"Beam" - what is it, definition of the term
A long, slender structural member that spans between supports, designed to resist bending moments and shear forces generated by applied loads, thereby transferring those forces to columns, walls, or foundations.
Detailed information
The term refers to a linear transmission of energy, either electromagnetic or mechanical, that propagates without significant divergence over a defined distance. In optics it denotes a collimated light stream; in physics it can describe a directed flow of particles; in engineering it denotes a structural member designed to support loads.
Key physical parameters include length, cross‑sectional geometry, material composition, and the distribution of internal stresses. For a supporting element, the moment of inertia and section modulus determine resistance to bending, while for a light stream the wavelength, coherence, and beam waist define focusability and diffraction characteristics.
Categories:
- Optical stream – characterized by wavelength, polarization, and divergence angle.
- Particle stream – defined by particle type, energy, and flux density.
- Structural member – specified by material, profile (I‑section, rectangular, tubular), and load capacity.
In laboratory work with rodents, directed energy streams serve several purposes. Laser illumination enables precise tracking of movement and behavior, often integrated with high‑speed cameras for kinematic analysis. Particle streams, such as X‑ray or proton beams, are employed in imaging and therapeutic studies, requiring strict dose calibration to avoid tissue damage. Mechanical support elements are used in cage design to create reinforced pathways or tunnels that withstand animal interaction while maintaining structural integrity.
Design considerations for experiments include alignment accuracy, safety interlocks, and dose uniformity. Optical systems must incorporate beam expanders or spatial filters to achieve the desired spot size. Particle delivery devices require collimators and shielding to protect both subjects and operators. Structural components must meet regulatory standards for load bearing and material toxicity, ensuring longevity and animal welfare.