Source: https://guthlabs.ai/docs/instruments/critical-angle-total-internal-reflection-calculator/implementation/

instrument implementation / implementation-contract

# Critical Angle / Total Internal Reflection Calculator implementation

A source-bound implementation contract for Critical Angle / Total Internal Reflection Calculator; deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-clean

**Evidence ID**: t5-140

**Effect**: Computation or source lookup only

## Input and validation requirements

The specification does not define handling for n1 <= n2, out-of-domain asin arguments, or signed incidence angles. Invalid-index inputs can produce undefined results, and retaining a negative incidence sign changes the TIR branch unless an unsigned-from-normal convention is enforced.

## Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "inputs": {
    "n1": 1.5,
    "n2": 1,
    "incidence_angle_deg": 50
  },
  "expected_outputs": {
    "critical_angle_deg": 41.8103,
    "tir": true
  },
  "working": "n2/n1 = 1.0/1.5 = 0.6666667. θc = asin(0.6666667) = 41.8103°. Compare incidence angle: 50.0° > 41.8103°, so TIR = yes."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/critical-angle-total-internal-reflection-calculator/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/critical-angle-total-internal-reflection-calculator/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/critical-angle-total-internal-reflection-calculator/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche5/tranche5-results.json`