光傲——All For Light 以光电产品为核心业务的专业代理商、服务商

应用案例

通用光谱仪 & 多通道光谱仪

拉曼光谱仪

超光谱成像

激光超短脉冲压缩及展宽

外腔可调谐激光 External Cavity Laser Tuning

光学相干层析 / Optical Coherence Tomography

DWDM

通用光谱仪 & 多通道光谱仪

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Description
Spectroscopy is the analysis o f the energy distribution in the wavelengths emitted from an object. Spectroscopy de vices such as spectrometers and optical spectrum analyzers normally emplo y a diff raction grating to separate the wavelengths in the spectrum emitted by the object. Every photon collected is very important because the energy in the individual wavelength components of the emitted spectrum may be very weak. Furthermore , the emitted light may be randomly polarized. Therefore, high diffraction efficiency in both polarizations is necessary to provide maximum performance. Volume Phase Holographic Gratings (VPHGs) are ideally suited for spectroscopic applications because they are capable of providing high diffraction efficiency for unpolarized light.

Two generic spectrometer geometries are shown below using transmission gratings/grisms and not reflection gratings. Our staff has developed a variety of innovative designs to take advantage of VPHG high performance in transmission modes.

Spectrometer	In-Line Spectrometer Design

VPHGs for Spectroscopy
Description	Spatial Frequency	Bandwidth Or CWL¹	CWL¹ AOI/AOD²	S & P Diffraction Efficiencies
Dickson Grating: transmission	940 lpmm	1525-1565nm	46.5^o	>88%
Dickson Grism: reflection (2 passes)	940 lpmm	1525-1565nm	46.5^o	>77%
Grating: transmission	600 lpmm	1525-1565nm	27.6^o	>85%
Grism: reflection (2 passes)	600 lpmm	1525-1565nm	27.6^o	>73%
Grating: transmission	1200 lpmm	500nm	17.5^o
Grating: transmission	1200 lpmm	800nm	28.7^o
Dickson Grating: transmission	1364 lpmm	1064nm	46.5^o	>90%
Dickson Grating: transmission	1750 lpmm	830nm	46.5^o	>90%
Dickson Grating: transmission	1850 lpmm	785nm	46.5^o	>90%
Dickson Grating: transmission	2290 lpmm	633nm	46.5^o	>90%
Dickson Grating: transmission	2730 lpmm	532nm	46.5^o	>90%
Dickson Grating: transmission	2820 lpmm	514nm	46.5^o	>90%
Dickson Grating: transmission	2970 lpmm	488nm	46.5^o	>90%
Grating: transmission	474 lpmm
Grating: transmission	385 lpmm
Grating: transmission	315 lpmm
Grating: transmission	210 lpmm
Custom VPHG: Inquire	Specify	350-2500nm	Fill In Customer Grating Worksheet
1. CWL=center wavelength 2. AOI/AOD=angle of incidence/angle of diffraction

拉曼光谱仪

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Description
In Raman Spectroscopy, a specimen is illuminated with laser light and its corresponding spectrum analyzed. Ground-level vibrational and/or rotational energy changes in molecules caused by inelastic light scattering produce a characteristic molecular "fingerprint".

Raman Spectroscopy systems normally employ a diffraction grating. There are stringent grating requirements in Raman Spectroscopy because of the extremely weak spectral lines produced very close to the very strong laser illumination wavelengths. Each scattered photon counts and scattering polarizations are random. Therefore, high efficiencies in both polarizations along with minimal stray light are necessary and are best provided by volume phase holographic gratings.

We provide a high level of customer service. Additionally, we offer consulting, design, prototype, product integration, and quantity production at competitive prices.

超光谱成像

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HSI is normally represented as a image cube consisting of millions of elements; the spatial data is in the XY plane and the spectral data is in the Z-axis. An HSI first maps an image strip onto an X-Y row of pixels in a CCD camera. Each pixel in this row is simultaneously spread into a Z column of spectral data and then the frame is read. Next, the HSI scans to the next XY strip. This is repeated until a 2-dimensional spatial image is built up.

