• Spectral transmission graph with a peak at around 900 nm on a white background
  • Black bandpass filter with technical specifications on a white background
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BP940-20 Bandpass Filter(CWL=940nm,FWHM=20nm)

BP940-20 Bandpass Filter(CWL=940nm,FWHM=20nm)

PartNumber:SO3010721

$50.00 USD
$50.00 USD
Sale Sold out
Shipping calculated at checkout.
Center Wavelength (CWL) // FWHM
Optical Density // Peak Transmission (Tpk)
Dimension

In Stock.

Ships within 5 working days of order.
  • Wavelength: Center wavelength 940nm with 20nm FWHM bandwidth for narrow-band near-infrared spectrum transmission
  • Spectral Features: Narrow bandwidth with steep edge transitions for precise NIR spectral isolation
  • Optical Density: OD3+ blocking outside passband for strong background suppression
  • Filter Dimension Availability: Available in standard round and square formats to fit common optical mounts

Request Raw Data

You can request the raw transmission data from us.

Copy the link of the product page and send email to shop@syronoptics.com, you will get reply within 1 working days.

Shipment & Delivery

  • Stocked products ship within 5 business days after order confirmation.
  • Custom-made products typically ship within 4–8 weeks.
  • Delivery times may be affected by holidays, customs clearance, or other unforeseen events.
  • Tracking information becomes available 3–5 days after dispatch when the parcel is handed to the local courier.
  • Some deliveries may require customer pickup. Please ensure your contact information is correct and respond promptly to courier communications.
  • General international parcel shipping cost: USD 35 (for reference).

Return & Refund

1. Eligible Products

Stocked (catalog) products with a unit price under USD 500 are eligible for return within 14 days after delivery.

Custom-made or non-stock items are not eligible for no-reason returns.

2. No-Reason Return (Buyer’s Remorse)

If you wish to return an item for reasons other than product defect or seller error:

  • Please email shop@syronoptics.com to request a return authorization and return address.
  • Buyer is responsible for all return shipping costs.
  • Items must be unused, in original condition, and with original packaging.
  • Refund will be issued after inspection of the returned item.

3. Seller’s Fault (Defective / Wrong / Damaged Item)

If the return is due to seller error (defective product, wrong item shipped, or damage during shipping):

Please provide clear evidence (photos or videos) showing the issue.

We will evaluate the case and either:

  • Provide a replacement, or
    Issue a refund (with or without requiring the item to be returned).
  • Return shipping cost will be covered by the seller in confirmed seller-fault cases.

4. Important Notes

  • Returned items are subject to inspection before refund approval.
  • Shipping fees, customs duties, and taxes are non-refundable unless the return is due to seller fault.
  • Unauthorized returns will not be accepted.

Custom Sizing

Custom sizing is available from 3 × 3 mm (or Ø5 mm) up to 60 × 60 mm. For custom cut sizes, please contact shop@syronoptics.com for a quotation.

Pricing is not significantly lower for small-size orders in low quantities due to operational costs.

Payment Terms

Payments can be made online using Credit Card, Apple Pay, Google Pay, WeChat Pay, and Alipay.

If you prefer to pay by bank transfer, please contact shop@syronoptics.com to request an invoice with our banking details.

If you require deferred payment terms, you may request NET 7 or NET 30 at the time of placing your order.

All requests for deferred payment are subject to approval and will be confirmed by SyronOptics via email.

View full details
  • BP940-20 Bandpass Filter - Covert Surveillance & Night Vision

    BP940-20 Bandpass Filter - Covert Surveillance & Night Vision

    Covert Surveillance & Night Vision

    • Why: Unlike 850nm light, which emits a faint visible "red glow" at the source, 940nm is completely invisible to the human eye. This makes it ideal for covert operations where you do not want the camera to be detected.
    • Use Cases: Security cameras in banks or ATMs, wildlife observation (prevents scaring animals), and covert military surveillance.

    Recommended Light Sources

    • 940nm High-Power IR LED: Matches the filter's specific 940nm wavelength to maximize transmission while remaining completely invisible to the human eye (eliminating the "red glow" of 850nm), ensuring the surveillance source remains undetected.
    • 940nm VCSEL Illuminator: Provides a narrower spectral bandwidth (<5nm) that fits entirely within the BP940-20's 20nm bandwidth, resulting in higher optical efficiency and longer effective range than standard LEDs for distant monitoring.
  • BP940-20 Bandpass Filter - Outdoor Machine Vision & Remote Sensing

    BP940-20 Bandpass Filter - Outdoor Machine Vision & Remote Sensing

    Outdoor Machine Vision & Remote Sensing

    • Why: There is a natural "dip" in the solar spectrum around 940nm due to atmospheric water absorption. This means there is less background noise from sunlight at this wavelength compared to 850nm.
    • Use Cases: Traffic monitoring, License Plate Recognition (LPR), and outdoor autonomous navigation systems that need to function in daylight.

