Modes of a laser resonator with a retroreflecting roof mirror

Petal-like modes in Porro prism resonators

A new approach to modeling the spatial intensity profile from Porro prism resonators is proposed based on rotating loss screens to mimic the apex losses of the prisms. A numerical model based on this approach is presented which correctly predicts the output transverse field distribution found experimentally from such resonators.

Compact, passively Q-switched Nd:YAG laser for the MESSENGER mission to Mercury

A compact, passively Q-switched Nd:YAG laser has been developed for the Mercury Laser Altimeter, an instrument on the Mercury Surface, Space Environment, Geochemistry, and Ranging mission to the planet Mercury. The laser achieves 5.4% efficiency with a near-diffraction-limited beam. It passed all space-flight environmental tests at subsystem, instrument, and satellite integration testing and successfully completes a postlaunch aliveness check en route to Mercury. The laser design draws on a heritage of previous laser altimetry missions, specifically the Ice Cloud and Elevation Satellite and the Mars Global Surveyor, but incorporates thermal management features unique to the requirements of an orbit of the planet Mercury.

Lateral displacement of the mode axis in a misaligned Porro prism resonator

The lateral shift of the mode axis in a misaligned Porro prism resonator is analyzed. A method to find the tilted mode axis in a misaligned Porro prism resonator is introduced. Expressions for the displacement of the mode axis are deduced. They predict that the lateral displacement of the mode axis is proportional to the horizontal misalignment angle beta and highly dependent of the prism azimuth angle theta. Experimental results obtained agree well with theory.

Method of calculating the alignment tolerance of a Porro prism resonator

A method of calculating the angular alignment tolerance of a Porro prism laser oscillator is presented. The reduction in mode volume due to misalignment is found by a ray optical approach. An analytical expression for alignment tolerance, in terms of resonator length L, prism azimuth angle theta, rod location L(2), and rod aperture radius alpha is obtained. An experiment was set up to measure the laser output reduction due to reflector tilting. Results obtained are in good agreement with the theoretical predictions.

Beam pointing direction changes in a misaligned Porro prism resonator

The relative change of the beam pointing direction for a misaligned Porro prism resonator is analyzed. A concept of the oscillation axis for the Porro prism resonator is introduced to find the beam direction. Expressions for the beam tilting angles are deduced. They predict that the angular misalignment in the horizontal direction will lead to beam tilting in both the horizontal and vertical directions. Experimental results obtained agree well with theory.

Theory of the rooftop resonator: resonant frequencies and eigenpolarizations

The eigenpolarizations and resonant frequencies are derived for a circular dielectric waveguide resonator (EH11 mode) terminated by perfectly reflecting metallic rooftop mirrors. It is demonstrated that, in the far-IR region, circularly polarized helical standing waves result from an arbitrary angular misalignment of the rooftop creases. Further, the right and left circularly polarized modes have different resonant frequencies.

Modes of a laser resonator with a retroreflecting corner cube mirror

The self-consistent integral equation for the field distribution of the resonant modes in a resonator with a tilted retroreflecting corner cube mirror is solved. The corner cube acts like a convex lens with radius of curvature -L cot(2)theta in the rotation direction (L is the cavity length and theta the rotation angle) and like a flat plane in the direction of the rotation axis. The field distribution can be described in terms of Hermite-Gaussian functions, and these results have been confirmed experimentally using an Ar-ion laser. The equivalent beam matrix for a reflecting corner cube is also found.