Description
HyperSpectral Imaging (HSI) is also known as imaging spectroscopy*. It is a passive, electro-optical, remote sensing technology that reveals hidden image information by collecting and examining spectral data. Typically this data is in the visible and near-IR with the UV rarely being used. Most natural and man-made materials contain characteristic or diagnostic absorption/reflectance features. Much of the useful data is not discernible to the human eye.

Defense

	Camouflaged and Stealth Target Detection (e.g. tanks in jungles, submarines underwater, mines)
	Target Ranging

Agriculture

	Mineral Identification
	Terrain/Geophysical Exploration
	Food Inspection/Crop Monitoring

Medical

	Burn Assessment
	Cancer Cell Detection
	Drug Screening/Testing

Many defense airborne and spaceborne reconnaissance systems already have shifted from single sensor systems to those using high spatial resolution. More medical and agriculture applications are developing.

Volume Phase Holographic Gratings provide high dispersions with very high efficiencies in both polarizations over very wide bandwidths. This is important because the number of photons may be limited and their polarizations are random. All gratings are made in hardened, baked, and environmentally stable dichromated gelatin (DCG). The gratings are sealed with glass on both sides resulting in a rugged, scratch resistant, easily handled product. They may be cleaned with soap and water.

Diffraction Efficiencies-Te(S) & Tm(P) Polarizations Best Performance Plots CWL (center or blaze wavelength) & Spatial Frequency
LD-220 lpmm, CWL=550nm, 400-700nm (>35%)	600 nm at 600 lpmm (hyperspectral)
LD-155 lpmm, CWL=1325nm, 950-1700nm (>35%)	633 nm at 600 lpmm (hyperspectral)
LD-125 lpmm, CWL=550nm, 400-700nm (>35%)	650 nm at 400 lpmm (hyperspectral)
LD-118 lpmm, CWL=550nm, 400-700nm (>35%)	1700 nm at 250 lpmm (hyperspectral)
These are just a few representative grating graphs. We can customize gratings for your specific needs.

*Terminology
Electro-Optic Sensors (field tested <1970): one wavelength band
Multispectral Imaging (field tested ~1989): 10 wavelength bands, each 100 nm wide
Hyperspectral Imaging (field tested ~1994): 100 wavelength bands, each 10 nm wide
Ultraspectral Imaging (field tested soon?): 1000 wavelength bands, each 1 nm wide

激光超短脉冲压缩及展宽

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Description
Highly effective compression and stretching of picosecond and femtosecond laser pulses can be accomplished by using matched pairs of Volume Phase Holographic Gratings (VPHGs) in transmission geometry. As shown in the figure below, compression and stretching is proportional to the distance between the parallel gratings. A mirror can be inserted to double the dispersion and/or two identical lenses can be placed two focal lengths apart for compression purposes.

Benefits

Diffraction efficiencies >90%, combined with angles up to 70 degrees for S (TE) polarization, produce high throughput, compact devices.

Example Graph Below of 1213 lpmm grating (70.1 degrees) for 1550nm

Energy Density Information

We are collecting energy density data from various pulsed laser companies. Energy density failure is a mostly a function of the glue/gelatin/glass assembly with the glue usually failing first by softening. Below is information typical of a successful medical pulsed laser application. Continuous wave (CW) energy densities of up to ~10 watts/cm^2 are fine; up to ~100 10 watts/cm^2 is possible with suitable epoxies..