    Recommended Light Sources

    • High-Intensity 940nm LED Strobe: Concentrates high-power pulses in the 940nm "solar blind spot," allowing the sensor to overpower the reduced sunlight background and capture crisp, motion-blur-free images of fast-moving targets like license plates.
    • 940nm VCSEL Array: Emits a narrow spectral band that aligns perfectly with the solar absorption dip and the filter's bandwidth, maximizing signal-to-noise ratio in bright daylight conditions where broadband sunlight would otherwise wash out the image.

Fequently Asked Questions

Different Types of Filter Mountings

Unmounted:

  • a bare glass optical filter

Mounted:

  • Smooth Mount for protection of the optics. No thread is there on the mount.

Metric Mount:

  • Start with M as prefix, usually seens as M25.5x0.5mm. Mostly used as camera filters

Imperial Mount:

  • Start with SM as prefix, usually seen SM1, SM05 etc... Mostly used in Optical system. (You will have a SM external thread to connecting to other objects)

C-Mount:

  • Very frequently used mounting. C-Mount is 1‘’-32TPI. And it is not the same thing as SM1, or M25.5x0.5mm.

What are the Thickness of the Optical Filters?

For Unmounted Optics:

  • 0.5mm
  • 1.1mm
  • 2.0mm

*Most of our optics are coming with 1.1mm and 2.0mm

With Standard Mounting (Mounted, No Thread):

  • 3.5mm (Default)
  • 6mm (Upon Request)

Thread Mounted:

  • 6mm - 8mm

  • dia12.5mm(unmounted)

    Clear Aperture:

    >90%

    Mounting Thickness:

    n.a

    Internal/External Thread:

    n.a/n.a

  • dia12.5mm(mounted)

    Clear Aperture:

    dia9mm

    Mounting Thickness:

    3.5mm

    Internal/External Thread:

    n.a/n.a

  • dia25mm(mounted)

    Clear Aperture:

    dia21mm

    Mounting Thickness:

    3.5mm

    Internal/External Thread:

    n.a/n.a

  • dia25mm(unmounted)

    Clear Aperture:

    >90%

    Mounting Thickness:

    n.a

    Internal/External Thread:

    n.a/n.a

  • SM05(0.535″-40TPI)

    Clear Aperture:

    dia9mm

    Mounting Thickness:

    7.62mm

    Internal/External Thread:

    SM05/SM05

  • SM1(1.035″-40TPI)

    Clear Aperture:

    dia21mm

    Mounting Thickness:

    7.62mm

    Internal/External Thread:

    SM1/SM1

  • C-Mount(1″-32TPI)

    Clear Aperture:

    dia21mm

    Mounting Thickness:

    Internal/External Thread:

    C-Mount/C-Mount

  • M25.5x0.5mm(mounted)

    Clear Aperture:

    dia20.5mm

    Mounting Thickness:

    6.5mm

    Internal/External Thread:

    M25.5x0.5mm/M25.5x0.5mm

  • M27x0.5mm(mounted)

    Clear Aperture:

    dia22mm

    Mounting Thickness:

    6.5mm

    Internal/External Thread:

    M27x0.5mm/M27x0.5mm

  • M30.5x0.5mm(mounted)

    Clear Aperture:

    dia25.5mm

    Mounting Thickness:

    6.5mm

    Internal/External Thread:

    M30.5x0.5mm/M30.5x0.5mm

  • M34x0.5mm(mounted)

    Clear Aperture:

    dia29mm

    Mounting Thickness:

    6.5mm

    Internal/External Thread:

    M34x0.5mm/M34x0.5mm

  • M35.5x0.5mm(mounted)

    Clear Aperture:

    dia30.5mm

    Mounting Thickness:

    6.5mm

    Internal/External Thread:

    M35.5x0.5mm/M35.5x0.5mm

  • M37x0.5mm(mounted)

    Clear Aperture:

    dia32mm

    Mounting Thickness:

    6.5mm

    Internal/External Thread:

    M37x0.5mm/M37x0.5mm

  • M52x0.75mm(mounted)

    Clear Aperture:

    dia47mm

    Mounting Thickness:

    6.5mm

    Internal/External Thread:

    M52x0.75mm/M52x0.75mm

  • M55x0.75mm(mounted)

    Clear Aperture:

    dia50mm

    Mounting Thickness:

    6.5mm

    Internal/External Thread:

    M55x0.75mm/M55x0.75mm

  • dia27mm(unmounted)

    Clear Aperture:

    >90%

    Mounting Thickness:

    n.a

    Internal/External Thread:

    n.a/n.a

  • dia34mm(unmounted)

    Clear Aperture:

    >90%

    Mounting Thickness:

    n.a

    Internal/External Thread:

    n.a/n.a

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