Abstract An optoacoustic analyzer which allows the light from a laser resonator to enter a differential cell assembly can not provide accurate measurement of a specific component of ultralow concentration because the laser light, as it passes through the sample chamber and reference chamber, is absorbed to cause significant attenuation and the adverse effect of a low concentration of an inhibitory component in the fluid sample can not be effectively eliminated. Further, this type of anaylzer receives the laser light at the detector after it has passed through mirrors, and therefore, only few percents of the light within the resonator reaches the detector, thus providing only low sensitivity. To solve these problems, the differential cell type, light transmitting, optoacoustic analyzer of this invention has the sample chamber and reference chamber disposed on the beam path between the resonating mirrors in the gas laser resonator.
An optoacoustic analyzer comprising a gas laser resonator defined by two resonator mirrors, a gas laser discharge tube including spaced windows located within said resonator, an optoacoustic detector including a sample chamber and a reference chamber which are disposed in the path of laser light between the resonator mirrors, the laser discharge tube being arranged between the sample chamber and the reference chamber, each of the chambers being defined on one side by one of the resonating mirrors and on the other side by one of the windows of the discharge tube, the sample and reference chambers cooperating to form a differential cell and to provide a detector output signal which represents the pressure difference between the sample and the reference chamber due to the different absorption of the laser light in the chambers, a discharge interrupter associated with the gas laser discharge tube to provide an interrupter output signal which is passed to a lock-in amplifier to rectify the detector output signal in synchronization with the interrupter output signal.
Claim 2
Dependent Claim
170 words
An optoacoustic analyzer comprising a gas laser resonator defined by two resonator mirrors, a gas laser discharge tube including spaced windows located within said resonator, an optoacoustic detector including a sample chamber and a reference chamber which are disposed in the path of laser light between the resonator mirrors, the laser discharge tube being arranged between the sample chamber and the reference chamber, each of the chambers being defined on one side by one of the resonating mirrors and on the other side by one of the windows of the discharge tube, the sample and reference chambers cooperating to form a differential cell and to provide a detector output signal which represents the pressure difference between the sample and the reference chamber due to the different absorption of the laser light in the chambers, a discharge interrupter associated with the gas laser discharge tube to provide an interrupter output signal which is passed to a lock-in amplifier to rectify the detector output signal in synchronization with the interrupter output signal.
Claim 3
Dependent Claim
31 words
An optoacoustic analyzer according to claim 1 wherein each of said sample chamber and reference chamber of said detector is provided with a fluid introducing passageway and a fluid discharging passageway.
Claim 4
Dependent Claim
19 words
An optoacoustic analyzer according to claim 2 wherein a gas is sealed in said sample chamber and/or reference chamber.
Claim 5
Dependent Claim
19 words
An optoacoustic analyzer according to claim 2 wherein a solid or liquid sample is placed in said sample chamber.