Dichroic Filters

10 Jan 2022

Dichroic Filters for Every Application

A dichroic filter is 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 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.

Types of Dichroic Filters

Longpass filters are filters which transmit all wavelengths above a given cut-on wavelength. Shortpass filters, on the other hand, transmit wavelengths below a given cut-off. Bandpass filters will transmit wavelengths over a narrow range, which may be specified.

These filters have applications in LCD projectors, laser harmonics separators, and in fluorescence microscopy or multispectral imaging. They can also be used as cold or hot mirrors, or to monitor UV water purification.

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.
 

Shanghai Optics Dichroic Filters

Our state of the art dichroic filters feature a sharp transition from reflection to transmission. They also have exhibit high transmission in the pass band.  All of our filters are dielectric coated with IBS technology. We use hard coatings and no adhesives in order to improve the filters life span. 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 to about 85, 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 lenses to meet your specifications. Please contact us to discuss available substrates and our manufacturing limit for custom specifications. Our team has experience with designing optics for many applications, and we can help you every step of the way, from design to prototype to production.

Key Features

• Sharp transition from reflection to transmission
• High transmission in pass band
• Hard coatings and no adhesives for long filter life span
• All dielectric coated with IBS technology

Factory Standard

• Angle of Incidence: 45.0°
• Shortpass Type Transmittance: Tabs>85%
• Dimensions: 25.2mm*35.6mm*1.1 mm
• Clear Aperture: >95%
• Operating Temperature: -45°C ~ 85°C
• Physical Durability: MIL-C-48497A
• Longpass Type Transmittance: Tabs>90%
• Reflection Band: Rabs>98%
• Thickness Tolerance: ±0.1 mm
• Transmitted Wavefront: 1/4λRMS@633nm (per inch)
• Environmental Durability: MIL-STD-810F
• Substrate: UV Grade Fused Silica

Contact us for manufacturing limit or custom specifications.

 

 

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