US 4,307,960 A · Spectrophotometer

Abstract

A dual-beam ratio recording spectrophotometer has signal processing circuitry for determining the transmittance of a substrate. The signal processing circuitry has a bandwidth which is dependent on the magnitude of the radiation passing through a reference cell and includes control logic circuitry which produces a pulse whose width is proportional to the square of the magnitude of the radiation detected when the beam passes through the reference cell. A sample and hold circuit whose sample time is controlled by this pulse samples the output of an integrator which produces at regular intervals a signal representative of the transmittance of a substance. Thus, the response time of the sample and hold circuit and hence the bandwidth of the signal processing circuitry depends on the magnitude of the radiation passing through the reference cell.

Claims7

Dependent claims

A dual beam ratio recording spectrophotometer comprising a radiation source, a radiation detector, a first path between said source and detector which includes a sample cell, a second path between said source and detector which includes a reference cell, means for alternately directing radiation through said first and second paths onto said detector, and a processing circuit for processing output signals from said detector, said processing circuit including means for producing a characteristic signal representative of a characteristic of a substance in said sample cell and for updating said characteristic signal at regular intervals, and means for measuring said characteristic signal, said measuring means including means for varying the bandwidth of said measuring means in proportion to the magnitude of radiation received by said detector from said second path.

Dependencies are inferred from the claim text.

Spectrophotometer

Life of this patent

Spectrophotometer

Life of this patent

Abstract

Claims7