Guide/Miniscope V4 Assembly
Overview
This guide covers bench assembly of the Miniscope V4 from a parts kit. Assembly takes approximately 1–2 hours per scope for a first-time builder; experienced builders average 30–45 minutes. Steps are sequential — do not skip ahead, and in group sessions, keep everyone at the same step.
The annotated exploded diagram below shows where each step occurs in the scope. Step numbers on the diagram correspond to the steps in this guide.
Parts and Tools
Optics
| Qty | Part | Spec | Notes |
|---|---|---|---|
| 2 | Achromat lens | 3 mm Ø, 6 mm FL | Objective module; curved side up |
| 1 | Achromat lens | 4 mm Ø, 10 mm FL | Emission module; curved side down |
| 1 | Half ball lens | 3 mm | Top of scope body |
| 1 | Dichroic mirror | T495LpXR | Coated side toward excitation light |
| 1 | Excitation filter | ET470 | Excitation module |
| 1 | Emission filter | ET525/50m | Emission module |
Hardware
| Qty | Part | Notes |
|---|---|---|
| — | M1 × 3 mm screws | McMaster-Carr only (outside the US — these are not reliably available elsewhere; order spares). Handle carefully — they get lost easily. |
| 1 | Objective module | — |
| 1 | Emission module | — |
| 1 | Excitation module | — |
| 1 | PCB assembly (EWL flex PCB + Python480 PCB) | Arrives with flex legs flat; must be folded before assembly |
| 1 | UV-cure epoxy | Norland 68 or equivalent |
| 1 | UV curing gun | — |
Tools
| Part | Notes |
|---|---|
| Precision screwdriver | ~$15 each; order extras — one per person if running a group session |
| Flat-tipped cotton swabs | Must be flat-tipped (not ear-cleaning type); wooden stick or toothpick works in a pinch and will not scratch lenses |
| Toothpicks | For UV epoxy application |
| Compressed air can | For clearing debris from threaded holes |
Assembly Steps
Step 1–3 — Objective module: thread holes and insert 3 mm achromat lenses
Step 1: Thread all screw holes before any assembly.
Before putting anything together, thread all screw holes in the objective module, emission module, and excitation module by screwing a screw in and then backing it out. This pre-taps the holes and makes assembly significantly easier at every subsequent step.
Steps 2–3: Insert the two 3 mm achromat lenses into the objective module.
Open lens packets carefully — lenses eject easily and tend to land on the floor.
Orientation: curved side faces UP (toward the image sensor / top of scope).
To check orientation before inserting:
- Hold the lens by its edge and look at the profile — one side curves outward, one is flat.
- Alternatively, set it flat on the bench. If it sits stably, flat side is down (correct). If it rocks, flip it.
To insert: place the lens over the opening, then press it flush using the flat end of a cotton swab or a similar tool. Do not drop it in — it must seat flat.
Repeat for the second 3 mm achromat. Same orientation (curved side up).
Step 4 — Emission module: insert 4 mm achromat lens
The 4 mm achromat (4 mm Ø, 10 mm FL) goes into the emission module, not the objective module.
Orientation: curved side faces DOWN (toward the brain/sample). Flat side faces up.
This is the opposite of the objective module lenses. A mnemonic: light traveling up from the brain hits the curved surface first.
Insert using the flat end of a cotton swab. Push until flush. A small protrusion is acceptable — this lens sits in infinity space and does not require precise axial positioning, only firm seating.
Step 5 — Emission module: insert dichroic mirror (T495LpXR)
This step requires care. An incorrectly oriented dichroic means the scope will not work.
How to identify the coated side:
Printed arrows on filters are not reliable — they may be absent on small filters, faded, or pointing in the wrong direction. Always use the visual method:
- Look at one face of the filter. If it appears metallic or highly reflective, that is the coated side.
- Flip it over. If you can see a colorful internal reflection (the room around you visible within the glass), that is the uncoated side.
Orientation in the emission module: coated side faces down (toward the brain/sample). The excitation light enters from below, and the coated side must intercept it.
Confirmation check: after placing the dichroic and closing the module, shine light from the top of the scope body — you should see blue reflected back. Looking through from the top should appear yellowish-green. If so, orientation is correct.
