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Teledyne Flir Software Engineer Interview Guide

Teledyne Flir Software Engineer interview guide: reported rounds, questions and how candidates describe the process.

The 60-second brief

A Software Engineer at Teledyne Flir plays a critical role in bridging the gap between cutting-edge hardware sensors and powerful, real-world software applications. Teledyne Flir is a global leader in the design and production of thermal imaging cameras, components, and imaging sensors. In this role, you will write the software, firmware, and SDKs that enable defense forces, industrial inspectors, research scientists, and first responders to see the invisible and make split-second, life-saving decisions. The impact of your work as a Software Engineer is highly visible, directly influencing how raw sensor data is processed, visualized, and integrated into complex ecosystems. You will work on sophisticated systems where performance, latency, and reliability are paramount.

This guide is scoped to a Software Engineer candidate at Teledyne Flir.

Focus areas

  • Technical Communication (Presentations)
  • Quality & Test Mindset
  • Software Engineering Problem Solving

The Teledyne Flir interview process

Teledyne Flir candidates report 3 rounds over 3-5 weeks. The stages below are what candidates describe, not a published process.

Phone Screen

Initial call to discuss background, career goals, and alignment with the role.

What to demonstrate

  • Initial call to discuss background, career goals, and alignment with the role
  • Depth in Technical Communication (Presentations)

How to prepare

  • Be able to walk your CV end to end in two minutes, and say why this company specifically.
  • Have your salary expectations, notice period and location constraints ready, and ask for the rest of the loop in writing.

Technical Rounds

One or two technical interviews via video call focusing on coding proficiency and system design.

What to demonstrate

  • One or two technical interviews via video call focusing on coding proficiency and system design
  • Depth in Technical Communication (Presentations)

How to prepare

  • Answer aloud and timed: Describe the process of debugging a memory leak or a segmentation fault in a C++ environment.
  • Answer aloud and timed: What are volatile variables in C, and why are they critical when writing code that interfaces with hardware registers?

Onsite Interview

Final stage involving a 30-minute technical presentation to an engineering panel, followed by Q&A and interviews.

What to demonstrate

  • Final stage involving a 30-minute technical presentation to an engineering panel, followed by Q&A and interviews
  • Depth in Technical Communication (Presentations)

How to prepare

  • Answer aloud and timed: How would you optimize a latency-critical image processing algorithm to run on a resource-constrained microcontroller?
  • Answer aloud and timed: How would you design a robust software development kit (SDK) that allows third-party developers to control a thermal camera's settings and stream video?

Where candidates lose points

Showcase your hardware curiosity

Even if you are applying for a pure software role, demonstrating an interest in physics, optics, or electronics will resonate strongly with the hiring team.

Be ready to explain your design decisions

During the presentation and panel interviews, always justify why you chose a specific technology, language, or architectural pattern over alternatives.

Highlight debugging and troubleshooting skills

A huge part of working with hardware is finding out why things don't work. Share concrete examples of how you isolated and resolved complex, intermittent bugs in the past.

Questions & practice

Explain the difference between stack and heap memory allocation, and when you would use each in an embedded sy

Medium · Technical & Low-Level Programming

Explain the difference between stack and heap memory allocation, and when you would use each in an embedded system.

Approach

  1. Say what the runtime actually does before reasoning about the code.
  2. Name what is shared across threads and what owns each piece of state.
  3. Identify the window where an invariant is briefly untrue.
  4. Distinguish a value from a reference to it, and say which one you handed out.

Follow-up

  • What happens if two callers reach this at the same time?
  • Where could this allocate more than you expect?

How do you handle concurrency and prevent race conditions in a multi-threaded application?

Medium · Technical & Low-Level Programming

Approach

  1. Say what the runtime actually does before reasoning about the code.
  2. Name what is shared across threads and what owns each piece of state.
  3. Identify the window where an invariant is briefly untrue.
  4. Distinguish a value from a reference to it, and say which one you handed out.

Follow-up

  • What happens if two callers reach this at the same time?
  • Where could this allocate more than you expect?

What are volatile variables in C, and why are they critical when writing code that interfaces with hardware re

Medium · Technical & Low-Level Programming

What are volatile variables in C, and why are they critical when writing code that interfaces with hardware registers?

