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Diffraction integrals are calculated for a distribution of CDH -LOC diode lasers to assess efficiency of matching them to fixed and variable magnification optical recording systems.High power diode lasers are characterized, in general, by far -fields having an elliptical cross-section°1In addition, while the intensity profiles of these far -fields in the planes parallel and perpendicular to the plane of the semiconductor junction are often approximated as gaussians,2 the true far -fields may differ significantly from such a shape.The development of the constricted double heterojunction large optical cavity (CDH -LOC) diode laser at RCA Laboratories3 has created a commercial device4 with applicability to optical recording in the near infrared.5 We have evaluated a sample of CDH -LOC's in order to determine how to tailor the optics of recording systems to utilize the output of the CDH -LOC device as advantageously as possible, i.e., high throughput efficiency and small spot diameter.We first must understand how the diameter and peak intensity of a spot formed by collecting, collimating, and focussing the laser output vary with truncation of the beam by the entrance pupil of the focussing objective. We then must determine the range of far -field widths which will be encountered when real high power lasers are installed in recording heads. We can then make a judgement as to the relative economics of using fixed optical systems for all lasers of the sample as opposed to optimizing the optical parameters for individual lasers.Lastly, we may determine whether departures of true CDH -LOC far -fields from the gaussian approximation will have a significant effect on the spot formed and optical efficiency.

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