4 SphericalSinglets 697-709.qxd.P
7/17/07
9:45 AM
Page 706
Optics
Optical Systems
Free Space Isolators
E-O Devices
Spherical Singlets
Multi-Element
Lenses
Cylindrical Lenses
Aspheric Lenses
Mirrors
Diffusers
& Lens Arrays
Windows
Teflon Plano-Convex Lenses
- THz Transmission
Plastic lenses can be used for THz radiation. Polytetrafluoroethylene (PTFE,
Teflon™) is a rather commonly used material for THz applications; it has a low
dielectric constant, about 1.96 @ 520GHz, which corresponds to an index of
refraction of 1.4. The low dielectric constant creates a reasonably low insertion loss.
PTFE is usable for frequencies up to 2THz (roughly). See page 578 for our THz
Transmitter and Receiver.
Specifications
■
■
■
■
■
■
■
Material: Teflon, Dielectric Constant = 1.96 at 520GHz
Design Frequency: 500GHz (n = 1.4)
Surface Irregularity: 10µm, Corresponding to λ/20 at 1.5THz
Dia. Tolerance: +0.00/-0.20mm
Scratch-Dig: 60-40
Centration: 3arcmin
Clear Aperture: >85% of Diameter
Prisms
PLANO-CONVEX
Gratings
Polarization Optics
f
Beamsplitters
Redrawn from C. Winnewisser, F. Lewen, H. Helm, “Transmission
characteristics of dichroic filters measured by THz time-domain spectroscopy,”
Appl. Phys. A 66, 593-598 (1998).
Filters
& Attenuators
Gas Cells
Plano-Convex Lenses: Teflon
ITEM #
DIA
f
@500GHz
LAT100
LAT300
LAT500
50mm
50mm
50mm
100mm
300mm
500mm
PRICE
£
€
£ 19.00
£ 19.00
£ 19.00
€ 28,10
€ 28,10
€ 28,10
$
$
$
$
30.20
30.20
30.20
RMB
¥
¥
¥
288.40
288.40
288.40
R
(mm)
tc
(mm)
te1
(mm)
fb
(mm)
SUGGESTED
MOUNT2
40
120
200
12.8
7.6
6.6
5.0
5.0
5.0
95
295
495
LMR2
1) Edge thickness given before 0.2mm at 45° typical chamfer. 2) See the Lens Mount Section, Starting on Page 153.
High-Resistivity Silicon Lenses
High-resitivity silicon lenses transmit more than 50% of terahertz radiation in the 501000µm spectral region when the lens thickness is less than 0.5mm. As can be seen from
the plot, HRFZ-Si has superior transmission properties due to its high resistance and lack
of absorption lines in this spectral region. Each Ø50.8mm lens offered here has a meniscus
shape, which performs nearly as well as a best form lens.
Specifications
■
■
■
■
■
■
■
■
Material: High Resistivity Float Zone
Silicon (HRFZ-Si)
Resitivity: >10kΩ/cm
Refractive Index:
λ→ ∞ : n=3.416
λ=9µm: n=3.4232
Transmission (Thickness = 0.5mm):
>51% for 50µm ≤ λ ≤ 1000µm
Diameter: 50.8 ± 0.1mm
Center Thickness: 0.276 ± 0.1mm
Scratch-Dig: 80-50
Clear Aperture: >90%
Design Wavelength:
300µm (n = 3.4180)
Silicon Transmission
16-1000µm, Thickness = 0.05mm
60
R1
40
A
(50.8mm)
Ø2.00"
R2
SECTION A-A
30
20
Fused Si
n-type, 10 Ω-cm
10
0
200
400
600
800
1000
Wavelength (µm)
706
(7.0mm)
0.28"
High Resistivity Si
0
ITEM #
A
50
Transmission, %
■
€
R1(mm)
LAHR2050
50.23
77.27
LAHR2075
73.45
115.08
LAHR2100
95.94
151.01
LAHR2150
143.22
228.00
LAHR2200
187.50
297.90
$
£
LAHR2050
$ 660.00
£ 415.80
€
613,80
¥
6,303.00
LAHR2075
$ 540.00
£ 340.20
€
502,20
¥
5,157.00
High-Resistivity Lens, 75mm EFL, Ø50.8mm
LAHR2100
$ 460.00
£ 289.80
€
427,80
¥
4,393.00
High-Resistivity Lens, 100mm EFL, Ø50.8mm
LAHR2150
$ 410.00
£ 258.30
€
381,30
¥
3,915.50
High-Resistivity Lens, 150mm EFL, Ø50.8mm
LAHR2200
$ 360.00
£ 226.80
€
334,80
¥
3,438.00
High-Resistivity Lens, 200mm EFL, Ø50.8mm
www.thorlabs.com
RMB
ITEM #
DESCRIPTION
High-Resistivity Lens, 50mm EFL, Ø50.8mm
R2(mm)