Approach

  1. Say what the runtime actually does before reasoning about the code.
  2. Name what is shared across threads and what owns each piece of state.
  3. Identify the window where an invariant is briefly untrue.
  4. Distinguish a value from a reference to it, and say which one you handed out.

Follow-up

  • What happens if two callers reach this at the same time?
  • Where could this allocate more than you expect?

How would you optimize a latency-critical image processing algorithm to run on a resource-constrained microcon

Medium · Technical & Low-Level Programming

How would you optimize a latency-critical image processing algorithm to run on a resource-constrained microcontroller?

Approach

  1. Restate the input: its shape, its size, and what is guaranteed about it.
  2. Name the brute-force solution and its complexity before improving on it.
  3. Choose the data structure from the access pattern, not from familiarity.
  4. State the target complexity and say which constraint rules the naive version out.

Follow-up

  • How does this change if the input no longer fits in memory?
  • What is the worst case, and how likely is it on real data?

Stop tag and share joins from fanning out a page

Medium · join fan-out · semi-joins · many-to-many

resource_tag is (resource_id, tag_id) with PK (resource_id, tag_id); resource_share is (resource_id, shared_with_user_id, permission). The tagged-and-shared listing inner-joins resource to both, filters tenant_id, tag_id = ANY($2) and shared_with_user_id = $3, orders by updated_at DESC and takes 50. Pages come back with fewer than 50 distinct resources and the total in the header is far too high. Explain the row multiplication, rewrite both the page query and the count query so each is correct, and name the index each one needs. PostgreSQL 16.

Approach

  1. Do the arithmetic against the predicates that are actually there. An inner join emits one row per matching child row, and both joins are filtered: tag_id = ANY($2) admits only the requested tags, shared_with_user_id = $3 admits one user's share rows. So a resource holding three of the requested tags and shared with $3 once yields three rows, not one — the multiplier is its count of matching tags times its share rows for that single user, and that second factor is 1 unless the table admits duplicate (resource_id, shared_with_user_id) pairs. LIMIT 50 then limits rows rather than resources, and COUNT(*) counts pairs — the header is the product, not the population.
  2. Reject DISTINCT as the fix. It deduplicates after the product has been built, so the planner must materialise and sort the fanned-out set before the LIMIT can apply, and it leaves any SUM or AVG in the same select list wrong.
  3. Rewrite both filters as semi-joins, keeping resource as the only row source: AND EXISTS (SELECT 1 FROM resource_tag rt WHERE rt.resource_id = r.resource_id AND rt.tag_id = ANY($2)) and the same shape against resource_share. A semi-join stops at the first match per resource and preserves the driving index order, so ORDER BY updated_at DESC, resource_id DESC LIMIT 50 still stops after 50 rows.
  4. Count with the same predicates and no join at all: SELECT count(*) FROM resource r WHERE r.tenant_id = $1 AND r.status = 'active' AND EXISTS (...) AND EXISTS (...). Nothing multiplies a resource, so the number is the population.

Follow-up

  • The filter changes from 'any of these tags' to 'all of these tags'. Rewrite it and state what it costs relative to the ANY form.
  • A resource can be shared with the same user twice under different permissions. Does your count change, and should it?

Keep soft-deleted accounts from blocking re-registration

Easy · soft delete · unique constraints · engine differences

app_user holds user_id, tenant_id, email CITEXT, password_hash (NULL for SSO principals), email_verified_at, auth_version, status ('invited','active','suspended','deactivated'), created_at, updated_at, deleted_at. Two live accounts for one address inside a tenant must be impossible, but an address freed by a soft delete must be reusable, and the same tenant may delete and re-register it repeatedly. Write the uniqueness DDL for PostgreSQL 16, then the equivalent for MySQL 8 where partial indexes do not exist, and say what each permits once three deleted rows already hold that address.

