Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Telescoping Spectrophotometer Dip Probe

IP.com Disclosure Number: IPCOM000085523D
Original Publication Date: 1976-Apr-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 3 page(s) / 44K

Publishing Venue

IBM

Related People

Levine, SL: AUTHOR [+2]

Abstract

Spectrophotometers are commonly used to measure the concentration of materials by application of the well-known principle of Beer's law. In accordance with such law, absorbance of a material is proportional to the absorptivity of the material, the concentration of the material and the length of the light path through the material.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 3

Telescoping Spectrophotometer Dip Probe

Spectrophotometers are commonly used to measure the concentration of materials by application of the well-known principle of Beer's law. In accordance with such law, absorbance of a material is proportional to the absorptivity of the material, the concentration of the material and the length of the light path through the material.

Many conventional spectrophotometers use a constant fixed path length for given analysis. The instrument is first calibrated and then used to measure the absorbance of a series of samples of known concentration to establish a calibration plot. The unknown sample is then measured and compared against the calibration plot to determine the concentration.

If a sample has an absorbance exceeding that of the highest concentration, the sample is diluted by some known proportion to reduce its absorbance. The results are then determined using this dilution factor. Concentration of a sample with too low an absorbance can also be done although somewhat more difficult.

Another means of compensating for high or low absorbance measurements would be to change the path length. This procedure is not normally followed in conventional instruments due to the need for recalibration. However, an automatic calibrating computer controlled spectrophotometer utilizing a dip probe can use such technique. The drawing schematically shows a spectrophotometric system and a cross section of a dip probe that can be used to vary the path length.

As shown, spectrophotometric system 1 is used to measure the concentration of a material 2 in the form of a liquid held in a suitable container. A dip probe 3 is connected to the system and includes a pair of fiber optic bundles 4 and 5. The upper portions are separated while the lower portions of the fiber optic bundles extend downwardly through a tube 10, the fibers being randomly oriented. Light emerging from the lower end of bundle 4 is directed to a mirror 6 spaced from the end of the bundles to establish the desired path length. Light reflected from the mirror 6 is collected by bundle 5.

Mirror 6 is connected by two arms 7 to the lower end of a tube 8. The upp...