Beyond the Dichroic vs. Notch Filter Debate
The industry conversation often centers on cost-driven compromises—replacing notch filters with dichroic mirrors, trading performance for affordability. But the reality is more nuanced. At OPTOStokes, we engineer solutions that transcend this false dichotomy.
Notch Filters: Precision at a Premium
Notch filters remain the gold standard for maximum flexibility. Using 50+ alternating dielectric layers deposited via ion beam sputtering (IBS), they achieve:
- OD6+ blocking at exact laser lines (e.g., 785nm ±0.5nm)
- <8nm edge transitionspreserving anti-Stokes peaks
- Angle-insensitive designs for compact handheld systems
The Cost Factor: The IBS process requires nanometer-level precision, increasing production time by 10-20× versus simpler coatings. This is why they're typically reserved for research-grade systems.
Modern Dichroics: The Overlooked Evolution
Advanced dichroic filters have closed the performance gap significantly. OPTOStokes' stock dichroic series delivers:
- OD5-6 laser rejection (surpassing legacy OD4-5 designs)
- >90% transmission starting 15cm⁻¹ above laser line
- Mechanical durability resistant to thermal shift
The Tradeoff: Broader transition bands (~15-20nm) may obscure anti-Stokes signals—a non-issue for 95% of industrial Raman applications.
OPTOStokes' TriPath Solution
Your application dictates the optimal path:
| Solution | Best For | Tech Specs | Lead Time |
|---|---|---|---|
| Stock Dichroics | Material ID, QC Systems | OD5-6, 810nm LP | 24hrs |
| Hybrid Filters | Pharma, Semiconductors | OD6, 10nm transition | 2-3 weeks |
| Custom Notch | anti-Stokes, Low-frequency Raman | OD7+,<5nm transition | 4-6 weeks |
Engineering Note: Our hybrid filters utilizegraded refractive index layersto achieve dichroic-like costs with near-notch performance. (Patent pending)
The Instrument Designer's Verdict
The choice between filter types isn't about cutting corners—it's about aligning optical engineering with real-world applications. When you collaborate with OPTOStokes, you gain:
- Data-Driven Selection: Send sample spectra to sales@optofilters.com for filter performance simulation
- Risk-Free Prototyping: Test filters in your system with 30-day evaluation terms
- Legacy Support: Still using PMTs or HeNe lasers? We optimize filters for classic configurations
OPTOStokes: Where cost control and uncompromised performance converge.