Approach

  1. Start from what is actually unique: not (tenant_id, email), but (tenant_id, email) among live rows. PostgreSQL says that directly — CREATE UNIQUE INDEX app_user_live_email ON app_user (tenant_id, email) WHERE deleted_at IS NULL. A full constraint over the same two columns burns the address permanently the first time someone deletes an account.
  2. Keep case-insensitivity in the type or the index, never in the application: CITEXT as given, or UNIQUE (tenant_id, lower(email)) as an expression index where the extension is unavailable. A case-sensitive unique column is exactly how two accounts for one human appear.
  3. For MySQL 8 the predicate has to move inside the key: add a discriminator column that is a constant 0 while the row is live and is set to user_id on delete, with UNIQUE (tenant_id, email, deleted_marker). Live rows share the constant and still collide; deleted rows differ from each other and stop colliding.
  4. State the NULL variant and its dependency: leaving the marker NULL for deleted rows also works, because a unique index treats NULLs as distinct — true in MySQL, and true in PostgreSQL only under the default NULLS DISTINCT, which PostgreSQL 15 lets you reverse. Check the polarity against the three existing deleted rows: constant-on-live is what preserves the collision you want, and reversing it silently admits duplicate live accounts.

Follow-up

  • A deleted account re-registers with the same address the next day. Do the old resource rows follow the new user_id, and how does the API keep the two principals apart?
  • How do you honour an erasure request while resource_revision.actor_user_id still references this table?

How would you design a robust software development kit (SDK) that allows third-party developers to control a t

Medium · Architecture & System Design

How would you design a robust software development kit (SDK) that allows third-party developers to control a thermal camera's settings and stream video?

Approach

  1. Fix the scope first: who calls this, how often, and what they do when it fails.
  2. Name the read and write paths separately; they rarely have the same bottleneck.
  3. Choose a partition key and say what query it makes expensive.
  4. State the consistency you need, and where you are willing to be stale.

Follow-up

  • What breaks first when traffic grows ten times?
  • How does this behave when that dependency is down for an hour?

Describe how you would implement a state machine to manage the calibration and startup sequences of an infrare

Medium · Architecture & System Design

Describe how you would implement a state machine to manage the calibration and startup sequences of an infrared sensor.

Approach

  1. Fix the scope first: who calls this, how often, and what they do when it fails.
  2. Name the read and write paths separately; they rarely have the same bottleneck.
  3. Choose a partition key and say what query it makes expensive.
  4. State the consistency you need, and where you are willing to be stale.

Follow-up

  • What breaks first when traffic grows ten times?
  • How does this behave when that dependency is down for an hour?

What design patterns would you use to build a cross-platform desktop application that interfaces with multiple

Medium · Architecture & System Design

What design patterns would you use to build a cross-platform desktop application that interfaces with multiple USB and Ethernet cameras?

Approach

  1. Fix the scope first: who calls this, how often, and what they do when it fails.
  2. Name the read and write paths separately; they rarely have the same bottleneck.
  3. Choose a partition key and say what query it makes expensive.
  4. State the consistency you need, and where you are willing to be stale.

Follow-up

  • What breaks first when traffic grows ten times?
  • How does this behave when that dependency is down for an hour?

How do you ensure backward compatibility when updating firmware or communication protocols on legacy hardware

Medium · Architecture & System Design

How do you ensure backward compatibility when updating firmware or communication protocols on legacy hardware devices?

Approach

  1. Fix the scope first: who calls this, how often, and what they do when it fails.
  2. Name the read and write paths separately; they rarely have the same bottleneck.
  3. Choose a partition key and say what query it makes expensive.
  4. State the consistency you need, and where you are willing to be stale.

Follow-up

  • What breaks first when traffic grows ten times?
  • How does this behave when that dependency is down for an hour?

Walk us through a complex technical project you owned from end to end, focusing on the architectural decisions

Medium · Behavioral & Project Presentation

Walk us through a complex technical project you owned from end to end, focusing on the architectural decisions you made and why.

Approach

  1. Fix the scope first: who calls this, how often, and what they do when it fails.
  2. Name the read and write paths separately; they rarely have the same bottleneck.
  3. Choose a partition key and say what query it makes expensive.
  4. State the consistency you need, and where you are willing to be stale.

Follow-up

  • What breaks first when traffic grows ten times?
  • How does this behave when that dependency is down for an hour?

Describe the process of debugging a memory leak or a segmentation fault in a C++ environment.

Medium · Technical & Low-Level Programming

Approach

  1. Establish what changed and when, before forming any theory.
  2. Pick a bisection that eliminates candidates whichever way it turns out.
  3. Check the instrumentation before believing the symptom.
  4. Separate the trigger from the cause; the deploy is rarely the bug.

