U.S. Patent No. 7,876,443 and references therein discloses a method of creating a multipass cell having a toroidal configuration in which light is injected into the cavity via a hole or penetration into the wall of the reflective toroidal surface. Subsequent to this, a similar cavity is described in the scientific literature that provides additional design guidance for constructing a typical cell.[i],[ii] Both of the referenced papers also describe an absorbing mask that is placed against the cell wall to suppress unwanted reflections which the authors state contribute to coherent noise, often referred to as 'fringing" as the main laser beam interferes with stray reflections that can occur if the launch angle into the cell does not adhere to the value determined by the design equations. These interference patterns contribute noise to the desired signal and degrade the instrument's sensitivity. We disclose an alternate method of injecting light into a toroidal multipass cell using a small mirror (either plane or with optical power) affixed to the wall of the cell in place of a hole or penetration. This approach simplifies construction and offers a path to reduced construction costs and potential replication methods such as casting, injection molding, 3D printing, electroforming or metal spinning. [i] B. Tuzson, M. Mangold, H. Looser, A. Manninen, and L. Emmenegger, 'Compact multipass optical cell for laser spectroscopy", Opt. Lett., Vol 38 (3), 257-259 (2013) [ii] M. Mangold, B. Tuzson, M. Hundt, J. Jagerska, H. Looser, and L. Emmenegger, 'Circular paraboloid reflection cell for laser spectroscopic gas analysis", JOSA A, Vol. 33 (5), 913-919 (2016). U.S. Patent No. 7,876,443 and references therein discloses a method of creating a multipass cell having a toroidal configuration in which light is injected into the cavity via a hole or penetration into the wall of the reflective toroidal surface. Subsequent to this, a similar cavity is described in the scientific literature that provides additional design guidance for constructing a typical cell.[i],[ii] Both of the referenced papers also describe an absorbing mask that is placed against the cell wall to suppress unwanted reflections which the authors state contribute to coherent noise, often referred to as 'fringing" as the main laser beam interferes with stray reflections that can occur if the launch angle into the cell does not adhere to the value determined by the design equations. These interference patterns contribute noise to the desired signal and degrade the instrument's sensitivity. We disclose an alternate method of injecting light into a toroidal multipass cell using a small mirror (either plane or with optical power) affixed to the wall of the cell in place of a hole or penetration. This approach simplifies construction and offers a path to reduced construction costs and potential replication methods such as casting, injection molding, 3D printing, electroforming or metal spinning. [i] B. Tuzson, M. Mangold, H. Looser, A. Manninen, and L. Emmenegger, 'Compact multipass optical cell for laser spectroscopy", Opt. Lett., Vol 38 (3), 257-259 (2013) [ii] M. Mangold, B. Tuzson, M. Hundt, J. Jagerska, H. Looser, and L. Emmenegger, 'Circular paraboloid reflection cell for laser spectroscopic gas analysis", JOSA A, Vol. 33 (5), 913-919 (2016).