications, including use in LCD projectors, laser harmonic separators, fluorescence microscopy, and multispectral imaging.
They can also serve as cold or hot mirrors and are often utilized in systems that monitor UV water purification.
Cold mirrors and hot mirrors are special types of dichroic filters that help manage heat within a system.
A cold mirror, when placed behind a light source, reflects all visible light forward while transmitting unwanted near-infrared (NIR) light at a 45° angle.
A hot mirror works in the opposite way, reflecting NIR heat and allowing visible light to pass through at a 0° angle.
Key Features of Dichroic Filters
Our cutting-edge dichroic filters are engineered with a sharp transition from reflection to transmission, ensuring high transmission in the pass band.
All of our filters are dielectric coated using IBS technology, with hard coatings and no adhesives to enhance durability. These hard coatings offer excellent resistance to abrasion and temperature fluctuations, extending the filters' lifespan.
Our standard dichroic filters are made from UV-grade fused silica, with an operating temperature range from -45°C to approximately 85°C and an angle of incidence of 45°.
The thickness tolerance is ±0.1 mm, and each filter provides a clear aperture of at least 95%. The standard dimensions of our filters are 25.2 mm by 35.6 mm by 1.1 mm.
We also offer custom dichroic lenses tailored to your specific requirements. Contact us to discuss substrate options and our capabilities for custom designs.
With extensive experience in optics design, our team is ready to assist you through every stage, from concept to prototype to full-scale production.
Dichroic Filter Standards
Dichroic Longpass Filter
| Cut-off Wavelength(nm) | Reflection Band(nm) | Transmission Band(nm) | Size(mm) |
| 411 | 344-404 | 415-570 | 25.2*35.6*1.1 |
| 458 | 426-450 | 467-600 | 25.2*35.6*1.1 |
| 497 | 442-488 | 502-730 | 25.2*35.6*1.1 |
| 508 | 446-500 | 513-725 | 25.2*35.6*1.1 |
| 520 | 488-512 | 528-655 | 25.2*35.6*1.1 |
| 555 | 493-548 | 562-745 | 25.2*35.6*1.1 |
| 565 | 499-555 | 569-730 | 25.2*35.6*1.1 |
| 595 | 530-585 | 601-800 | 25.2*35.6*1.1 |
| 655 | 470-645 | 665-726 | 25.2*35.6*1.1 |
| 660 | 594-651 | 669-726 | 25.2*35.6*1.1 |
| 665 | 350-650 | 680-1100 | 25.2*35.6*1.1 |
| 669 | 350-660 | 677-800 | 25.2*35.6*1.1 |
| 735 | 350-720 | 750-1100 | 25.2*35.6*1.1 |
| 740 | 480-720 | 750-825 | 25.2*35.6*1.1 |
Dichroic Shortpass Filter
| Cut-off Wavelength(nm) | Transmission Band(nm) | Reflection Band(nm) | Size(mm) |
| 550 | 400-548 | 575-725 | 25.2*35.6*1.1 |
| 600 | 400-580 | 625-795 | 25.2*35.6*1.1 |
| 700 | 400-680 | 725-900 | 25.2*35.6*1.1 |
| 750 | 400-725 | 800-990 | 25.2*35.6*1.1 |
| 800 | 400-775 | 850-1050 | 25.2*35.6*1.1 |
| 850 | 400-820 | 910-1110 | 25.2*35.6*1.1 |
| 900 | 425-865 | 960-1170 | 25.2*35.6*1.1 |
| 950 | 450-910 | 1025-1235 | 25.2*35.6*1.1 |
| 1000 | 465-940 | 1085-1305 | 25.2*35.6*1.1 |
| 1050 | 485-1000 | 1130-1370 | 25.2*35.6*1.1 |