Energy Density Measurements (approximate) from Customers 2 Piece Glass Construction: Grating Diagrams BK7 (2mm substrate + 2mm cover glass) and water white (1mm substrate + 1mm cover glass NOA 61 or NOA 63 Epoxy: thickness ~25-50 microns DCG Films: thicknesses vary from ~3-10 microns
Description	Application #1	Application #2	Application #3
Pulsed Laser Type	1054nm, S polarized	800nm, P polarized	530nm, P polarized
Grating Size	>25mm	>10mm	>10mm
Beam Diameter	5mm	3mm	1.5mm
Pulse Duration	500 fs	130 fs	<200 fs
Energy/pulse	30 microjoules	360 microjoules	7 microjoules
Repetition Rate	>10 KHz	1 KHz	1 KHz
Average Power (Energy/pulse X Repetition Rate )	>300 mW	>300 mW	>7 mW
Average Power Density (Average Power / Beam Area)	>1.5 Watts/cm2	>5 Watts/cm2	0.5 Watts/cm2
Peak Power ((Energy/pulse) / Pulse Duration)	6x10^7 Watts	3x10^9 Watts	>3x10^7 Watts
Peak Power Density (Peak Power / Beam Area)	3x10^8 Watts/cm2	4x10^10 Watts/cm2	2x10^9 Watts/cm2
Test Duration	In commercial use	1.5 hours with no failure	Preliminary

外腔可调谐激光 External Cavity Laser Tuning

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Description
External cavity diode and dye lasers can be spectrally tuned and made to operate in a single-mode. Light exiting from the laser cavity diverges, passes through a collimator, and is imaged on a grating. In Littrow and Littman configurations, the grating is positioned so that light of the correct wavelength is redirected back through the collimator and focused into the laser cavity. Gratings for single or dual polarizations can be produced.

Littman System Using VPH Transmission Gratings, S (TE) Maximized

Grating Enhanced External Cavity Laser Diode (GEECLD): Graphs & diagrams courtesy of Andreas Wicht, University of Dusseldorf

Benefits

Tunable Diffraction Efficiency (>90%): High diffraction efficiencies are helpful to detune the laser far away from gain maximum. Alternatively, to circumvent the gain maximum, especially at high currents, lower diffraction efficiencies are preferred.
Higher Spatial Frequencies (=> More Compact): In all Littman diode setups, transmission gratings allow the application of line densities which are about twice as large as for reflection gratings. This is because the first order is diffracted back into the laser diode, and not at ~90 degrees with respect to the incident beam.
Maximum Diffraction Efficiency: Higher efficiency than commercial reflection gratings.
Continuous Tuning Over A Wide Band


*Stock: Dual* Polarization VPH Transmission Gratings: AOI=AOD**
Description	Spatial Frequency	Center Wavelength	AOI/AOD at CWL	S & P Efficiencies
*Dickson®* Grating	940 lpmm	1550nm	46.8o	>90%
*Dickson®* Grating	1145 lpmm	1310nm	48.6o	>90%

Custom VPH Transmission Gratings: >90% Efficiencies Polarizations Maximized: Single or dual polarization gratings (including *Dickson®* Gratings) Symmetric or Non-Symmetric: Angle of Incidence (AOI) = Angle of Diffraction (AOD) or AOI ¹ AOD Frequencies: 400-4000 l/mm · Wavelength Ranges: 350nm-2500nm · Sizes: <5mm to >100mm Environmentally Rugged · Substrates: BK7, Fused Silica · Wavefront: <1/4 wave available Energy Density: Continuous Wave is 100 watts/cm2 with appropriate epoxy selection.

These VPHGs can be customized for almost any wavelength or spatial frequency, are environmentally rugged, and scratch resistant. Process Instruments uses of our volume phase holographic gratings for their diode laser systems.

We provide a high level of customer service. Additionally, we offer consulting, design, prototype, product integration, and quantity production at competitive prices.

光学相干层析 / Optical Coherence Tomography

阅读: 2356

DWDM

阅读: 2359

Description
Dickson® Gratings are advanced forms of VPH gratings. Many DWDM devices and subsystems vendors can utilize Volume Phase Holographic Gratings (VPHGs) for their dispersive optical platforms. These applications are shown by the green colored devices in the diagram below.

