SU559127A1 - Dual beam photometer - Google Patents

Description

one

The invention relates to the field of optical measurements, and more specifically for measuring the transmittance of various objects by means of two ray photometers.

Two-beam photometers are known for measuring the transmittance of various objects containing a light source, a light beam divider, reflecting mirrors, a photodetector, a photometric device or a recording device.

A disadvantage of the known device is low accuracy.

A two-beam photometer is known, which contains a source of polarized light, a light beam divider, a reflector, an optical aperture wedge, a lens, a photodetector, a zero indicator.

A disadvantage of the known photometer is its complexity and the low accuracy of measuring small transmittances.

The aim of the invention is to simplify the design and improve the accuracy of the two-beam photometer.

This is achieved by the fact that the divider of the beam of a beam is made in the form of a parallel-sided plate and forms a dihedral angle with the reflector, the edge of which with & falls to the axis of rotation of the base on which the divider is rigidly mounted on the body, and one of them is rigidly connected to the reflector .

The drawing shows a diagram / two-beam photometer.

The photometer consists of a source of polarization radiation, for example, an optical quantum generator 1, placed successively along the beam of a polarizer 2 of a plane-parallel plate 3 with a reflector 4 mounted on a base 5, the reflector installed in the path of the beam reflected from the plate, diaphragm 6, a measuring device 7, consisting of a collecting bright lens 8, a photodetector 9, a mechanical chopper 1O installed in front of the photoreceiver, and a zero indicator 11. Measurement sample 12 is placed after the phoscope llelnoy plate 3 coaxially with the beam gfoshedshim lposkopa shlelnuyu plate. One of the diaphragms is rigidly connected to the plane-parallel plate 3. The photometer works as follows; The radiation from source 1 after passing through polarizer 2 is incident on a plane-parallel plate 3, which serves as a calibrated beam splitter. The passing beam, the measured sample, passes through the lens to the photodetector. The part of the beam that is reflected on the flat-plate is incident on the reflector 4. The plate and the reflector are rigidly fixed on the base 5. The transmitted beam is the measuring beam and the reflected beam is the reference one. The reference and measuring beams passing through the diaphragm 6 fall onto the measuring device 7. The measuring sample is placed in the path of the measuring beam. Base 5 is made with the possibility of a turning point in the plane of incidence of the reference and measuring rays. When the base 5 is rotated, the angle of incidence of the rays on the plane-parallel layer and the reflector changes, which, in accordance with Formula 4, Enkel changes the intensities of the transmitted and reflected rays. The measurement of the transmittance on the photometer is as follows. In the measuring beam, a measurable sample 12 is installed and, by rotating the base 5, which is equipped with an angle reading mechanism, the equal intensities of the two beams are achieved. The following is done.

 ,./-"P..

denied

where 3 is the intensity of the incident light, the intensity coefficients of reflection from the plates and the reflector, respectively.

From formula I, the coefficient is determined

otpropuskan pl.

t

Ii.)

When measuring low transmittances, it is more advantageous to use a dielectric reflector, for example, of crystalline quartz. Then the transmittance, in accordance with formula II, is only slightly dependent on the angle of rotation of the base 5, while the requirements on the accuracy of base rotation and the divergence decrease.

Claims (1)

Invention Formula 40 Dual-beam photometer containing the source. nickname of polarized light, light beam divider, reflector, optical diaphragm wedge, lens, photodetector, zero indicator, characterized in that, in order to simplify its design and improve accuracy, the light beam divider is made in the form of a plane-parallel plate and forms a dihedral angle with the reflector whose edge coincides with the axis of rotation of the base on which the divider and the reflector are rigidly mounted, one of the diaphragms being rigidly connected to the reflector. light source output. In addition, to obtain large attenuations of the reference beam when measuring low transmittances, the plane of polarization of the output beam of the light source should lie in the plane of incidence, and the angle of incidence of light on a plane-parallel plate or dielectric reflector should be close to the Brewster angle. a plane-parallel plate, a diaphragm is installed, and for better separation of the measuring beam from the side ones caused by multiple reflections in the plate, the diaphragm The hmu in this beam is more convenient to associate with the rim of the plate. The calibration curve of the photometer (dependence, transmittance on the angle of base rotation) can be controlled within wide limits, the angle between the beam-splitting plane-parallel plazgane and the reflector changes. An enlightened focusing lens is used as a device for converting the reference and measurement rays. In this case, insignificant displacements of the measuring beam will not lead to its displacements along the surface of the photodetector, since it is placed in the focus of the lens. When the divider and the reflector are set at an angle to each other, the axis of rotation is aligned with the edge of the dihedral angle formed by the surfaces of the plate and the reflector. In this case, when turning the base, the reference beam will be fixed.