CALCULATORS / OPTICS, IMAGING AND ILLUMINATION

Photometric conversion with spectral data calculator

Monochromatic radiometric-to-luminous conversion with supplied photopic weighting.

optics-photometry.napkin / editable

SCENARIO COMPARISON

Compare the numbers.

This source describes an analytical model. Its quantities and checks are the view.

Scenario	lumenslm
	546.4
	437.12

All calculated quantities are listed with the inputs. Switch to Source to inspect the equations.

SCENARIOS / CALCULATED VALUESSAME SOURCE

Change an input to see the consequences.

luminous flux target546.40 lm✓ passes

BASELINE INPUTS

radiantPower1 WphotopicWeight0.8 efficacy683 lm/W

CALCULATED

lumens546.4 lm

Edits change the baseline source.

THE SOURCE

Edits below update the same model.

# Photometric conversion with spectral data
# Scope: Monochromatic radiometric-to-luminous conversion with supplied photopic weighting.
# Status: illustrative worked example; engineering review pending.
# Inputs are example values. Checks are editable example requirements, not standards.

radiantPower = 1 W
photopicWeight = 0.8
efficacy = 683 lm/W

lumens := radiantPower*photopicWeight*efficacy [lm]

check luminous flux target: lumens >= 500 lm

scenario alternative: radiantPower = 0.8 W

Calculated from your source · not saved

Baseline · Baseline

luminous flux target546.40 lm ✓ passes

alternative · alternative

luminous flux target437.12 lm × fails

Illustrative first-order example. Checks are editable requirements, not design standards. The broader topic may require additional equations, data, and validation.

Formula and units

This example uses the following equations. Input names and units match the editable source above.

lumens: lumens = radiantPower*photopicWeight*efficacy [lm]

Original worked example

These are the baseline values in the downloadable source. Edits above let you test your own values.

Given

radiant power: 1 W
photopic weight: 0.8
efficacy: 683 lm/W

Calculated

lumens: 546.4 lm

Assumptions and limits

Monochromatic radiometric-to-luminous conversion with supplied photopic weighting.

The requirement checks use the limits written in this example. Passing a check does not establish that the model covers every load, material behavior, or operating condition in a real design.

Download this .napkin example ↓

Take it further with your agent

Napkin keeps the inputs, equations, checks and assumptions together in one study. Your agent sets it up; you change the numbers.

Try with Claude ↗

codex 'Use Napkin (https://napkin.engineering/mcp, or the local Napkin plugin) to build a study: Photometric conversion with spectral data. Inputs: spectrum; radiant quantities; photopic weighting. Outputs: luminous flux/intensity; stated spectral dependence. Model scope: Paraxial geometry or calibrated radiometric/photometric models. Read napkin_capabilities and the current snapshot. Ask me for the values that matter, label assumptions with units, author .napkin source, validate it and apply it with napkin_source using the current revision, then open the study. Add checks for the limits I supply. Keep unsupported analyses explicit.'

Claude needs the Napkin connector; Codex needs the Napkin plugin. Set up your agent ↗

The broader study

The topic brief below describes the broader scope. The worked example above states the particular calculation it implements.

Inputs: spectrum, radiant quantities, photopic weighting
Outputs: luminous flux/intensity, stated spectral dependence
Modes: calculate, compare, sweep
Drawing: Ray diagram and camera view

EXECUTABLE WORKED EXAMPLE · FIRST-ORDER MODEL · CHECK THE SCOPE & ASSUMPTIONS