Required Optical Density

Calculate required optical density from unprotected and permissible exposure values in matching units.

Description

Optical density is logarithmic attenuation of transmitted power.

Optical density is logarithmic attenuation of transmitted power. Required density compares exposure with a permissible value established outside this tool.^{[1, 2]}

Calculate required optical density from unprotected and permissible exposure values in matching units.

When to use Required Optical Density

Use this tool to calculate required optical density from unprotected and permissible exposure values in matching units.

Prepare the optical measurements, geometry, fitted coefficients or caller-selected thresholds requested. Confirm wavelength, radius/diameter, pulse-width, angle and unit conventions before running the calculation.

How to use Required Optical Density and understand its results

Prepare the optical measurements, geometry, fitted coefficients or caller-selected thresholds requested. Confirm wavelength, radius/diameter, pulse-width, angle and unit conventions before running the calculation.
Enter unprotectedExposure, permissibleExposure using the field table and calculation rules, then run the tool.
Read requiredOpticalDensity, attenuationFactor. The explanation below defines the units, signs, ordering and any flags or placeholder values.
If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.

Input field	Meaning	Value type; see rules below	Requirement
unprotectedExposure	Unprotected exposure	number; minimum: 0	Required
permissibleExposure	Permissible exposure	number; minimum: 0	Required

Enter nonnegative unprotected exposure and positive permissible exposure in matching units. Return factor and nonnegative OD; exposure at or below permissible yields OD zero.

factor=max(1,unprotected/permissible); OD=log10(factor)

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
requiredOpticalDensity	Required optical density	number; minimum: 0
attenuationFactor	Required attenuation factor	number; minimum: 1

json

{
  "input": {
    "unprotectedExposure": 1000,
    "permissibleExposure": 1
  },
  "output": {
    "requiredOpticalDensity": 3,
    "attenuationFactor": 1000
  }
}

Limitations and assumptions

The tool does not derive exposure limits, choose certified eyewear or verify wavelength coverage, pulse ratings and fit.

Numeric inputs must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.

Alternative or Complementary methods

Use Eyewear OD–Visibility Score: Score supplied laser-eyewear optical-density adequacy while retaining visible-light transmission. For a complementary task, use Laser Safety Audit: Compare required laser-safety controls with documented controls.

Further background: OSHA Technical Manual: Laser Hazards.

References

Required Optical Density — tool.io
OSHA Technical Manual: Laser Hazards — Occupational Safety and Health Administration

Similar or alternative tools

Eyewear OD–Visibility Score
Score supplied laser-eyewear optical-density adequacy while retaining visible-light transmission.
Laser Safety Audit
Compare required laser-safety controls with documented controls.