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High-Quality Notch Interference Filters - China Suppliers & Factory with Custom Specifications
🔬 Product Overview
Notch filters are also known as interference filters — optical films used for spectral or color segmentation. According to the shape of the divided spectrum, they are divided into band-pass filters, cut-off filters, Notch filters, and special filters. Generally called a band-stop or band-suppression filter, a Notch filter has a concave spectral characteristic, transmitting light of a given wavelength as little as possible while allowing as many other wavelengths through as possible. It is primarily used to eliminate or reduce specific light and enhance other spectral energy. The cut-off depth and flatness of the transmission area are the key measurement parameters. Notch filters can mainly transmit most wavelengths, but attenuate light in a specific wavelength range (stop band) to an incredibly low level — which is opposite to the use method and spectral curve of bandpass filters.
- Attenuates specific wavelength ranges (stop band) to extremely low levels
- Transmits most other wavelengths with high efficiency (T ≥ 90%)
- Cut-off depth (OD4) is a key performance parameter
- Opposite spectral behavior compared to bandpass filters
📊 Application Areas & Specifications
| Center Wavelength | FWHM (nm) | Blocking | Transmittance (Average) | Wavelength Range | Custom Made |
|---|---|---|---|---|---|
| 405 nm | 40 nm | OD4 | T ≥ 90% | 350–900 nm | ✓ Yes |
| 488 nm | 40 nm | OD4 | T ≥ 90% | 350–900 nm | ✓ Yes |
| 532 nm | 40 nm | OD4 | T ≥ 90% | 350–900 nm | ✓ Yes |
| 632.8 nm | 40 nm | OD4 | T ≥ 90% | 350–900 nm | ✓ Yes |
| 785 nm | 40 nm | OD4 | T ≥ 90% | 350–900 nm | ✓ Yes |
| 808 nm | 40 nm | OD4 | T ≥ 90% | 400–1100 nm | ✓ Yes |
⚙️ Production Process
❓ Frequently Asked Questions
Q
What is a Notch filter and how does it differ from a bandpass filter?
A Notch filter (also known as a band-stop or band-suppression filter) attenuates light within a specific wavelength range (stop band) to an extremely low level while transmitting most other wavelengths. This is the opposite of a bandpass filter, which only allows a specific wavelength range to pass through and blocks everything else.
Q
What does OD4 blocking mean in a Notch filter?
OD4 (Optical Density 4) means the filter attenuates the light in the stop band by a factor of 10,000 (i.e., only 0.01% of the light at the blocked wavelength is transmitted). This is a standard measure of the filter's blocking performance and ensures effective suppression of unwanted laser lines or specific wavelengths.
Q
What center wavelengths are available for your Notch filters?
Our standard Notch filters are available at center wavelengths of 405 nm, 488 nm, 532 nm, 632.8 nm, 785 nm, and 808 nm. All models feature a 40 nm FWHM, OD4 blocking, and average transmittance of T ≥ 90% in the pass band. Custom wavelengths are also available upon request.
Q
Can Notch filters be customized for specific applications?
Yes. All of our Notch filter models support custom manufacturing (marked "Y" in the specification table). We can tailor center wavelength, FWHM, blocking depth, substrate size, and coating specifications to meet your specific application requirements in laser systems, fluorescence imaging, Raman spectroscopy, and more.
Q
What are the typical applications of Notch filters?
Notch filters are widely used in Raman spectroscopy (to block the laser excitation line), fluorescence microscopy, laser-based imaging systems, telecommunications, machine vision, and any optical system where a specific wavelength must be suppressed without affecting surrounding spectral regions.
Q
What is the transmittance performance of your Notch filters outside the stop band?
Outside the stop band (blocking region), our Notch filters achieve an average transmittance of T ≥ 90% across the specified wavelength range (typically 350–900 nm or 400–1100 nm depending on the model). This ensures minimal signal loss in the pass band while maintaining strong attenuation at the target wavelength.