What is the primary purpose of this standard?

To specify the design, material, and manufacturing requirements for graticules used in microscopes to measure the size of powder particles.

What types of graticules are covered?

The standard covers two types: eyepiece graticules (inserted into the microscope eyepiece) and projection screen graticules (for microscopes that project the image).

What material should the graticule be made of?

According to Clause 3, it should be made of good quality optical glass, which is clear, flat, and free from defects that could interfere with observation.

How is the graticule calibrated?

The graticule itself is not calibrated by this standard, but it must be used in conjunction with a stage micrometer to calibrate its scale for a specific microscope objective.

IS 5257

: 1969

eyepiece and screen graticules for determination of particle size of powders

CurrentSpecializedSpecificationMaterials Science · Sieves, Sieving and Other Sizing Methods

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This standard specifies the requirements for eyepiece and projection screen graticules used for the quantitative determination of the particle size of powders. It covers the material, types, patterns, line thickness, and marking of these graticules to ensure consistency and accuracy in microscopic analysis.

eyepiece and screen graticules for determination of particle size of powders

Quick Reference Values

Graticule materialOptical glass, clear and free from defects

Eyepiece graticule diameterTo suit the eyepiece of the microscope

Protective coatingShall be applied to the pattern if required

Pattern typeGrid of squares, or a combination of lines and circles

Practical Notes

This standard is for the tool, not the method. The actual method of using the graticule for particle size analysis is detailed in other standards like IS 11283.

Essential for quality control in industries where particle size is critical, such as pharmaceuticals, pigments, cement, and metallurgy.

Accurate measurement requires periodic calibration of the eyepiece graticule against a certified stage micrometer.