The Polariscope

For more than 60 years Tiedemann has been built a large number of suitable polariscopes for different applications and customer demands.

Diffuse Light Polariscope
One popular device is the Tiedemann diffuse light polariscope with compensation analyser. This polariscope can be conducted in the most qualitative and quantitative photoelastic studies. All filters are glued between glass plates to avoid scratches and newton rings and lead to the best optical quality and life time.

The device consists of several components:
– Light box with diffuse white and monochromatic light source
– Frame for different distances of the filters and load frames
– Polarizer/quarter wavelength combination
– Compensation analyser with two scaled and pivoted polarizing filter and quarter-wave plate for Senarmont and Tardy method for quantifying orders of main stress at each point in the model or tested sample

The Polariscopes are available in two diameters:
– Type A and AS: Field of view 340 mm in diameter
– Type B and BS: Field of view 460 mm in diameter

Portable Polariscopes

Portable polariscopes are diffuse light polariscopes for linear and circular semi quantitative photoelasticity. Because of its versatility, its ease of handling and reasonable price, it is very often used. All parts of the polariscope (lamps, diffuser, polarizers and cable) are in the housing virtually packable. The fold-down front lid serves as a base plate, into which the filter can be inserted, and the model is placed. All filters are glued between glass plates as well. Furthermore, the filters can also be used for other applications.

Tiedemann offers different portable polariscopes:

The Type C has white light only and two single polarization filters for linear polarisation. The field of view is 190 x 190 mm.

Type D is somewhat larger with a field of 215 x 215 mm. The light can be switched between white and sodium light. The filters for D and the following polariscopes are made for linear and circular photoelasticity. The filters of polariscope D can be fixed in a special attachment for overhead projectors.

The larger polariscopes are Type AQ with a field of view of 390 x 390 mm and Type BQ with 470 x 470 mm.

Lecture Polariscopes

Special polariscopes are need for lectures in bigger auditoriums. We offer two different options, the LED polariscope for beamer and another one for overhead projector.
 

LED Polariscope for Beamer

This polariscope is made by a flat light box for white light with filter for circular polarisation. Further a camera is mounted in der right position with the second circular polarization filter. The camera can be connected via USB to a computer. This polariscope may be placed vertical or horizontal and fits with all our demonstration models. The lecturer may explain the stress pattern in the models with a view on his monitor or by using our analysation glasses.
Of course all our polariscopes can adapted to a camera for beamer presentations.

Polariscope for Overhead Projector and Flat Models

A simple way to demonstrate stress conditions in models by photoelasticity offers the overhead projector attachment. Between two frames with streched polarization films simply placed on the overhead projector, flat loadings frames can be placed.

Specifications

Field of view
250 mm x 250 mm

Load frames
3 pieces

Models
srew wrench, L-frame with bearing circular disc, U-frame

Special Polariscopes

Besides the polariscope models shown above we offer special solutions for large industrial applications or museums. Polariscopes with nearly any size can be created. They are used e.g. for the investigation of safety glass in the automotive industry, stretched films in the plastic industry or for presentations on exhibitions or museums.The previously manufactured special polariscopes range from fields of view of 48 x 48 cm up to 191 x 126 cm. They can be standing or hanging. They consist of a light box with white lighting, a frosted glass and the circular polarization film. The analyser could be stretched in a frame the same size. Alternatively, instead of a large analyser a portable analyzer in the size of about 48 x 48 cm is an option as well as our analyser glasses.

These special polariscopes are available on request only.

Reflection Polariscope

Unlike the transmitted light polariscopes above the reflection polariscope works as an incident light polariscope, even over long distances. The model is irradiated with almost parallel light. On the back of the only a few millimeters thick model a matte silver paint is applied. The model can then be loaded in the loading frame or alternatively is glued on the body to be examined.

The polarized light passes through the model that is reflected on the back side and passes through the analyser to a camera that displays the result on a computer screen. The filter are stepper motor driven. Due to the double pass through the model the reflection polariscope is twice as sensitive as the transmitted light polariscope.

Load Frames and Models

For accompanying explanation of the method of photoelasticity, the demonstration of elementary and complex stress states and for practical experiments in engineering education different photoelasticity models have been developed. With the models tension rod, bending beams smooth or with different notches, frame corners, screw wrench, wall and disks etc. Tiedemann offers a comprehensive overview of experimental strength theory and for structural design. Beside the flat models (s. above) we offer a kit 16 models or 5 models, always including the fitting load frame.

Load Frame with Large Model Kit

The stresses in the components can be ideally demonstrated through this load frame placed in a polariscope. Tensile, compressive and bending forces can be applied.

With its models, it is often used in technical training for materials science and structural design. It is particularly impressive to demonstrate the influence of notches or holes on the stress distribution.

Tiedemann has compiled a set with 16 models, which provides a comprehensive overview of the basic strength and constructive design. All 16 models can be loaded in this frame, usually two loaded models can be viewed simultaneously. The load and fasteners are attached with locking pins and are easily replaceable.

The load frame and the models are clearly laid out in an aluminum case. We include a textbook, outlining all experiments described here.

Specifications

Load frame 
Mechanical framework for tensile, compressive and bending forces

Models   
1 wall model with cuts
1 flat wrench model
6 tension models (different widths, circular hole, with a notch, two notches, with rib)
7 beam of bending  models (with different heights, centric circular hole, with a notch, with two notches, with rib, model of armoured concrete with a limp and prestressed reinforcement)
The seven beam of bending models can be mounted as a cantilever as well
1 frame model for tensile and compressive force

Model material 
Polycarbonate

Packaging
all conveniently in aluminum laminated suitcase

Tension Frame with Five Models

Tiedemann also provides a framework for quantitative tensile load. The frame has a drawing spindle, an analogous ring dynamometer for force measurement and a holder for the tension models.

The set of five different models are included. The models can be easily fixed by plugging in the frame. The framework and the models are designed for the large polariscope.

Specifications

Load frame 
Mechanical load frame for tension forces

Tension measurement 
analog ring dynamometer 10 kN

Models 
5 models (without a notch, with a circular hole with two notches, with constriction, with constriction and notch)

© Tiedemann Instruments GmbH & Co. KG // Zur Maximilianshöhe 6 // 82467 Garmisch-Partenkirchen // Tel: 08821/3068 // Fax: 08821/3922