450nm Bandpass Filter

Context: This patent describes high-brightness direct diode laser systems, specifically using blue laser diodes (approx. 450nm) for applications like welding copper and other metals. Blue light is absorbed much more efficiently by copper than infrared light.

Usage of Filter: The 450nm filter (or wavelength-selective element like a Volume Bragg Grating, VBG) is placed in the optical path of the laser beam array.

Function: It acts as a spectral locking or beam combining element. In some embodiments, it functions to lock the emission of the laser diode bars to a specific narrow band around 450nm to enable dense wavelength beam combining (DBC). Alternatively, in the sensor monitoring path, a 450nm bandpass filter allows the camera to specifically monitor the reflected laser light from the workpiece for seam tracking or focus control while blocking thermal radiation (IR).

Result: Enables the generation of a high-power, high-brightness blue laser beam capable of spatter-free welding of highly reflective metals (like copper and gold) or precise process monitoring of the blue laser interaction.

Context: A sensor head for non-invasive monitoring of renal function (kidney health). The system detects the clearance of a fluorescent tracer agent (e.g., MB-102) injected into the body.

Usage of Filter: A 450nm bandpass filter is used on the LED excitation source (or effectively as the LED's spectral cleanup filter).

Function: The filter ensures that the light entering the skin is strictly within the 450nm excitation band (blue light) and does not contain any wavelengths that overlap with the tracer's emission band (approx. 560nm, green/orange).

Result: Causes the tracer agent to fluoresce without "polluting" the detection channel with source light. The system then measures the decaying fluorescence signal over time to accurately calculate the Glomerular Filtration Rate (GFR) in real-time.