Follow-up

  • What would you look at first, and what would it rule out?
  • How would you tell a cause from a coincidence here?

Suggested practice checklist

Built from the rounds and topics Teledyne Flir candidates report.

Day 1 — Map the Teledyne Flir loop

  • Write out the reported sequence: Phone Screen, Technical Rounds, Onsite Interview.
  • For each round, write one sentence on what it is judging, from the description above, and mark the one you are least ready for.

Deliverable: A one-page map of the 3 reported rounds, with the weakest marked.

Day 2 — Work Technical Communication (Presentations)

  • Spend the session on Technical Communication (Presentations), which Teledyne Flir candidates report being tested on.
  • Write one worked example in Technical Communication (Presentations) and time yourself on it.

Deliverable: One timed worked example in Technical Communication (Presentations).

Day 3 — Work Quality & Test Mindset

  • Spend the session on Quality & Test Mindset, which Teledyne Flir candidates report being tested on.
  • Write one worked example in Quality & Test Mindset and time yourself on it.

Deliverable: One timed worked example in Quality & Test Mindset.

Day 4 — Work Software Engineering Problem Solving

  • Spend the session on Software Engineering Problem Solving, which Teledyne Flir candidates report being tested on.
  • Write one worked example in Software Engineering Problem Solving and time yourself on it.

Deliverable: One timed worked example in Software Engineering Problem Solving.

Day 5 — Answer out loud: Technical & Low-Level Programming

  • Answer aloud, timed: Explain the difference between stack and heap memory allocation, and when you would use each in an embedded system.
  • Answer aloud, timed: How do you handle concurrency and prevent race conditions in a multi-threaded application?

Deliverable: Spoken answers to 2 reported Technical & Low-Level Programming question(s), under time.

Day 6 — Answer out loud: Architecture & System Design

  • Answer aloud, timed: How would you design a robust software development kit (SDK) that allows third-party developers to control a thermal camera's settings and stream video?
  • Answer aloud, timed: Describe how you would implement a state machine to manage the calibration and startup sequences of an infrared sensor.

Deliverable: Spoken answers to 2 reported Architecture & System Design question(s), under time.

Day 7 — Answer out loud: Behavioral & Project Presentation

  • Answer aloud, timed: Walk us through a complex technical project you owned from end to end, focusing on the architectural decisions you made and why.
  • Answer aloud, timed: Describe a time when you had to debug a challenging hardware-software integration issue. How did you isolate the problem, and how did you collaborate with the hardware team?

Deliverable: Spoken answers to 2 reported Behavioral & Project Presentation question(s), under time.

Behavioural preparation

Behavioural rounds judge the decision you made and what it cost.

Describe a time when you had to debug a challenging hardware-software integration issue. How did you isolate t

Medium · Behavioral & Project Presentation

Describe a time when you had to debug a challenging hardware-software integration issue. How did you isolate the problem, and how did you collaborate with the hardware team?

Approach

  1. Pick a story where you made the decision, not one where you watched it.
  2. State the situation in two sentences and spend the rest on the reasoning.
  3. Give the blast radius: what could have broken, and what you measured.
  4. Name the disagreement and how you resolved it with evidence.

Follow-up

  • What would you do differently if you ran that again?
  • How did you know your change caused the improvement?

How do you handle a situation where a project's requirements change mid-development cycle?

Medium · Behavioral & Project Presentation

Approach

  1. Pick a story where you made the decision, not one where you watched it.
  2. State the situation in two sentences and spend the rest on the reasoning.
  3. Give the blast radius: what could have broken, and what you measured.
  4. Name the disagreement and how you resolved it with evidence.

Follow-up

  • What would you do differently if you ran that again?
  • How did you know your change caused the improvement?

Tell me about a time you had to deliver a technical solution under a tight deadline with incomplete specificat

Medium · Behavioral & Project Presentation

Tell me about a time you had to deliver a technical solution under a tight deadline with incomplete specifications.

Approach

  1. Pick a story where you made the decision, not one where you watched it.
  2. State the situation in two sentences and spend the rest on the reasoning.
  3. Give the blast radius: what could have broken, and what you measured.
  4. Name the disagreement and how you resolved it with evidence.

Follow-up

  • What would you do differently if you ran that again?
  • How did you know your change caused the improvement?