Calculations

How to Calculate Laser, Optics, and Photonics Manufacturing Metrics

Work through the core formulas for laser cutting, optics polishing, alignment, and photonics test with real units and fully worked numbers.

Start with laser cut time, the input that feeds almost everything downstream. Cut time in seconds equals total cut length divided by feed rate, plus pierce time per hole. A 1.5 mm 304 stainless sheet at 4000 W runs roughly 2800 mm per minute, so 6000 mm of contour is 6000 / 2800 = 2.14 min, or 128 s. Add 12 pierces at 0.4 s each, 4.8 s. Total 133 s per part. Feed rate comes from the machine cut chart for that thickness, gas, and nozzle, never from the rapid-traverse spec. The Laser Process Cost calculator uses this cut time as its primary machine-time driver.

Laser cutting yield is the fraction of good parts leaving the machine. Yield equals good parts divided by total parts started, so 940 good out of 1000 nested blanks is 94.0 percent. First-pass yield strips reworked parts from the numerator: if 22 of those 940 needed edge dressing, first-pass is 918 / 1000 = 91.8 percent. Track dross, burr, and heat-affected-zone rejects separately because each has a different fix. The Laser Cutting Yield calculator wants total started and each reject category, not just a single scrap percentage, so log rejects by defect code at the machine.

Optics polishing time scales with the material removal you need and the removal rate of your process. Time in minutes equals stock removal in micrometers divided by removal rate in micrometers per minute. Grinding a BK7 flat that needs 8 um removed at a pitch-lap rate of 0.15 um per minute is 8 / 0.15 = 53 min per side. Removal rate follows Preston's relation, proportional to pressure times relative velocity times the Preston coefficient, so doubling lap RPM roughly doubles rate but also risks subsurface damage. The Optics Polishing Time calculator lets you enter removal target and rate per operation rather than guessing a flat number.

Optical alignment workload converts alignment complexity into labor minutes. Estimate it as degrees of freedom times iterations times minutes per iteration, plus a fixed setup. A fiber-to-chip coupling with 5 axes, 4 tuning iterations, and 3 minutes per iteration is 5 x 4 x 3 = 60 min, plus 15 min setup, so 75 min per unit. Active alignment to sub-micron tolerance can push minutes per iteration to 8 or more. Feed this into the Optical Alignment Workload calculator to size a build; it separates first-light acquisition from fine peaking, which have very different iteration counts.

Photonics test time is the sum of every measurement dwell plus handling. Test time equals sum of test-step durations plus load and unload time. A transceiver run with insertion-loss sweep at 45 s, return-loss at 20 s, thermal soak at 90 s, and 25 s handling totals 180 s per unit. Parallelism matters: testing 4 devices at once on a shared instrument divides the shared steps but not the per-device handling. The Photonics Test Time calculator models serial versus parallel steps so you do not overstate throughput by assuming everything runs concurrently.

Laser energy per part ties the beam to your utility bill in physical terms. Energy in kilowatt-hours equals laser output power divided by wall-plug efficiency, times beam-on time in hours. A 4000 W laser at 40 percent efficiency draws 10 kW from the wall; running 133 s (0.037 h) per part uses 10 x 0.037 = 0.37 kWh. Add chiller and motion loads, typically 30 to 60 percent on top, so budget near 0.55 kWh per part. The Laser Energy Cost calculator asks for rated power, efficiency, and beam-on time separately so idle and cutting states are not blended.

Chain these together for a full unit model. For 1000 laser-cut optic mounts: cut time 133 s each gives 37.0 machine-hours; at 94 percent yield you start 1064 blanks to ship 1000. Polishing at 53 min per side for two sides is 106 min per lens, and alignment adds 75 min per assembly. Always carry units explicitly, seconds to hours by dividing by 3600, micrometers to millimeters by dividing by 1000, because a single unit slip in removal rate or feed rate throws the whole build estimate off by an order of magnitude.

Validate each formula against a measured sample before trusting it at volume. Run 20 real parts, record actual cut, polish, alignment, and test times with a stopwatch, and compare to calculated values. If measured polishing runs 62 min against a predicted 53, your removal rate is 0.13 um per minute, not 0.15, so correct the input rather than padding the answer. Re-derive removal rate, feed rate, and iteration counts from your own floor data every quarter; vendor charts assume ideal consumables and drift as laps glaze and nozzles wear.

Published 2026-07-01.