Industrial-Grade Environmental Adaptability
A module that ranges perfectly on a bench and fails after two weeks in the field has an environmental problem, not an optical one. This page sets out the environmental specifications that matter, what the numbers mean in practice, and how to read a qualification claim.
Vibration
ERDI laser modules are specified to withstand the environmental conditions equivalent to flight vibration and vehicle transportation:
| Parameter | Specification |
|---|---|
| Frequency band 1 | 15–33 Hz at 0.91 mm constant displacement |
| Frequency band 2 | 33–700 Hz at 2 g constant acceleration |
| Sweep direction | Three orthogonal directions |
| Duration | 1 hour per axis |
| Post-test requirement | Product must operate normally |
The two-band profile is standard practice: constant displacement at low frequency (where displacement is the damaging parameter) and constant acceleration at high frequency (where acceleration is). One hour per axis on three axes is a meaningful qualification, not a token shake.
The post-test requirement is the important part. "Survives" is not enough; the module must still operate and still hold boresight.
Shock
| Parameter | Specification |
|---|---|
| Peak acceleration | 10 g |
| Waveform | Post-peak sawtooth |
| Duration | 11 ms |
| Axes | Vertical, lateral, longitudinal, both directions |
| Total shocks | 18 |
| Post-test requirement | Product must operate normally |
Ten g is a modest shock by munition standards but typical of transport, handling and vehicle mounting. What matters is not the peak alone but the sawtooth waveform, which delivers a defined energy spectrum rather than a simple step.
Temperature
Operating and storage temperature ranges are specified per model. The critical question is not survival at the extremes — electronics generally survive — but boresight stability across the range.
A module that operates from cold soak to hot soak but walks 0.4 mrad in between is unusable at long range: 0.4 mrad at 10 km is a 4 m offset, larger than the target.
Ask for boresight drift over temperature as an explicit specification, not as an inference from "operates over the range".
Moisture and contamination
Electronics are conformally coated to protect against moisture and contamination. This matters more than it sounds:
- Condensation forms when a cold module is brought into a warm humid environment — common after a cold-soak flight or a night in the field.
- Salt fog attacks coatings and connectors in coastal and maritime deployment.
- Dust and mud accumulate on the aperture window and are cleaned, often abrasively.
The module is sealed; the aperture window is the exposed surface and needs a coating that tolerates cleaning.
How to read a qualification claim
Three phrases look similar and mean very different things:
| Claim | What it means |
|---|---|
| "Designed to MIL-STD-810" | Design intent only. No test evidence. |
| "Tested per MIL-STD-810 method X" | A test was run to that method. Ask for the report and the pass criteria. |
| "Qualified to [profile], post-test functional" | Specific profile, specific pass criteria, evidence available. This is what you want. |
Always ask which of the three you are being offered. The first is marketing, the third is an engineering commitment.
Module qualification is not assembly qualification
This is the most common misunderstanding in integration.
A module qualified to its own datasheet has been tested as a module. Once you bolt it to a bracket, add a harness and fit a window, you have a new assembly with new resonances, new thermal paths and new failure modes.
The installed assembly must be qualified separately. Budget for it.
Environment-specific considerations
| Environment | Dominant risk | Mitigation |
|---|---|---|
| Airborne (UAV, helicopter) | Vibration + rapid thermal cycling | Module qualification + boresight spec over temperature |
| Vehicle | Low-frequency shock, dust, EMI | Isolated mount, window purge, shielded harness |
| Maritime | Salt fog, humidity, condensation | Hardened coating, window heating, sealed connectors |
| Industrial fixed site | Continuous vibration, temperature soak | Conduction cooling, thermal design margin |
| Man-portable | Drop, handling, temperature extremes | Ruggedised housing, wide storage range |
Frequently asked questions
What vibration specification do ERDI modules meet?
15–33 Hz at 0.91 mm constant displacement and 33–700 Hz at 2 g constant acceleration, one hour per axis in three orthogonal directions, with normal operation required after the test.
What shock specification?
10 g peak, post-peak sawtooth waveform, 11 ms duration, 18 shocks total across three axes in both directions, with normal operation after the test.
Is conformal coating applied?
Yes — electronics are conformally coated to protect against moisture and contamination.
Does the module survive cold soak?
Operating and storage ranges are specified per model. More important is boresight behaviour at the extremes; ask for that explicitly.
Is the installed assembly covered by the module qualification?
No. The bracket, harness and window form a new assembly with its own resonances and thermal paths, and must be qualified by the integrator.
Related: EO system integration, OEM/ODM custom development, laser modules for EO pods, maritime applications.