Apparatus

Claim 2

In a device for measuring the intensity of minute magnetic fields with an optical magnetometer having a source for the emission of resonance radiation, a radiation cell means having radiation emitted from said source directed therethrough to produce alignment of atoms in said cell, means to produce an alternating magnetic field in said cell of a frequency which diminishes the alignment of said atoms, and detector means for producing an output proportional to the intensity of impinging radiation from said source which passes through said cell, the improvement wherein said detector means comprises a paraboloidal mirror and a detector element sensitive to the radiation, said detector element being arranged within said mirror in a plane parallel to and in front of the latus rectum of the mirror, the open end of said mirror facing said cell means and having a diameter sufficient to receive the full beam of radiation passing through said cell whereby the radiation is collected by said mirror and directed toward said detector element, said detector element having a radiation sensitive area at least equal to the area of the cross-section of said mirror in said plane.

Claim 3

A device according to claim 1 including filter means intermediate said absorption cell means and detector means and forming a unit with said mirror.

Claim 4

The device of claim 1 wherein the reflective surface of the mirror is formed by rotating a simple parabola about an axis parallel to but not coincident with its principal axis.

Claim 5

The device of claim 1 wherein the open end of the parabaloid of the mirror has a diameter essentially equal to that of the cell means.

Claim 6

The device of claim 1 wherein said detector element is mounted at an aperture formed by a transverse cut in said mirror and having a size substantially equal to the cross sectional size of the detector element.

Claim 7

The device of claim 5 wherein the mirror includes cap means, the detector element being mounted in said cap means and arranged at said aperature.

Claim 8

The device of claim 6 wherein the mirror and cap means are of a material having a high thermal conductivity.

Claim 9

The device of claim 7 wherein the material is aluminum.

Claim 10

The device of claim 5 wherein the reflective surface of the mirror is formed by rotating a simple parabola about an axis parallel to but not coincident with its principal axis.

Claim 11

In a device for measuring the strength of a magnetic field comprising a contained body of helium gas the atoms of which are acted upon by said magnetic field when in the presence thereof; means to excite the body of helium gas for continuously producing metastable helium atoms; a source of resonance radiation impingeable upon and interacting with the body of helium gas for producing alignment of said metastable helium atoms contained therein; means to create and direct into the body of helium gas an alternating magnetic field of such frequency as to diminish the alignment of metastable helium atoms contained in the body of helium gas; and means to measure the changes in the amount of resonance radiation absorbed by said metastable helium atoms including means for detecting said radiation after passage through said gas, the improvement wherein said detecting means comprises a paraboloidal mirror and a lead sulfide infrared detector element sensitive to the 1.08 micron resonance line of helium, said detector element being arranged within said mirror in a plane parallel to and in front of the latus rectum of the mirror, the open end of said mirror facing said contained body and having a diameter sufficient to receive the full beam of radiation passing through said body whereby the radiation is collected by said mirror and directed toward said detector element, said detector element having a radiation sensitive area at least equal to the area of the cross-section of said mirror in said plane.

Claim 12

In a device for measuring the strength of a magnetic field comprising a contained body of helium gas the atoms of which are acted upon by said magnetic field when in the presence thereof; means to excite the body of helium gas for continuously producing metastable helium atoms; a source of resonance radiation impingeable upon and interacting with the body of helium gas for producing alignment of said metastable helium atoms contained therein; means to create and direct into the body of helium gas an alternating magnetic field of such frequency as to diminish the alignment of metastable helium atoms contained in the body of helium gas; and means to measure the changes in the amount of resonance radiation absorbed by said metastable helium atoms including means for detecting said radiation after passage through said gas, the improvement wherein said detecting means comprises a paraboloidal mirror and a lead sulfide infrared detector element sensitive to the 1.08 micron resonance line of helium, said detector element being arranged within said mirror in a plane parallel to and in front of the latus rectum of the mirror, the open end of said mirror facing said contained body and having a diameter sufficient to receive the full beam of radiation passing through said body whereby the radiation is collected by said mirror and directed toward said detector element, said detector element having a radiation sensitive area at least equal to the area of the cross-section of said mirror in said plane.

Claim 13

The improvement of claim 10 wherein the mirror is polished aluminum.

Claim 14

The device of claim 10 wherein the reflective surface of the mirror is formed by rotating a simple parabola about an axis parallel to but not coincident with its principal axis.