The BP850 Narrow Bandpass Filter is an optical filter designed to selectively transmit light within a narrow wavelength range while blocking light outside this range. It is engineered to focus on a central wavelength of 850 nm with specific bandwidth characteristics. The filter is particularly suited for applications where precise wavelength selection is crucial.

Key Parameters:

• Center Wavelength (CWL): 850 nm ± 5 nm
  The filter is centered around 850 nm, with a tolerance of ± 5 nm, ensuring that the transmission peak is accurately aligned within this range.

• Full Width at Half Maximum (FWHM): 30 nm ± 5 nm
  The FWHM specifies the range of wavelengths over which the filter maintains a significant level of transmission. For the BP850, this range is 30 nm, with a tolerance of ± 5 nm, defining the width of the band of transmitted wavelengths at half of the maximum transmission value.

• Transmission at Center Wavelength (T): >90% @ 850 nm
  The filter provides high transmission efficiency, exceeding 90%, at its center wavelength of 850 nm, ensuring that most of the light at this wavelength passes through the filter.

• Out-of-Band Transmission: T < 1% @ 350-1100 nm
  Outside the specified band, from 350 nm to 1100 nm, the filter’s transmission is less than 1%. This high level of attenuation ensures minimal leakage of light in unwanted wavelengths, improving the selectivity and purity of the filtered signal.

Applications:

1. Optical Communication:
   Used in optical communication systems to isolate specific wavelength channels and reduce cross-talk between different channels. It ensures that only the desired wavelength is transmitted while filtering out other wavelengths.

2. Spectroscopy:
   Ideal for use in spectroscopic applications where precise wavelength measurement is required. The filter helps to isolate specific spectral features for accurate analysis.

3. Imaging Systems:
   Employed in imaging systems and cameras to enhance image quality by filtering out unwanted wavelengths and reducing background noise.

4. Scientific Research:
   Useful in various scientific experiments and research applications where wavelength-specific data collection is crucial, such as fluorescence microscopy or photometry.

5. Environmental Monitoring:
   Applied in environmental sensors and monitoring devices to focus on specific wavelength bands for detecting pollutants or other environmental parameters.

Construction and Material:

• Optical Coating:
  The filter is typically coated with high-precision optical coatings to achieve the desired transmission and blocking characteristics.

• Substrate Material:
  Made from high-quality optical glass or synthetic materials with minimal absorption and scatter, ensuring durability and performance.

• Mounting Options:
  Available in various formats including circular or rectangular mounts, with options for custom sizes and coatings as per application requirements.

This narrow bandpass filter provides a precise and efficient solution for applications requiring specific wavelength isolation and minimal out-of-band interference.