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A dichroic filter is a thin optical filter crafted to transmit light in only one narrowly defined wavelength band while reflecting all other wavelengths. These optical filters are also known as thin-film or interference filters.
Dichroic filters are typically placed at a 45-degree angle to a light source. With this placement, blocked light is reflected at a 90-degree angle while specified wavelengths of light pass through the filter. If a light source is emitting white light, the light filtered through a filter of this type will seem to be highly saturated in color. A red filter, for instance, will transmit red wavelengths and reflect cyan. A green filter will transmit green and reflect magenta.
Shanghai Optics manufactures high-quality dichroic filters in longpass, shortpass, bandpass, bandblocking, and color correction types. These filters are carefully crafted to exact specifications, and since the color is intrinsically part of the filter, it will not bleach out. This gives our filters a much longer useful life than other conventional filters. Our dichroic filters also have a very high laser damage threshold.
Dichroic filters play a vital role in various applications, including:
In systems requiring color separation, such as projectors or imaging devices, these filters effectively control RGB light. Variants like cold and hot mirrors, which are also based on dichroic principles, aid in high power heat management by reflecting visible light and allowing infrared light to pass or vice versa.
Longpass filters transmit all wavelengths above a given cut-on wavelength. Shortpass filters transmit wavelengths below a given cut-off. Bandpass filters transmit wavelengths over a narrow range, which may be specified.
Cold mirrors and hot mirrors are dichroic filters that remove unwanted heat from a system. When placed behind a light source, a cold mirror reflects all visible light forward while transmitting unwanted NIR light out at a 45° angle. A hot mirror will reflect NIR heat and transmit visible light out at a 0° angle.
Our state-of-the-art dichroic filters feature a sharp transition from reflection to transmission. They also exhibit high transmission in the pass band. All of our filters are dielectric coated with IBS technology. We use hard coatings and no adhesives to improve the filters’ lifespan. These hard coatings provide good resistance to abrasion and temperature.
Our factory standard dichroic features are manufactured from UV-grade fused silica. They have an operating temperature from -45°C to about 85°C, and an angle of incidence of 45.0°. Our thickness tolerance limits are ±0.1 mm, and each of our filters has a clear aperture of at least 95%. Our standard dichroic filters are 25.2 mm by 35.6 mm by 1.1 mm.
We can also manufacture custom dichroic filters tailored to your specific needs. Our expert team will guide you through the design, prototyping, and production stages, ensuring that your custom filters are optimized for transmitted and reflected wavelengths and are designed for high-power optical systems. Please contact us to schedule a free consultation or request a quote for your next project.
Contact us for manufacturing limit or custom specifications.
| 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 |
| 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 |