Patent ID: 6967722

Claim:
A spectrometer comprising: a source of a primary beam of radiant energy, a beamsplitter for dividing the primary beam into at least a first beam and a second beam, wherein the first beam traverses a first optical path, and the second beam traverses a second optical path, at least a first reflector having a first orientation and positioned to receive the first beam along the first optical path and to reflect a first returning beam along the first optical path back through the beamsplitter where the first returning beam traverses a recombined beam optical path, a second reflector having a second orientation opposite the first orientation of the first reflector, a roof reflector, wherein the second beam following the second optical path is reflected and inverted by the roof reflector and directed along the second optical path to the second reflector, and wherein the second reflector receives and reflects a second returning beam back along the second optical path to the roof reflector, and wherein the roof reflector reflects and inverts the second returning beam along the second optical path back to the beamsplitter, and wherein the second returning beam is reflected by the beamsplitter and traverses the recombined optical beam path, a detector to receive the first and second returning beams from the recombined beam optical path.