250nm Bandpass Filter

Context: This patent describes a dual-band camera system used to inspect high-voltage electrical infrastructure (like transmission lines) for faults. These faults emit "corona" discharges, which are invisible to the naked eye but emit weak ultraviolet (UV) light.

Usage: The 250nm bandpass filter (described as having a passband including 250nm–400nm, often narrowing to the "solar-blind" region of 240–280nm) is placed in front of an image intensifier or UV sensor.

Function: Its function is to block the overwhelming visible sunlight while transmitting only the specific Deep UV photons emitted by the electrical discharge.

Result: The system can detect and visualize electrical leaks in broad daylight. The UV signal is typically processed and overlaid onto a standard visible image, allowing maintenance crews to pinpoint the exact location of a failing insulator or conductor.

Context: This patent relates to high-precision analytical instruments, such as HPLC (High-Performance Liquid Chromatography) or spectrophotometers, which are used to analyze chemical substances like proteins or DNA.

Usage: A rare-earth doped glass standard (calibration medium) acts as a reference filter with a known, stable optical transmission feature specifically at 250 nm (and other wavelengths like 350nm or 580nm).

Function: The instrument passes light through this "filter" standard. The detector measures the transmission and compares the detected peak/trough against the known 250nm value of the physical standard.

Result: This achieves automated and highly accurate wavelength calibration of the instrument, ensuring that subsequent measurements of sensitive biological samples (which often rely on precise absorption readings at 250–280nm) are scientifically valid.

Context: This patent describes a modern detector for Liquid Chromatography that uses a Digital Micromirror Device (DMD) to select wavelengths.

Usage: The system is configured to create specific narrow bands of light, including a 250 nm band, from a broadband UV source (like a Deuterium lamp) to illuminate the flow cell.

Function: The filter (digitally created or physical) isolates the 250 nm wavelength to match the peak absorption of specific analytes passing through the chromatography column.

Result: This allows for the real-time detection and quantification of chemical compounds that specifically absorb Deep UV light, providing higher sensitivity for compounds that might be invisible at standard 254nm or 280nm wavelengths.