• Spectral transmission graph with wavelength on the x-axis and transmission on the y-axis
  • Black bandpass filter with specifications on a white background
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BP1940-20 Bandpass Filter(CWL=1940nm,FWHM=20nm)

BP1940-20 Bandpass Filter(CWL=1940nm,FWHM=20nm)

PartNumber:SO3010055

$115.00 USD
$115.00 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.

Holiday notice: Orders placed Feb 10–25 may ship later than usual. Free shipping applies during this period.
  • Wavelength: Center wavelength 1940nm with 20nm FWHM bandwidth for short-wave infrared spectrum transmission
  • Spectral Features: Narrow bandwidth with steep edge transitions for precise SWIR 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
  • BP1940-20 Bandpass Filter - Moisture Detection & Measurement

    BP1940-20 Bandpass Filter - Moisture Detection & Measurement

    Moisture Detection & Measurement

    • Because water absorbs light strongly at 1940 nm (appearing "black" or dark to a sensor), this filter is used to measure the moisture content in paper, wood, textiles, or agricultural grains.

    Recommended Light Sources

    • Use Halogen for high-power, industrial reflectance systems
    • Use SWIR LEDs for compact, low-power, or heat-sensitive applications.
  • BP1940-20 Bandpass Filter - Plastic Sorting & Recycling

    BP1940-20 Bandpass Filter - Plastic Sorting & Recycling

    Plastic Sorting & Recycling

    • In recycling facilities, SWIR spectroscopy is used to identify different polymer types. 1940 nm is a key spectral band for distinguishing specific plastics (like PET or PVC) or detecting wet plastics that need drying.

    Recommended Light Sources

    • Tungsten-Halogen Lamps (Broadband): This is the workhorse of the recycling industry.
    • Multi-Wavelength LED Arrays: While less common for general sorting, some modern systems use "strobed" LED arrays.

Fequently Asked Questions

What are the Thickness of the Optical Filters?

For standard mounting (mounted,non-thread):

  • 3.5mm (by default)
  • 6mm (by request)

For unmounted Optics:

  • 0.5mm
  • 1.1mm
  • 2mm

(most of the unmounted optics are having thickness of 1.1mm ~ 2mm)

What is the difference between 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.

  • dia12.5mm(mounted)

    Clear Aperture:

    dia9mm

    Mounting Thickness:

    3.5mm

    Internal/External Thread:

    n.a/n.a

  • dia12.5mm(unmounted)

    Clear Aperture:

    >90%

    Mounting Thickness:

    n.a

    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

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