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The characteristics of 2-D holographic scanners utilizing a concave auxiliary reflector are analyzed. The total resolution capability of the scanner is discussed in detail for the scanner operated at both finite and infinite conjugations, and the factors limiting resolution are indicated. The resolution considerations lead to a near-optimal design procedure which is used in design examples for typical applications in the visible, millimeter, and ultrasonic wavelength regions.

Intravascular ultrasound imaging catheters and forward firing laser atherectomy systems are both being used in the coronary vascular tree of man. When used in conjunction, ultrasound imaging may reduce the probability of perforation and dissection related to laser atherectomy. A novel system is presented which combines ultrasound imaging and laser atherectomy capabilities on the same catheter. The system incorporates a holmium YAG laser directed perpendicular to the long axis of the catheter along with a co-directional ultrasound sensor. Ultrasound images are assembled by computer using the angle of the catheter tip and its linear advance associated with each ultrasound echo signal.In vivo experimental results are presented.

Catheter systems for laser atherectomy in peripheral and coronary arteries are subject to many design constraints. Ideal mechanical, laser and imaging requirements for these systems are proposed, and compared to the design features of a laser atherectomy system currently under development by Intra-Sonix. This system uses high resolution ultrasound for real-time guidance and control and is potentially capable of characterizing lesions and imaging critical structures in the coronary arteries, to guide physicians in the application of laser therapy. Precise catheter location and rotational direction can be provided continuously as the therapeutic intervention proceeds. Examples are given of the imaging modes and ultrasound images of an artery produced by the Intra-Sonix system.

Holographic scanners are suggested for imaging in the 8–13-μm spectral region. Advantages in refrigeration and reliability are pointed out. The narrow linewidth of received irradiance may limit passive systems to applications such as thermography, where multispectral imaging should be a useful diagnostic tool. Active systems, which do not suffer from this range limitation, offer inherent advantages with regard to resolution improvement via background discrimination and also with respect to countermeasures.