A gas cell for absorption spectroscopy, the gas cell comprising: a channel providing at least a passage from a first end to a second end, the channel comprising an inlet for receiving a gas sample from a gas source and an outlet for releasing the gas sample from the gas cell, the first end being substantially opposite from the second end; a first end component mounted to the channel at the first end, the first end component comprising a first extending member having a first member end mounted to the first end of the channel and a second member end extending inwardly within the channel; a first optically transparent portion coupled to the first end so as to be positioned inwardly within the channel and positioned to receive an incident beam from a light source into the channel, the first optically transparent portion being mounted at the second member end of the first extending member; a second end component mounted to the channel at the second end, the second end component comprising a second extending member having a first member end mounted to the second end of the channel and a second member end extending inwardly within the channel; and a second optically transparent portion coupled to the second end so as to be positioned inwardly within the channel, the second optically transparent portion being positioned to permit optical transmission into and out of the channel, the second optically transparent portion being mounted to the second member end of the second extending member; characterized in that at least one of the first optically transparent portion and the second optically transparent portion comprises two optical layers, and a first optical layer (462, 466) of the two optical layers is positioned relative to a second optical layer (464, 468) of the two optical layers at an optical layer tilt angle (494f, 494s). a channel providing at least a passage from a first end to a second end, the channel comprising an inlet for receiving a gas sample from a gas source and an outlet for releasing the gas sample from the gas cell, the first end being substantially opposite from the second end; a first end component mounted to the channel at the first end, the first end component comprising a first extending member having a first member end mounted to the first end of the channel and a second member end extending inwardly within the channel; a first optically transparent portion coupled to the first end so as to be positioned inwardly within the channel and positioned to receive an incident beam from a light source into the channel, the first optically transparent portion being mounted at the second member end of the first extending member; a second end component mounted to the channel at the second end, the second end component comprising a second extending member having a first member end mounted to the second end of the channel and a second member end extending inwardly within the channel; and a second optically transparent portion coupled to the second end so as to be positioned inwardly within the channel, the second optically transparent portion being positioned to permit optical transmission into and out of the channel, the second optically transparent portion being mounted to the second member end of the second extending member; characterized in that at least one of the first optically transparent portion and the second optically transparent portion comprises two optical layers, and a first optical layer (462, 466) of the two optical layers is positioned relative to a second optical layer (464, 468) of the two optical layers at an optical layer tilt angle (494f, 494s).