Non-imaging optical energy transfer system

For use with an infrared spectrometer of the type having an extended source of infrared energy, and an absorption cell with entrance and exit windows, said cell and said source forming distinct sections between which optical energy is to be transferred, each section including means for defining respective extended beam foci and associated pupils thereby establishing an f/# requirement within each section, the f/# requirements in said cell section differing from those in said source section, improved energy transfer apparatus comprising:

• a tapered light pipe positioned within the optical beam path between said source and said cell sections with its small end positioned at the extended beam focus in said source section, with its large end positioned at the extended beam focus in said cell;
• focusing means located between said large end and the pupil in said cell section;
• the pupil in said source section being established at the vertex of said tapered light pipe by the combination of said focusing means and said light pipe such that the concentration of energy on said source section pupil in conjugate with symmetrically positioned points on the pupil in said said cell section and the product of the area of the extended beam focus and the solid angle of the beam respectively at each end of said light pipe is equal whereby energy is transferred between both of said pupils substantially without vignetting loss.

In an internal reflection spectrometer of the type having in one section a multiple internal reflection crystal having respective light entrance and exit faces for making attenuated total reflection measurements after receiving optical energy from another section of the spectrometer at said light entrance face of said crystal, non-imaging energy transfer apparatus comprising:

• means within each of said sections for defining an extended beam focus and associated pupil thereby establishing an f/# requirement therein, one of said sections having a high f/# requirement and the other of said sections having a smaller f/# requirement;
• a tapered light pipe positioned within the optical beam path between said sections with its small end positioned at the extended beam focus in said other section, with its large end positioned at the extended beam focus in said one section;
• focusing means positioned intermediate said large and and said one section pupil;
• said other section pupil being established at the vertex of said tapered light pipe by the combination of said focusing means and said light pipe such that the concentration of energy on said other section pupil is conjugate with symmetrically positioned points on said one section pupil and the product of the area of the extended beam focus and the solid angle of the beam respectively at each end of said light pipe is equal whereby energy is transferred between both of said pupils substantially without vignetting loss.