Spectral analysis apparatus and method

In a method of determining the spectral absorbance of a sample, the steps of:

• passing light through the sample;
• varying the length of the path of the light passing through the sample to control the amount of light absorbed by the sample;
• determining the absorbance of the sample from the length of the path and the amount of light passing through the sample;
• and
• performing the foregoing steps utilizing an apparatus having an outer tube including a valve and at least two seals for engaging an inner spectrophotometry assembly, and further including the steps of sealing the inner assembly within said outer tube, actuating said value, and then shifting the position of said spectrophotometry assembly within said outer tube, whereby said spectrophotometry assembly may be mounted to take samples or removed without significant loss or escape of the fluid being measured.

In an apparatus for determining the spectral absorbance of a sample:

• a light source;
• single strand optical waveguide means for directing light from said light source through the sample;
• light intensity measuring means;
• optical waveguide means for coupling light which has passed through said sample to said light intensity measuring means;
• means for varying the length of the path of the light passing through the sample to control the amount of light absorbed by the sample without changing the length of the optical path from said light source to said sample and from said sample to said measuring means;
• means for determining the length of the path and the corresponding intensity as measured by said measuring means, whereby the sample absorbance may be calculated;
• said means for passing light through the sample and coupling light to said measuring means including a pair of optical waveguides having end portions separated by a gap and aligned for transmitting and receiving light through the sample, and the means for varying the length of the path including means for moving one of the waveguides to adjust the width of the gap;
• and
• said apparatus including means defining a chamber for the sample, a pair of probes connected to the waveguides and positioned in axial alignment within the chamber on opposite sides thereof, fluid inlet and outlet means for delivering the sample to and from the chamber, and means for moving one of the probes to vary the spacing between the probes.