Quantum Cascade Lasers (QCL) are highly efficient, compact, and wavelength-agile devices in Mid-Wavelength InfraRed (MWIR – generally 3.7 – 4.8 microns wavelength) and Long-Wavelength InfraRed (LWIR – generally 8 – 12 microns wavelength). Wall-plug efficiencies have been shown to be above 20% [1,2]. which make them highly desirable for any application where SWaP (Size, Weight, and Power) are critical to fielded systems. Multiple applications exist for both pulsed and continuous-wave (CW) format QCLs in communications, remote sensing, and electronic warfare. Specifically, there are few competitive comparable alternatives in CW to these products. They also are capable of operation close to the diffraction limit, making them practical as long-range devices beyond that of a laboratory device. Single QCL emitter CW power levels tend to be limited to around 1 W in the lower part of the MWIR and in LWIR and higher in the upper part of the MWIR. Under a Navy Small Business Innovative Research contract and funding from the Office of Naval Research, Naval Research Laboratory (NRL) has worked with Forward Photonics, LLC to increase power, improve spectral output, and reduce SWaP for these devices. Among the technologies explored have been spectral beam combining [3-6], polarization beam combining, spectral tailoring, and innovative ideas in laser packaging. As a result, QCL-based laser systems can be scaled in power and efficiently packaged to deliver adequate power on target at significant ranges. Both air-cooled and water-cooled versions of higher power devices in MWIR have been successfully field tested by NRL. Plans are underway to duplicate this success in LWIR and to further reduce SWaP and cost for practical, affordable, production devices.
This work was funded under a grant from the Office of Naval Research Code 312.
One of the biggest and challenging limitations of infrared cameras in surveillance applications is the limited dynamic range. Image blooming and other artifacts may hide important details in the scene when saturation occurs. Many different techniques such as using multiple exposure times have been developed in the past to help overcome these issues. However all these techniques feature non-negligible limitations. This paper presents a new high-dynamic range algorithm called Optimized Enhanced High Dynamic Range Imaging (OEHDRI). It is based on a pixel-wise exposure-time independent calibration as well as a pixel based frame summing with proper interleaved integration times. This technique benefits from the use of a high frame rate camera (< 20,000 fps). Description of the hardware is also included.