Unmounted, AR-Coated Bandpass Colored Glass Filters
- AR Coating for 245 - 400 nm or 350 - 700 nm
- Ø25 mm Filters
- Broadband Alternative to Dielectric Bandpass Filters
FGB37-A Mounted in KB1P
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The blue shaded region indicates the specified 245 - 400 nm wavelength range for optimum performance.
- Transmissive at UV or Visible Wavelengths
- AR Coated for 245 - 400 nm or 350 - 700 nm
- Ø25 mm Filter
- Peak Transmission Greater than 90% in Specified Range
- Easily Mounted in SM1-Compatible Mounts
Thorlabs is pleased to offer a selection of its bandpass colored glass filters with a broadband antireflective coating designed for either the 245 - 400 nm (-UV) or 350 - 700 nm (-A) wavelength range. The broadband AR coating is deposited on both faces of a Schott® glass substrate that has been selected for its high transmission in the ultraviolet or visible. These Ø25 mm filters can be easily mounted in our manual or motorized filter wheels. They can also be mounted in our series of SM1 (1.035"-40) lens tubes.
The high-performance, multilayer, broadband -UV or -A coating deposited on each filter is designed to minimize surface reflections within the specified range, thereby increasing the amount of light transmitted within the specified wavelength region. This helps to improve measurement sensitivity under low light conditions. These coatings provide an average reflectivity that is less than 0.5% over the specified range when light is normally incident on the filter surface. Please see below for a representative transmission curve for each filter type, or refer to the Comparison tab for plots of the performance of the coated and uncoated filters.
For applications in the ultraviolet, the FGUV5-UV and FGUV11-UV are recommended for use in the 240 - 395 nm and 275 - 375 nm spectral ranges, respectively. The FGUV5-UV provides greater than 98% peak transmission within the specified range, while the FGUV11-UV features greater than 90% peak transmission and a nearly zero transmission up into the infrared. For applications at visible wavelengths, consider the FGS900-A and FGB37-A, designed for use in the 315 - 710 nm and 335 - 610 nm spectral ranges, respectively. The FGS900-A provides greater than 90% peak transmission over the visible wavelength range and suppresses wavelengths up into the infrared, while the FGB37-A provides greater than 98% peak transmission in the visible.
Several of the colored glasses used for our filters are fluorescent at certain wavelengths; for more details on how this may affect certain applications, contact Technical Support. For narrowband sources, we recommend our dielectric bandpass filters.
If an appropriate filter is not listed here, Thorlabs also provides an extended variety of uncoated bandpass colored glass filters for wavelengths extending from the ultraviolet to the infrared.
|Schott® Glass #||UG5||UG11||KG3||BG40|
|AR Coating Range||245 - 400 nm||245 - 400 nm||350 - 700 nm||350 - 700 nm|
|Recommended Range*||240 - 395 nm||275 - 375 nm||315 - 710 nm||335 - 610 nm|
|Clear Aperture||80% of Diameter|
|Ravg||<0.5% in Coating Range|
|Surface Quality||40-20 Scratch-Dig|
|Surface Flatness||<λ @ 632.8 nm|
|Dimensional Tolerance||+0.0/-0.4 mm|
|Item #||Recommended Range|
|FGUV5-UV||240 - 395 nm|
|FGUV11-UV||275 - 375 nm|
|FGS900-A||315 - 710 nm|
|FGB37-A||335 - 610 nm|
Effect of AR Coating on Transmission Properties
The bandpass colored glass filters shown on this page have been AR coated for either the 245 - 400 nm range (-UV) or the 350 - 700 nm range (-A). These filters are also available without AR coatings, but their transmission in the specified range is significantly diminished, as shown in the graphs below. At the peak transmission wavelength, the AR coatings provide an 8 - 10% increase in the total transmission.
The shaded region in each graph denotes the range over which the wavelength-dependent transmission is >50% of the peak transmission. This range is also listed in the table above.
|Item #||Diameter||Thickness||Clear Aperture||Schott® Glass #||AR Coating||Recommended Range*|
|FGUV5-UV||25 mm||2 mm||80% of Diameter||UG5||245 - 400 nm||240 - 395 nm|
|FGUV11-UV||25 mm||2 mm||80% of Diameter||UG11||245 - 400 nm||275 - 375 nm|
*The recommended range is the range for which the wavelength-dependent transmission is >50% of the peak transmission. This region is shaded in the graphs shown above.
|Item #||Diameter||Thickness||Clear Aperture||Schott® Glass #||AR Coating||Recommended Rangea|
|FGS900-A||25 mm||2 mm||80% of Diameter||KG3||350 - 700 nm||315 - 710 nm|
|FGB37-A||25 mm||2 mm||80% of Diameter||BG40||350 - 700 nm||335 - 610 nmb|
a The recommended range is the range for which the wavelength-dependent transmission is >50% of the peak transmission. This region is shaded in the graphs shown above.
b The transmission of the FGB37-A is between 0% and 50% in the 610 - 700 nm spectral range.