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IS 5257:1969 is the Indian Standard (BIS) for eyepiece and screen graticules for determination of particle size of powders. 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
Overview
Status
Current
Usage level
Specialized
Domain
Materials Science — Sieves, Sieving and Other Sizing Methods
! 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.
Covers the modern, digital equivalent method for particle sizing but focuses on automated image analysis rather than manual graticules.
BS 3406-4:1963BSI (British Standards Institution), UK
HighWithdrawn
Methods for the determination of particle size of powders - Part 4: Optical microscope methods
Defines the method that uses the graticules specified in BS 3625, making it the procedural counterpart to IS 5257.
ASTM E1951-17ASTM International, USA
MediumCurrent
Standard Guide for Calibrating Reticles and Light Microscope Magnifications
Focuses specifically on the calibration process for microscope reticles (graticules), a key procedural element of IS 5257.
Key Differences
≠IS 5257 specifies physical glass graticules for manual, visual comparison, whereas modern standards like ISO 13322-1 are based on digital image capture and software-based analysis.
≠The Indian standard is a specification for the apparatus (the graticule itself), while ISO 13322-1 is a comprehensive standard for the entire analytical method, including sampling, dispersion, and data analysis.
≠Modern digital methods (ISO 13322-1) automatically calculate a wide array of size and shape descriptors (e.g., equivalent circular diameter, Feret diameters, circularity, convexity) which are difficult or impossible to measure manually with an IS 5257 graticule.
≠IS 5257 provides two distinct graticule designs (one for eyepiece, one for projection screen), while modern digital methods use virtual overlays or algorithms, making the distinction irrelevant.
Key Similarities
≈Both IS 5257 and its modern counterparts like ISO 13322-1 are based on the same fundamental principle of static image analysis, where a 2D projection of a particle is measured.
≈The use of a stage micrometer for calibrating the scale of the graticule (or the pixel size in a digital image) is a mandatory and critical step in both the old and new standards to ensure accuracy.
≈Both standards are intended for the same core application: determining the size and size distribution of powders and other fine particulate matter through optical microscopy.
≈The geometric progression of reference circles (√2 in diameter) in IS 5257 serves the same purpose as logarithmic or geometric binning of results in modern software, allowing for efficient analysis over a wide size range.
Parameter Comparison
Parameter
IS Value
International
Source
Primary Sizing Tool
Physical glass graticule with engraved patterns (eyepiece and screen types).
Digital image analysis software applying virtual measurements to a captured image.
ISO 13322-1:2014
Geometry of Reference Circles (Eyepiece)
Series of 9 circles with diameters in a √2 progression.
Series of 10 circles with diameters in a √2 progression (Patterson-Cawood graticule).
BS 3625:1963
Primary Calibration Standard
Stage micrometer.
Certified stage micrometer or other traceable length standards.
ISO 13322-1:2014
Line Thickness (Eyepiece Graticule)
Preferably not exceeding 0.01 mm.
Not applicable; virtual lines are typically 1 pixel. Focus is on image resolution.
ISO 13322-1:2014
Record of Measurement
Manual tallying of particles into size classes based on visual comparison.
Automatic generation of a data file containing measurements for every individual particle detected.
ISO 13322-1:2014
Methodology
Specification for an apparatus, implying a manual method.
Specification for a complete test method, including sample prep, analysis, and reporting.
BS 3406-4:1963
⚠ Verify details from original standards before use
Key Values4
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
Tables & Referenced Sections
Key Tables
No tables data
Key Clauses
Clause 3 - Material
Clause 4 - Types of Graticules
Clause 5 - Pattern
Clause 6 - Lines
Clause 7 - Marking
Frequently Asked Questions4
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.