Step 6 — Excitation module: insert ET470 excitation filter
The excitation module is the detached side piece. Thread its two screw holes before inserting the filter (same reason as Step 1 — these holes are particularly small in some batches and benefit from threading).
Identifying the coated side: same visual method as Step 5. Smaller filters (like the ET470) often have no printed arrow — rely entirely on the coated-side visual check.
Orientation: coated side faces the LED (toward excitation light source). In the excitation module, the LED enters from one end — the coated surface should intercept incoming excitation light.
Step 7 — Insert 3 mm half ball lens
The half ball lens is stored in a small protective container (often an Eppendorf tube). Handle by the edges only.
This lens has one correct orientation. Confirm before inserting — the flat face and curved face are distinguishable by feel and by profile.
Insert into the designated opening in the scope body. It should seat without excessive force.
Steps 8–9 — Fold PCB flex legs and sandwich onto module assembly
The PCB ships with its flex legs lying flat. Before assembly:
Step 8 — Fold the flex legs: bring the gold contact pads (shiny strips) together so they face each other. The legs will spring back partially — a partial fold is sufficient. Do not crease all the way.
Step 9 — Sandwich PCB onto the module assembly: this is the most mechanically demanding step.
- Place the emission module upright.
- Hold the PCB with the bottom ring facing down.
- Bring the excitation module and emission module together while threading the PCB between them.
- Use pre-threaded screws as guides — insert one screw partially to hold position before tightening anything.
Do not tighten all screws simultaneously. Seat one screw first, check alignment, then seat the others.
Watch the flex leg loop: the loop of PCB flex should sit flush against the module body. If it disappears inside or kinks outward, re-thread it before tightening.
PCB lateral alignment: when tightening, hold the PCB in position to prevent it from rotating sideways as the screw seats. Check visually that the PCB sits straight before fully tightening.
Step 10 — Attach excitation module
Screw the excitation module onto the assembled body using two screws, one on each side.
Step 11 — Seal emission module with UV epoxy
- Gather: UV epoxy (Norland 68), toothpick, UV curing gun. All three must be in hand before opening.
- Remove the cover from the emission module.
- Place the emission filter (ET525/50m) in the correct orientation (coated side down — same visual check as Steps 5–6).
- Close the cover immediately. Hold it with your thumb on the objective and fingers on top — do not let go.
- Using the toothpick, apply a small amount of epoxy along 3 sides of the cover seam. Skip the PCB-adjacent side.
- Cure each side with the UV gun.
Three sealed sides is sufficient. The PCB side is left open intentionally.
Step 12 — Final PCB bending and cable attachment
Remove one of the two temporary assembly screws and bend the PCB into its final position along the body of the scope.
Connect the coax cable (quad cable). The cable connector can be soldered directly if the connector is removed first — use flux. This step is typically completed during the software setup session immediately following assembly.
Workshop Tips
These apply specifically to group assembly sessions (workshops with multiple builders).
| Tip | Reason |
|---|---|
| Keep everyone at the same step at all times | People who move ahead tend to make orientation errors that are difficult to diagnose later; the assembler running the session ends up troubleshooting while everyone else waits |
| One screwdriver per builder enforces pacing | Without this, some builders will pre-assemble future steps — usually incorrectly |
| Thread all holes before beginning (Step 1) before distributing any other parts | Modules vary batch to batch — some holes are tight. Better to discover this before the module is partially assembled |
| Never leave screws loose on the bench | They roll, fall, and disappear. Return every screw to its hole immediately after threading |
| Announce lens-opening steps as a group | Lenses fly. Having everyone open their packet at the same time means one person's lost lens can be quickly located |
| Mark assembled scopes immediately | Assembled scopes are visually identical. Use nail polish, a scratch mark, or any other physical ID before leaving the bench |
Sourcing Notes
| Component | Primary source | Notes |
|---|---|---|
| M1 × 3 mm screws | McMaster-Carr | Only reliably available source outside the US; validated for this application |
| Achromat lenses | Edmund Optics | Japan-sourced; ~$90 each for 3 mm achromats |
| Filters (ET470, ET525/50m, T495LpXR) | Chroma / AHF | Verify coated-side orientation regardless of batch |
| PCBs | Taiwan (fabricated) | Shipped through assembly house; not available separately through standard vendors |
| Module bodies | US (machined) | Shipped to assembly point; not available separately |