Patent ID: 8873140

Claim:
An ATR (attenuated total reflection) objective for examination of a sample in an IR (infrared) microscope, the objective comprising: a frame structure; a Cassegrain objective cooperating with said frame structure, said Cassegrain objective focussing IR radiation onto the sample at a sample position, said Cassegrain objective comprising a first mirror having a first central bore and a second mirror having a second central bore; an ATR crystal; a holding bar guided through said first and said second central bores, said holding bar having an end facing the sample to which said ATR crystal is mounted; a holding element disposed proximate to or beyond a side of said Cassegrain objective facing away from the sample; thin struts, which rigidly connect said holding bar to said holding element and intersect an optical path of said ATR objective entering or exiting said Cassegrain objective, wherein said thin struts shade less than 10% of a beam cross-section of said optical path; and a motor drive for axial movement of said holding element relative to the sample position.