Dickson® and VPH Grating Benefits for DWDM Customers
	Dickson® Gratings	Surface Relief Gratings	Thin Film & Fiber Bragg	AWG
Hi-Channel Counts	Yes: 80+	Yes: 80+	No: < 32	Yes: up to 40
Cost/Channel	Very Low	Low	Higher	Low
Thermal Stability	A-Thermal	Maybe	A-Thermal	Requires Controls
Hi-Channel Performance	Low IL , Low PDL	Med. IL & PDL	NA	Higher IL & PDL
Channel Separation Method	Parallel	Parallel	Serial	Parallel
Footprint Size	Very Small	Very Small	Large	Small
Packaging Ease	Good	Good	Good	Medium
Integration Ease	Good	Good	Medium	Good
Agile Wavelength Tunability	Yes	No	No	No
Basic Technology >25 Years Old	Yes	Yes	Yes/No	No
Rugged, Scratch Resistant	Yes	No	Yes	Yes

DWDM systems transmit and receive multiple signals over a fiberoptic network. Each signal, containing separate data streams, is assigned to a different wavelength of laser light. This leverages the existing fiberoptic infrastructure by multiplying the amount of information that can be sent, thereby providing a migration path for telecom companies.

	DWDM Multiplexer (Mux): A transmitter that combines (multiplexes) many laser light signals of different wavelengths coming from individual glass fibers and inputs them into an optical fiber transmission line. This can also be performed through free space, without fiberoptic lines.
	DWDM Demultiplexer (DeMux): A receiver that separates (demultiplexes) many laser light signals of different wavelengths coming from an optical fiber transmission line and outputs them into individual glass fibers. This can also be performed through free space, without fiberoptic lines.
	Dynamic Gain Equalizer (DGE): DGEs correct the power imbalance in multiple channels, through user-selectable criteria, and without bit-stream interruption. To ensure low data-error rates, it is critical that all DWDM channels have approximately the same power level.
	Optical Channel Monitor (OCM): A spectrometer module for identifying DWDM channels along with measurements of wavelength, power, and OSNR (Optical Signal to Noise Ratio).
	Optical Add/Drop Multiplexer (OADM): A switching/routing device that adds and drops multiple wavelengths at various locations along an optical network.
	Reconfigurable Optical Add/Drop Multiplexer (R-OADM): A dynamically configurable switching/routing device that adds and drops multiple wavelengths at various locations along an optical network.

VPHGs Benefits

	Low Polarization Dependent Loss (PDL): over 40 nm C, S, or L Bands
	Low Insertion Loss (IL): over 40 nm C, S, or L Bands; reduced need for EDFAs
	Higher Channel Counts: high dispersion enables 40, 80, & 160 channels with close channel spacing (25, 50, & 100 GHz)
	Smaller Package: high dispersion enables small footprint
	Wider Usable Bandwidth: flat response allows increase in usable operating wavelength ranges

	Lower System Costs: extremely low pdl, low IL, a-thermal performance, and high dispersion produces a multiplicative reduction in overall cost. Reduces EDFAs, optical parts/surfaces, and maintenance
	Scalability: large quantities made quickly
	Ease of Integration:
	Technology Maturity: >25 years
	Environmental Stability: meets Telcordia GR-1221/1209 specs. Encapsulation provides a-thermal performance over -5 to 70^oC, scratch resistance, and easy handling

Diffraction Efficiencies-S (TE) & P (TM) Polarizations Best Performance Plots
Designs below are for 1525-1565 nm CWL (center or blaze wavelength) & Spatial Frequency
Dickson Gratings® highlighted in yellow
940 lpmm Dickson grating (transmission)	1550 nm at 600 lpmm (2-pass reflection)
940 lpmm Dickson grating Double Pass
940 lpmm (tunable for agile networks)	1550 nm at 600 lpmm (transmission)
940 lpmm (2-pass reflection)	1550 nm at 300 lpmm (2-pass reflection)
These are just a few representative grating graphs. We can customize gratings for your specific needs.

We provide a high level of customer service. Additionally, we offer consulting, design, prototype, product integration, and quantity production at competitive prices.

Dickson® 940 lpmm Grating: Dispersion = 3.14 degrees/40 nm