IR-Block/Visible Transmitting Optical Filters

MidOpt announces the availability of three new imaging filters primarily intended for blocking unwanted near-infrared light. Filters include: SP635 Absorptive Visible Shortpass/Near-IR Block Filter, SP644 Near-IR/Mid-Red Dichroic Block Shortpass Filter, and AB555 Acrylic Absorptive Near-IR/UV-Block Visible Bandpass Filter. Mounting solutions are available to help customize any imaging application. MidOpt’s unique filter mounting options include: Standard Threaded Mounts, Slip Mounts that easily adapt to lenses without filter threads, the exclusive 25.4 C-Mount for easy installation into cameras, and custom fabrication of unmounted shapes and sizes.

MidOpt’s SP635 Absorptive Visible Shortpass/Near-IR Block Filter is commonly used inside cameras to block infrared light. When working with any camera that has been modified and its internal IR cut filter has been removed, a SP635 filter mounted on the front of the lens, when desired, can return function once again like the unmodified camera. This is an absorptive infrared rejection filter that is also recommended for protecting a camera’s sensor from stray light emitted by lasers or other high power near-IR light sources. SP635 filters are A/R coated on both sides to maximize visible band transmission while offering superior out-of-band blocking. Peak transmission is ≥90%.

SP644 Near-IR/Mid-Red Dichroic Block Shortpass Filter is one of several dichroic filters offered mainly for use as an internal infrared blocking filter in color cameras. This design offers an attractive price/performance option compared to other designs. Uniform blocking of near-infrared wavelengths out to 1100nm, uniformly high transmission across the visible range, and a 50% point in the middle of the red portion of the spectrum make this an ideal choice for cameras with typical CMOS sensor responsivity. SP644 is useful to achieve natural color rendition with superior response in the blue channel. Its useful range is 395-638nm with a peak transmission ≥90%.

The AB555 Acrylic Absorptive Bandpass filter passes light in the visible range and blocks all near-infrared, ultraviolet and violet wavelengths. This filter offers excellent laser protection at 1064nm (O.D. 6). Additionally, optical density exceeds 5.0 in the UV (190-375nm), near-IR (760-1070nm) and at 10,600nm. Standard thickness is 3.5mm. The material is a light greenish color in transmission. Sheet stock can be quickly laser cut to a wide variety of custom sizes and shapes, particularly when used as a cover for an enclosure or a laser protective window.