Yes, the wavelength of a helium-neon (HeNe) laser can change over time due to heating during continuous usage. Temperature can indeed affect the wavelength of a laser.
In a typical HeNe laser, a mixture of helium and neon gases is excited by an electrical discharge, which causes the emission of laser light. The laser cavity, where the light is amplified, consists of mirrors at either end. The mirrors determine the length of the cavity, which in turn affects the wavelength of the emitted laser light.
When a HeNe laser operates continuously, it generates heat. The heat can cause expansion or contraction of the laser cavity, which affects the distance between the mirrors and therefore alters the resonance conditions for the laser light. These changes can lead to shifts in the output wavelength of the laser.
In addition to thermal effects, other factors such as the gas pressure and gas composition can also influence the wavelength stability of a HeNe laser. Manufacturers often take measures to minimize these effects, such as incorporating temperature stabilization mechanisms or using specific gas mixtures that are less prone to wavelength shifts.
However, despite these efforts, it is still possible for the wavelength of a HeNe laser to undergo slight variations over time due to heating or other factors. To maintain precise wavelength stability, calibration and periodic adjustments may be required to compensate for any shifts that occur during continuous usage.